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Results of a one-year prospective clinical trial (CONTROL) of the use of bifocal soft contact lenses to control myopia progression
Abstract
Objectives: CONTROL is a one-year prospective, randomized and double-masked clinical trial comparing the myopia progression of children with near eso fixation disparities when wearing bifocal soft contact lenses (BSCL) vs. single vision soft contact lenses (SVSCL).
Methods: Multi-zone simultaneous vision BSCL and SVSCL were randomly assigned to children aged 8-18 years; groups were matched for age, sex, ethnicity and degree of associated esophoria (BSCL, n=38, SVSCL, n=40). Masking was aided by the choice of lenses; both were 58% water, two-week disposable lenses, identical in appearance and supplied in masked packaging. Distance corrections generally matched subjective spherical equivalent refractions (SER) and bifocal additions were selected to maximally reduce near associated esophorias, while still maintaining clear distance vision. Baseline refractive error, binocular vision and biometric data were collected, with most measurements repeated after 6 and 12 months of lens wear. Data include cycloplegic subjective as well as objective refractions (with Nidek ARK 700A refractometer) and axial lengths (with Zeiss IOLMaster).
Results: Baseline cycloplegic subjective SERs at baseline for the BSCL and SVSCL groups, averaged across right and left eyes, were -2.76 1.37 and -3.01 1.44D respectively (mean SD), changing across the 12-months study period by –0.10 0.36 and –0.75 0.50D. Equivalent changes in cycloplegic objective SERs were similar, i.e. -0.22 0.34 vs. -0.78 0.45D for BSCL and SVSCL groups. Axial lengths increased by 0.05 0.14 and 0.24 0.17 mm for the BSCL and SVSCL groups respectively. All intergroup differences in the changes across the study period are highly significant (t-test).
Conclusions: Bifocal soft contact lenses significantly reduce myopia progression relative to the changes seen with single vision soft contact lens wear. Whether their inhibitory effect on myopia progression persists beyond the first year of wear and/or is restricted to those with associated esophoria at near remains to be established.
... The effect of concentric ring bifocal soft CLs is probably a little bit more intense than in MFSCLs (339). So, bifocal or multifocal CLs have proven effective for myopia management (4,114,115,117,325,326,379,380). A MFSCL for myopia management shall provide: ...
... Research on lens design found center-distance multifocal designs with two distinct portions within the optical zone to be effective for myopia management. They need a central part for distance correction and an outer part that has to be relatively more positively powered than the central zone (4,114,115,117,379,380). The theory of peripheral defocus says that this positive power in the periphery induces myopic defocus across the non-central retina (115,379). ...
... They need a central part for distance correction and an outer part that has to be relatively more positively powered than the central zone (4,114,115,117,379,380). The theory of peripheral defocus says that this positive power in the periphery induces myopic defocus across the non-central retina (115,379). ...
The increasing prevalence of myopia throughout the industrialized world in recent decades has caused costs and problems for the eye health. Changed lifestyle and behavior are the main causes. For the pathogenesis of myopia, the amount of time spent outdoor and near activities play an important role. Various options for the treatment of myopia have been described as effective in the literature. Normal single vision glasses and contact lenses can only provide clear vision, but do not reduce myopia progression. Orthokeratology shows a slowing of axial growth, but has an increased risk of infectious keratitis. Low-dose atropine (0.01%) is currently the best pharmacological option. It proved safe, effective and showed the least rebound effect with negligible side effects. Other options for the treatment of myopia include special glasses, behavioral changes and prolonged outdoor exposure (to prevent the onset of myopia), as well as other methods. An increasingly important myopia management option is multifocal contact lenses, that provide a peripheral treatment zone producing myopic defocus. Such myopia control lenses are available as customized or as daily or monthly lenses. Children benefit from wearing contact lenses more than just having refractive error correction and myopia control, they have a better self-esteem and improved quality of life. The numerous findings on the safety and efficacy of soft multifocal distance center contact lenses in children to reduce the progression of myopia suggest that this modality should be considered as a main treatment option. Less, but similar to orthokeratology, when wearing soft lenses there is a risk of developing potentially serious complications such as microbial keratitis. The introduction of child-appropriate risk minimization strategies, and patient and parent education with regular monitoring is essential and leads to successful contact lens wear. This literature review summarized the actual knowledge about myopia management, prevalence, etiology and the visual and healthy consequences of myopia. The three currently most important strategies for slowing the progression of myopia are soft multifocal distance center contact lenses, Orthokeratology and low-dose atropine ophthalmic drops.
... The relatively positive power region (plus power) is intended to reduce the hyperopic defocus and/or induce myopic defocus. 22, [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] The position of this region on the lens can vary. For example, to reduce accommodative lag, the plus power is positioned such that the wearer is required to look through the plus zone while viewing near distances. ...
... Contact lenses for myopia control are multifocal or specially designed multifocal-like lenses, having an optical zone with a central portion that corrects for the distance refractive error and 1 or more peripheral portions of relatively positive power (plus power). As described previously, the plus power was intended to reduce peripheral defocus or induce myopic defocus and commonly incorporated as rings, 56,59,61,66 steps, 48 or gradually rising power. [55][56][57]62 An exception is the extended depth of focus (EDOF) contact lens that features a nonmonotonic power profile (ie, both relatively positive and negative zones feature in relation to the mean power and the power profile designed to degrade the image quality for points behind retina to prevent axial elongation). ...
... As described previously, the plus power was intended to reduce peripheral defocus or induce myopic defocus and commonly incorporated as rings, 56,59,61,66 steps, 48 or gradually rising power. [55][56][57]62 An exception is the extended depth of focus (EDOF) contact lens that features a nonmonotonic power profile (ie, both relatively positive and negative zones feature in relation to the mean power and the power profile designed to degrade the image quality for points behind retina to prevent axial elongation). 58 The treatment effect with contact lenses varied from 20% to 70% for spherical equivalent and 27% to 79% for axial length. ...
The burden associated with the rising prevalence of myopia and high myopia, and the associated vision impairment and sight-threatening complications, has triggered the need to evaluate strategies to control the progression of myopia. We provide an overview of the literature on the use of optical (spectacles, contact lenses, and orthokeratology) and pharmaceutical approaches to slow progress of myopia. The evidence indicates that myopia progression can be slowed by varying degrees using these strategies. All approaches play a role in the management of myopia as needs and requirements of an individual vary based on age, suitability, affordability, safety of the approach, subjective needs of the individual, and rate of progression. This review also identifies and discusses the lack of long-term efficacy data and rebound on discontinuation of myopia control products.
... Thus it is plausible that correction of such lags [23][24][25][26] contribute to the reported myopia control effects of multifocal (MF) spectacles and contact lenses [26][27][28]. As subjects with near esophorias or fixation disparities tend to exhibit increased accommodative lags, the larger myopia control effects of MF optical corrections in such patients are also as predicted [26,[28][29][30]. Improvements in accommodation performance, i.e., reduced lags, have also been reported with orthokeratology [31], lending further support to the notion that reduction or elimination of accommodative lags contributes to the myopia control effects of such treatments. ...
... The underlying premise is that by manipulating the defocus experience of the peripheral retina, one can either neutralise the optical defocus stimulus for excessive axial length elongation, i.e., by correcting peripheral (off-axis) hyperopia, or reverse it by imposing myopic defocus, thereby inhibiting eye growth. Thus peripheral myopic defocus is believed to contribute to the reduced myopia progression reported with orthokeratology [12,[37][38][39], and also that of MFSCLs designed with a distance centre and near add periphery [9][10][11]27,29,30]. ...
... MFSCLs with distance centre and near add periphery designs are being increasingly used for myopia control yet many of the lenses in current use were originally designed as presbyopic corrections. While it is commonly assumed that related changes in the defocus experience of the peripheral retina is responsible for the reduced myopia progression reported with such lenses, [9][10][11]27] reductions in on-axis errors related to altered binocular vision/accommodation function may also contribute to these myopia control effects [23,29,30]. Either way, tolerance of the lenses is critical to good compliance. ...
Purpose:
To characterise the effects on accommodation and binocular vision in young adults of 2 distance centre multifocal soft contact lenses (MFSCLs), differing in add power.
Methods:
Twenty-four young adult myopes (18-28 years; 20 females, 4 males) had baseline visual acuity, accommodation, near phoria, fixation disparity and stereopsis data collected with single vision (SV) SCLs. The same set of measurements was repeated immediately after subjects were fitted with each of two MFSCLs (with either +1.50 or +3.00 D add), and after 2 weeks of daily wear in each case. The order of testing was randomised and a one-week washout period was allowed between the first and second MFSCL trials.
Results:
Differences in distance and near acuities with MFSCLs compared to SVSCLs were small and clinically insignificant. Compared to responses with SVSCLs, MFSCLs increased accommodative lags with this change reaching statistical significance for the +1.50 D add lens. Furthermore, both MFSCLs induced significant shifts in near phorias in the exo direction. Finally, there were no significant differences in stereopsis and fixation disparity with MFSCLs compared to SVSCLs.
Conclusion:
Differences in acuities, accommodation accuracy and binocular posture with MFSCLs compared to SVSCLs were clinically small and mostly not significant. These results predict good tolerance of MFSCLs in young patients fitted with them for myopia control.
... Bifocal soft contact lenses (SCLs) designed to induce myopic defocus at the peripheral visual fields have been tested to slow down myopia progression. [26][27][28][29] In addition to correcting foveal refractive error, one or more concentric add power zones were designed to provide myopic shift in peripheral refractive error. The other design goal of these lenses was to reduce accommodative lag by extending depth of focus (DoF) at fovea, reducing accommodation demand. ...
... A 1-year clinical trial found a reduction of 71% in refraction development of myopic endophoric patients with Acuvue bifocal SCL. 27 In another clinical trial in which DF lens and single vision lenses were randomly assigned to each of the two eyes in myopic children, DF lens showed 36% less myopic refractive error development in 10 months period. 26 Multifocal SCLs Proclear â also showed a 50% control effect compared with single vision contact lenses in a 2-year trial. ...
Purpose
To characterise the impact of monofocal soft contact lens (SCL) and bifocal SCLs on refractive error, depth of focus (DoF) and orientation of blur in the peripheral visual field.
Methods
Monofocal and two bifocal SCLs, Acuvue Bifocal (AVB, Johnson & Johnson) and Misight Dual Focus (DF, CooperVision) with +2.0 D add power were modelled using a ray tracing program (ZEMAX) based on their power maps. These SCLs were placed onto the anterior corneal surface of the simulated Atchison myopic eye model to correct for −3.0 D spherical refractive error at the fovea. To quantify through‐focus retinal image quality, defocus from −3.5 D to 1.5 D in 0.5 D steps was induced at each horizontal eccentricity from 0 to 40° in 10° steps. Wavefront aberrations were computed for each visual eccentricity and defocus. The retinal images were simulated using a custom software program developed in Matlab (The MathWorks) by convolving the point spread function calculated from the aberration with a reference image. The convolved images were spatially filtered to match the spatial resolution limit of each peripheral eccentricity. Retinal image quality was then quantified by the 2‐D cross‐correlation between the filtered convolved retinal images and the reference image. Peripheral defocus, DoF and orientation of blur were also estimated.
Results
In comparison with the monofocal SCL, the bifocal SCLs degraded retinal image quality while DoF was increased at fovea. From 10 to 20°, a relatively small amount of myopic shift (less than 0.3 D) was induced by bifocal SCLs compared with monofocal. DoF was also increased with bifocal SCLs at peripheral vision of 10 and 20°. The trend of myopic shift became less consistent at larger eccentricity, where at 30° DF showed a 0.75 D myopic shift while AVB showed a 0.2 D hyperopic shift and both AVB and DF exhibited large relative hyperopic defocus at 40°. The anisotropy in orientation of blur was found to increase and change its direction through focus beyond central vision. This trend was found to be less dominant with bifocal SCLs compared to monofocal SCL.
Conclusions
Bifocal SCLs have a relatively small impact on myopic shift in peripheral refractive error while DoF is increased significantly. We hypothetically suggest that a mechanism underlying myopia control with these bifocal or multifocal contact lenses is an increase in DoF and a decrease in anisotropy of peripheral optical blur.
... Owing to the severity of ocular complications associated with high myopia, tremendous efforts have been put into the investigation of interventions that may retard the progression of myopia in children, thus decreasing the severity of myopia at maturity. [10][11][12][13] It has been consistently demonstrated in various animal models including primates that optical interventions have a strong impact on refractive error development. 12,14,15 OrthoK, among other novel contact lens designs being investigated, has been shown in multiple clinical studies as effective in slowing down myopic progression. ...
... 2,3,96,101 Mid-peripheral corneal thickening and steepening has been postulated as the main "myopia-controlling" stimulus, as it imposes significant myopic shift on peripheral retinal defocus, which has been considered as a potent myopia-inhibiting signal. [7][8][9][10][11][12][13][14][15] The overall magnitude of midperipheral corneal thickening and steepening has been reported to correlate with the level of baseline (pretreated) myopia hence corresponding central thinning and flattening induced by the treatment; however, more recent reverse geometry designs have been attempted on inducing more significant mid-peripheral steepening, that is, independent of central thinning and flattening (Personal communication with proprietary lens designers, Patrick Caroline, 2014). ...
Objectives: The aim of this review is to evaluate the ocular safety of orthokeratology (OrthoK) treatment of myopia correction and retardation. Data Sources: Clinical studies published in English and Chinese were identified from MEDLINE, EMBASE CNKI, CQVIP, and WANFANG DATA (all from 1980 to April 2015). The reference lists of the studies and the Science Citation Index were also searched. Selection Criteria: Relevant clinical studies including case series, case reports, patient/practitioner surveys, retrospective and prospective cohort studies, and clinical trials were all included in the review. The material of OrthoK lenses was limited to gas-permeable lens. Main Results: This review incorporated a total of 170 publications, including 58 English and 112 Chinese literature. The risk of microbial keratitis in overnight OrthoK was similar to that of other overnight modality. The most common complication was corneal staining. Other clinically insignificant side effects included epithelial iron deposit, prominent fribrillary lines, and transient changes of corneal biomechanical properties. There was no long-term effect of OrthoK on corneal endothelium. Conclusions: There is sufficient evidence to suggest that OrthoK is a safe option for myopia correction and retardation. Long-term success of OrthoK treatment requires a combination of proper lens fitting, rigorous compliance to lens care regimen, good adherence to routine follow-ups, and timely treatment of complications.
... They were also the stimulus for our industry-sponsored collaborative controlled clinical study using distance center soft contact lenses (CONTROL), the data from which have never been authorized for release in full by the sponsoring company although a related published abstract has attracted much attention. 12 Nonetheless, the publication of this abstract and a follow-up identical twin case report may have helped to stimulate the on-going, related research investments by many contact lens companies. Indeed, since our randomized clinical trial of bifocal soft contact lenses demonstrated almost 90% less progression as compared with single vision contact lenses, two new soft contact lenses have emerged -a 5-zone dual power MySight design from New Zealand 10,13 and another based on the Fresnel design from Hong Kong. ...
... 14 In considering the role of soft bifocal and multi-zonal contact lenses in myopia management, it is important to recognize the significant variability in outcomes in published studies, 10,13-16 with reports of up to 50% 14 control of myopia progression -all less impressive than the results of the authors' unpublished CONTROL study. 12 Plausible explanations rest with differences in study designs, including the decision to restrict our CONTROL study to myopes with near associated esophoria and to customize "adds" to correct near eso fixation disparities. The former decision was based on published evidence of effective control for this group with bifocal and multifocal spectacle lenses. ...
This article presents a clinical perspective on recent myopia research related to the development and testing of optical treatments for controlling myopia progression. The perspective is from that of a clinician in private practice and a clinician researcher, both with long-term involvement in myopia management and research.
... These however do not appear to have strong effects in controlling underlying myopia progression. In addition, spectacles or contact lenses with defocus designs can slow myopia progression with a significant but smaller effect compared to atropine or orthokeratology [22][23][24][25] , although a recently published single-center clinical trial demonstrated reduced axial elongation by as much as 62% using defocus incorporated multiple segments (DIMS) spectacles [26] . These treatment modalities may represent alternatives for individuals who are unable to tolerate atropine or fail to fit orthokeratology. ...
Myopia has become a major visual disorder among school-aged children in East Asia due to its rising prevalence over the past few decades and will continue to be a leading health issue with an annual incidence as high as 20%-30%. Although various interventions have been proposed for myopia control, consensus in treatment strategies has yet to be fully developed. Atropine and orthokeratology stand out for their effectiveness in myopia progression control, but children with rapid progression of myopia require treatment with higher concentrations of atropine that are associated with increased rates of side effects, or with orthokeratology that carries risk of significant complication. Therefore, improved risk assessment for myopia onset and progression in children is critical in clinical decision-making. Besides traditional prediction models based on genetic effects and environmental exposures within populations, individualized prediction using machine learning and data based on age-specific refraction is promising. Although emerging treatments for myopia are promising and some have been incorporated into clinical practice, identifying populations who require and benefit from intervention remains the most important initial step for clinical practice.
... The first publications investigating multifocal soft contact lenses for myopia control employed designs originally designed for presbyopia. An abstract [556] and a twin study case report [557] investigated a commercially available multi-zone simultaneous vision design, being distance centred with alternating near and distance zones. The results indicated a halting of myopia progression in the twin case report and a reduction of progression by around 2/3rds in the abstract of a one-year randomised clinical trial. ...
This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia).
However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation.
In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.
... [7][8][9][10][11] Pharmacologic therapies using pirenzepine or atropine at varying doses have been attempted. [12][13][14][15] Optical treatments include orthokeratology, 16,17 peripheral defocus modifying contact lenses, 18 peripheral defocus modifying spectacle lenses, bifocal spectacle lenses, 19 progressive addition spectacle lenses, contact lens, prismatic bifocal spectacle lenses, and rigid gas-permeable contact lenses. 20 showed some effect on myopic progression, lowdose atropine is currently the most effective treatment available. ...
Purpose:
To compare the progression of myopia in eyes that underwent unilateral refractive surgery with non-operated eyes.
Methods:
Three patients who underwent refractive myopic correction in one eye are described. The collected preoperative and postoperative data included age, gender, subjective refraction, best corrected visual acuity, and uncorrected visual acuity.
Results:
The first patient (19-year-old woman) had photorefractive keratectomy in her left eye and the myopic progression was 1.20 diopters (D) (3 years postoperatively) compared to -2.50 D in her non-operated eye. The second patient (30-year-old man) had laser-assisted in situ keratomileusis in his left eye with a myopic progression of 0.25 D compared to 0.75 D in his non-operated eye (10 years postoperatively). The third patient (22-year-old man) underwent photorefractive keratectomy in his right eye with no myopic progression compared to -1.50 D in his non-operated eye (3 years postoperatively).
Conclusions:
These three cases suggest that refractive surgery for myopia correction may be associated with a slower progression of myopia postoperatively. [J Pediatr Ophthalmol Strabismus. 2019;56(2):78-82.].
... Multifocal contact lenses are available in several different formats, and although principally designed for correction of presbyopia, simultaneous designs and aspheric designs were shown to be influential in slowing progression of myopia. [18][19][20][21][22] BIOSENSORS Development of contact lens sensors presents a noninvasive alternative for detection and management of various diseases. Recent work [23][24][25][26][27] has resulted in commercialization of a device to monitor intraocular pressure (IOP) for up to 24 hours in patients with glaucoma, and extensive efforts are underway to develop a contact lens sensor that is capable of continuously monitoring glucose levels in the tear film for management of diabetes. ...
Contact lenses have been a common means of vision correction for more than half a century. Recent developments have raised the possibility that the next few decades will see a considerable broadening of the range of applications for contact lenses, with associated expansions in the number and type of individuals who consider them a valuable option. The novel applications of contact lenses include treatment platforms for myopic progression, biosensors, and ocular drug delivery. Orthokeratology has shown the most consistent treatment for myopia control with the least side effects. Recent work has resulted in commercialization of a device to monitor intraocular pressure for up to 24 hours, and extensive efforts are underway to develop a contact lens sensor capable of continuous glucose tear film monitoring for the management of diabetes. Other studies on drug-eluting contact lenses have focused on increasing the release duration through molecular imprinting, use of vitamin E, and increased drug binding to polymers by sandwiching a poly (lactic-co-glycolic acid) layer in the lens. This review demonstrates the potential for contact lenses to provide novel opportunities for refractive management, diagnosis, and management of diseases.
... Bifocal contact lenses significantly reduce the rate of myopia progression, in terms of both the spherical equivalent of refractive error and axial length. It has been suggested that bifocal contact lenses act by reducing accommodative lag (73); however, it is more likely that they act by reducing peripheral hyperopic defocus or imposing myopic defocus (74). Peripheral defocus correction by peripheral-plus contact lenses results in a 50% reduction in the rate of myopic progression, in terms of both spherical equivalent and axial length (75). ...
http://www.who.int/blindness/causes/MyopiaReportforWeb.pdf
The prevalence of myopia and high myopia are increasing globally at an alarming rate, with
significant increases in the risks for vision impairment from pathologic conditions associated
with high myopia, including retinal damage, cataract and glaucoma. The impact of myopia is
difficult to determine, because there are no standard definitions of myopia and high myopia,
and recognition that myopia can lead to vision impairment is limited by the absence of a
defined category of myopic retinal disease that causes permanent vision impairment. A further
impediment to progress in this area is insufficient evidence of the efficacy of various methods
for controlling myopia.
In view of concern about the current and future impact of myopia, the Minister of Health for
Australia, the Right Honourable Mr Peter Dutton, contacted the Director-General of WHO, Dr
Margaret Chan, to request the involvement of WHO in an international scientific meeting on
myopia to be held by the Brien Holden Vision Institute (BHVI). As a result, a three-day joint
WHO–BHVI meeting was convened on 16–18 March 2015 at the University of New South
Wales in Sydney, Australia. Scientific and clinical experts in myopia were invited from all six WHO regions (see Annex 1).
Keynote presentations, working groups and plenary sessions were held to review the evidence
on the major issues in myopia. The results of these deliberations were reported to plenary for
discussion, and agreement was reached on a series of statements, definitions and priorities for
research.
... The study design and results are described in the following sections, and implications are discussed in the context of potential underlying mechanisms and the broader topic of control of myopia progression. Study results have also been reported in abstract form previously. 34,35 ...
... Pirenzepine is a partially selective M1/M4 anti-muscarinic drug that does not affect accommodation or pupil size. The efficacy of atropine is more than that of pirenzepineEdwards et al., 2002 Fulk et al., 2000 Gwiazda et al., 2003 Hasebe et al., 2008 Aller & Millodot, 2006 Chung et al., 2002 Holden et al., 2010 Sankaridurg et al., 2010 Anstice & Phillips, 2011 Sankaridurg et al., 2011 Walline et al., 2013 Lam et al., 2014 Aller et al., 2006 Charm & Cho, 2013 Walline et al., 2009 Cho & Cheung, 2012 Chen et al., 2013 Kakita et al., 2011 Santodomingo-Rubido et al., 2012 Chua et al., 2006 Fan et al., 2007 Yen et al., 1989 Wu et al., 2011 Chia et al., 2012Bifocal respectively. The ATOM 1 & 2 studies used atropine in two different concentrations to control myopia progression. ...
Myopia has become a Worldwide epidemic. It is potentially sight threatening and costly to treat and manage. Research has shown that it is not only possible to prevent the progression of school myopia but it may also be possible to prevent it occurring in the first place. This article reviews some of the recent peer-reviewed literature on myopia and the different strategies to control myopia.
... The study design and results are described in the following sections, and implications are discussed in the context of potential underlying mechanisms and the broader topic of control of myopia progression. Study results have also been reported in abstract form previously. 34,35 ...
Purpose:
Most studies have reported only minimal reductions in myopia progression with bifocal or progressive multifocal spectacles, although somewhat larger, although mostly still clinically insignificant, effects have been reported in children with nearpoint esophoria and/or accommodative dysfunctions. The CONTROL study was a 1-year, prospective, randomized, clinical trial of bifocal contact lenses for control of myopia in children with eso fixation disparities at near.
Methods:
Eighty-six myopic subjects, aged 8 to 18 years, were enrolled in the study after passing the screening examination. Of these, 79 completed lens assignment and 78 completed the study. The mean refractive error of these 79 subjects was -2.69 ± 1.40D (SD), and all had progressed by -0.50D or more since their last examination. All subjects also had eso fixation disparity at near. Subjects were randomly assigned to wear either Vistakon Acuvue 2 (single-vision soft contact lenses [SVSCLs]) or Vistakon Acuvue Bifocal (bifocal soft contact lenses [BFSCLs]). Bifocal adds were selected to neutralize the associated phoria. Treatment outcomes included cycloplegic autorefraction and axial length, assessed in terms of changes after 6 and 12 months of treatment from pretreatment baseline values.
Results:
The BFSCLs significantly slowed myopia progression, with statistically significant differences between the treatment groups after 6 months. After 12 months of treatment, the SVSCL group had progressed by -0.79 ± 0.43D compared with -0.22 ± 0.34D for the BFSCL group (cycloplegic objective spherical equivalent, average of two eyes). Corresponding axial length changes were 0.24 ± 0.17 mm and 0.05 ± 0.14 mm, respectively. All of these differences were found to be statistically significant (unpaired t-tests, p < 0.001).
Conclusions:
The distance center bifocal contact lenses tested in this study achieved greater control over myopia progression and axial elongation (>70%) compared with most published results with multifocal spectacles. Further studies are warranted to identify the critical factors and mechanisms underlying this myopia control effect.
... Several nonrandomized, controlled clinical trials have shown the myopia control benefit of soft bifocal contact lenses. [80][81][82][83] Shih et al 107 Chua et al 67 Fan et al 70 Yen et al 73 Wu et al 108 Chia et al 68 Aller 111 Anstice and Phillips 80 Walline et al 83 Sankaridurg et al 82 Lam et al 81 Charm and Cho 74 Walline et al 79 Cho and Cheung 76 Chen et al 75 Kakita Overall, soft bifocal contact lenses slow the progression of myopia in children by nearly 50%, which is similar to orthokeratology contact lenses ( Table 2). ...
Myopia is a common disorder, affecting approximately one-third of the US population and over 90% of the population in some East Asian countries. High amounts of myopia are associated with an increased risk of sight-threatening problems, such as retinal detachment, choroidal degeneration, cataracts, and glaucoma. Slowing the progression of myopia could potentially benefit millions of children in the USA. To date, few strategies used for myopia control have proven to be effective. Treatment options such as undercorrection of myopia, gas permeable contact lenses, and bifocal or multifocal spectacles have all been proven to be ineffective for myopia control, although one recent randomized clinical trial using executive top bifocal spectacles on children with progressive myopia has shown to decrease the progression to nearly half of the control subjects. The most effective methods are the use of orthokeratology contact lenses, soft bifocal contact lenses, and topical pharmaceutical agents such as atropine or pirenzepine. Although none of these modalities are US Food and Drug Administration-approved to slow myopia progression, they have been shown to slow the progression by approximately 50% with few risks. Both orthokeratology and soft bifocal contact lenses have shown to slow myopia progression by slightly less than 50% in most studies. Parents and eye care practitioners should work together to determine which modality may be best suited for a particular child. Topical pharmaceutical agents such as anti-muscarinic eye drops typically lead to light sensitivity and poor near vision. The most effective myopia control is provided by atropine, but is rarely prescribed due to the side effects. Pirenzepine provides myopia control with little light sensitivity and few near-vision problems, but it is not yet commercially available as an eye drop or ointment. Several studies have shown that lower concentrations of atropine slow the progression of myopia control with fewer side effects than 1% atropine. While the progression of myopic refractive error is slowed with lower concentration of atropine, the growth of the eye is not, indicating a potentially reversible form of myopia control that may diminish after discontinuation of the eye drops. This review provides an overview of the myopia control information available in the literature and raises questions that remain unanswered, so that eye care practitioners and parents can potentially learn the methods that may ultimately improve a child’s quality of life or lower the risk of sight-threatening complications.
... 59 Furthermore, the authors reported in 2006 on a 1-year clinical trial testing the efficacy of ACUVUE Bifocal CL in myopic endophoric patients. They reported a 71% reduction in refractive change as measured with cycloplegic autorefraction and a 79% reduction in axial length with the bifocal CL. 60 The only human randomized controlled clinical trial with this category of lenses was conducted by Anstice and Phillips 66 with refractive bifocal (dual-focus) CLs in the Dual-focus Inhibition of Myopia Evaluation in New Zealand study. Dual-focus CLs consist of a hydrophilic soft CL made of hioxifilcon A, nonionic 49% water content material (Benz Research and Development, Sarasota, FL), with a total diameter of 14.2 mm and a base curve of 8.5 mm. ...
Higher myopic refractive errors are associated with serious ocular complications that can put visual function at risk. There is respective interest in slowing and if possible stopping myopia progression before it reaches a level associated with increased risk of secondary pathology. The purpose of this report was to review our understanding of the rationale(s) and success of contact lenses (CLs) used to reduce myopia progression.
A review commenced by searching the PubMed database. The inclusion criteria stipulated publications of clinical trials evaluating the efficacy of CLs in regulating myopia progression based on the primary endpoint of changes in axial length measurements and published in peer-reviewed journals. Other publications from conference proceedings or patents were exceptionally considered when no peer-review articles were available.
The mechanisms that presently support myopia regulation with CLs are based on the change of relative peripheral defocus and changing the foveal image quality signal to potentially interfere with the accommodative system. Ten clinical trials addressing myopia regulation with CLs were reviewed, including corneal refractive therapy (orthokeratology), peripheral gradient lenses, and bifocal (dual-focus) and multifocal lenses.
CLs were reported to be well accepted, consistent, and safe methods to address myopia regulation in children. Corneal refractive therapy (orthokeratology) is so far the method with the largest demonstrated efficacy in myopia regulation across different ethnic groups. However, factors such as patient convenience, the degree of initial myopia, and non-CL treatments may also be considered. The combination of different strategies (i.e., central defocus, peripheral defocus, spectral filters, pharmaceutical delivery, and active lens-borne illumination) in a single device will present further testable hypotheses exploring how different mechanisms can reinforce or compete with each other to improve or reduce myopia regulation with CLs.
... However, considering the similar change in the peripheral refractive pattern induced by these lenses [17][18][19], it has been hypothesized that such designs can be useful to slow myopia progression [20]. Bifocal contact lenses for presbyopia have previously been used to slow myopia progression [21,22]. Recently dual-focus contact lens has been proved to be effective in reducing myopia progression by up to 34% in children over a 10-month period [23]. ...
Purpose:
To evaluate the impact of eye and head rotation in the measurement of peripheral refraction with an open-field autorefractometer in myopic eyes wearing two different center-distance designs of multifocal contact lenses (MFCLs).
Methods:
Nineteen right eyes from 19 myopic patients (average central M ± SD = -2.67 ± 1.66 D) aged 20-27 years (mean ± SD = 23.2 ± 3.3 years) were evaluated using a Grand-Seiko autorefractometer. Patients were fitted with one multifocal aspheric center-distance contact lens (Biofinity Multifocal D(®)) and with one multi-concentric MFCL (Acuvue Oasys for Presbyopia). Axial and peripheral refraction were evaluated by eye rotation and by head rotation under naked eye condition and with each MFCL fitted randomly and in independent sessions.
Results:
For the naked eye, refractive pattern (M, J0 and J45) across the central 60° of the horizontal visual field values did not show significant changes measured by rotating the eye or rotating the head (p > 0.05). Similar results were obtained wearing the Biofinity D, for both testing methods, no obtaining significant differences to M, J0 and J45 values (p > 0.05). For Acuvue Oasys for presbyopia, also no differences were found when comparing measurements obtained by eye and head rotation (p > 0.05). Multivariate analysis did not showed a significant interaction between testing method and lens type neither with measuring locations (MANOVA, p > 0.05). There were significant differences in M and J0 values between naked eyes and each MFCL.
Conclusion:
Measurements of peripheral refraction by rotating the eye or rotating the head in myopic patients wearing dominant design or multi-concentric multifocal silicone hydrogel contact lens are comparable.
... Clinically and in studies, they have primarily been used to attempt to slow myopia progression in those patients with eso fixation disparity at near. [34][35][36] In this patient population group, these lenses prescribed with this method slow myopia progression by 80-90%. The best measure of effectiveness for these lenses would be the reduction in axial length increases found in the randomized clinical trial where there was an 80% slowing of axial elongation in children wearing bifocal contact lenses. ...
Myopia has been increasing in prevalence throughout the world, reaching over 90% in some East Asian populations. There is increasing evidence that whereas genetics clearly have an important role, the type of visual environment to which one is exposed to likely influences the onset, progression, and cessation of myopia. Consequently, attempts to either modify the environment or to reduce the exposure of the eye to various environmental stimuli to eye growth through the use of various optical devices are well under way at research centers around the globe. The most promising of current treatments include low-percentage atropine, bifocal soft contact lenses, orthokeratology, and multifocal spectacles. These methods are discussed briefly and are then categorized in terms of their expected degree of myopia progression control. A clinical strategy is presented for selecting the most effective treatment for the appropriate type of patient at the optimal stage of refractive development to achieve the maximum control of myopia progression.Eye advance online publication, 20 December 2013; doi:10.1038/eye.2013.259.
... One option currently being tested is to use multifocal and bifocal soft contact lenses with a centre distance design. [10][11][12][13][14][15][16] Two recent studies using lenses with 2 D add have reported a reduction in myopia progression from À0.86 to À0.57 D per year and from À0.69 to À0.44 D per 10 months respectively. ...
Multifocal soft contact lenses have been used to decrease the progression of myopia, presumably by inducing relative peripheral myopia at the same time as the central image is focused on the fovea. The aim of this study was to investigate how the peripheral optical effect of commercially available multifocal soft contact lenses can be evaluated from objective wavefront measurements.
Two multifocal lenses with high and low add and one monofocal design were measured over the ±40° horizontal field, using a scanning Hartmann-Shack wavefront sensor on four subjects. The effect on the refractive shift, the peripheral image quality, and the depth of field of the lenses was evaluated using the area under the modulation transfer function as the image quality metric.
The multifocal lenses with a centre distance design and 2 dioptres of add induced about 0.50 dioptre of relative peripheral myopia at 30° in the nasal visual field. For larger off-axis angles the border of the optical zone of the lenses severely degraded image quality. Moreover, these multifocal lenses also significantly reduced the image quality and increased the depth of field for angles as small as 10°-15°.
The proposed methodology showed that the tested multifocal soft contact lenses gave a very small peripheral myopic shift in these four subjects and that they would need a larger optical zone and a more controlled depth of field to explain a possible treatment effect on myopia progression.
Rationale:
The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Interventions to slow its progression are needed in childhood, when myopia progression is most rapid. This is a review update, conducted as part of a living systematic review.
Objectives:
To assess the comparative efficacy and safety of interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of interventions according to their efficacy. To produce a brief economic commentary, summarising economic evaluations.
Search methods:
We searched CENTRAL, MEDLINE, Embase, and three trial registers. The latest search date was 19 February 2024.
Eligibility criteria:
We included randomised controlled trials (RCTs) of optical, pharmacological, light therapy and behavioural interventions for slowing myopia progression in children, up to 18 years old.
Outcomes:
Critical outcomes were progression of myopia (mean difference (MD) in the change in spherical equivalent refraction (SER, dioptres (D)), and axial length (AL, mm) in the intervention and control groups at one year or longer), and difference in the change in SER and AL following cessation of treatment (rebound).
Risk of bias:
We assessed the risk of bias (RoB) for SER and AL using the Cochrane RoB 2 tool.
Synthesis methods:
We followed standard Cochrane methods. We rated the certainty of evidence using the GRADE approach for change in SER and AL at one and two years. We used the surface under the cumulative ranking curve (SUCRA) to rank the interventions for all available outcomes.
Included studies:
We included 104 studies (40 new for this update) that randomised 17,509 children, aged 4 years to 18 years. Most studies were conducted in China or other Asian countries (66.3%), and North America (14.4%). Eighty-four studies (80.8%) compared myopia control interventions against inactive controls. Study durations ranged from 12 months to 48 months.
Synthesis of results:
Since most of the networks in the NMA were poorly connected, our estimates are based on direct (pairwise) comparisons, unless stated otherwise. The median change in SER for controls was -0.65 D (55 studies, 4888 participants; one-year follow-up). These interventions may reduce SER progression compared to controls: repeated low intensity red light (RLRL: MD 0.80 D, 95% confidence interval (CI) 0.71 to 0.89; SUCRA = 93.8%; very low-certainty evidence); high-dose atropine (HDA (≥ 0.5%): MD 0.90 D, 95% CI 0.62 to 1.18; SUCRA = 93.3%; moderate-certainty evidence); medium-dose atropine (MDA (0.1% to < 0.5%): MD 0.55 D, 95% CI 0.17 to 0.93; NMA estimate SUCRA = 75.5%; low-certainty evidence); low dose atropine (LDA (< 0.1%): MD 0.25 D, 95% CI 0.16 to 0.35; SUCRA = 53.2%; very low-certainty evidence); peripheral plus spectacle lenses (PPSL: MD 0.45 D, 95% CI 0.16 to 0.74; SUCRA = 50.2%; very low-certainty evidence); multifocal soft contact lenses (MFSCL: MD 0.27 D, 95% CI 0.18 to 0.35; SUCRA = 49.9%; very low-certainty evidence); and multifocal spectacle lenses (MFSL: MD 0.14 D, 95% CI 0.08 to 0.21; SUCRA = 30.8%; low-certainty evidence). The median change in AL for controls was 0.33 mm (58 studies, 9085 participants; one-year follow-up). These interventions may reduce axial elongation compared to controls: RLRL (MD -0.33 mm, 95% CI -0.37 to -0.29; SUCRA = 98.6%; very low-certainty evidence); HDA (MD -0.33 mm, 95% CI -0.35 to -0.30; SUCRA = 88.4%; moderate-certainty evidence); MDA (MD -0.24 mm, 95% CI -0.34 to -0.15; NMA estimate SUCRA = 75.8%; low-certainty evidence); LDA (MD -0.10 mm, 95% CI -0.13 to -0.07; SUCRA = 36.1%; very low-certainty evidence); orthokeratology (ortho-K: MD -0.18 mm, 95% CI -0.21 to -0.14; SUCRA = 79%; moderate-certainty evidence); PPSL (MD -0.13 mm, 95% CI -0.21 to -0.05; SUCRA = 52.6%; very low-certainty evidence); MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09; SUCRA = 45.6%; low-certainty evidence); and MFSL (MD -0.06 mm, 95% CI -0.09 to -0.04; SUCRA = 26.3%; low-certainty evidence). Ortho-K plus LDA probably reduces axial elongation more than ortho-K monotherapy (MD -0.12 mm, 95% CI -0.15 to -0.09; SUCRA = 81.8%; moderate-certainty evidence). At two-year follow-up, change in SER was reported in 34 studies (3556 participants). The median change in SER for controls was -1.01 D. The ranking of interventions to reduce SER progression was close to that observed at one year; there were insufficient data to draw conclusions on cumulative effects. The highest-ranking interventions were: HAD (SUCRA = 97%); MDA (NMA estimate SUCRA = 69.8%); and PPSL (SUCRA = 69.1%). At two-year follow-up, change in AL was reported in 33 studies (3334 participants). The median change in AL for controls was 0.56 mm. The ranking of interventions to reduce axial elongation was similar to that observed at one year; there were insufficient data to draw conclusions on cumulative effects. The highest-ranking interventions were: ortho-K plus LDA (SUCRA = 94.2%); HAD (SUCRA = 96.8%); and MDA (NMA estimate SUCRA = 88.4%). There was limited evidence on whether cessation of myopia control therapy increases progression beyond the expected rate of progression with age. Adverse events and treatment adherence were not consistently reported. Two studies reported quality of life, showing little to no difference between intervention and control groups. We were unable to draw firm conclusions regarding the relative costs or efficiency of different myopia control strategies in children.
Authors' conclusions:
Most studies compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. These interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. Less evidence is available for two years and beyond; uncertainty remains about the sustained effect of these interventions. Longer term and better quality studies comparing myopia control interventions alone or in combination are needed, with improved methods for monitoring and reporting adverse effects.
Funding:
Cochrane Eyes and Vision US Project is supported by grant UG1EY020522, National Eye Institute, National Institutes of Health.
Registration:
The previous version of this living systematic review is available at doi: 10.1002/14651858.CD014758.pub2.
Background:
Myopia is a common refractive error, where elongation of the eyeball causes distant objects to appear blurred. The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Since myopia is usually detected in children before 10 years of age and can progress rapidly, interventions to slow its progression need to be delivered in childhood.
Objectives:
To assess the comparative efficacy of optical, pharmacological and environmental interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of myopia control interventions according to their efficacy. To produce a brief economic commentary, summarising the economic evaluations assessing myopia control interventions in children. To maintain the currency of the evidence using a living systematic review approach. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE; Embase; and three trials registers. The search date was 26 February 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of optical, pharmacological and environmental interventions for slowing myopia progression in children aged 18 years or younger. Critical outcomes were progression of myopia (defined as the difference in the change in spherical equivalent refraction (SER, dioptres (D)) and axial length (mm) in the intervention and control groups at one year or longer) and difference in the change in SER and axial length following cessation of treatment ('rebound'). DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methods. We assessed bias using RoB 2 for parallel RCTs. We rated the certainty of evidence using the GRADE approach for the outcomes: change in SER and axial length at one and two years. Most comparisons were with inactive controls.
Main results:
We included 64 studies that randomised 11,617 children, aged 4 to 18 years. Studies were mostly conducted in China or other Asian countries (39 studies, 60.9%) and North America (13 studies, 20.3%). Fifty-seven studies (89%) compared myopia control interventions (multifocal spectacles, peripheral plus spectacles (PPSL), undercorrected single vision spectacles (SVLs), multifocal soft contact lenses (MFSCL), orthokeratology, rigid gas-permeable contact lenses (RGP); or pharmacological interventions (including high- (HDA), moderate- (MDA) and low-dose (LDA) atropine, pirenzipine or 7-methylxanthine) against an inactive control. Study duration was 12 to 36 months. The overall certainty of the evidence ranged from very low to moderate. Since the networks in the NMA were poorly connected, most estimates versus control were as, or more, imprecise than the corresponding direct estimates. Consequently, we mostly report estimates based on direct (pairwise) comparisons below. At one year, in 38 studies (6525 participants analysed), the median change in SER for controls was -0.65 D. The following interventions may reduce SER progression compared to controls: HDA (mean difference (MD) 0.90 D, 95% confidence interval (CI) 0.62 to 1.18), MDA (MD 0.65 D, 95% CI 0.27 to 1.03), LDA (MD 0.38 D, 95% CI 0.10 to 0.66), pirenzipine (MD 0.32 D, 95% CI 0.15 to 0.49), MFSCL (MD 0.26 D, 95% CI 0.17 to 0.35), PPSLs (MD 0.51 D, 95% CI 0.19 to 0.82), and multifocal spectacles (MD 0.14 D, 95% CI 0.08 to 0.21). By contrast, there was little or no evidence that RGP (MD 0.02 D, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.07 D, 95% CI -0.09 to 0.24) or undercorrected SVLs (MD -0.15 D, 95% CI -0.29 to 0.00) reduce progression. At two years, in 26 studies (4949 participants), the median change in SER for controls was -1.02 D. The following interventions may reduce SER progression compared to controls: HDA (MD 1.26 D, 95% CI 1.17 to 1.36), MDA (MD 0.45 D, 95% CI 0.08 to 0.83), LDA (MD 0.24 D, 95% CI 0.17 to 0.31), pirenzipine (MD 0.41 D, 95% CI 0.13 to 0.69), MFSCL (MD 0.30 D, 95% CI 0.19 to 0.41), and multifocal spectacles (MD 0.19 D, 95% CI 0.08 to 0.30). PPSLs (MD 0.34 D, 95% CI -0.08 to 0.76) may also reduce progression, but the results were inconsistent. For RGP, one study found a benefit and another found no difference with control. We found no difference in SER change for undercorrected SVLs (MD 0.02 D, 95% CI -0.05 to 0.09). At one year, in 36 studies (6263 participants), the median change in axial length for controls was 0.31 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.33 mm, 95% CI -0.35 to 0.30), MDA (MD -0.28 mm, 95% CI -0.38 to -0.17), LDA (MD -0.13 mm, 95% CI -0.21 to -0.05), orthokeratology (MD -0.19 mm, 95% CI -0.23 to -0.15), MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09), pirenzipine (MD -0.10 mm, 95% CI -0.18 to -0.02), PPSLs (MD -0.13 mm, 95% CI -0.24 to -0.03), and multifocal spectacles (MD -0.06 mm, 95% CI -0.09 to -0.04). We found little or no evidence that RGP (MD 0.02 mm, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.03 mm, 95% CI -0.10 to 0.03) or undercorrected SVLs (MD 0.05 mm, 95% CI -0.01 to 0.11) reduce axial length. At two years, in 21 studies (4169 participants), the median change in axial length for controls was 0.56 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.47mm, 95% CI -0.61 to -0.34), MDA (MD -0.33 mm, 95% CI -0.46 to -0.20), orthokeratology (MD -0.28 mm, (95% CI -0.38 to -0.19), LDA (MD -0.16 mm, 95% CI -0.20 to -0.12), MFSCL (MD -0.15 mm, 95% CI -0.19 to -0.12), and multifocal spectacles (MD -0.07 mm, 95% CI -0.12 to -0.03). PPSL may reduce progression (MD -0.20 mm, 95% CI -0.45 to 0.05) but results were inconsistent. We found little or no evidence that undercorrected SVLs (MD -0.01 mm, 95% CI -0.06 to 0.03) or RGP (MD 0.03 mm, 95% CI -0.05 to 0.12) reduce axial length. There was inconclusive evidence on whether treatment cessation increases myopia progression. Adverse events and treatment adherence were not consistently reported, and only one study reported quality of life. No studies reported environmental interventions reporting progression in children with myopia, and no economic evaluations assessed interventions for myopia control in children.
Authors' conclusions:
Studies mostly compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. Effects at one year provided evidence that these interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. A smaller body of evidence is available at two or three years, and uncertainty remains about the sustained effect of these interventions. Longer-term and better-quality studies comparing myopia control interventions used alone or in combination are needed, and improved methods for monitoring and reporting adverse effects.
Background:
Nearsightedness (myopia) causes blurry vision when one is looking at distant objects. Interventions to slow the progression of myopia in children include multifocal spectacles, contact lenses, and pharmaceutical agents.
Objectives:
To assess the effects of interventions, including spectacles, contact lenses, and pharmaceutical agents in slowing myopia progression in children.
Search methods:
We searched CENTRAL; Ovid MEDLINE; Embase.com; PubMed; the LILACS Database; and two trial registrations up to February 2018. A top up search was done in February 2019.
Selection criteria:
We included randomized controlled trials (RCTs). We excluded studies when most participants were older than 18 years at baseline. We also excluded studies when participants had less than -0.25 diopters (D) spherical equivalent myopia.
Data collection and analysis:
We followed standard Cochrane methods.
Main results:
We included 41 studies (6772 participants). Twenty-one studies contributed data to at least one meta-analysis. Interventions included spectacles, contact lenses, pharmaceutical agents, and combination treatments. Most studies were conducted in Asia or in the United States. Except one, all studies included children 18 years or younger. Many studies were at high risk of performance and attrition bias. Spectacle lenses: undercorrection of myopia increased myopia progression slightly in two studies; children whose vision was undercorrected progressed on average -0.15 D (95% confidence interval [CI] -0.29 to 0.00; n = 142; low-certainty evidence) more than those wearing fully corrected single vision lenses (SVLs). In one study, axial length increased 0.05 mm (95% CI -0.01 to 0.11) more in the undercorrected group than in the fully corrected group (n = 94; low-certainty evidence). Multifocal lenses (bifocal spectacles or progressive addition lenses) yielded small effect in slowing myopia progression; children wearing multifocal lenses progressed on average 0.14 D (95% CI 0.08 to 0.21; n = 1463; moderate-certainty evidence) less than children wearing SVLs. In four studies, axial elongation was less for multifocal lens wearers than for SVL wearers (-0.06 mm, 95% CI -0.09 to -0.04; n = 896; moderate-certainty evidence). Three studies evaluating different peripheral plus spectacle lenses versus SVLs reported inconsistent results for refractive error and axial length outcomes (n = 597; low-certainty evidence). Contact lenses: there may be little or no difference between vision of children wearing bifocal soft contact lenses (SCLs) and children wearing single vision SCLs (mean difference (MD) 0.20D, 95% CI -0.06 to 0.47; n = 300; low-certainty evidence). Axial elongation was less for bifocal SCL wearers than for single vision SCL wearers (MD -0.11 mm, 95% CI -0.14 to -0.08; n = 300; low-certainty evidence). Two studies investigating rigid gas permeable contact lenses (RGPCLs) showed inconsistent results in myopia progression; these two studies also found no evidence of difference in axial elongation (MD 0.02mm, 95% CI -0.05 to 0.10; n = 415; very low-certainty evidence). Orthokeratology contact lenses were more effective than SVLs in slowing axial elongation (MD -0.28 mm, 95% CI -0.38 to -0.19; n = 106; moderate-certainty evidence). Two studies comparing spherical aberration SCLs with single vision SCLs reported no difference in myopia progression nor in axial length (n = 209; low-certainty evidence). Pharmaceutical agents: at one year, children receiving atropine eye drops (3 studies; n = 629), pirenzepine gel (2 studies; n = 326), or cyclopentolate eye drops (1 study; n = 64) showed significantly less myopic progression compared with children receiving placebo: MD 1.00 D (95% CI 0.93 to 1.07), 0.31 D (95% CI 0.17 to 0.44), and 0.34 (95% CI 0.08 to 0.60), respectively (moderate-certainty evidence). Axial elongation was less for children treated with atropine (MD -0.35 mm, 95% CI -0.38 to -0.31; n = 502) and pirenzepine (MD -0.13 mm, 95% CI -0.14 to -0.12; n = 326) than for those treated with placebo (moderate-certainty evidence) in two studies. Another study showed favorable results for three different doses of atropine eye drops compared with tropicamide eye drops (MD 0.78 D, 95% CI 0.49 to 1.07 for 0.1% atropine; MD 0.81 D, 95% CI 0.57 to 1.05 for 0.25% atropine; and MD 1.01 D, 95% CI 0.74 to 1.28 for 0.5% atropine; n = 196; low-certainty evidence) but did not report axial length. Systemic 7-methylxanthine had little to no effect on myopic progression (MD 0.07 D, 95% CI -0.09 to 0.24) nor on axial elongation (MD -0.03 mm, 95% CI -0.10 to 0.03) compared with placebo in one study (n = 77; moderate-certainty evidence). One study did not find slowed myopia progression when comparing timolol eye drops with no drops (MD -0.05 D, 95% CI -0.21 to 0.11; n = 95; low-certainty evidence). Combinations of interventions: two studies found that children treated with atropine plus multifocal spectacles progressed 0.78 D (95% CI 0.54 to 1.02) less than children treated with placebo plus SVLs (n = 191; moderate-certainty evidence). One study reported -0.37 mm (95% CI -0.47 to -0.27) axial elongation for atropine and multifocal spectacles when compared with placebo plus SVLs (n = 127; moderate-certainty evidence). Compared with children treated with cyclopentolate plus SVLs, those treated with atropine plus multifocal spectacles progressed 0.36 D less (95% CI 0.11 to 0.61; n = 64; moderate-certainty evidence). Bifocal spectacles showed small or negligible effect compared with SVLs plus timolol drops in one study (MD 0.19 D, 95% CI 0.06 to 0.32; n = 97; moderate-certainty evidence). One study comparing tropicamide plus bifocal spectacles versus SVLs reported no statistically significant differences between groups without quantitative results. No serious adverse events were reported across all interventions. Participants receiving antimuscarinic topical medications were more likely to experience accommodation difficulties (Risk Ratio [RR] 9.05, 95% CI 4.09 to 20.01) and papillae and follicles (RR 3.22, 95% CI 2.11 to 4.90) than participants receiving placebo (n=387; moderate-certainty evidence).
Authors' conclusions:
Antimuscarinic topical medication is effective in slowing myopia progression in children. Multifocal lenses, either spectacles or contact lenses, may also confer a small benefit. Orthokeratology contact lenses, although not intended to modify refractive error, were more effective than SVLs in slowing axial elongation. We found only low or very low-certainty evidence to support RGPCLs and sperical aberration SCLs.
Purpose:
To determine the effectiveness of different interventions to slow down the progression of myopia in children.
Methods:
We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov from inception to August 2014. We selected randomized controlled trials (RCTs) involving interventions for controlling the progression of myopia in children with a treatment duration of at least 1 year for analysis.
Main outcome measures:
The primary outcomes were mean annual change in refraction (diopters/year) and mean annual change in axial length (millimeters/year).
Results:
Thirty RCTs (involving 5422 eyes) were identified. Network meta-analysis showed that in comparison with placebo or single vision spectacle lenses, high-dose atropine (refraction change: 0.68 [0.52-0.84]; axial length change: -0.21 [-0.28 to -0.16]), moderate-dose atropine (refraction change: 0.53 [0.28-0.77]; axial length change: -0.21 [-0.32 to -0.12]), and low-dose atropine (refraction change: 0.53 [0.21-0.85]; axial length change: -0.15 [-0.25 to -0.05]) markedly slowed myopia progression. Pirenzepine (refraction change: 0.29 [0.05-0.52]; axial length change: -0.09 [-0.17 to -0.01]), orthokeratology (axial length change: -0.15 [-0.22 to -0.08]), and peripheral defocus modifying contact lenses (axial length change: -0.11 [-0.20 to -0.03]) showed moderate effects. Progressive addition spectacle lenses (refraction change: 0.14 [0.02-0.26]; axial length change: -0.04 [-0.09 to -0.01]) showed slight effects.
Conclusions:
This network analysis indicates that a range of interventions can significantly reduce myopia progression when compared with single vision spectacle lenses or placebo. In terms of refraction, atropine, pirenzepine, and progressive addition spectacle lenses were effective. In terms of axial length, atropine, orthokeratology, peripheral defocus modifying contact lenses, pirenzepine, and progressive addition spectacle lenses were effective. The most effective interventions were pharmacologic, that is, muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including orthokeratology and peripheral defocus modifying contact lenses, had moderate effects, whereas specially designed spectacle lenses showed minimal effect.
Previous studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years.
Eight- to eleven-year-old children with -1.00 D to -6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal "D"; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers.
Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was -1.03 ± 0.06 D for the single-vision contact lens wearers and -0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016).
Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.
In order to develop effective optical treatment strategies for myopia, it is important to understand how visual experience influences refractive development. Beginning with the discovery of the phenomenon of form deprivation myopia, research involving many animal species has demonstrated that refractive development is regulated by visual feedback. In particular, animal studies have shown that optically imposed myopic defocus slows axial elongation, that the effects of vision are dominated by local retinal mechanisms, and that peripheral vision can dominate central refractive development. In this review, the results obtained from clinical trials of traditional optical treatment strategies employed in efforts to slow myopia progression in children are interpreted in light of the results from animal studies and are compared to the emerging results from preliminary clinical studies of optical treatment strategies that manipulate the effective focus of the peripheral retina. Overall, the results suggest that imposed myopic defocus can slow myopia progression in children and that the effectiveness of an optical treatment strategy in reducing myopia progression is influenced by the extent of the visual field that is manipulated.
Significant advances during the past decade in silicone hydrogel lenses have made them the primary mode for new contact lens wear. Their dominance in the market place is driven largely by the elimination of structural and physiological changes induced by contact lens-induced hypoxia, as exemplified especially by the reduction in limbal redness. However, end-of-day dryness and discomfort still drives many to discontinue lens wear. Evidence also indicates that the rate of serious adverse events, such as microbial keratitis, have not been impacted with the use of silicone hydrogel lenses. Moreover, there are additional challenges relating to 'corneal staining' and corneal infiltrates associated with the incompatibility of lens care product with contact lens polymers. On the other hand, technological advances enabled by the high oxygen platform present opportunities for expanding the use of contact lenses in areas that have exhibited limited uptake in the past such as astigmatism, presbyopia, and importantly myopia control. The challenges and opportunities facing the field will be discussed.
The aim of this study was to evaluate ocular aberration changes through different simultaneous vision multifocal contact lenses (CLs).
Eighteen young-adult subjects with a mean age of 29.8±2.11 years took part. Changes in accommodative response, spherical aberration (C(4)(0)), horizontal coma (C(3)(1)), vertical coma (C(3)(-1)), and root mean square (RMS) of higher-order aberrations (HOAs, third to sixth orders) were evaluated. Measurements were obtained with a distance-single vision CL and 2 aspheric multifocal CLs of simultaneous focus center-near design (PureVision Low Add and PureVision High Add) for 2 accommodative stimuli (-2.50 and -4.00 D). All measurements were performed monocularly with a Hartmann-Shack aberrometer (IRX-3; Imagine Eyes, Orsay, France).
No statistically significant differences were found in accommodative responses to -2.50- and -4.00-D stimuli between the single vision CL and the 2 multifocal CLs. Spherical aberration was found to decrease and become more negative with accommodation for both stimuli with all three CLs. Horizontal coma decreased significantly with accommodation (-2.5- and -4.00-D stimuli) for the distance-single vision CLs (P=0.002 and P=0.003). No differences were found in vertical coma Zernike coefficients. The RMS of HOAs was found to decrease only with the single vision CLs for both stimuli (P<0.01).
Data obtained in this study suggest that in young subjects, the multifocal CLs studied do not induce large changes in accommodative response compared with the distance-single vision CLs. Spherical aberration reduced significantly with accommodation.
We investigated the effects on refractive development and ocular growth of 2-zone concentric lenses with different negative powers in each of the optical zones, in normal and myopic eyes in young chicks.
Monocular defocusing lenses were worn for 10-15 days from 12 days of age. Two 2-zone concentric lens types combining -5 and -10 diopter (D) powers, with center zone diameters ranging from 4.5-7.5 mm were tested. One group of chickens wore 2-zone negative lenses from 12 days of age for 10 days, without any previous lens treatment. A second group of 12-day-old chickens were treated initially with -10 D single vision (SV) lenses for 5 days to induce myopia, and then for another 10 days with 2-zone lenses, when the zone of lower power served as a positive addition.
With the 2-zone negative lens treatment alone, the magnitude of on-axis-induced myopia fell between that expected for two negative powers presented in SV lens format, while for eyes first made myopic by pretreatment with -10 SV lenses, the 2-zone negative lenses caused regression of the induced myopia due to inhibitory effects on axial ocular growth, with the greatest effects observed in eyes with higher baseline myopia.
Our results provided further evidence for a role of the peripheral retina in ocular growth regulation. They also lent weight to the idea of using concentric multifocal contact lenses to appropriately manipulate peripheral retinal defocus as one approach to controlling human myopia progression.
A study was conducted to test the effectiveness of bifocal soft contact lenses in controlling myopic progression in pre-presbyopic esophoric subjects of all ages. 84 myopic patients who exhibited progressive myopia and esophoria or eso associated phoria at near were followed. In general, bifocal soft contact lenses were effective in limiting the rate of myopic progression to clinically insignificant levels.
Background:
Nearsightedness (myopia) causes blurry vision when looking at distant objects. Highly nearsighted people are at greater risk of several vision-threatening problems such as retinal detachments, choroidal atrophy, cataracts and glaucoma. Interventions that have been explored to slow the progression of myopia include bifocal spectacles, cycloplegic drops, intraocular pressure-lowering drugs, muscarinic receptor antagonists and contact lenses. The purpose of this review was to systematically assess the effectiveness of strategies to control progression of myopia in children.
Objectives:
To assess the effects of several types of interventions, including eye drops, undercorrection of nearsightedness, multifocal spectacles and contact lenses, on the progression of nearsightedness in myopic children younger than 18 years. We compared the interventions of interest with each other, to single vision lenses (SVLs) (spectacles), placebo or no treatment.
Search methods:
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 11 October 2011. We also searched the reference lists and Science Citation Index for additional, potentially relevant studies.
Selection criteria:
We included randomized controlled trials (RCTs) in which participants were treated with spectacles, contact lenses or pharmaceutical agents for the purpose of controlling progression of myopia. We excluded trials where participants were older than 18 years at baseline or participants had less than -0.25 diopters (D) spherical equivalent myopia.
Data collection and analysis:
Two review authors independently extracted data and assessed the risk of bias for each included study. When possible, we analyzed data with the inverse variance method using a fixed-effect or random-effects model, depending on the number of studies and amount of heterogeneity detected.
Main results:
We included 23 studies (4696 total participants) in this review, with 17 of these studies included in quantitative analysis. Since we only included RCTs in the review, the studies were generally at low risk of bias for selection bias. Undercorrection of myopia was found to increase myopia progression slightly in two studies; children who were undercorrected progressed on average 0.15 D (95% confidence interval (CI) -0.29 to 0.00) more than the fully corrected SVLs wearers at one year. Rigid gas permeable contact lenses (RGPCLs) were found to have no evidence of effect on myopic eye growth in two studies (no meta-analysis due to heterogeneity between studies). Progressive addition lenses (PALs), reported in four studies, and bifocal spectacles, reported in four studies, were found to yield a small slowing of myopia progression. For seven studies with quantitative data at one year, children wearing multifocal lenses, either PALs or bifocals, progressed on average 0.16 D (95% CI 0.07 to 0.25) less than children wearing SVLs. The largest positive effects for slowing myopia progression were exhibited by anti-muscarinic medications. At one year, children receiving pirenzepine gel (two studies), cyclopentolate eye drops (one study), or atropine eye drops (two studies) showed significantly less myopic progression compared with children receiving placebo (mean differences (MD) 0.31 (95% CI 0.17 to 0.44), 0.34 (95% CI 0.08 to 0.60), and 0.80 (95% CI 0.70 to 0.90), respectively).
Authors' conclusions:
The most likely effective treatment to slow myopia progression thus far is anti-muscarinic topical medication. However, side effects of these medications include light sensitivity and near blur. Also, they are not yet commercially available, so their use is limited and not practical. Further information is required for other methods of myopia control, such as the use of corneal reshaping contact lenses or bifocal soft contact lenses (BSCLs) with a distance center are promising, but currently no published randomized clinical trials exist.
To evaluate accommodative response and facility in presbyopic patients fitted with several types of simultaneous-image multifocal contact lenses (CLs).
Six presbyopic patients, unadapted wearers of simultaneous-image bifocals, were fitted with the Focus Progressives and the low- and high-addition Pure Vision simultaneous vision multifocal CLs. Each individual wore each of the three types of lenses in successive random order. Accommodative response, accommodative facility, visual acuity, and contrast sensitivity at distance and near were evaluated in all cases. A control group of eight non-presbyopic patients was also studied.
The mean age was 28.6 ± 2.72 and 51.2 ± 5.81 years in the non-presbyopes and presbyopic patients, respectively. For the presbyopic group, statistically significant differences were not found for distance visual acuity between the baseline situations and with the three different CLs types. For the near visual acuity, there were no statistically significant differences between baseline situation (without add) compared with patients wearing the Focus Progressives and with PureVision Low Add. With the Purevision High Add, the near visual acuity was slightly better than baseline situation (p = 0.03). Non-presbyopic subjects showed relatively linear 1:1 stimulus response functions for all situations. Presbyopic subjects showed an increasing lag of accommodation with amplitude as they approach to the maximum amplitude for all situations. Distance and near accommodative facility rate for the presbyopic patients was zero for all conditions.
The results of this study suggest that simultaneous-image multifocal CLs studied do not alter accommodative functions. The high add of the Purevision CL enhances near vision for advanced presbyopes compared with the other models studied.
Myopia is the result of a mismatch between the optical power and the length of the eye, with the latter being too long. Driving the research in this field is the need to develop myopia treatments that can limit axial elongation. When axial elongation is excessive, as in high myopia, there is an increased risk of visual impairment and blindness due to ensuing pathologies such as retinal detachments. This article covers both clinical studies involving myopic children, and studies involving animal models for myopia. Atropine, a nonselective muscarinic antagonist, has been studied most extensively in both contexts. Because it remains the only drug used in a clinical setting, it is a major focus of the first part of this article, which also covers the many shortcomings of topical ophthalmic atropine. The second part of this article focuses on in vitro and animal-based drug studies, which encompass a range of drug targets including the retina, retinal pigment epithelium and sclera. While the latter studies have contributed to a better understanding of how eye growth is regulated, no new antimyopia drug treatments have reached the clinical setting. Less conservative approaches in research, and in particular, the exploration of new bioengineering approaches for drug delivery, are needed to advance this field.
To characterize the effects on refractive error development and eye growth in young chicks of two-zone concentric lens designs, which differentially affect the defocus experiences of central and peripheral retinal regions.
Monocular defocusing lenses were worn for 5 days from 17 days of age. Four two-zone concentric lens designs (overall optical zone diameter, 10 mm) combining plano with either -5- or +5-D power were used. Lens designs were as follows: (1) +5 D center (+5C), (2) +5 D periphery (+5P), (3) -5 D center (-5C), and (4) -5 D peripheral (-5P), with plano in periphery for all C-designs and in the center for P-designs. Five central zone diameters (CZDs) were tested, ranging from 2.5 to 6.5 mm in 1-mm increments. Plano, +5- and -5-D single-vision (SV) lenses were used as the control. A minimum of six birds were included in each lens group.
For the two-zone lenses, the P designs (i.e., peripheral defocus) had greater effects than the C designs (i.e., central defocus) on both on-axis eye growth and refractions. All but the 6.5-mm CZD +5P lens induced larger changes than the +5SV lens. The +5C lenses with CZD less than 5.5 mm had little effect. The two-zone -5-D lenses had less effect than the -5SV lens, and only the 6.5-mm CZD lens of the -5C series had a significant effect.
The results demonstrate that peripheral defocus can influence both peripheral and central refractive development. The inhibitory effect on axial eye growth of the +5P lenses opens the possibility that appropriately designed concentric lenses may control the progression of human myopia.
This study explores the relationship between the recalled age of first distance prescription and the final myopic refractive error developed in adults.
Adult office workers, sent for a general health check-up without refractive selection, completed a questionnaire about age of first distance prescription, years of university study, and parental history of myopia, and were subjectively refracted by an ophthalmologist.
Average age of the 397 consecutive myopic subjects was 42.6 +/- 9.6 years and 80.6% were males. The median age of first prescription was 20 years. In the group with earlier first distance prescription (ages 3 to 10), 25.6% developed low final refractive errors (-0.50 to -3.0 diopters), 38.5% developed moderate myopia (< -3.0 to -6.0 diopters), and 35.9% developed high myopia (< -6.0 diopters), while in the groups with later first distance prescription (ages 23 to 30), 90-100% developed low final refractive errors.
Subjects developing myopia after age 20 had low myopia. Those subjects with an early recalled age of first prescription had a broad spectrum of myopic refractive errors, including a high proportion (approximately 2/3) of moderate to high myopia, and approximately 1/3 of low myopia.
To assess the effect of bifocal soft contact lenses on the accommodative errors (lags) of young adults. Recent studies suggest that bifocal soft contact lenses are an effective myopia control treatment although the underlying mechanism is not understood.
Accommodation responses were measured for four target distances: 100, 50, 33 and 25 cm in 35 young adult subjects (10 emmetropes and 25 myopes; mean age, 22.8 +/- 2.5 years). Measurements were made under both monocular and binocular conditions with three types of lenses: single vision distance soft contact lenses (SVD), single vision near soft contact lenses (SVN; +1.50 D added to the distance prescription) and bifocal soft contact lenses (BF; +1.50 D add).
For the SVD lenses, all subjects exhibited lags of accommodation, with myopes accommodating significantly less than emmetropes for the 100 and 50 cm target distances (p < 0.05). With the SVN lenses, there was no significant difference in accommodative responses between emmetropes and myopes. With the BF lenses, both emmetropic and myopic groups exhibited leads in accommodation for all target distances, with emmetropes showing significantly greater leads for all distances (p < 0.005).
Overall, myopes tended to accommodate less than emmetropes, irrespective of the contact lens type, which significantly affected accommodation for both groups. The apparent over-accommodation of myopes when wearing the BF contact lenses may explain the reported efficacy as a myopia control treatment, although further studies are required to elucidate the mechanism underlying this accommodative effect.
Purpose:
To analyze the association between myopia and educational level in an adult European cohort.
Design:
Population-based cross-sectional study.
Participants:
A cohort of the Gutenberg Health Study, including 4658 eligible enrollees between 35 and 74 years of age.
Methods:
We applied a standardized protocol entailing a comprehensive questionnaire; thorough ophthalmic, general, cardiovascular, and psychological examinations; and laboratory tests, including genetic analyses. We documented achievement levels in school education and post-school professional education. The spherical equivalent (SE) was determined by noncycloplegic autorefractometry. We fitted mixed linear models including age, gender, and 45 myopia-associated single nucleotide polymorphisms (SNP) as covariates.
Main outcome measures:
Prevalence and magnitude of myopia in association with years spent in school and level of post-school professional education.
Results:
Individuals who graduated from school after 13 years were more myopic (median, -0.5 diopters [D]; first quartile [Q1]/third quartile [Q3], -2.1/0.3 D) than those who graduated after 10 years (median, -0.2 D; Q1/Q3, -1.3/0.8 D), than those who graduated after 9 years (median, 0.3 D; Q1/Q3, -0.6/1.4 D), and than those who never finished secondary school (median, 0.2 D; Q1/Q3, -0.5/1.8 D; P<0.001, respectively). The same holds true for persons with a university degree (median, -0.6 D; Q1/Q3, -2.3/0.3 D) versus those who finished secondary vocational school (median, 0 D; Q1/Q3, -1.1/0.8 D) or primary vocational school (median, 0 D; Q1/Q3, -0.9/1.1 D) versus persons without any post-school professional qualification (median, 0.6 D; Q1/Q3, -0.4/1.7 D; P<0.001, respectively). Of persons who graduated from school after 13 years, 50.9% were myopic (SE, ≤-0.5 D) versus 41.6%, 27.1%, and 26.9% after 10 years, in those who graduated after 9 years, and in those who never graduated from secondary school, respectively (P<0.001). In university graduates, the proportion of myopic persons was higher (53%) than that of those who graduated from secondary (34.8%) or primary (34.7%) vocational schools and than in those without any professional training (23.9%; P<0.001, respectively). In multivariate analyses: higher school and professional levels of education were associated with a more myopic SE independent of gender. There was a small effect of age and SNPs.
Conclusions:
Higher levels of school and post-school professional education are associated with a more myopic refraction. Participants with higher educational achievements more often were myopic than individuals with less education.
Importance:
Myopia is a significant public health problem, making it important to determine whether a bifocal spectacle treatment involving near prism slows myopia progression in children.
Objective:
To determine whether bifocal and prismatic bifocal spectacles control myopia in children with high rates of myopia progression and to assess whether the treatment effect is dependent on the lag of accommodation and/or near phoria status.
Design, setting, and participants:
This 3-year randomized clinical trial was conducted in a private practice. A total of 135 (73 female and 62 male) Chinese-Canadian children (aged 8-13 years; mean [SE] age, 10.29 [0.15] years; mean [SE] myopia, -3.08 [0.10] D) with myopia progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments. A total of 128 (94.8%) completed the trial.
Interventions:
Single-vision lenses (control, n = 41), +1.50-D executive bifocals (n = 48), and +1.50-D executive bifocals with 3-Δ base-in prism in the near segment of each lens (n = 46). MAIN OUTCOMES AND MEASURES Myopia progression (primary) measured using an automated refractor following cycloplegia and increase in axial length (secondary) measured using ultrasonography at intervals of 6 months for 36 months. RESULTS Myopia progression over 3 years was an average (SE) of -2.06 (0.13) D for the single-vision lens group, -1.25 (0.10) D for the bifocal group, and -1.01 (0.13) D for the prismatic bifocal group. Axial length increased an average (SE) of 0.82 (0.05) mm, 0.57 (0.07) mm, and 0.54 (0.06) mm, respectively. The treatment effect of bifocals (0.81 D) and prismatic bifocals (1.05 D) was significant (P < .001). Both bifocal groups had less axial elongation (0.25 mm and 0.28 mm, respectively) than the single-vision lens group (P < .001). For children with high lags of accommodation (≥ 1.01 D), the treatment effect of both bifocals and prismatic bifocals was similar (1.1 D) (P < .001). For children with low lags (<1.01 D), the treatment effect of prismatic bifocals (0.99 D) was greater than of bifocals (0.50 D) (P = .03). The treatment effect of both bifocals and prismatic bifocals was independent of the near phoria status.
Conclusions and relevance:
Bifocal spectacles can slow myopia progression in children with an annual progression rate of at least 0.50 D after 3 years. These results suggest that prismatic bifocals are more effective for myopic children with low lags of accommodation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00787579.
Purpose:
Eye growth compensates in opposite directions to single vision (SV) negative and positive lenses. We evaluated the response of the guinea pig eye to Fresnel-type lenses incorporating two different powers.
Methods:
A total of 114 guinea pigs (10 groups with 9-14 in each) wore a lens over one eye and interocular differences in refractive error and ocular dimensions were measured in each of three experiments. First, the effects of three Fresnel designs with various diopter (D) combinations (-5D/0D; +5D/0D or -5D/+5D dual power) were compared to three SV lenses (-5D, +5D, or 0D). Second, the ratio of -5D and +5D power in a Fresnel lens was varied (50:50 compared with 60:40). Third, myopia was induced by 4 days of exposure to a SV -5D lens, which was then exchanged for a Fresnel lens (-5D/+5D) or one of two SV lenses (+5D or -5D) and ocular parameters tracked for a further 3 weeks.
Results:
Dual power lenses induced an intermediate response between that to the two constituent powers (lenses +5D, +5D/0D, 0D, -5D/+5D, -5D/0D and -5D induced +2.1 D, +0.7 D, +0.1 D, -0.3 D, -1.6 D and -5.1 D in mean intraocular differences in refractive error, respectively), and changing the ratio of powers induced responses equal to their weighted average. In already myopic animals, continued treatment with SV negative lenses increased their myopia (from -3.3 D to -4.2 D), while switching to SV positive lenses or -5D/+5D Fresnel lenses reduced their myopia (by 2.9 D and 2.3 D, respectively).
Conclusions:
The mammalian eye integrates competing defocus to guide its refractive development and eye growth. Fresnel lenses, incorporating positive or plano power with negative power, can slow ocular growth, suggesting that such designs may control myopia progression in humans.
To determine if 'Defocus Incorporated Soft Contact' (DISC) lens wear slows childhood myopia progression.
A 2-year double-blind randomised controlled trial was carried out in 221 children aged 8-13 years, with myopia between -1.00 and -5.00 Dioptres (D) and astigmatism ≤1.00 D. Subjects were randomly assigned to the DISC (n=111) or single vision (SV; n=110) contact lens group. DISC lenses incorporated concentric rings, which provided an addition of +2.50 D, alternating with the normal distance correction. Refractive error (cycloplegic autorefraction) and axial length were measured at 6-month intervals. Differences between groups were analysed using unpaired t test.
In total, 128 children completed the study, n=65 in the DISC group and n=63 in the SV group. Myopia progressed 25% more slowly for children in the DISC group compared with those in the control group (0.30 D/year; 95% CI -0.71 to -0.47 vs 0.4 D/year; 95% CI -0.93 to -0.65, p=0.031). Likewise, there was less axial elongation for children in the DISC versus SV groups (0.13 mm/year; 95% CI 0.20 to 0.31 vs 0.18 mm/year; 95% CI 0.30 to 0.43, p=0.009). Treatment effect correlated positively with DISC lens wearing time (r=0.342; p=0.005). Indeed, myopia in children who wore the DISC lenses for five or more hours/day progressed 46% (mean difference=-0.382 D, p=0.001; 95% CI -0.59 to -0.17) less than those in the SV group.
The daily wearing of DISC lens significantly slowed myopia progression and axial elongation in Hong Kong schoolchildren. The findings demonstrated that simultaneous clear vision with constant myopic defocus can retard myopia progression.
To compare the effect of wearing, then ceasing to wear, progressive addition lenses (PALs) versus single vision lenses (SVLs) on myopia progression in children with high accommodative lag to evaluate accommodative lag and mechanical tension as theories of myopia progression.
Eighty-five children (age range, 6-11 years) with spherical equivalent (SE) cycloplegic autorefraction between -0.75 D and -4.50 D were randomly assigned to wear SVLs or PALs for 1 year; all children wore SVLs a second year. Children had high accommodative lag and also had near esophoria if their myopia was greater than -2.25 D SE. The primary outcome after each year was the previous year's change in SE.
When the children were randomly assigned to SVLs or PALs, the adjusted 1-year changes in SE were -0.52 D (SVL group) and -0.35 D (PAL group; treatment effect = 0.18 D; P = 0.01). When all children wore SVLs the second year, there was no difference in myopia progression between SVL and former PAL wearers (0.06 D; P = 0.50). Accommodative lag was not associated with myopia progression.
The statistically significant, but clinically small, PAL effect suggests that treatments aimed at reducing foveal defocus may not be as effective as previously thought in myopic children with high accommodative lag. Finding no evidence of treatment loss after discontinuing PAL wear supports hyperopic defocus-based theories such as accommodative lag; however, not finding an association between accommodative lag and myopia progression is inconsistent with the PAL effect being due to decreased foveal blur during near work. (Clinical Trials.gov number, NCT00335049.).
Registered data can provide valuable information regarding blindness. The purpose of this study was to evaluate the main causes and 3-year incidence of registered blindness in Jing-An district in Shanghai, China.
Data from the blindness registry (age, gender and cause of visual disability) were collected and analyzed. The prevalence of blindness for 2003, 2007, 2009 and the 3-year incidence of blindness were calculated.
The reported blindness increased significantly from 113.7 per 100,000 in 2003 to 145.8 per 100,000 in 2006 to 165.9 per 100,000 in 2009 (P < 0.05, P < 0.05, respectively). Age significantly affects prevalence; the odd ratios (OR) were 2.57 in the 30 y - 49 y range (P < 0.001), 7.27 in the 50 y - 69 y range (P < 0.001) and 21.2 in the ≥ 70 y (P < 0.001). The 3-year incidence increased from 32.3 per 100,000 in 2001-2003 to 34.2 per 100,000 in 2004-2006 to 40.8 per 100,000 in 2007-2009. The causes of new blindness registered in 2001-2009 were myopic macular degeneration (19.4%), followed by glaucoma (17.7%), age-related macular degeneration (11.8%), optical nerve atrophy (9.4%), retinitis pigmentosa (8.6%), diabetic retinopathy (7.8%) and corneal opacity (5.8%).
The 3-year incidence and prevalence of registered blindness increased in the past 9 years. The leading causes of new blindness were myopic macular degeneration, glaucoma and age-related macular degeneration. The pattern of causes has changed little in the past 9 years and is different from other locations in China. The pattern is similar to that of Taiwan, Hongkong, and Western countries.
Anecdotal evidence indicates that corneal reshaping contact lenses may slow myopia progression in children. The purpose of this investigation is to determine whether corneal reshaping contact lenses slow eye growth.
Forty subjects were fitted with corneal reshaping contact lenses. All subjects were 8 to 11 years and had between -0.75 D and -4.00 D myopia with less than 1.00 D astigmatism. Subjects were age-matched to a soft contact lens wearer from another myopia control study. A-scan ultrasound was performed at baseline and annually for 2 years.
Twenty-eight of 40 (70%) subjects wore corneal reshaping contact lenses for 2 years. The refractive error and axial length were similar between the two groups at baseline. The corneal reshaping group had an annual rate of change in axial lengths that was significantly less than the soft contact lens wearers (mean difference in annual change = 0.16 mm, p = 0.0004). Vitreous chamber depth experienced similar changes (mean difference in annual change = 0.10 mm, p = 0.006).
Results confirm previous reports of slowed eye growth following corneal reshaping contact lens wear.
The aim of this study was to assess the effect on myopia progression after cessation of topical atropine treatment.
Parallel-group, placebo-controlled, randomized, double-masked study.
Four hundred children aged 6 to 12 years with refractive error of spherical equivalent -1.00 to -6.00 diopters (D) and astigmatism of -1.50 D or less.
No intervention was administered. Subjects were followed up for 12 months after stopping treatment, which consisted of either 1% atropine or vehicle eyedrops once nightly for 2 years. Only 1 eye of each subject was chosen through randomization for treatment.
The main efficacy outcome measures were change in spherical equivalent refraction as measured by cycloplegic autorefraction and change in ocular axial length as measured by ultrasonography.
After cessation of atropine drops, the mean progression in the atropine-treated group was -1.14+/-0.80 D over 1 year, whereas the progression in placebo-treated eyes was -0.38+/-0.39 D (P<0.0001). However, after 3 years of participation in the trial (with 2 years on atropine treatment), eyes randomized to atropine have less severe myopia than other eyes. Spherical equivalent was -4.29+/-1.67 D in the atropine-treated eyes compared with -5.22+/-1.38 D in the placebo-treated eyes (P<0.0001). Spherical equivalents in atropine-untreated and placebo-untreated eyes were -5.00+/-1.62 D and -5.28+/-1.43 D, respectively. Over the 3 years, the increase in axial length of the atropine-treated eyes was 0.29+/-0.37 mm compared with 0.52+/-0.45 mm in the placebo-treated eyes (P<0.0001). After cessation of atropine, the amplitude of accommodation and near visual acuity returned to pretreatment levels.
After stopping treatment, eyes treated with atropine demonstrated higher rates of myopia progression compared with eyes treated with placebo. However, the absolute myopia progression after 3 years was significantly lower in the atropine group compared with placebo.
In chicks, visual deprivation leads to myopia and enlargement of the vitreous chamber of the eye. When chicks were raised with white translucent occluders over their eyes so that either the nasal half, the temporal half, or all of the retina was visually deprived, the resulting myopia (median = -15 diopters) was limited to the deprived part of the retina, regardless of which half of the retina was visually deprived; the nondeprived part remained nearly emmetropic. Correspondingly, the vitreous chamber was elongated only in the region of the visual deprivation, resulting in eyes with different asymmetric shapes depending on which retinal region was deprived. These results argue for a local regulation of ocular growth that is dependent on vision and suggest a hypothesis to explain the epidemiological association of myopia in humans with large amounts of reading. Because most nonfoveal retinal neurons have large receptive fields, they cannot resolve the individual letters on the printed page; this may lead to their activity being less during reading than during most other forms of visual stimulation. Thus, the impoverished stimulus situation of reading may lead to myopia, as do other types of visual form deprivation.
In the chick, compensation for experimentally induced defocus involves changes in the thickness of the choroid. The choroid thickens in response to imposed myopic defocus and thins in response to imposed hyperopic defocus. This study was undertaken to determine whether similar choroidal changes occur in the primate eye with induced refractive errors.
Thirty-three common marmosets were used. Eyes in 26 monkeys served as untreated control eyes, and eyes in 7 received 3 weeks of monocular lid suture to induce changes in eye growth and refractive state. Refractive errors were measured using refractometry and retinoscopy, and axial ocular dimensions, including choroidal thickness, were measured using high-frequency A-scan ultrasonography. Eyes were measured before the lids were sutured and at frequent intervals after lid opening.
In the marmoset, choroidal thickness ranges from 88 to 150 microm and increases significantly during the first year of life. Monocular lid suture initially results in short, hyperopic eyes that then become elongated and myopic. In these animals the choroids of both the experimental and the fellow control eyes also increase in thickness with age but additionally show interocular differences that vary significantly with the relative changes in vitreous chamber depth and refraction. In eyes that are shorter and more hyperopic than control eyes the choroids are thicker, and in eyes that are longer and more myopic than control eyes the choroids are thinner.
In marmosets, the thickness of the choroid increases during postnatal eye growth. Superimposed on this developmental increase in choroidal thickness there are changes in thickness that are correlated with the induced changes in eye size. These changes are small (<50 microm) in comparison with those observed in the chick, contributing to less than a diopter change in refractive error.
To determine the relation of refractive error to environmental factors, including close up work, in Singapore military conscripts.
A cross sectional study was conducted on 429 Singapore military conscripts. Non-cycloplegic refraction and A-scan biometry were performed in both eyes. A detailed questionnaire was administered by in-person interview to obtain information about current and past near work activity, extra tuition lessons, educational experiences, and family demographics.
Myopia associated with the conscript having been educated in the (gifted, special, or express) educational streams (adjusted odds ratio (OR) = 3.8, 95% confidence interval CI 2.0-7.3), and having completed pre-university education (OR=4.1, 95% CI 1.9-8.8). The reported close up work activity at age 7 years did correlate with age of onset of myopia (p<0.001). In parallel, supplemental tuition lessons in primary school has (OR=2.6, 95% CI 1.4-4.9) associated with conscript myopia. Parental myopia was positively associated with myopia (p<0.001), but this relation disappeared when adjusted for environmental factors. Current (p=0.83) and past close up work activity at age 7 years (p=0.13) did not correlate with myopia.
Educational level and educational stream positively related to myopia. A relation was observed with reported close up work activity in early childhood and with tuition classes during elementary school, but not with current close up work activity. These results underscore the strong influence of environment in myopia pathogenesis but a role for close up work activity remains indeterminate.
The purpose of the Correction of Myopia Evaluation Trial (COMET) was to evaluate the effect of progressive addition lenses (PALs) compared with single vision lenses (SVLs) on the progression of juvenile-onset myopia.
COMET enrolled 469 children (ages 6-11 years) with myopia between -1.25 and -4.50 D spherical equivalent. The children were recruited at four colleges of optometry in the United States and were ethnically diverse. They were randomly assigned to receive either PALs with a +2.00 addition (n = 235) or SVLs (n = 234), the conventional spectacle treatment for myopia, and were followed for 3 years. The primary outcome measure was progression of myopia, as determined by autorefraction after cycloplegia with 2 drops of 1% tropicamide at each annual visit. The secondary outcome measure was change in axial length of the eyes, as assessed by A-scan ultrasonography. Child-based analyses (i.e., the mean of the two eyes) were used. Results were adjusted for important covariates, by using multiple linear regression.
Of the 469 children (mean age at baseline, 9.3 +/- 1.3 years), 462 (98.5%) completed the 3-year visit. Mean (+/-SE) 3-year increases in myopia (spherical equivalent) were -1.28 +/- 0.06 D in the PAL group and -1.48 +/- 0.06 D in the SVL group. The 3-year difference in progression of 0.20 +/- 0.08 D between the two groups was statistically significant (P = 0.004). The treatment effect was observed primarily in the first year. The number of prescription changes differed significantly by treatment group only in the first year. At 6 months, 17% of the PAL group versus 30% of the SVL group needed a prescription change (P = 0.0007), and, at 1 year, 43% of the PAL group versus 59% of the SVL group required a prescription change (P = 0.002). Interaction analyses identified a significantly larger treatment effect of PALs in children with lower versus higher baseline accommodative response at near (P = 0.03) and with lower versus higher baseline myopia (P = 0.04). Mean (+/- SE) increases in the axial length of eyes of children in the PAL and SVL groups, respectively, were: 0.64 +/- 0.02 mm and 0.75 +/- 0.02 mm, with a statistically significant 3-year mean difference of 0.11 +/- 0.03 mm (P = 0.0002). Mean changes in axial length correlated with those in refractive error (r = 0.86 for PAL and 0.89 for SVL).
Use of PALs compared with SVLs slowed the progression of myopia in COMET children by a small, statistically significant amount only during the first year. The size of the treatment effect remained similar and significant for the next 2 years. The results provide some support for the COMET rationale-that is, a role for defocus in progression of myopia. The small magnitude of the effect does not warrant a change in clinical practice.
To examine baseline measurements of accommodative lag, phoria, reading distance, amount of near work, and level of myopia as risk factors for progression of myopia and their interaction with treatment over 3 years, in children enrolled in the Correction of Myopia Evaluation Trial (COMET).
COMET enrolled 469 ethnically diverse children (ages, 6-11 years) with myopia between -1.25 and -4.50 D. They were randomly assigned to either progressive addition lenses (PALs) with a +2.00 addition (n = 235) or single vision lenses (SVLs; n = 234), the conventional spectacle treatment, and were observed for 3 years. The primary outcome measure was progression of myopia by autorefraction after cycloplegia with 2 drops of 1% tropicamide. Other measurements included accommodative response (by an open field of view autorefractor), phoria (by cover test), reading distance, and hours of near work. Independent and interaction analyses were based on the mean of the two eyes. Results were adjusted for important covariates with multiple linear regression.
Children with larger accommodative lags (>0.43 D for a 33 cm target) wearing SVLs had the most progression at 3 years. PALs were effective in slowing progression in these children, with statistically significant 3-year treatment effects (mean +/- SE) for those with larger lags in combination with near esophoria (PAL - SVL progression = -1.08 D - [-1.72 D] = 0.64 +/- 0.21 D), shorter reading distances (0.44 +/- 0.20 D), or lower baseline myopia (0.48 +/- 0.15 D). The 3-year treatment effect for larger lags in combination with more hours of near work was 0.42 +/- 0.26 D, which did not reach statistical significance. Statistically significant treatment effects were observed in these four groups at 1 year and became larger from 1 to 3 years.
The results support the COMET rationale (i.e., a role for retinal defocus in myopia progression). In clinical practice in the United States children with large lags of accommodation and near esophoria often are prescribed PALs or bifocals to improve visual performance. Results of this study suggest that such children, if myopic, may have an additional benefit of slowed progression of myopia.
To determine axial, vertical, and horizontal eye dimensions in myopic and emmetropic eyes by using magnetic resonance imaging (MRI) and to relate these to different ocular expansion models of myopia development.
The internal length (cornea to retina), height and width (both retina to retina) were measured in emmetropic and myopic eyes (up to -12 D) of 88 participants aged 18 to 36 years. Participants were positioned supine in a clinical MRI scanner. The fixation target was imaged straight ahead of the subject by an overhead 45 degrees inclined mirror. Eye images were acquired with a 7.5-cm receive-only radio frequency surface coil. Axial (horizontal through middle of eye) and sagittal (vertical through visual axis) sections were taken with a T(1)-weighted fast spin-echo sequence.
With an increase in myopic refractive correction, myopic eyes became much larger in all three dimensions, but more so in length (0.35 mm/D, 95% confidence interval [CI] 0.28-0.40) than in height (0.19 mm/D, 95% CI 0.09-0.29) and more so in height than in width (0.10 mm/D, 95% CI 0.01-0.20). Based on height and length dimensions, 25% and 29% of myopic eyes exclusively fitted global expansion and axial elongation models, respectively. Based on width and length dimensions, 17% and 39% of myopic eyes exclusively fitted the global expansion and axial elongation models, respectively.
Although there are considerable individual variations, in general myopic eyes are elongated relative to emmetropic eyes, more in length than in height and even less in width. Approximately a quarter of the myopic participants fitted each of the global expansion or axial elongation model exclusively. The small proportions are due primarily to the large variability in the dimensions of emmetropic eyes.
Given the prominence of central vision in humans, it has been assumed that visual signals from the fovea dominate emmetropization. The purpose of this study was to examine the impact of peripheral vision on emmetropization.
Bilateral, peripheral form deprivation was produced in 12 infant monkeys by rearing them with diffusers that had either 4- or 8-mm apertures centered on the pupils of each eye, to allow 24 degrees or 37 degrees of unrestricted central vision, respectively. At the end of the lens-rearing period, an argon laser was used to ablate the fovea in one eye of each of seven monkeys. Subsequently, all the animals were allowed unrestricted vision. Refractive error and axial dimensions were measured along the pupillary axis by retinoscopy and A-scan ultrasonography, respectively. Control data were obtained from 21 normal monkeys and 3 infants reared with binocular plano lenses.
Nine of the 12 treated monkeys had refractive errors that fell outside the 10th- and 90th-percentile limits for the age-matched control subjects, and the average refractive error for the treated animals was more variable and significantly less hyperopic/more myopic (+0.03 +/- 2.39 D vs. +2.39 +/- 0.92 D). The refractive changes were symmetric in the two eyes of a given animal and axial in nature. After lens removal, all the treated monkeys recovered from the induced refractive errors. No interocular differences in the recovery process were observed in the animals with monocular foveal lesions.
On the one hand, the peripheral retina can contribute to emmetropizing responses and to ametropias produced by an abnormal visual experience. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses.
To evaluate the efficacy and safety of topical atropine, a nonselective muscarinic antagonist, in slowing the progression of myopia and ocular axial elongation in Asian children.
Parallel-group, placebo-controlled, randomized, double-masked study.
Four hundred children aged 6 to 12 years with refractive error of spherical equivalent -1.00 to -6.00 diopters (D) and astigmatism of -1.50 D or less.
Participants were assigned with equal probability to receive either 1% atropine or vehicle eye drops once nightly for 2 years. Only 1 eye of each subject was chosen through randomization for treatment.
The main efficacy outcome measures were change in spherical equivalent refraction as measured by cycloplegic autorefraction and change in ocular axial length as measured by ultrasonography. The primary safety outcome measure was the occurrence of adverse events.
Three hundred forty-six (86.5%) children completed the 2-year study. After 2 years, the mean progression of myopia and of axial elongation in the placebo-treated control eyes was -1.20+/-0.69 D and 0.38+/-0.38 mm, respectively. In the atropine-treated eyes, myopia progression was only -0.28+/-0.92 D, whereas the axial length remained essentially unchanged compared with baseline (-0.02+/-0.35 mm). The differences in myopia progression and axial elongation between the 2 groups were -0.92 D (95% confidence interval, -1.10 to -0.77 D; P<0.001) and 0.40 mm (95% confidence interval, 0.35-0.45 mm; P<0.001), respectively. No serious adverse events related to atropine were reported.
Topical atropine was well tolerated and effective in slowing the progression of low and moderate myopia and ocular axial elongation in Asian children.
PURPOSE. To determine whether the use of progressive addition spectacle lenses reduced the progression of myopia, over a 2-year period, in Hong Kong children between the ages of 7 and 10.5 years. METHODS. A clinical trial was carried out to compare the progression in myopia in a treatment group of 138 (121 retained) subjects wearing progressive lenses (PAL; add + 1.50 D) and in a control group of 160 (133 retained) subjects wearing single vision lenses (SV). The research design was masked with random allocation to groups. Primary measurements outcomes were spherical equivalent refractive error and axial length (both measured using a cycloplegic agent). RESULTS. There were no statistically significant differences between the PAL and the SV groups for of any of the baseline outcome measures. After 2 years there had been statistically significant increases in myopia and axial length in both groups; however, there was no difference in the increases that occurred between the two groups. CONCLUSIONS. The research design used resulted in matched treatment and control groups. There was no evidence that progression of myopia was retarded by wearing progressive addition lenses, either in terms of refractive error or axial length.
To investigate the effect of overnight orthokeratology (OK) contact lens wear on axial length growth in East Asian children with progressive myopia.
A prospective, randomized, contralateral-eye crossover study conducted over a 1-year period.
We enrolled 26 myopic children (age range, 10.8-17.0 years) of East Asian ethnicity.
Subjects were fitted with overnight OK in 1 eye, chosen at random, and conventional rigid gas-permeable (GP) lenses for daytime wear in the contralateral eye. Lenses were worn for 6 months. After a 2-week recovery period without lens wear, lens-eye combinations were reversed and lens wear was continued for a further 6 months, followed by another 2-week recovery period without lens wear. Axial eye length was monitored at baseline and every 3 months using an IOLMaster biometer. Corneal topography (Medmont E300) and objective refraction (Shin-Nippon NVision-K 5001 autorefractor) were also measured to confirm that OK lens wear was efficacious in correcting myopia.
Axial length elongation and myopia progression with OK were compared with conventional daytime rigid contact lens wear.
After 6 months of lens wear, axial length had increased by 0.04±0.06 mm (mean ± standard deviation) in the GP eye (P = 0.011) but showed no change (-0.02±0.05 mm) in the OK eye (P = 0.888). During the second 6-month phase of lens wear, in the OK eye there was no change from baseline in axial length at 12 months (-0.04±0.08 mm; P = 0.218). However, in the GP eye, the 12-month increase in axial length was significant (0.09±0.09 mm; P < 0.001). The GP lens-wearing eye showed progressive axial length growth throughout the study.
These results provide evidence that, at least in the initial months of lens wear, overnight OK inhibits axial eye growth and myopia progression compared with conventional GP lenses. Apparent shortening of axial length early in OK lens wear may reflect the contribution of OK-induced central corneal thinning, combined with choroidal thickening or recovery due to a reduction or neutralization of the myopiogenic stimulus to eye growth in these myopic children.
Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
To investigate the influence of monocular hyperopic defocus on the normal diurnal rhythms in axial length and choroidal thickness of young adults.
A series of axial length and choroidal thickness measurements (collected at ∼3 hourly intervals, with the first measurement at ∼9 am and the final measurement at ∼9 pm) were obtained for 15 emmetropic young adults over three consecutive days. The natural diurnal rhythms (day 1, no defocus), diurnal rhythms with monocular hyperopic defocus (day 2, -2.00 DS spectacle lens over the right eye), and the recovery from any defocus induced changes (day 3, no defocus) in diurnal rhythms were examined.
Both axial length and choroidal thickness underwent significant diurnal changes on each of the three measurement days (p < 0.0001). The introduction of monocular hyperopic defocus resulted in significant changes in the diurnal variations observed in both parameters (p < 0.05). A significant (p < 0.001) increase in the mean amplitude (peak to trough) of change in axial length (mean increase, 0.016 ± 0.005 mm) and choroidal thickness (mean increase, 0.011 ± 0.003 mm) was observed on day 2 with hyperopic defocus compared to the two "no defocus" days (days 1 and 3). At the second measurement (mean time 12:10 pm) on the day with hyperopic defocus, the eye was significantly longer by 0.012 ± 0.002 mm compared to the other two days (p < 0.05). No significant difference was observed in the average timing of the daily peaks in axial length (mean peak time 12:12 pm) and choroidal thickness (21:02 pm) over the three days.
The introduction of monocular hyperopic defocus resulted in a significant increase in the amplitude of the diurnal change in axial length and choroidal thickness that returned to normal the following day after removal of the blur stimulus.
Previous studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years.
Eight- to eleven-year-old children with -1.00 D to -6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal "D"; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers.
Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was -1.03 ± 0.06 D for the single-vision contact lens wearers and -0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016).
Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.
Purpose:
This nonrandomized clinical study aimed to investigate the effectiveness of toric orthokeratology (ortho-k) for myopia control in myopic children with moderate-to-high astigmatism
Methods:
We enrolled 80 subjects (aged 6-12 years; ortho-k, 43; control, 37) with myopia of 0.50 to 5.00 diopters (D), and with-the-rule astigmatism of -1.25 to -3.50 D, and unremarkable ocular and general conditions. Data collection, including visual acuity, subjective and objective refraction, axial length, corneal topography, and biomicroscopy examination, was performed every 6 months during the 24-month study period. Results from the right eye or the eye with higher astigmatism were reported.
Results:
A total of 35 ortho-k and 23 control subjects completed the study successfully. Subjects in both groups demonstrated axial elongation (P < 0.001). The average axial elongation at the end of study was 0.31 ± 0.27 and 0.64 ± 0.31 mm in the ortho-k and control groups, respectively (P < 0.001). At the end of 24 months, axial elongation in ortho-k subjects was 52% slower than that in the control group. Axial elongation was correlated significantly with the initial age of the subjects (P = 0.02) and treatment assigned (P = 0.04), but not with sex, initial myopia, initial refractive cylinder, or initial corneal toricity (P > 0.08).
Conclusions:
Toric ortho-k lenses can slow axial elongation effectively in myopic children with moderate-to-high astigmatism. (ClinicalTrials.gov number, NCT00978692.).
Young eyes compensate for the defocus imposed by spectacle lenses by changing their rate of elongation and their choroidal thickness, bringing their refractive status back to the pre-lens condition. We asked whether the initial rate of change either in the ocular components or in refraction is a function of the power of the lenses worn, a result that would be consistent with the existence of a proportional controller mechanism.
Two separate studies were conducted; both tracked changes in refractive errors and ocular dimensions. Study A: To study the effects of lens power and sign, young chicks were tracked for 4 days after they were fitted with positive (+5, +10 or +15 D) or negative (-5, -10, -15 D) lenses over one eye. In another experiment, biometric changes to plano, +1, +2 and +3 D lenses were tracked over a 24 h treatment period. Study B: Normal emmetropisation was tracked from hatching to 6 days of age and then a defocusing lens, either +6 D or -7 D, was fitted over one eye and additional biometric data collected after 48 h.
In study A, animals treated with positive lenses (+5, +10 or +15 D) showed statistical similar initial choroid responses, with a mean thickening 24 μm h(-1) over the first 5 h. Likewise, with the low power positive lenses, a statistically similar magnitude of choroidal thickening was observed across groups (+1 D: 46.0 ± 7.8 μm h(-1) ; +2 D: 53.5 ± 9.9 μm h(-1) ; +3 D 53.3 ± 24.1 μm h(-1) ) in the first hour of lens wear compared to that of a plano control group. These similar rates of change in choroidal thickness indicate that the signalling response is binary in nature and not influenced by the magnitude of the myopic defocus. Treatments with -5, -10 and -15 D lenses induced statistically similar amounts of choroidal thinning, averaging -70 ± 15 μm after 5 h and -96 ± 45 μm after 24 h. Similar rates in inner axial length changes were also seen with these lens treatments until compensation was reached, once again indicating that the signalling response is not influenced by the magnitude of hyperopic defocus. In study B, after 48 h of +6 D lens treatment, the average refractive error and choroidal changes were found to be larger in magnitude than expected if perfect compensation had taken place, with a + 2.4 D overshoot in refractive compensation.
Taken together, our results with both weak and higher power positive lenses suggest that eye growth is guided more by the sign than by the magnitude of the defocus, and our results for higher power negative lenses support a similar conclusion. These behaviour patterns and the overshoot seen in Study B are more consistent with the behaviour of a bang-bang controller than a proportional controller.
Purpose:
To describe the time course of changes in both peripheral refraction and corneal topography in myopic adults wearing myopic orthokeratology (OK) lenses.
Methods:
Nineteen adult myopes were fitted with OK lenses in both eyes for overnight wear. Central and peripheral refraction and corneal topography were measured along the horizontal meridian at baseline and after 1, 4, 7 and 14 nights of lens wear.
Results:
At baseline, refraction was myopic at all positions along the horizontal meridian. Two weeks of OK lens wear caused a significant change in refraction where the general trend was a hyperopic shift in spherical equivalent (M) except at 35° in the nasal visual field where there was instead a myopic shift in M. The most significant change in M occurred between baseline and after 1 night of OK lens wear and the effect became less dramatic across subsequent days of OK treatment. Similarly, OK caused significant change in corneal refractive power at all positions along the horizontal corneal chord. There was a reduction in corneal power or flattening of the cornea at all positions except at 2.4 mm and 2.8 mm on the nasal cornea where there was an increase in corneal refractive power or steepening of the cornea. This change was most apparent after 1 night of OK lens wear and, similar to changes in peripheral refraction, changes in corneal refractive power on subsequent days of OK treatment became less marked.
Conclusions:
Orthokeratology caused significant changes in both peripheral refraction and corneal topography. The greatest change in refraction and corneal refractive power across the horizontal corneal meridian occurred during the first night of OK lens wear. Subsequent changes in both peripheral refraction and corneal topography were less dramatic, in the same manner as reported changes in apical radius and central refraction after OK. This study confirms that with OK treatment, the peripheral retina experiences myopic defocus, which is conjectured to underlie the observed slowing of myopia progression.
Purpose:
Myopia is an important cause of correctable visual impairment worldwide. Genetic and environmental factors contribute to its development. The population of Chinese university students consists of approximately 30 million young people characterized by academic excellence and similar ages. To date, little is known about their refractive status. Our study is designed to investigate the prevalence of myopia in this specific population.
Methods:
This is a cross-sectional study of myopia among university students in Shanghai, China; 5083 students from Donghua University were enrolled. All participants first responded to a detailed questionnaire, including questions on ethnicity, birth date, and family history, and then undertook a standardized ophthalmologic examination, including visual acuity, a slit-lamp examination, and non-cycloplegic autorefraction.
Results:
The mean spherical equivalent refraction (SER) of the university students was -4.1 diopters (D). Of the subjects 95.5% were myopic (SER < -0.50 D), 19.5% were highly myopic (SER < -6.0 D), and only 3.3% were emmetropic (-0.5 D ≤ SER ≤ 0.5 D). The postgraduates were more myopic than the undergraduates (96.9% and 94.9%, respectively). Being female (-4.1 ± 2.4 D in female versus -3.8 ± 2.4 D in male subjects), of Han ethnicity (-4.1 ± 2.4 D in Han versus -3.4 ± 2.2 D in minorities), and of older age were associated with a higher probability of myopia only in the undergraduate population.
Conclusions:
The prevalence of myopia and high myopia in this university student population was high. The refractive status of this population deserves further attention.
Purpose:
This single-masked randomized clinical trial aimed to evaluate the effectiveness of orthokeratology (ortho-k) for myopic control.
Methods:
A total of 102 eligible subjects, ranging in age from 6 to 10 years, with myopia between 0.50 and 4.00 diopters (D) and astigmatism not more than 1.25D, were randomly assigned to wear ortho-k lenses or single-vision glasses for a period of 2 years. Axial length was measured by intraocular lens calculation by a masked examiner and was performed at the baseline and every 6 months. This study was registered at ClinicalTrials.gov, number NCT00962208.
Results:
In all, 78 subjects (37 in ortho-k group and 41 in control group) completed the study. The average axial elongation, at the end of 2 years, were 0.36 ± 0.24 and 0.63 ± 0.26 mm in the ortho-k and control groups, respectively, and were significantly slower in the ortho-k group (P < 0.01). Axial elongation was not correlated with the initial myopia (P > 0.54) but was correlated with the initial age of the subjects (P < 0.001). The percentages of subjects with fast myopic progression (>1.00D per year) were 65% and 13% in younger (age range: 7-8 years) and older (age range: 9-10 years) children, respectively, in the control group and were 20% and 9%, respectively, in the ortho-k group. Five subjects discontinued ortho-k treatment due to adverse events.
Conclusions:
On average, subjects wearing ortho-k lenses had a slower increase in axial elongation by 43% compared with that of subjects wearing single-vision glasses. Younger children tended to have faster axial elongation and may benefit from early ortho-k treatment. (ClinicalTrials.gov number, NCT00962208.).
To examine prevalence of refractive errors and its associated factors, such as body stature and educational level, among 19-year-old males in Seoul, Korea.
A population-based cross-sectional study was performed in male subjects (n = 23,616; age = 19 years) who were normally resident in Seoul for male compulsory conscripts during the study period (2010). Refractive examination was performed with cycloplegia. Height, weight, and educational level were examined. Myopia was defined as a spherical equivalent less than -0.5 diopters (D) and high myopia less than -6.0 D. The association of myopia with body stature and educational level was analyzed using logistic regression analysis.
The prevalence of myopia in 19-year-old males in Seoul was 96.5%. The prevalence of high myopia was 21.61%. Body stature was not significantly associated with myopia. Four- to 6-year university students (odds ratio [OR] 1.69; P < 0.001) and 2 to 3-year college students (OR 1.68; P < 0.001) showed significantly higher risk for myopia than those with lower academic achievement (< high school graduation).
The 19-year-old male population in Seoul, Korea, demonstrated a very high myopic prevalence. Myopic refractive error was associated with academic achievement, not with body stature.
Our prospective study was conducted to compare axial length elongation in myopic children receiving long-term overnight orthokeratology (OK) treatment to those wearing spectacles as controls.
There were 59 subjects enrolled in this study. The OK group comprised 29 subjects who matched the inclusion criteria for OK. The control group comprised 30 subjects who also matched the inclusion criteria for OK, but preferred spectacles for myopia correction. Axial length was measured periodically for 5 years using an IOLMaster device, and the time course of changes was evaluated and compared between the groups.
A total of 43 subjects (22 and 21 in the OK and control groups, respectively) completed the 5-year follow-up examinations. At baseline, the mean age ± SD was 10.04 ± 1.43 and 9.95 ± 1.59 years, the spherical equivalent refractive error was -1.89 ± 0.82 and -1.83 ± 1.06 diopters (D), and the axial length was 24.09 ± 0.77 and 24.22 ± 0.71 mm in the OK and control groups, respectively, with no significant differences between the groups. The increase in axial length during the 5-year study period was 0.99 ± 0.47 and 1.41 ± 0.68 mm for the OK and control groups, respectively, and the difference was statistically significant (P = 0.0236, unpaired t-test). The annual increases in axial length were significantly different between the groups for the first (P = 0.0002), second (P = 0.0476), and third years (P = 0.0385), but not for the fourth (P = 0.0938) and fifth (P = 0.8633) years. There were no severe complications throughout the study period.
The current 5-year follow-up study indicated that OK can suppress axial length elongation in childhood myopia.
To test the efficacy of an experimental Dual-Focus (DF) soft contact lens in reducing myopia progression.
Prospective, randomized, paired-eye control, investigator-masked trial with cross-over.
Forty children, 11-14 years old, with mean spherical equivalent refraction (SER) of -2.71 ± 1.10 diopters (D).
Dual-Focus lenses had a central zone that corrected refractive error and concentric treatment zones that created 2.00 D of simultaneous myopic retinal defocus during distance and near viewing. Control was a single vision distance (SVD) lens with the same parameters but without treatment zones. Children wore a DF lens in 1 randomly assigned eye and an SVD lens in the fellow eye for 10 months (period 1). Lens assignment was then swapped between eyes, and lenses were worn for a further 10 months (period 2).
Primary outcome was change in SER measured by cycloplegic autorefraction over 10 months. Secondary outcome was a change in axial eye length (AXL) measured by partial coherence interferometry over 10 months. Accommodation wearing DF lenses was assessed using an open-field autorefractor.
In period 1, the mean change in SER with DF lenses (-0.44 ± 0.33 D) was less than with SVD lenses (-0.69 ± 0.38 D; P < 0.001); mean increase in AXL was also less with DF lenses (0.11 ± 0.09 mm) than with SVD lenses (0.22 ± 0.10 mm; P < 0.001). In 70% of the children, myopia progression was reduced by 30% or more in the eye wearing the DF lens relative to that wearing the SVD lens. Similar reductions in myopia progression and axial eye elongation were also observed with DF lens wear during period 2. Visual acuity and contrast sensitivity with DF lenses were not significantly different than with SVD lenses. Accommodation to a target at 40 cm was driven through the central distance-correction zone of the DF lens.
Dual-Focus lenses provided normal acuity and contrast sensitivity and allowed accommodation to near targets. Myopia progression and eye elongation were reduced significantly in eyes wearing DF lenses. The data suggest that sustained myopic defocus, even when presented to the retina simultaneously with a clear image, can act to slow myopia progression without compromising visual function.
Proprietary or commercial disclosure may be found after the references.
The purpose of this study was to evaluate some of the methods used to calculate objective refractions from wavefront aberrations, to determine their applicability for accommodation research. A wavefront analyzer was used to measure the ocular aberrations of 13 emmetropes and 17 myopes at distance, and 4 near target vergences: 2, 3, 4, and 5 D. The accommodative response was calculated using the following techniques: least squares fitting (Zernike defocus), paraxial curvature matching (Seidel defocus), and 5 optical quality metrics (PFWc, PFSc, PFCc, NS, and VSMTF). We also evaluated a task-specific method of determining optimum focus that used a through-focus procedure to select the image that best optimized both contrast amplitude and gradient (CAG). Neither Zernike nor Seidel defocus appears to be the best method for determining the accommodative response from wavefront aberrations. When the eye has negative spherical aberration, Zernike defocus tends to underestimate, whereas Seidel defocus tends to overestimate the accommodative response. A better approach is to first determine the best image plane using a suitable optical quality metric and then calculate the accommodative error relative to this plane. Of the metrics evaluated, both NS and VSMTF were reasonable choices, with the CAG algorithm being a less preferred alternate.
To characterize the effects on refractive error development and eye growth in young chicks of two-zone concentric lens designs, which differentially affect the defocus experiences of central and peripheral retinal regions.
Monocular defocusing lenses were worn for 5 days from 17 days of age. Four two-zone concentric lens designs (overall optical zone diameter, 10 mm) combining plano with either -5- or +5-D power were used. Lens designs were as follows: (1) +5 D center (+5C), (2) +5 D periphery (+5P), (3) -5 D center (-5C), and (4) -5 D peripheral (-5P), with plano in periphery for all C-designs and in the center for P-designs. Five central zone diameters (CZDs) were tested, ranging from 2.5 to 6.5 mm in 1-mm increments. Plano, +5- and -5-D single-vision (SV) lenses were used as the control. A minimum of six birds were included in each lens group.
For the two-zone lenses, the P designs (i.e., peripheral defocus) had greater effects than the C designs (i.e., central defocus) on both on-axis eye growth and refractions. All but the 6.5-mm CZD +5P lens induced larger changes than the +5SV lens. The +5C lenses with CZD less than 5.5 mm had little effect. The two-zone -5-D lenses had less effect than the -5SV lens, and only the 6.5-mm CZD lens of the -5C series had a significant effect.
The results demonstrate that peripheral defocus can influence both peripheral and central refractive development. The inhibitory effect on axial eye growth of the +5P lenses opens the possibility that appropriately designed concentric lenses may control the progression of human myopia.
It has been suggested that emmetropic and low-hyperopic eyes in which the refractive error in the periphery of the visual field is relatively hyperopic with respect to the axial refraction may be at greater risk of developing myopia than eyes with similar refractions but relatively myopic peripheral refractive errors. The animal and human evidence to support this hypothesis is reviewed. The most persuasive studies are those in which emmetropization has been shown to occur in infant rhesus monkeys with ablated foveas but intact peripheral fields, and the demonstration that, in similar animals, lens-induced relative peripheral hyperopia produces central axial myopia. Evidence for emmetropization in animals with severed optic nerves suggests that emmetropization is primarily controlled at the retinal level but that the higher levels of the visual system play a significant role in refining the process: there appear to be no directly equivalent human studies. Since any contribution of the higher centres to the control of refractive development must depend upon the sensitivity to defocus, the results of human studies of the changes in depth-of-focus across the field and of the contribution of the retinal periphery to the accommodation response are discussed. Although peripheral resolution is relatively insensitive to focus, this is not the case for detection. Moreover accommodation occurs to peripheral stimuli out to a field angle of at least 10 deg, and the presence of a peripheral stimulus can influence the accommodation to a central target. Although the basic hypothesis that a relatively hyperopic peripheral refractive error can drive the development of human myopia remains unproven, the available data support the possibility of an interaction between the states of focus on axis and in the periphery.
Purpose: The accommodation response to changing levels of
longitudinal spherical aberration (LSA) was measured. The LSA
of the eye is known to change from positive to negative as the
level of accommodation of the eye increases. However, little is
known about the effect of these changes in spherical aberration
on the overall accommododation response.
Methods: The existing monochromatic aberrations of three
young subjects were measured using the objective aberroscope
procedure across a range of accommodation levels. LSA was induced
through the use of aspheric surface, rigid contact lenses
(in-air) positioned over a 5 mm aperture at a distance of 12 mm
from the eye. Seven levels of LSA were induced ranging from
-3 D and +3 D of LSA. The subjects viewed a high contrast Maltese
cross with the right eye at distances of 33 cm and 67 cm in
photopic conditions. Measurements of accom~nodationle vel for
each LSA condition were made from tlie left (occluded) eye using
the Canon Autoref R-1, a free-space objective infra-red optometer.
Results: For the three subjects who were tested, negative LSA
caused an increased accommodation response and positive LSA
a decreased accommodation response. Pooling the data across
subjects and test distances, a linear regression on induced LSA
versus accommodation response gave: Accommodation response
(D) = 0.23 - 0.25 LSA (D) (rz= 0.90). Therefore, for every one
dioptre of LSA, there was approximately 0.25 D of accommodation
response. Some individual variations occurred and there
was some apparent flattening of the slope at the extremes of
induced LSA.
Conclusions: These findings suggest that the accommodation
response of the eye will be influenced by the natural changes in
spherical aberration of the eye associated with accommodation
and by optical corrections of the eye which induce spherical aberration.
To evaluate the effectiveness of progressive addition lenses (PALs), with a near addition of +1.50 D, on the progression of myopia in Chinese children.
We enrolled 178 Chinese juvenile-onset acquired myopes (aged 7-13 years, -0.50 to -3.00 D spherical refractive error), who did not have moderately or highly myopic parents, for a 2-year prospective study. They were randomly assigned to the PAL group or single vision (SV) group. Primary measurements, which included myopia progression and ocular biometry, were performed every 6 months. Treatment effect was adjusted for important covariates, by using a multiple linear regression model.
One hundred and forty-nine subjects (75 in SV and 74 in PAL) completed the 2-year study. The myopia progression (mean +/- S.D.) in the SV and PAL groups was -1.50 +/- 0.67 and -1.24 +/- 0.56 D, respectively. This difference of 0.26 D over 2 years was statistically significant (p = 0.01). The lens type (p = 0.02) and baseline spherical equivalent refraction (p = 0.05) were significant contributing factors to myopia progression. Mean increase in the depth of vitreous chamber was 0.70 +/- 0.40 and 0.59 +/- 0.24 mm, respectively. This difference of 0.11 mm was statistically significant (p = 0.04). Age (p < 0.01) was the only contributing factor to the elongation of vitreous chamber. Different near phoria (p < 0.01) and gender (p = 0.02) caused different treatment effects when wearing SV lenses. However, there were no factors found to influence the treatment effect of wearing PALs.
Compared with SV lenses, myopia progression was found to be retarded by PALs to some extent in Chinese children without moderately or highly myopic parents, especially for subjects with near esophoria or females.
Three studies on the effect of bifocal lenses on childhood myopia progression are discussed and re-analyzed. In all three, the rates of progression were less with bifocals than with single-vision lenses in esophoria. Rates with the two types of correction were similar in patients who had nearpoint orthophoria or exophoria.
Randomized consent designs were introduced to make it easier for physicians to enter patients in randomized clinical trials. Physician reluctance to participate in randomized clinical trials is often a reflection that the physician-patient relationship could be compromised if the physician makes known to the patient his/her inability to select a preferred therapy. Clinical trials having a no-treatment control or placebo amplify this concern. This paper reviews the main ideas of randomized consent designs (single and double) and the statistical model underlying the analysis, and presents some recent experiences.
It is known that when hyperopic or myopic defocus is imposed on chick eyes by spectacle lenses, they rapidly compensate, becoming myopic or hyperopic respectively, by altering the depth of their vitreous chamber. Changes in two components--ocular length and choroidal thickness--underlie this rapid compensation. With monocular lens treatment, hyperopic defocus imposed by negative lenses resulted in substantially increased ocular elongation and a slight thinning of the choroid, both changes resulting in myopia; myopic defocus imposed by positive lenses resulted a dramatic increase in choroidal thickness, which pushed the retina forward toward the image plane, and a slight decrease in ocular elongation, both changes resulting in hyperopia. The refractive error after 5 days of lens wear correlated well with vitreous chamber depth, which reflected the changes in both choroidal thickness and ocular length. The degree of compensation for lenses was not affected by whether the fellow eye was covered or open. Both form-deprivation myopia and lens-induced myopia declined with age in parallel, but wearing a -15 D lens produced more myopia than did form deprivation. The spectacle lenses affected the refractive error not only of the lens-wearing eye, but also, to a much lesser degree, of the untreated fellow eye. At lens removal refractive errors were opposite in sign to the lense worn, and the subsequent changes in choroidal thickness and ocular length were also opposite to those that occurred when the lenses were in place. In this situation as well, effects of the spectacle lenses on the fellow eyes were observed. Eyes with no functional afferent connection to the brain because of either prior optic nerve section or intraocular tetrodotoxin injections showed compensatory changes to imposed defocus, but these were limited to compensation for imposed myopic defocus, at least for the eyes with optic nerve section. In addition, optic nerve section, but not tetrodotoxin treatment, moved the set-point of the visual compensatory mechanism toward hyperopia. Optic nerve section prevents myopia in response to negative lenses but not to diffusers, suggesting that compensation for hyperopia requires the central nervous system.
The chick eye is able to change its refractive state by as much as 7 D by pushing the retina forward or pulling it back; this is effected by changes in the thickness of the choroid, the vascular tissue behind the retina and pigment epithelium. Chick eyes first made myopic by wearing diffusers and then permitted unrestricted vision developed choroids several times thicker than normal within days, thereby speeding recovery from deprivation myopia. Choroidal expansion does not occur when visual cues are reduced by dim illumination during the period of unrestricted vision. Furthermore, in chick eyes presented with myopic or hyperopic defocus by means of spectacle lenses, the choroid expands or thins, respectively, in compensation for the specific defocus imposed. Consequently, when the lenses are removed, the eye finds its refractive error suddenly of opposite sign, and the choroidal thickness again compensates by changing in the opposite direction. If a local region of the eye is made myopic by a partial diffuser and then given unrestricted vision, the choroid expands only in the myopic region. Although the mechanism of choroidal expansion is unknown, it might involve either a increased routing of aqueous humor into the uveoscleral outflow or osmotically generated water movement into the choroid. The latter is compatible with the increased choroidal proteoglycan synthesis either when eyes wear positive lenses or after diffuser removal.
Myopic progression has been noted, especially during the period of puberty. It is interesting to investigate whether myopia will progress after the age of puberty and at what rate the changes in ocular components occur during its progression.
A 5-year longitudinal study was made of refraction and its components among 345 National Taiwan University medical students (690 eyes). The examinations included corneal curvature and cycloplegic refraction measured by auto-refractor and retinoscopy, and axial length measurement with A scan ultrasonography. The same procedures and instruments were used again after 5 years.
The myopic prevalence increased from 92.8 to 95.8%; 21 new cases of myopia developed in the 5 years. The mean refractive error significantly increased from -4.26 +/- 2.66 D of freshmen to -4.94 +/- 2.70 D of clerks. The change in refractive error at the 5-year follow-up was 0.70 +/- 0.65 D more myopic for males and 0.54 +/- 0.64 D for females. The main change in the ocular components was in axial length, which increased from 25.54 to 26.05 mm in males and from 24.60 to 24.95 mm in females. Other optical components-including corneal curvature, anterior chamber depth, lens thickness-all remained relatively unchanged from the initial values.
Myopia can progress after the age of puberty, but at a slower rate than during childhood. Axial elongation of the eyeball is the main component that changes in myopic progression.
There is increasing evidence from animal studies in support of the concept of an active emmetropization mechanism which has potentially important clinical ramifications for the management of refractive errors.
Recent research into retractive development and emmetropization is reviewed, with emphasis given to work involving the chick, tree shrew and monkey, which represent the three most widely used animal models in this field. The findings of this research are reviewed in a clinical context.
Compensatory eye growth responses to focusing errors imposed by lenses represent the most compelling evidence for active emmetropization. These observations are complemented by other evidence showing recovery from induced refractive errors such as form-deprivation myopia. Of the animals listed above, chicks show the most impressive emmetropization, being able to compensate fully (using choroidal and scleral mechanisms) to lens powers ranging from +15 D to -10 D. The range of lens powers eliciting appropriate compensatory responses is narrower in the tree shrew and monkey, and the response patterns generally are also more complex to interpret. These data relate to young animals and together indicate refractive plasticity during development. Extrapolation of these findings to humans predicts that natural emmetropization will be inhibited in neonates by early intervention with prescription lenses, and that refractive correction of myopia will lead to accelerated progression.
This convincing evidence for active emmetropization warrants due consideration in developing clinical management strategies for refractive errors.
The purpose of our investigation was to determine whether early ocular growth and refractive development was regulated by visual feedback in infant monkeys. Specifically, we examined the ability of infant monkeys to compensate for optically induced changes in the eye's refractive state and to recover from experimentally induced refractive errors. For moderate-powered anisometropic lenses, infants exhibited differential interocular axial growth rates that reduced the lens-induced refractive imbalance between the two eyes. Infants treated with equal-powered lenses over both eyes also showed compensating growth. For lens powers between approximately -3 and +6 D, the resulting refractive-error changes, which were primarily due to alterations in vitreous chamber growth rates, were well correlated with the effective refractive state produced by the treatment lenses. When the stimulus for altered eye growth was removed and the infants were provided unrestricted vision, monkey eyes consistently grew toward emmetropia. The remarkable degree of adaptability exhibited by the eyes of infant monkeys demonstrates that emmetropization in this higher primate is an active process that is regulated on a continuous basis by optical defocus. Consequently, early in life spectacle lenses by changing the eye's effective focus can predictably alter ocular growth and the refractive status of one or both eyes.
To investigate by histochemistry and immunohistochemistry the distribution and innervation of nonvascular contractile cells in the sclera and choroid of humans and monkeys.
Globes were obtained from 2 macaque monkeys and 19 human cadavers that ranged in age from fetal life to 94 years. Immunohistochemistry was performed using monoclonal antibody against human smooth muscle (SM) alpha-actin and tyrosine hydroxylase (TH). The nicotinamide-adenine dinucleotide phosphate (NADPH)- diaphorase reaction was used as a marker for nitric oxide synthase.
The scleras of all but fetal, newborn, and infant globes exhibited myofibroblasts, amelanotic, fibroblastlike cells having SM alpha-actin immunoreactivity. In the choroid of all but fetal eyes, SM cells were present in the suprachoroidal layer, forming a reticulum of flattened laminae, and in the choriocapillaris where ovoid-to-spindle-shaped SM cells were arrayed in parallel layers immediately adjacent to Bruch's membrane. Contractile cells in the sclera and choroid were most concentrated subfoveally and were sparse anteriorly. Nerve terminals positive for NADPH- diaphorase were colocalized with SM alpha-actin-positive cells in the sclera and choroid, whereas TH-positive nerve terminals colocalized with SM cells in the choroid. Clusters of ganglion cells were present on the posterior surface of globes near SM cells.
The posterior choroid and sclera of humans and monkeys contain nonvascular contractile cells. The presence of nerve terminals and adjacent ganglion cells suggests neural control of these contractile cells. The absence of such contractile cells in fetal, newborn, and infant eyes is an argument against a major role of these cells in promoting ocular enlargement. These contractile cells may instead participate in regulation of refractive state by maintenance of ocular size in the face of intraocular pressure or in intermediate-term regulation of choroidal thickness.
Bifocals have long been thought to reduce progression of childhood myopia. However, this hypothesis has not been definitively evaluated.
We conducted a randomized clinical trial to test the hypothesis that bifocals slow myopia progression in children with near-point esophoria. Eighty-two myopic children were randomized to single-vision glasses (n = 40) or to bifocals with a +1.50 D add (n = 42) and were followed for 30 months. Refraction was measured by an automated refractor after cycloplegia. The primary outcome was myopia progression defined as the difference between the spherical equivalent at baseline and at the 30-month examination, averaged over both eyes.
Follow-up was incomplete for six children in the bifocal group and one child in the single-vision group. Among the children completing the 30 months of follow up, myopia progression (mean spherical equivalent of the two eyes) averaged 0.99 D for bifocals and 1.24 D for single vision (unadjusted, p = 0.106; adjusted for age, p = 0.046). Treatment groups differed in their cumulative distributions (Kolmogorov-Smirnov procedure, p = 0.031). Evidence for a treatment effect on growth in vitreous chamber depth was similar (p = 0.046 by K.S.).
Use of bifocals, instead of single-vision glasses, by children with near-point esophoria seemed to slow myopia progression to a slight degree.
Active emmetropization describes the process by which young eyes regulate their growth to eliminate refractive errors. The purpose of this study was to re-investigate the role of the brain in compensation to imposed hyperopic defocus (negative lenses), specifically, to assess whether a retina-brain link and/or an intact ciliary nerve are required for this emmetropizing response. Data from previous related studies are equivocal.
Unilateral lesion surgery involving either or both optic nerve section (ONS) and ciliary nerve section (CNS), was performed on 2-3 day old White-Leghorn chicks to interrupt communication between the eye (retina in the case of ONS) and brain. After a recovery period of 4 days, lesioned eyes were fitted with either -5 or -15 D lenses or diffusers (6-9 per group). An additional lesion group underwent unilateral CNS and was fitted with -5 D lenses bilaterally. Finally 3 groups that underwent the same unilateral optical treatments but no surgery were included as controls for analyzing lesion-induced changes. Complete sets of measurements, involving retinoscopy for refractive errors, and high frequency A-scan ultrasonography for axial ocular dimensions, were made at the beginning (baseline), and end of a 4 day treatment period. Additional ultrasonography data were collected after 1 and 2 days of treatment. Optical treatment effects were expressed as changes in interocular differences from baseline values.
All three lesions produced hyperopic shifts in refraction (evident in baseline values), although this effect was minimal for the ONS+CNS group. Choroidal thickening as well as increased anterior chamber depth and lens thinning were observed in all cases but vitreous chamber depth was reduced in only the ONS group. In response to the -5 D lens, the control (nonlesioned) group showed nearly complete compensation, while full compensation was not achieved to the -15 D lens over this short treatment period. The diffuser group showed the largest change, which was also in the direction of myopia. Both the ONS and CNS groups showed near normal compensation, as indexed by the changes in refractive errors relative to their respective baseline values. In contrast, the ONS+CNS lens groups overcompensated, by 130% and 54% for the -5 D and the -15 D lens groups respectively. Form deprivation responses were slightly exaggerated in both ONS and ONS+CNS groups, the latter group again showing the largest response. Enhanced vitreous chamber growth was evident under all conditions and correlated well with the refractive changes across the groups.
The data imply that an intact retina-brain link is not required for compensation to hyperopic defocus and thus emmetropization. However, the data also imply interactions between higher centers and the eye. The emmetropization set-point appears to be recalibrated after ONS surgery. The data also indicate a role of the ciliary nerve as an important conduit for signals that exercise a restraining influence on eye growth.
As with other organs, the eye's growth is regulated by homeostatic control mechanisms. Unlike other organs, the eye relies on vision as a principal input to guide growth. In this review, we consider several implications of this visual guidance. First, we compare the regulation of eye growth to that of other organs. Second, we ask how the visual system derives signals that distinguish the blur of an eye too large from one too small. Third, we ask what cascade of chemical signals constitutes this growth control system. Finally, if the match between the length and optics of the eye is under homeostatic control, why do children so commonly develop myopia, and why does the myopia not limit itself? Long-neglected studies may provide an answer to this last question.
Myopia is a common ocular disorder, and progression of myopia in children is of increasing concern. Modern overnight orthokeratology (ortho-k) is effective for myopic reduction and has been claimed to be effective in slowing the progression of myopia (myopic control) in children, although scientific evidence for this has been lacking. This 2 year pilot study was conducted to determine whether ortho-k can effectively reduce and control myopia in children.
We monitored the growth of axial length (AL) and vitreous chamber depth (VCD) in 35 children (7-12 years of age), undergoing ortho-k treatment and compared the rates of change with 35 children wearing single-vision spectacles from an earlier study (control). For the ortho-k subjects, we also determined the changes in corneal curvature and the relationships with changes of refractive errors, AL and VCD.
The baseline spherical equivalent refractive errors (SER), the AL, and VCD of the ortho-k and control subjects were not statistically different. All the ortho-k subjects found post-ortho-k unaided vision acceptable in the daytime. The residual SER at the end of the study was -0.18 +/- 0.69 D (dioptre) and the reduction (less myopic) in SER was 2.09 +/- 1.34 D (all values are mean +/- SD). At the end of 24 months, the increases in AL were 0.29 +/- 0.27 mm and 0.54 +/- 0.27 mm for the ortho-k and control groups, respectively (unpaired t test; p = 0.012); the increases in VCD were 0.23 +/- 0.25 mm and 0.48 +/- 0.26 mm for the ortho-k and control groups, respectively (p = 0.005). There was significant initial corneal flattening in the ortho-k group but no significant relationships were found between changes in corneal power and changes in AL and VCD.
Ortho-k can have both a corrective and preventive/control effect in childhood myopia. However, there are substantial variations in changes in eye length among children and there is no way to predict the effect for individual subjects.
To clarify how the downward deviation of progressive addition lenses (PALs) reduces their near-addition effect in schoolchildren participating in a myopia control trial.
Among 95 schoolchildren wearing PALs for 6 months (age range: 6-12 years; refractive error range: -6.00 to -1.25 D), facial images were captured with a digital still camera placed 60 cm in front of the eyes while he or she was looking ahead with natural head posture. The vertical deviations of PALs from their ideal position (mm) were evaluated by analysing these images.
The mean (+/-SD) downward deviations of PALs for the right and left eyes were 3.7 +/- 2.3 and 3.7 +/- 2.0 mm, respectively, and the largest downward deviation was 10.2 mm. For simulations using the average downward deviation, the near-addition effect of PALs was reduced to 30 and 63% of the expected value at the 10 degrees and 20 degrees downward eye positions, respectively.
The downward deviation of PALs is a significant factor in reducing their therapeutic effect for near-addition. To ensure the proper alignment of PALs in children, the conventional spectacle-frame-fitting procedure is not sufficient, and repeated confirmation using a testing method similar to that used in this study is required.
Besides the direct economic and social burden of myopia, associated ocular complications may lead to substantial visual loss. In several population and clinic-based cohorts, case-control and cross-sectional studies, higher risks of posterior subcapsular cataract, cortical and nuclear cataract in myopic patients were reported. Patients with high myopia (spherical equivalent at least -6.0 D) are more susceptible to ocular abnormalities. The prevalent risks of glaucoma were higher in myopic adults, and risks of chorioretinal abnormalities such as retinal detachment, chorioretinal atrophy and lacquer cracks increased with severity of myopia and greater axial length. Myopic adults were more likely to have tilted, rotated, and larger discs as well as other optic disc abnormalities. Often, these studies support possible associations between myopia and specific ocular complications, but we cannot infer causality because of limitations in study methodology. The detection and treatment of possible pathological ocular complications is essential in the management of high myopia. The ocular risks associated with myopia should not be underestimated and there is a public health need to prevent the onset or progression of myopia.
To identify differences in potential biometric markers for predicting refractive error in school children.
Biometric data on 895 Tibetan children, aged 6 to 18 years, residing in Katmandu, Nepal, were collected biennially from 1992 to 2000. Measurements included cycloplegic autorefraction, A-scan ultrasonography, and video phakometry. Only those children who had been studied at least once at age 12 years or more were included in the analysis. Subjects were divided into two groups: a myopia group if the refractive error was myopic by more than -0.50 D and a nonmyopia group if the refractive error was maximally myopic by -0.50 D, expressed as a spherical equivalent error in the left eye.
Biometric measures that differed significantly with increasing age between the two refractive groups included: anterior chamber depth + 0.012 mm/year (p = 0.014), anterior lens radius of curvature + 0.073 mm/year (p = 0.001), lens power -0.059 D/year (p = 0.082), lens thickness -0.005 mm/year (p = 0.02), and vitreous chamber depth + 0.084 mm/year (p < 0.001). Corneal radii of curvature of the myopic group were steeper at all ages by 0.09 mm (p < 0.001), but the rate of change with age was equivalent across the refractive groups.
Compared with those who remained nonmyopic, children who developed myopia had a crystalline lens that was initially thicker and steeper, and a vitreous chamber that was initially shorter. With age, children who became myopic developed greater lens thinning, greater flattening of the anterior lens surface radius, and a greater increase in vitreous chamber depth than their nonmyopic counterparts.
To determine the prevalence and causes of low vision and blindness in a Japanese adult population.
Population-based cross-sectional study.
Randomly selected residents (n = 3870) of Tajimi City, Japan, who were 40 years of age or older.
Of the 3021 study participants (78.1% of 3870 eligible persons), 2977 (76.9%) underwent a complete ophthalmologic examination including measurement of the best-corrected visual acuity (BCVA) with full subjective refraction using a Landolt ring chart at 5 m. Age- and gender-specific prevalence rates of low vision and blindness were estimated and causes were identified.
Low vision and blindness were defined as BCVA in the better eye worse than 20/60 to a lower limit of 20/400 and worse than 20/400, respectively (World Health Organization [WHO] criteria) and worse than 20/40 but better than 20/200 and 20/200 or worse, respectively (United States criteria).
The overall prevalence of blindness according to the WHO or U.S. criteria was 0.14% (n = 4; 95% confidence interval [CI], 0.06-0.32). The primary causes were optic atrophy, myopic macular degeneration, retinitis pigmentosa, and uveitis. The overall prevalence of low vision according to the WHO criteria was 0.39% (95% CI, 0.18%-0.60%) and according to the U.S. criteria was 0.98% (95% CI, 0.66%-1.30%), which was significantly greater in women and in the older half of the participants than in the younger half (P = 0.0079 and <0.0001, respectively). The leading causes of low vision in descending order were cataract followed by glaucoma, and those of monocular blindness were myopic macular degeneration, glaucoma, and trauma.
The prevalence of low vision and blindness in Japanese adults was one of the lowest among those reported. The major causes of low vision were cataract and glaucoma, and the leading cause of monocular blindness was myopic macular degeneration.