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Case Series Analysis of Myopic Progression Control With a Unique Extended Depth of Focus Multifocal Contact Lens
Abstract
Objectives:
To determine the rate of myopia progression in children fit with a commercially available extended depth of focus (center distance) multifocal soft contact lens with attributes theoretically expected to slow the progression of myopia.
Methods:
A retrospective case series analysis of 32 patients (ages 6-19 years, mean 10.98±2.95) from 10 practice locations was performed. At initial presentation, 44% wore spectacles, 37.5% spherical soft contact lenses, 15.6% a different soft multifocal contact lens, and 3% orthokeratology lenses. All participants showed progression of at least -0.50 diopter with current corrections and were fit with an extended depth of focus (center distance) multifocal soft contact lens (NaturalVue Multifocal 1 Day Contact Lenses; Visioneering Technologies, Inc., Alpharetta, GA). Follow-up time was 6 to 25 months (mean: 10.94±4.76).
Results:
Reductions in the annualized rate of myopic progression from -0.85 D per year ±0.43 D to -0.04 D per year ±0.18 D (P<0.00000) OD, -0.90 D per year ±0.57 D to -0.03 D per year ±0.17 D (P<0.00000) OS were observed. These data represent a reduction of 95.4% OD and 96.25% OS. Approximately 98.4% of the children showed reduction of annualized myopic progression; 91% showed a decrease of 70% or greater. Overall, 81.25% showed complete halting of myopic progression, including 6.25% demonstrating myopic regression.
Conclusions:
This unique extended depth of focus (center distance) daily disposable multifocal contact lens was effective in slowing myopic progression in these children. These findings add to the growing evidence that center distance multifocal soft contact lenses may slow the progression of myopia.
... Animal studies and models have further shown that the choroid plays an active role in emmetropization through thickness modulation to adjust the retina to the focal plane of the eye (choroidal accommodation) and through the release of growth factors that have regulatory scleral extracellular matrix remodeling potential [32,33]. Experimental studies have identified that several biochemical compounds, such as retinal dopamine, retinoic acid, and nitric oxide, are involved in axial length (AL) modulation [34][35][36]. ...
... This lens has exhibited high potential at halting myopia progression in a multicenter case series analysis of 32 patients. Approximately 98% showed a decrease in annual myopia progression, 91% showed a 70% decrease or more, and a few patients exhibited myopia regression [34]. ...
... While incomplete and still under investigation, the published data to date suggests that after orthokeratology, the most effective soft lens for myopia control is MiSight, manufactured by CooperVision and the two best spectacle lenses are MiyoSmart, manufactured by Hoya, and Stellest, manufactured by Essilor (Table 3 and Fig. 2) [34][35][36]47,52,54,55,75,76,[82][83][84][85]. ...
Myopia is the most common refractive error in the world, and its’ prevalence continually increases. The potential pathological and visual complications of progressive myopia have inspired researchers to study the sources of myopia, axial elongation, and explore modalities to arrest progression. Considerable attention has been given over the past few years to the myopia risk factor known as hyperopic peripheral blur, the focus of this review. The primary theories currently believed to be the cause of myopia, the parameters considered to contribute and influence the effect of peripheral blur, such as the surface retinal area or depth of blur will be discussed. The currently available optical devices designed to provide peripheral myopic defocus will be discussed, including bifocal and progressive addition ophthalmic lenses, peripheral defocus single vision ophthalmic lenses, orthokeratology lenses, and bifocal or multifocal center distance soft lenses, as well as their effectivity as mentioned in the literature to date.
... The factors that produce forgetting but enhance learning are driven by a few effects in education. The Context Effect suggests that changing study contexts can introduce desirable difficulties [196], improving recall by blending subtopics rather than tackling them sequentially [23,42]. The Spacing Effect demonstrates that spaced learning, as opposed to cramming, leads to better long-term retention by revisiting material over time [24,211]. ...
This survey investigates the multifaceted nature of forgetting in machine learning, drawing insights from neuroscientific research that posits forgetting as an adaptive function rather than a defect, enhancing the learning process and preventing overfitting. This survey focuses on the benefits of forgetting and its applications across various machine learning sub-fields that can help improve model performance and enhance data privacy. Moreover, the paper discusses current challenges, future directions, and ethical considerations regarding the integration of forgetting mechanisms into machine learning models.
... The demonstration that the peripheral retina is involved in the progression of myopia in the young eye 1,2 has led to the development of a therapeutic regime centred on children wearing specially designed multifocal contact lenses. [3][4][5][6][7] The exact refractive profile of the lenses varies, but they have in common some zones in the pupil aperture with plus power added to the patient's refractive correction, with the stated aim of conforming to the peripheral image defocus concept derived from the monkey experiment. ...
Clinical relevance:
That myopic defocus, even if restricted to the peripheral retina, inhibits eye growth in young monkey eyes has motivated the therapy of myopia control through multifocal contact lens wear in children.
Background:
To understand how eye-length regulating mechanisms are triggered by light requires knowledge of retinal light spread. That is largely lacking for the multifocal contact lenses used in the therapy because empirical methods identifying just the defocus in dioptres are inadequate.
Methods:
"Through-focus" diffraction computations in contact lens/eye models with typical normal eye parameters, including polychromatic light, the chromatic aberrations and an M-cone phototransduction layer, offer estimates of retinal image spread for a range of viewing distances.
Results:
Point- and edge-spread distributions of activation of phototransduction in the central retina show that the addition of multifocal zones produces some veiling for in-focus viewing and substantial improvement of image quality for near targets in the unaccommodated eye. These effects are much reduced in the retinal periphery.
Conclusion:
Whatever therapeutic value there is in prescribing multifocal contact lenses for myopia control, it is not particularly dependent on the precise configuration of the multifocal zones, nor can it be ascribed to changes in image quality specific to the retinal periphery; its origin is more likely less blur for near targets, reducing the stimulus to accommodation.
... Contact lenses uniquely designed to extend DoF have shown to slow myopia in children. 41 The use of atropine has also demonstrated the efficacy of myopic control in clinical trials. [42][43][44] The fact that two very different approaches produced similarly positive outcomes raises an interesting question about the potential mechanism of myopia control. ...
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.
The mechanism by which myopia-managing spectacle lenses slow myopia progression remains controversial. Understanding the changes these lenses introduce to peripheral imaging properties helps shed light on this controversial issue. Given the difficulty of directly measuring these changes in clinical settings, this study combined experimental and modeling approaches to evaluate changes in images at the retina induced by myopia-managing lenses. Optical characteristics that may related to the efficacy of the lenses with concentric cylindrical annular refractive elements (CARE) in myopia control were investigated. Three lenses were evaluated: MyoCare (MC), MyoCare S (MCS), and a single vision (SV) lens with a custom-built physical eye model and optical simulations for the analysis. The simulated PSFs are consistent with the measured ones. PSF analysis showed that MC and MCS lenses produce discrete curves, resulting in remarkable distortion in the simulated retina images, especially for large eccentricities. Whether they increase or decrease contrast depends on the spatial frequencies and eccentricities. These lenses also increase retinal light intensity at different eccentricities. The positive power of the CARE structure introduces myopic defocus of less than 0.25 D at only a limited range of eccentricities. The proposed approaches present relatively straightforward techniques for evaluating the optical performance of myopia-managing spectacle lenses.
Further to the previous article on evidence informed practice of ophthalmic dispensing, Tina Arbon Black and Peter Black discuss the most prominent and rapidly developing aspect of current ophthalmic dispensing, contact lens and optometric practice; myopia management. (C103841, suitable for logging as one provider-led distance learning CPD point for optometrists and dispensing opticians)
Following on from their recent article Myopia management with spectacle lenses – an update (Optician July 28, 2023) – Peter Black and Tina Arbon Black explore myopia evidence, new management options and some of the standards of practice issues that surround myopia management
Introduction. The presented study focuses on investigating the impact of acquired myopia on human central hemodynamics. Myopia, or nearsightedness, ranks as one of the most common ophthalmological disorders globally and in Ukraine, manifesting either congenitally or acquired over a lifetime. Ophthalmology specialists note a rapid increase in myopia cases across all age groups, with its prevalence posing a significant threat to vision and overall health. Viewing myopia as an adaptive response to a substantial visual strain one can presume that this adaptation might not be localized but generalized. The objective of the study is to examine the characteristics of central hemodynamics in individuals with acquired myopia. Materials and methods. The research was conducted on volunteers, 81 individuals aged 18 – 35, who were divided into a control group of 40 persons and a study group of 41 individuals diagnosed as having myopia. The diagnosis was established by specialists in Dnipro. The study was carried out at the General Practice Family Medicine Clinic No. 7 in Dnipro during 2022-2023. Central hemodynamic status was characterized by the following indicators: heart rate, systolic and diastolic blood pressure, pulse pressure, systolic blood volume, and minute blood volume. The Kerdo’s vegetative index was also calculated. Results. The study revealed that acquired myopia was accompanied by an increase in the absolute values of heart rate, systolic blood pressure, diastolic blood pressure, pulse pressure, and minute blood volume compared to the control group of volunteers. It is noteworthy that the systolic blood volume in the context of acquired myopia was lower than in the control group. The Kerdo’s index was higher in the group with acquired myopia compared to the control group. The obtained results indicate a certain dependency between central hemodynamics indicators, the Kerdo’s index value, and acquired myopia, which is an adaptive reaction of the visual system to significant loads in the modern information-cybernetic society. Changes in central hemodynamics indicators in individuals with myopia may reflect certain adaptive reactions of the cardiovascular system to this eye refraction disorder.
Objectives
Center-distance multifocal contact lenses (MFCLs) are used to slow myopia progression. We examined the effect of two MFCLs on intraocular straylight values in myopic individuals.
Methods
Twenty-five young myopic adults were enrolled and were fit with three contact lenses (Biofinity sphere, Biofinity Multifocal, and NaturalVue Multifocal) in a random order over two study visits. Pupil size (NeurOptics VIP-300, Laguna Hills, CA) and contact lens centration were measured. Right eye intraocular straylight measurements were collected (OCULUS C-Quant; Wetzlar, Germany) and compared with a spectacle trial lens. Log straylight (LogSL) values and straylight residuals were analyzed using repeated-measures analyses of variance with Tukey-corrected post hoc t -tests.
Results
The mean participant age (±SD) was 24.1±1.5 years, and right eye spherical equivalent refractive error was −3.38±1.53 DS. There was no difference in mesopic pupil size between visits ( P =0.68) and no difference in contact lens centration between lenses ( P =0.99). LogSL values differed by lens type ( P =0.004). LogSL with the spectacle trial lens was significantly greater than with each contact lens type (all P <0.05), but there were no significant differences in LogSL between the three contact lenses (all P >0.05). There was no difference between the three contact lens designs for straylight residuals ( P =0.33).
Conclusions
Measured intraocular straylight for both MFCLs was not different than with a spherical soft contact lens. A significant increase in intraocular straylight with spectacle trial lens correction was observed compared with all contact lenses.
Purpose
Multizone contact lenses control myopia progression by proposed introduction of myopic defocus. This project investigated how much of the pupil area and how many dioptres of myopic defocus are introduced by different lens zone geometries with near‐ and off‐axis viewing.
Methods
Ten young myopic adults (18–25 years) binocularly wore four soft contact lenses including a single vision (SV), concentric‐ring dual‐focus (DF), centre‐distance multifocal (MF) and a RingBoost™ (RB) multi‐zone design containing a combination of coaxial and non‐coaxial zones. A modified aberrometer captured aberrations and pupil sizes at four target vergences between −0.25 and −4.00 D (on‐axis) and across the central ±30° of the horizontal retina (off‐axis). Defocus was quantified as the difference between the measured refractive state and the target vergence within each zone of a multi‐zone design within the pupil and compared with that of equivalent zone areas of the SV lens. The percentage of the pupil containing myopic defocused light for each lens was calculated.
Results
Defocus within the distance correction zones of multi‐zone lenses was similar to that of the SV lens. When viewing on‐axis at −0.25 D target vergence, on average 11% of the pupil was myopic with SV, whereas 62%, 84% and 50% of the pupil was myopic for the DF, MF and RB designs, respectively. At −4.00 D target vergence, all lenses exhibited a systematic decrease in the percentage of pupil area having myopic defocus (SV: 3%; DF: 18%; MF: 5% and RB: 26%). The off‐axis proportions were similar across multi‐zone lenses; however, multi‐zone lenses retained approximately 1.25–3.0× more myopic defocus than the SV lens.
Conclusions
Subjects accommodated using the distance‐correction zones of multi‐zone lenses. Multi‐zone contact lenses introduced significant myopic defocus on‐axis and across the central ±30° retina. However, the magnitude and proportion of defocus were influenced by zone geometry, add power and pupil size.
Objectives:
Previous studies have shown that combined use of orthokeratology and 0.01% atropine (AT) eye drops can strongly prevent axial elongation in myopic children. However, the efficacy of combined use with multifocal contact lens (MFCL) and 0.01% AT remains unclear. The aim of this trial is to clarify the efficacy of MFCL+0.01% AT combination therapy for myopia control and safety.
Methods:
This prospective study is a randomized, double-masked, placebo-controlled trial with four arms. A total of 240 children aged 6 to 12 years with myopia is recruited and randomly assigned to one of the four groups in a ratio of 1:1:1:1 as follows: group 1: MFCL+AT combination therapy, group 2: MFCL monotherapy, group 3: AT monotherapy, and group 4: placebo. The participants will continue the assigned treatment for 1 year. The primary and secondary outcomes are the comparisons of axial elongation and myopia progression in the four groups during the 1-year study period.
Discussion:
The present trial would determine whether the MFCL+AT combination therapy is more effective in slowing axial elongation and myopia progression in schoolchildren as compared with each monotherapy or placebo, and it also confirm acceptable safety of the combination therapy.
Myopia is the most common refractive error in the world and has reached a pandemic level. The potential complications of progressive myopia have inspired researchers to attempt to understand the sources of myopia and axial elongation and to develop modalities to arrest progression. Considerable attention has been given over the past few years to the myopia risk factor known as hyperopic peripheral blur, which is the focus of this review. It will discuss the primary theories believed to be the cause of myopia and the parameters considered to contribute to and influence the effect of peripheral blur, such as the surface retinal area of blur or the depth of blur. The multitude of optical devices designed to provide peripheral myopic defocus will be mentioned, including bifocal and progressive addition ophthalmic lenses, peripheral defocus single-vision ophthalmic lenses, orthokeratology lenses, and bifocal or multifocal center distance soft lenses, as well as their effectivity as discussed in the literature to date.
Professor Nicola Logan offers an overview of the various myopia management strategies and reviews the evidence base behind them (C78774, one distance learning CET point suitable for optometrists, contact lens opticians and dispensing opticians)
Purpose:
To evaluate myopia progression over an approximately 6-year follow-up period in children and young adults wearing a commercially available, daily disposable, soft multifocal contact lens with an extended depth of focus (center distance) design.
Methods:
This retrospective cohort analysis included data from 196 patients of mean (SD) age 12.3 (2.7) years (range, 5-20 years), fit with the NaturalVue Multifocal (NVMF) contact lens at 15 practices in the United States over 6 years. All patients showed at least -0.50D of myopic progression in at least one eye prior to wearing the lens. Data from the right eye were analyzed. One-way ANOVA with Tukeys post-hoc t-tests were used for statistical analysis, with a significance level set at P < 0.05.
Results:
After wearing these lenses for 6-72 months, the average myopia progression slowed by approximately 0.84 D or 85% compared to baseline, which was statistically significant at all time points (P < 0.0001). Frequency distribution revealed that 91% of wearers showed a decrease in myopia progression compared to baseline, with 79% of wearers showing a ≥70% reduction in myopia progression. The average change in axial length in a subset of the population over 47 months of follow-up was approximately 0.10 mm/year. Compared with changes expected in an age- and ethnicity-matched myopic virtual control group obtained from published meta-analysis data, both myopic refractive error progression and axial elongation were significantly lower in NVMF wearers at 12, 24 and 36 months (P < 0.001). Analysis of the age- and ethnicity-matched virtual control group predicted that the Cumulative Absolute Reduction of axial Elongation (CARE) value over 3 years would be 0.45 mm.
Conclusion:
Wearers of the soft multifocal contact lens displayed significant reductions in myopia progression throughout a follow-up period of 6 years.
Objectives: Extant research on cost-sharing finds no impact on health care utilization when the amount is insubstantial. This research investigates the effects on nonacute outpatient services for schoolchildren with refractive errors in Taiwan and discusses the potential harm caused by cost sharing and relevant cost containment policies. Methods: Longitudinal claims data from the National Health Insurance database are employed. District demographic information is also used for aggregate-level analyses. Interventional modeling is conducted on pooled individual-level data with a Poisson model and negative binomial models. Generalized least square modeling is performed on aggregate district-level data to elucidate the impacts of cost sharing and the reimbursement rate with controls for patient and institutional characteristics, district socioeconomic factors, and competitiveness among institutions. Results: The findings of this study show that cost sharing does not significantly affect children’s utilization of outpatient services in the patient-level analyses. However, it significantly decreases the service volume based on the results of district aggregate analyses. There are potentially marginal patients in society, and they are more likely to be girls in poorer families, whose chances of seeking medical care significantly decrease when cost sharing increases. Conclusions: The gap in health inequity can be widened when stringent cost-containment policies are implemented. The offset effect caused by delayed care may also result in higher health care expenditures later. Cost sharing for children should be separately and prudently designed to better protect them from deprivations caused by changes in health policies.
Importance:
Reducing myopia progression can reduce the risk of associated ocular pathologies.
Objective:
To evaluate whether spectacle lenses with higher lenslet asphericity have a higher myopia control efficacy throughout 2 years.
Design, setting, and participants:
This double-masked randomized clinical trial was conducted between July 2018 and October 2020 at the Eye Hospital of Wenzhou Medical University in Wenzhou, China. Children aged 8 to 13 years with a cycloplegic spherical equivalent refraction (SER) of -0.75 D to -4.75 D and astigmatism with less than -1.50 D were recruited. A data and safety monitoring committee reviewed findings from a planned interim analysis in 2019.
Interventions:
Participants were randomly assigned in a 1:1:1 ratio to receive spectacle lenses with highly aspherical lenslets (HAL), spectacle lenses with slightly aspherical lenslets (SAL), or single-vision spectacle lenses (SVL).
Main outcome and measures:
Two-year changes in SER and axial length and their differences between groups.
Results:
Of 157 participants who completed each visit (mean [SD] age, 10.4 [1.2] years), 54 were analyzed in the HAL group, 53 in the SAL group, and 50 in the SVL group. Mean (SE) 2-year myopia progression in the SVL group was 1.46 (0.09) D. Compared with SVL, the mean (SE) change in SER was less for HAL (by 0.80 [0.11] D) and SAL (by 0.42 [0.11] D; P ≤ .001). The mean (SE) increase in axial length was 0.69 (0.04) mm for SVL. Compared with SVL, increase in axial length was slowed by a mean (SE) of 0.35 (0.05) mm for HAL and 0.18 (0.05) mm for SAL (P ≤ .001). Compared with SVL, for children who wore HAL at least 12 hours every day, the mean (SE) change in SER was slowed by 0.99 (0.12) D, and increase in axial length slowed by 0.41 (0.05) mm.
Conclusions and relevance:
In this study, HAL and SAL reduced the rate of myopia progression and axial elongation throughout 2 years, with higher efficacy for HAL. Longer wearing hours resulted in better myopia control efficacy for HAL.
Trial registration:
Chinese Clinical Trial Registry Identifier: ChiCTR1800017683.
Purpose
Multifocal soft contact lenses (MFCLs) are prescribed to inhibit myopia progression; these include aspheric and concentric designs. The effects of MFCLs on visual quality, accommodation and vergence in young-adult myopes were evaluated.
Methods
Participants were twenty-six myopes (19–25 years, spherical equivalent −0.50 to −5.75D), with normal binocular vision and no past myopia control. Pupil sizes were 4.4 ± 0.9 mm during distance viewing and 3.7 ± 0.8 mm at near. In random order, participants wore four MFCLs: Proclear single vision distance, MiSight concentric dual focus (+2.00D), distance center aspheric (Biofinity, +2.50D) (CooperVision lenses), and NaturalVue aspheric (Visioneering Technologies). Testing included visual acuity, contrast sensitivity (Pelli-Robson), stereoacuity, accommodation response, negative and positive relative accommodation, horizontal phorias, horizontal fusional vergence and AC/A ratio, and a visual quality questionnaire.
Results
The four lenses differed in distance (p = 0.001) and near visual acuity (p = 0.011), and contrast sensitivity (p = 0.001). Compared with the single vision lens, the Biofinity aspheric had the greatest visual impact: 0.19 ± 0.14 logMAR distance acuity reduction, 0.22 ± 0.15 log contrast sensitivity reduction. Near acuity was affected less than distance acuity; the reduction was greatest with the NaturalVue (0.05 ± 0.07 logMAR reduction). The MFCLs altered the autorefraction measure at distance and near (p = 0.001); the accommodation response was less with aspheric lenses. Negative relative accommodation reduced with the aspheric lenses (p = 0.001): by 0.9 ± 0.5D with Biofinity and 0.5 ± 0.7D with NaturalVue. Exophoric shifts were greater with aspheric lenses (1.8 ± 2.4Δ Biofinity, 1.7 ± 1.7Δ NaturalVue) than with the concentric MiSight (0.5 ± 1.3Δ).
Conclusions
MFCLs alter visual performance, refraction and vergence; two aspheric lenses had greater effect than a concentric lens.
Purpose
To develop an optical model of a child's eye to reveal the impact of target distance and accommodative behaviour on retinal image quality when fitted with multi‐zone lenses.
Methods
Pupil size, aberration levels and accommodative lag were adjusted for models viewing stimuli at 400, 100, 33 and 20 cm. Distributions of defocus across the pupil and simulated retinal images were obtained. An equivalent 16‐point letter was imaged at near viewing distances, while a 0.00 logMAR (6/6) letter was imaged at 400 cm. Multi‐zone lenses included those clinically utilised for myopia control (e.g., dual‐focus, multi‐segmented and aspherical optics).
Results
Viewing distance adjustments to model spherical aberration (SA) and pupil radius resulted in a model eye with wider defocus distributions at closer viewing distances, especially at 20 cm. The increasing negative SA at near reduced the effective add power of dual‐focus lenses, reducing the amount of myopic defocus introduced by the centre‐distance, 2‐zone design. The negative SA at near largely compensated for the high positive SA introduced by the aspheric lens, removing most myopic defocus when viewing at near. A 0.50 D accommodative lag had little impact on the legibility of typical text (16‐point) at the closer viewing distances.
Conclusions
All four multi‐zone lenses successfully generated myopic defocus at greater viewing distances, but two failed to introduce significant amounts of myopic defocus at the nearest viewing distance due to the combined effects of pupil miosis and negative SA. Typical 16‐point type is easily legible at near even in presence of the multi‐zone optics of lenses utilised for myopia control and accommodative lag.
Significance:
The contrast sensitivity function provides a more detailed assessment of vision than visual acuity. It was found that center-distance multifocal contact lens designs that are increasingly being prescribed for myopia control reduce distance photopic and mesopic contrast sensitivity in non-presbyopic patients across a range of spatial frequencies.
Purpose:
To determine the effect of center-distance multifocal soft contact lenses (MFCLs) on contrast sensitivity (CS) under photopic and mesopic conditions in non-presbyopic patients.
Methods:
Twenty-five myopic, non-presbyopic adults were fitted binocularly with three lenses: Biofinity single vision contact lens (SVCL), Biofinity D Multifocal +2.50 add, and NaturalVue Multifocal in random order. CS was measured at distance (4 m) under photopic and mesopic conditions and at near under photopic conditions. Log CS by spatial frequency and area under the log contrast sensitivity function (AULCSF) were analyzed between lenses.
Results:
Distance photopic CS at each spatial frequency was higher with the SVCL than the MFCLs (P < .001), but there was no difference between the MFCLs (P = .71). Distance mesopic CS from 1.5 to 12 cycles per degree (cpd) was higher with the SVCL than the MFCLs (all P < .018); however, at 18 cpd there was no difference in CS between NaturalVue and the SVCL (P = .76), possibly due to spurious resolution. Photopic AULCSF for the SVCL was roughly 10% greater than both MFCLs. CS at near was generally similar between lenses, only slightly lower with the NaturalVue at 11 and 15.5 cpd, but AULCSF at near was not different between lenses (P > .05).
Conclusions:
Multifocal contact lenses reduce distance contrast sensitivity under both photopic and mesopic conditions. There is no clinically significant difference in near CS among all three lenses. These data show that MFCLs have effects on vision that are not captured by standard high-contrast visual acuity testing.
Purpose
Prolonged nearwork has been implicated in myopia progression. Accommodation responses of young‐adult myopes wearing different multifocal contact lenses were compared.
Methods
Twenty adults, 18–25 years, with myopia (spherical equivalent refraction −0.50 to −5.50 D, mean −2.1 ± 1.6 D) wore five lens types in random order: Proclear single vision distance (SV), MiSight concentric dual‐focus +2.00 D Add (MS), Biofinity aspheric centre distance +1.50 D Add (CD1) and +2.50 D Add (CD2) (all Coopervision), and NaturalVue aspheric (Visioneering Technologies) (NVue). Using a Grand‐Seiko WAN‐5500 autorefractor with binocular correction and viewing right eye accommodative responses were measured after a 10 min adaptation period at 4.0, 1.0, 0.5, 0.33 and 0.25 m distances. Dynamic measurements were taken for 4 s at 6 Hz. Accommodative stimuli and responses were referenced to 4 m (i.e., refraction differences between 4 m and nearer distances). Accommodation lags and refraction instabilities (standard deviations of dynamic responses) were determined. For comparison, results were obtained for an absolute presbyopic eye, where trial lenses counteracted the accommodation stimulus.
Results
For SV and MS, accommodation responses were similar to the stimulus values. For aspheric lenses CD1, CD2 and NVue, accommodation responses were approximately 1.0 D lower across the stimulus range than with SV and MS, and rates of change were approximately 0.84 D per 1 D stimulus change. MS produced greater refraction instabilities than other lenses. For the presbyope, changes in refraction matched the trial lenses, indicating that corrections due to measurement through the different lenses were not needed.
Conclusion
Reductions in accommodation response occurred in young myopes wearing aspheric multifocal contact lenses independent of the labelled ‘add’ power. The concentric dual‐focus MS lens produced minimal lags but had greater instability than the other lenses. The results indicate that the mechanism of multifocal contact lenses slowing myopia progression is unlikely to be through relaxing accommodation, at least in young adults.
Significance:
Multifocal contact lenses (MFCLs) are being used clinically for myopia control. Center-distance designs caused myopic changes in defocus across the retina that varied by lens design, whereas the center-near design caused peripheral hyperopic changes. Multifocal lenses caused reductions in low-contrast vision that varied by lens design, affecting visual performance.
Purpose:
The purpose of this study was to compare changes in defocus with four MFCLs, three center-distance and one center-near.
Methods:
Two cohorts of 25 nonpresbyopic myopic adults were enrolled. The first cohort was fitted with Proclear D and Biofinity D MFCL (center-distance, +2.50 D add), and the second cohort was fitted with NaturalVue MFCL (center-distance) and Clariti 1-Day MFCL (center-near, high add), both in random order. Overrefraction was performed to maximize visual acuity. Cycloplegic autorefraction was performed with each lens and without a lens along the line of sight and at nasal and temporal retinal locations out to 40°. Data were analyzed with repeated-measures ANOVAs with post hoc t tests, when indicated.
Results:
Changes in defocus at each location differed between MFCL designs (lens by location; both, P < .001). Clariti 1-Day caused peripheral hyperopic retinal changes (40 and 30° nasal, and 20, 30, and 40° temporal; all, P < .05). NaturalVue MFCL caused myopic changes centrally and hyperopic changes at 40° nasal and 30° temporal (all, P < .05). The remaining center-distance designs caused myopic changes at multiple locations (all, P < .05).
Conclusions:
After overrefraction, the center-near MFCL design caused hyperopic defocus at multiple peripheral locations, which is not hypothesized to slow myopia progression. NaturalVue MFCL caused myopic changes in defocus centrally but hyperopic changes in the far periphery. Biofinity D and Proclear D caused myopic changes in retinal defocus. Further work is warranted to determine whether defocus profile differences between the center-distance designs influence any slowing of myopia progression.
Myopia, the 6th leading cause of loss of vision, is increasing at epidemic rates; by 2050, almost half of the world’s population will be myopic [1–3]. Thus, slowing the progression of myopia, specifically axial length, has been assumed to decrease associated myopia-related diseases that cause vision loss. Current methods of slowing progressive myopia are based upon light (spectral composition, brightness, contrast, and/or accommodative demand), optical defocus (either lag of accommodation or relative hyperopia in the retina periphery as a result of the shape of the eye), and/or pharmacological intervention [4, 5]. This chapter will deal with optical interventions.
The International Myopia Institute's (IMI) mission is to advance research, education, and management of myopia to decrease future vision impairment and blindness associated with increasing myopia. Its approach is to bring together scientists, clinicians, policymakers, government members, and educators into the field of myopia to stimulate collaboration and sharing of knowledge. The latest reports are on pathologic myopia, the impact of myopia, risk factors for myopia, accommodation and binocular vision in myopia development and progression, and the prevention of myopia and its progression. Together with the digest updating the 2019 International Myopia Institute white papers using the research published in the last 18 months, these evidence-based consensus white papers help to clarify the imperative for myopia control and the role of environmental modification initiatives, informing an evidence-based clinical approach. This guidance includes who to treat and when to start or stop treatment, and the advantages and limitations of different management approaches.
Background
The efficacy of peripheral low add multifocal soft contact lenses (SCLs) for suppressing the progression of myopia is controversial. The aim of the on-going present clinical study is to investigate whether or not multifocal SCLs with + 0.50 diopters (D) addition suppress the progression of myopia in myopic elementary school children.
Design
Prospective randomized controlled trial.
Subjects and methods
The study plans to include a total of 100 myopic school children. Target subjects are primary school male and female students with mild to moderate myopia. Children who have eye-related diseases other than myopia are excluded from the study, because they may affect the evaluation of the outcome. Subjects will be randomly assigned to wear daily disposable multifocal contact lenses with + 0.50D addition or daily disposable SCLs. Subjects will wear contact lenses on both eyes and will be observed for 2 years under a double-masked examination. Primary outcome is a change in the axial length over the 2-year period.
Objectives
The purpose of this study is to identify whether or not multifocal SCLs with + 0.5D addition suppress the progression of myopia in myopic elementary school children as compared with standard SCLs.
Trial registration
1. UMIN (University Hospital Medical Information Network) UMIN000027940. Registered on July 21, 2017
2. JRCT (Japan Registry of Clinical Trials) jRCTs052180172. Registered on March 26, 2019
Purpose:
The purpose of this study was to examine the visual performance of center-distance MFCLs in nonpresbyopic adults under different illumination and contrast conditions compared with a single-vision contact lens (SVCL).
Methods:
Twenty-five adult subjects were fit with three different lenses (CooperVision Biofinity D MFCL +2.50 add, Visioneering Technologies NaturalVue MFCL, CooperVision Biofinity sphere). Acuity and reading performance were evaluated.
Results:
A statistically significant difference in high-contrast distance acuity was observed (Biofinity, -0.18 ± 0.06; Biofinity MFCL, -0.14 ± 0.08; NaturalVue MFCL, -0.15 ± 0.03; repeated-measures [RM] ANOVA, P = .02). Under mesopic, high-contrast conditions, MFCLs performed worse than SVCLs (Biofinity, -0.05 ± 0.091; Biofinity MFCL, +0.03 ± 0.09; NaturalVue MFCL, +0.05 ± 0.091; RM-ANOVA, P < .0001). Under low-contrast conditions, MFCLs performed one line worse in photopic lighting and two lines worse under mesopic conditions (RM-ANOVA, P < .0001). Glare reduced acuity by 0.5 logMAR for all lenses (RM-ANOVA, P < .001). A statistically significant difference in near acuity was observed (RM-ANOVA, P = .02), but all lenses achieved acuity better than -0.1 logMAR (Biofinity, -0.16 ± 0.06; Biofinity MFCL, -0.17 ± 0.04; NaturalVue MFCL, -0.13 ± 0.08). Reading performance in words per minute (wpm) was worse with MFCLs (Biofinity MFCL, 144 ± 22 wpm; NaturalVue MFCL, 150 ± 28 wpm) than with SVCLs (156 ± 23 wpm; RM-ANOVA, P = .02) regardless of letter size (RM-ANOVA, P = .13). No difference in acuity between the MFCLs was detected (RM-ANOVA: all, P > .05).
Conclusions:
Multifocal contact lenses perform similarly to SVCLs for high-contrast targets and display reduced low-contrast acuity and reading speed. Practitioners should recognize that high-contrast acuity alone does not describe MFCL visual performance.
Background:
A range of myopia management (MM) contact lenses are becoming available to practitioners. These lenses are designed to slow myopia progression and axial elongation. This study explored the initial experience of participants wearing daily disposable MM contact lenses to investigate established factors previously associated with successful lens wear.
Methods:
This was a prospective, double-masked, crossover study. Twenty participants aged 18-30 years old were assigned to wear two daily disposable MM lenses in a randomised order. Visual acuity, contrast sensitivity, and amplitude/lag of accommodation were assessed at baseline, post-insertion, and after 2 and 6 h of lens wear. Self-reported lens comfort and vision quality were recorded at the same timepoints, and at 10 h post-insertion. Pairwise comparisons were performed between the two lenses at each timepoint, as well as assessing changes throughout wear. The relationship of the measured parameters to overall lens satisfaction was also assessed.
Results:
There were no significant differences between the two MM lenses at any timepoint for any of the participant-reported parameters, including overall satisfaction. A small difference in visual acuity was noted at 6 h post-insertion, although this is unlikely to be clinically significant. Comfort decreased throughout the day, most notably at 10 h post-insertion. A moderate positive correlation was observed between participant-reported visual quality and overall satisfaction. A similar pattern was seen for comfort and overall satisfaction. Self-reported vision quality and measured visual acuity were poorly correlated, highlighting the benefit of subjectively assessing the quality of vision with these lenses.
Conclusions:
The participants demonstrated comparable measures across a range of measures between the two MM lenses. Notably, half of the participants demonstrated a clear lens preference, although the preferred lens varied between individuals. Candidates for MM may benefit from trialling more than one MM lens design, to maximise initial wearing satisfaction.
Purpose
Centre‐distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined.
Methods
Three centre‐distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from −1.00D to −6.00D in 1D steps were stored in ISO 18369‐3:2017 standard phosphate buffered saline for 24 h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer‐reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One‐way anova with Tukey’s HSD post‐hoc t‐tests were used to analyse maximum add power by lens design.
Results
Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6 mm radius), intermediate zone (about 1.6 mm radius to 2.1 mm) and near zone (about 2 mm radius to 4 mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7 mm. From 2.7 mm to 3.0 mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32 ± 0.44D), then Proclear D (+1.84 ± 0.28D) and Biofinity D (+1.47 ± 0.34D) MFCLs (all p < 0.04). Add power peaked at different locations for different lens powers and designs.
Conclusions
Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.
https://www.sciencedirect.com/science/article/abs/pii/S1350946220300951
The loss of accommodation that accompanies pediatric cataract extraction presents several unique challenges not encountered in the management of presbyopia typical in adult cataract surgery. However, many adult techniques and technologies are useful to consider in the pediatric age group. Any implantation of intraocular lenses, regardless of design, is done in an off-label fashion, as randomized, controlled trials have not been performed in this age group. Much controversy and research exist on this subject; benefits and risks are present with each viewpoint, and each patient’s case requires unique considerations. This chapter will examine a systematic thought process for approaching loss of accommodation, techniques and tools that can be utilized in management, and a look to the frontier of emerging technology for continuous improvement in this field.
This review discusses the rapid rise of myopia among school-age children in East and Southeast Asia during the last 60 years. It describes the history, epidemiology, and presumed causes of myopia in Asia, but also in Europe and the United States. The recent myopia boom is attributed primarily to the educational pressure in Asian countries, which prompts children to read for long hours, often under poor lighting and on computer screens. This practice severely limits the time spent outdoors and reduces exposure to sunlight and far vision. As a consequence, the eyes grow longer and become myopic. In a breakthrough study in Taiwan, it has been found that by increasing the time spent outdoors, the incidence of new myopia cases was reduced to half when children were sent onto the schoolyard for at least 2 h daily. This protection is attributed to the light-induced retinal dopamine, which blocks the abnormal growth of the eyeball. Once myopia has set in, low-dose atropine and orthokeratology have shown positive results in slowing myopia progression. Also, prismatic bifocal lenses and specially designed multifocal soft contact lenses have recently been tested with promising results. Treatment, however, must be initiated early as the disease progresses once it has started, thereby enhancing the risk for severe visual impairment and ultimately blindness.
Purpose
Peripheral refraction is important in design of myopia control therapies. The aim was to investigate the influence of contact lens decentration associated with eye rotation on peripheral refraction in the horizontal visual field.
Methods
Participants were 10 emmetropes and 10 myopes in good general and ocular health. Right eyes underwent cycloplegic peripheral refraction, using a Grand‐Seiko WAM‐5500 Autorefractor, in 5° steps to ±35° eccentricities along the horizontal visual field. Targets were fixated using eye rotation only or head rotation only. Refractions were measured without correction and with three types of contact lenses: single vision, a multifocal centre‐distance aspheric with +2.50 D add and NaturalVue aspheric. Photographs of eyes during lens wear were taken for each eye rotation. Effects of visual field angle, lens type and test method (head or eye rotation) on vector components of relative peripheral refraction were evaluated using repeated measures anovas. Test method for each visual field angle/lens combination were compared via paired t‐tests.
Results
Horizontal decentration ranges across the visual field were 1.2 ± 0.6 mm for single vision and 1.2 ± 0.4 mm for multifocal lenses but smaller at 0.7 ± 0.4 mm for NaturalVue lenses. There were only two significant effects of test method across the visual field angle/lens type combinations (single vision: for emmetropes horizontal/vertical astigmatism component at 35° nasal with mean difference −0.38 D and for myopes spherical equivalent refraction at 20° temporal with mean difference +0.24 D).
Conclusion
Upon eye rotation the contact lenses decentred on the eye, but not enough to affect peripheral refraction. For the types assessed and for the horizontal visual field out to ±35° when measurements were performed with the Grand‐Seiko WAM‐5500 autorefractor, it is valid to use eye rotations to investigate peripheral refraction.
Purpose: Contact lenses used for myopia control incorporate variable power distribution across the optic zone potentially creating degradation of the high order aberrations. The present study aims to evaluate the retinal image quality and visual performance in three prototypes of contact lenses intended to control axial elongation of the eye before they are considered for clinical trials.
Methods: This is a non-dispensing cross-over, double blind study where 30 right eyes of myopic subjects worn 3 multifocal test lenses and 1 monofocal control lens in random order. Lens 1 was a Radial Refractive Gradient design (center distance) and Lens 2 and 3 Center Near with an additional annular ring for near. Nominal Add power was 2.00 D, 1.50 D and 2.00 D respectively. Subjects had an age 21.96±2.23years [18 to 30] and mean spherical equivalent refraction M=-2.23±1.50D [-0.75 to -5.50] with refractive astigmatism below -0.75D. Higher order aberrations (HOA), glare formation (halo), high and low contrast LogMAR visual acuity and contrast sensitivity function (CSF) was measured under monocular conditions.
Results: All individual terms of HOA and total RMS from 3rd to 8th order increased significantly with the 3 Test lenses compared to Control. Between test lenses, Lens 1 increased significantly the higher HOA compared with Lens 2 and 3. Halo size was significantly larger with test lenses compared with control, with Lens 1 showing the largest. Visual acuity under high contrast conditions was similar for all lenses. Under low contrast Lens 1 and Lens 2 performed significantly worse than Control (Bonferroni post-hoc correction, p<0.001). CSF was below normal limits with Lens 1 for 3 and 6 cpd spatial frequency but was not significantly different between Test lenses and Control.
Conclusions: Lenses with larger stabilized areas for distance vision interfere less with visual acuity and induce lower values of higher order aberrations and image degradation.
Significance:
The Bifocal & Atropine in Myopia (BAM) study aims to determine whether combining 0.01% atropine and +2.50-diopter add center-distance soft bifocal contact lenses (SBCL) slows myopia progression more than SBCL alone. The results could provide significant information on the myopia control effect of combining optical and pharmacological treatments.
Purpose:
This article describes the subject characteristics at baseline, the study methods, and the short-term effects of this combination treatment on visual acuity (VA) and vision-related outcomes.
Methods:
Subjects from the BAM study who met the baseline eligibility criteria were dispensed the combination treatment for 2 weeks to determine final eligibility. Outcome measures included VA at near and distance (Bailey-Lovie logMAR charts), near phoria (modified Thorington), accommodative lag (Grand Seiko WAM-5500), and pupil size (NeurOptics VIP-200 Pupillometer). Compliance was monitored using surveys. Two subgroups in the Bifocal Lenses In Nearsighted Kids study, single-vision contact lens wearers and those who wore +2.50-diopter add SBCL, will serve as the age-matched historical controls for BAM study.
Results:
Forty-nine BAM subjects (9.6 ± 1.4 years) were enrolled; mean spherical equivalent cycloplegic autorefraction was -2.33 ± 1.03 diopters. After 2 weeks of treatment, the best-corrected low-contrast (10% Michelson) distance VA was reduced (pre-treatment, +0.09 ± 0.07; post-treatment, +0.16 ± 0.08; P < .0001), but the high-contrast VA at near or distance was unaffected. Near phoria increased by approximately 2 in the exo direction (P = .01), but the accommodative lag was unchanged. The pupil size was not significantly different between pre-treatment and post-treatment of either the photopic or mesopic condition. Surveys indicated that the subjects wore SBCL 77 ± 22% of waking hours and used atropine 6.4 ± 0.7 days per week.
Conclusions:
Two weeks of combination treatment reduced low-contrast distance VA and increased near exophoria slightly, but the subjects were compliant and tolerated the treatment well.
Best practice clinical guidelines for myopia control involve an understanding of the epidemiology of myopia, risk factors, visual environment interventions, and optical and pharmacologic treatments, as well as skills to translate the risks and benefits of a given myopia control treatment into lay language for both the patient and their parent or caregiver. This report details evidence-based best practice management of the pre-, stable, and the progressing myope, including risk factor identification, examination, selection of treatment strategies, and guidelines for ongoing management. Practitioner considerations such as informed consent, prescribing off-label treatment, and guides for patient and parent communication are detailed. The future research directions of myopia interventions and treatments are discussed, along with the provision of clinical references, resources, and recommendations for continuing professional education in this growing area of clinical practice.
Myopia is an important public health problem due to its prevalence and significant public health cost. Elevating levels of myopia increase the risk of vision impairment, and therefore, high myopia has become one of the main causes of untreatable vision loss throughout the world due to its irreversible complications. At present, many options for slowing progression of myopia have already been proposed and evaluated such as progressive addition of executive bifocal spectacle lenses, peripheral defocusing lenses, overnight orthokeratology, pharmacological agents such as atropine eye drops, and multifocal soft contact lenses (MFSCLs). Use of MFSCLs has especially increased in recent years due to the growing demand to slow myopia progression during patient’s adolescent growth period to avoid pathological myopia in adulthood. Compared with the other traditional methods of controlling myopia, MFSCLs allow myopic patients to better maintain their clear visual quality and slow myopia progression. In this manuscript, we aim to review the basics of myopia, recent advances in contact lenses to control myopia with emphasis on MFSCLs, define the elements for proper MFSCL fittings (such as pupil size, aberrations, accommodation and centering), discuss the potential rebound effect after discontinuation of contact lenses, and future directions for improvements of contact lenses for the control of myopia.
Myopia occurs in more than 50% of the population in many industrialized countries and is expected to increase; complications associated with axial elongation from myopia are the sixth leading cause of blindness. Thus, understanding its etiology, epidemiology, and the results of various treatment regiments may modify current care and result in a reduction in morbidity from progressive myopia. This rapid increase cannot be explained by genetics alone. Current animal and human research demonstrates that myopia development is a result of the interplay between genetic and the environmental factors. The prevalence of myopia is higher in individuals whose both parents are myopic, suggesting that genetic factors are clearly involved in myopia development. At the same time, population studies suggest that development of myopia is associated with education and the amount time spent doing near work; hence, activities increase the exposure to optical blur. Recently, there has been an increase in efforts to slow the progression of myopia because of its relationship to the development of serious pathological conditions such as macular degeneration, retinal detachments, glaucoma, and cataracts. We reviewed meta-analysis and other of current treatments that include: atropine, progressive addition spectacle lenses, orthokeratology, and multifocal contact lenses.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Purpose:
To determine whether lens induced myopia in chicks can be reversed or reduced by wearing myopia progression control lenses of the same nominal (central) power but different peripheral designs.
Methods:
Newly hatched chicks wore -10D Conventional lenses unilaterally for 7 days. The myopic chicks were then randomly divided into three groups: one fitted with Type 1 myopia progression control lenses, the second with Type 2 myopia progression control lenses and the third continued to wear Conventional lenses for seven more days. All lenses had -10D central power, but Type 1 and Type 2 lenses had differing peripheral designs; +2.75D and +1.32D power rise at pupil edge, respectively. Axial length and refractive error were measured on Days 0, 7 and 14. Analyses were performed on the mean differences between treated and untreated eyes.
Results:
Refractive error and axial length differences between treated and untreated eyes were insignificant on Day 0. On Day 7 treated eyes were longer (T1; 0.44 ± 0.07 mm, T2; 0.27 ± 0.06 mm, C; 0.40 ± 0.06 mm) and more myopic (T1; -9.61 ± 0.52D, T2; -9.57 ± 0.61D, C; -9.50 ± 0.58D) than untreated eyes with no significant differences between treatment groups. On Day 14 myopia was reversed (+2.91 ± 1.08D), reduced (-3.83 ± 0.94D) or insignificantly increased (-11.89 ± 0.79D) in treated eyes of Type 1, Type 2 and Conventional treated chicks respectively. Relative changes in axial lengths (T1; -0.13 ± 0.09 mm, T2; 0.36 ± 0.09 mm, C; 0.56 ± 0.05 mm) were consistent with changes in refraction. Refractive error differences were significant for all group comparisons (p < 0.001). Type 1 length differences were significantly different from Conventional and Type 2 groups (p < 0.001).
Conclusions:
Myopia progression control lens designs can reverse lens-induced myopia in chicks. The effect is primarily due to axial length changes. Different lens designs produce different effects indicating that lens design is important in modifying refractive error.
Purpose
To investigate which baseline factors are predictive for axial length growth over an average period of 2.5 years in a group of children wearing orthokeratology (OK) contact lenses.
Methods
In this retrospective study, the clinical records of 249 new OK wearers between January 2012 and December 2013 from the contact lens clinic at the Eye and ENT Hospital of Fudan University were reviewed. The primary outcome measure was axial length change from baseline to the time of review (July-August 2015). Independent variables included baseline measures of age at initiation of OK wear, gender, refractive error (spherical equivalent), astigmatism, average keratometry, corneal toricity, central corneal thickness, white-to-white corneal diameter, pupil size, corneal topography eccentricity value (e-value), intraocular pressure (IOP) and total time in follow-up (months total). The contributions of all independent variables on axial length change at the time of review were assessed using univariate and multivariable regression analyses.
Results
Univariate analyses of the right eyes of 249 OK patients showed that smaller increases in axial length were associated with older age at the onset of OK lens wear, greater baseline spherical equivalent myopic refractive error, less time in follow-up and a smaller e-value. Multivariable analyses of the significant right eye variables showed that the factors associated with smaller axial length growth were older age at the onset of OK lens wear (p<0.0001), greater baseline spherical equivalent myopic refractive error (p = 0.0046) and less time in follow-up (p<0.0001).
Conclusions
The baseline factors demonstrating the greatest correlation with reduced axial length elongation during OK lens wear in myopic children included greater baseline spherical equivalent myopic refractive error and older age at the onset of OK lens wear.
There is an error in affiliation 1 for authors Yuan Sun, Fan Xu, Ting Zhang, Manli Liu, Danyang Wang, Yile Chen, and Quan Liu. Affiliation 1 should be: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
Purpose:
To determine the effect of using toric soft contact lenses on corneal biomechanical properties.
Methods:
We enrolled 33 healthy patients with mean age of 23.18 ± 4.06 and minimal cylinder power of 1 D (-1.98 ± 0.808 SD) and negative history of contact lens use; keratoconic patients were excluded from the study. Toric soft contact lenses (BIOFINITY, Comfilcon A, Coopervision, Southampton, UK) were fitted in all participants. The Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, New York, USA) was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), and the Pentacam HR (Oculus, Inc., Lynnwood, WA, USA) was used to measure central corneal thickness (CCT) and mean keratometry (K mean) before and one week, one month, and three months after using the toric soft contact lenses.
Results:
CH and CRF were decreased significantly one month after using the contact lens; mean CH decreased from 9.99 ± 1.44 to 9.59 ± 1.54 mmHg, and mean CRF decreased from 9.96 ± 1.71 to 9.63 ± 1.73 mmHg (P = 0.013 and P = 0.017, respectively). Mean CCT and K mean did not show a significant change during the period of toric soft contact lens use.
Conclusion:
CH and CRF decreased significantly one month after fitting toric soft contact lenses while CCT and Kmean did not change significantly. Corneal biomechanical parameters may alter with toric soft contact lens use and such changes may have implications with long-term use such lenses.
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.
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.
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.
This is a review of the current literature describing the effect of atropine, bifocals, and/or contact lenses on slowing the progression of myopia. Cumulative data from a number of studies have demonstrated atropine instilled once a day in myopic eyes resulted in a 90% average reduction of myopia progression, as compared to untreated eyes, i.e., from 0.50 D/year to 0.05 D/year. Pirenzepine, a muscarinic pharmacological agent, has a minimal effect on pupil size and accommodation, and it has been shown to slow myopia by 44%. Bifocals and progressive lenses, which have been used for years to slow the progression of myopia, have recently been shown to produce, on average, only small, clinically insignificant treatment effects. However, their effectiveness is increased in children who are esophoric and have a large lag of accommodation, reducing myopia progression to between 0.25 and 0.40 D/year. Traditional correcting soft and gas permeable contact lenses, as well as novel spectacle lens designs, have not been shown to be effective in reducing myopic progression. Under-correction of the refractive error has been shown not only to be ineffective in slowing myopia, but has also been associated with an increased rate of myopia progression. Orthokeratology, using reverse geometry designed lenses, has been shown to be moderately effective in decreasing the progression of myopia by between 30 to 50% in a number of short-term, well-controlled studies, reducing myopia progression to between -0.25 and -0.35 D/year. Recently, there have been pilot studies using novel peripherally correcting soft contact lenses to slow the progression of myopia. Two of those lens designs have been shown to be moderately effective in slowing the progression of myopia, both of which had a 30% efficacy, reducing myopia progression to 0.35 D/year. In summary, myopia control is entering a new era with the use of contact lenses and pharmaceutical agents to effectively slow its progression with minimal side effects.
To determine whether a novel optical treatment using contact lenses to reduce relative peripheral hyperopia can slow the rate of progress of myopia.
Chinese children, aged 7 to 14 years, with baseline myopia from sphere -0.75 to -3.50 D and cylinder ≤1.00 D, were fitted with novel contact lenses (n = 45) and followed up for 12 months, and their progress was compared with that of a group (n = 40) matched for age, sex, refractive error, axial length, and parental myopia wearing normal, single-vision, spherocylindrical spectacles.
On adjusting for parental myopia, sex, age, baseline spherical equivalent (SphE) values, and compliance, the estimated progression in SphE at 12 months was 34% less, at -0.57 D, with the novel contact lenses (95% confidence interval [CI], -0.45 -0.69 D) than at -0.86 D, with spectacle lenses (95% CI, -0.74 to -0.99 D). For an average baseline age of 11.2 years, baseline SphE of -2.10 D, a baseline axial length of 24.6 mm, and 320 days of compliant lens wear, the estimated increase in axial length (AL) was 33% less at 0.27 mm (95% CI, 0.22-0.32 mm) than at 0.40 mm (95% CI, 0.35-0.45 mm) for the contact lens and spectacle lens groups, respectively.
The 12-month data support the hypothesis that reducing peripheral hyperopia can alter central refractive development and reduce the rate of progress of myopia. (chictr.org number, chiCTR-TRC-00000029 or chiCTR-TRC-00000032.).
To compare US population prevalence estimates for myopia in 1971-1972 and 1999-2004.
The 1971-1972 National Health and Nutrition Examination Survey provided the earliest nationally representative estimates for US myopia prevalence; myopia was diagnosed by an algorithm using either lensometry, pinhole visual acuity, and presenting visual acuity (for presenting visual acuity > or =20/40) or retinoscopy (for presenting visual acuity < or =20/50). Using a similar method for diagnosing myopia, we examined data from the 1999-2004 National Health and Nutrition Examination Survey to determine whether myopia prevalence had changed during the 30 years between the 2 surveys.
Using the 1971-1972 method, the estimated prevalence of myopia in persons aged 12 to 54 years was significantly higher in 1999-2004 than in 1971-1972 (41.6% vs 25.0%, respectively; P < .001). Prevalence estimates were higher in 1999-2004 than in 1971-1972 for black individuals (33.5% vs 13.0%, respectively; P < .001) and white individuals (43.0% vs 26.3%, respectively; P < .001) and for all levels of myopia severity (>-2.0 diopters [D]: 17.5% vs 13.4%, respectively [P < .001]; < or =-2.0 to >-7.9 D: 22.4% vs 11.4%, respectively [P < .001]; < or =-7.9 D: 1.6% vs 0.2%, respectively [P < .001]).
When using similar methods for each period, the prevalence of myopia in the United States appears to be substantially higher in 1999-2004 than 30 years earlier. Identifying modifiable risk factors for myopia could lead to the development of cost-effective interventional strategies.
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 eyes of growing chicks adjust to correct for myopia (eye relatively long for the focal length of its optics) or hyperopia (eye relatively short for the focal length of its optics). Eyes made functionally hyperopic with negative spectacle lenses become myopic and long, whereas eyes made functionally myopic with positive spectacle lenses become hyperopic and short. We report here that these compensatory growth adjustments occur not only in normal eyes but also in eyes unable to accommodate (focus) because of lesions to the Edinger-Westphal nuclei. Thus, at least in chicks, accommodation is not necessary for growth that reduces refractive errors during development, and may not be necessary for the normal control of eye growth.
To study retrospectively the frequency of myopia progression and risk factors for progression in a sample of adult contact lens wearers.
From a database of 815 soft contact lens wearers, patients were identified whose age was between 20 and 40 years, who had at least -0.50 D spherical equivalent of myopia in both eyes, three or more refractions, and > or =5 years of follow-up. Only data from the right eye were used. Progression was defined as an increase of at least -1.00 D over 5 years. Subjects were also asked to complete a questionnaire regarding their ocular history, demographics, family history, and the amount of time spent performing different tasks at home and at work.
Two hundred ninety-one subjects met the eligibility criteria with a mean baseline refractive error of -3.29 +/- 1.92 D and a mean age of 28.5 +/- 5.0 years. Of these, 21.3% progressed by at least -1.00 D over the 5-year period. The 5-year rate of progression decreased with increasing age (chi(2) = 12.44, P = 0.006). One hundred ninety-seven subjects (67.6%) completed and returned questionnaires. "Progressors" (N = 41) did not differ from "nonprogressors" (N = 156) in terms of hours per day spent reading and writing, computer use, education level, family history of myopia, age of onset of myopia, and contact lens wear.
In this database of soft contact lens wearers, myopia progression was common for subjects in their twenties and less common for those in their thirties.
To determine the incidence and progression rates of myopia in young Singaporean children.
A prospective cohort study, the Singapore Cohort Study of the Risk Factors for Myopia (SCORM), was conducted in two schools in Singapore (1999-2002). Children aged 7 to 9 years (n=981) were followed up over a 3-year period. Cycloplegic autorefraction and biometry parameter measures were performed annually, according to the same protocol.
The 3-year cumulative incidence rates were 47.7% (95% confidence interval [CI]: 42.2-53.3), 38.4% (95% CI: 31.4-45.4), and 32.4% (95% CI: 21.8-43.1) for 7-, 8-, and 9-year-old children, respectively. The 3-year cumulative incidence rates were higher in Chinese (49.5% vs. 27.2%) and in 7-year-old compared with 9-year-old children at baseline (47.7% vs. 32.4%), though the latter relationship was of borderline significance after adjustment for race, gender, amount of reading (books/week), and parental myopia (P=0.057). Premyopic children with greater axial lengths, vitreous chamber depths, and thinner lenses were more prone to the development of myopia, after controlling for age, gender, race, reading, and parental myopia. The 3-year mean cumulative myopia progression rates were -2.40 D (95% CI: -2.57 to -2.22) in 7-year-old myopic children, -1.97 (95% CI: -2.16 to -1.78) in 8-year-olds, and -1.71 (95% CI: -1.98 to -1.44) in 9-year-olds.
Both the incidence and progression rates of myopia are high in Singaporean children.
Because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea dominate refractive development. To test this assumption, the authors determined whether an intact fovea was essential for either normal emmetropization or the vision-induced myopic errors produced by form deprivation.
In 13 rhesus monkeys at 3 weeks of age, the fovea and most of the perifovea in one eye were ablated by laser photocoagulation. Five of these animals were subsequently allowed unrestricted vision. For the other eight monkeys with foveal ablations, a diffuser lens was secured in front of the treated eyes to produce form deprivation. Refractive development was assessed along the pupillary axis by retinoscopy, keratometry, and A-scan ultrasonography. Control data were obtained from 21 normal monkeys and three infants reared with plano lenses in front of both eyes.
Foveal ablations had no apparent effect on emmetropization. Refractive errors for both eyes of the treated infants allowed unrestricted vision were within the control range throughout the observation period, and there were no systematic interocular differences in refractive error or axial length. In addition, foveal ablation did not prevent form deprivation myopia; six of the eight infants that experienced monocular form deprivation developed myopic axial anisometropias outside the control range.
Visual signals from the fovea are not essential for normal refractive development or the vision-induced alterations in ocular growth produced by form deprivation. Conversely, the peripheral retina, in isolation, can regulate emmetropizing responses and produce anomalous refractive errors in response to abnormal visual experience. These results indicate that peripheral vision should be considered when assessing the effects of visual experience on refractive development.
Purpose:
A number of optical methods for slowing myopia progression have been tested and are now available. However, data on real-world use in clinical use is scarce. Here, we present a review of the clinical outcomes for patients attending a specialist myopia control clinic at The University of Auckland Optometry School, NZ.
Case series:
We report a comparative case series of 110 patients (aged 4-33 years, mean: 12.13 ± 4.58 years, 62% female) who attended the clinic between 2010 and 2014. Fifty-six were prescribed orthokeratology, 32 dual focus soft contact lenses, and 22 received advice only. Initial myopia, vitreous and axial eye length, previous myopia progression, age, number of myopic parents, and gender were not significantly different between orthokeratology and dual focus soft contact lens groups. Mean follow-up time for the orthokeratology and dual focus lens groups was the same (orthokeratology: 1.30 ± 0.88 years; dual focus lens: 1.33 ± 0.80 years (p = 0.989)). There was a significant reduction in the annualized myopia progression in both groups (orthokeratology: -1.17 ± 0.55 to -0.09 ± 017 D/yr, p < 0.001; dual focus soft contact lens: -1.15 ± 0.46 to -0.10 ± 0.23 D/yr, p < 0.001). There was no difference between orthokeratology and dual focus lens treatment efficacy (p = 0.763), nor in axial or vitreous chamber length changes after treatment (p = 0.184). One adverse event was reported over the 4-year period.
Conclusions:
Both orthokeratology and dual focus soft contact lenses are effective strategies for targeting myopia progression in the clinic. We saw no significant difference in the efficacy of the two methods in this regard, and so we believe there are very few barriers for any contact lens practitioner to be actively promoting myopia control treatment to at-risk patients.
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.
: The growing incidence of pediatric myopia worldwide has generated strong scientific interest in understanding factors leading to myopia development and progression. Although contact lenses (CLs) are prescribed primarily for refractive correction, there is burgeoning use of particular modalities for slowing progression of myopia following reported success in the literature. Standard soft and rigid CLs have been shown to have minimal or no effect for myopia control. Overall, orthokeratology and soft multifocal CLs have shown the most consistent performance for myopia control with the least side effects. However, their acceptance in both clinical and academic spheres is influenced by data limitations, required off-label usage, and a lack of clear understanding of their mechanisms for myopia control. Myopia development and progression seem to be multifactorial, with a complex interaction between genetics and environment influencing myopigenesis. The optical characteristics of the individual also play a role through variations in relative peripheral refraction, binocular vision function, and inherent higher-order aberrations that have been linked to different refractive states. Contact lenses provide the most viable opportunity to beneficially modify these factors through their close alignment with the eye and consistent wearing time. Contact lenses also have potential to provide a pharmacological delivery device and a possible feedback mechanism for modification of a visual environmental risk. An examination of current patents on myopia control provides a window to the future development of an ideal myopia-controlling CL, which would incorporate the broadest treatment of all currently understood myopigenic factors. This ideal lens must also satisfy safety and comfort aspects, along with overcoming practical issues around U.S. Food and Drug Administration approval, product supply, and availability to target populations. Translating the broad field of myopia research into clinical practice is a multidisciplinary challenge, but an analysis of the current literature provides a framework on how a future solution may take shape.
To investigate the relationship between axial length (AL) increase and baseline spherical equivalent refractive errors (SER) in myopic children wearing orthokeratology contact lenses (OK).
One hundred fifteen Chinese (115 right eyes) children wearing OK were enrolled in this cohort study. Gender, age, baseline SER, corneal power, corneal astigmatism, and AL at baseline and 2 years after wearing OK were collected. Univariate analysis and trend test were used to estimate the relationship between change in AL and baseline SER.
After univariate analysis, a statistically significant relationship was found between change in AL and baseline SER (β=0.061, 95% CI: 0.015-0.111, P=0.015). In the trend test, after adjusting for potential confounders, higher SER was associated with smaller increases in AL (P trend=0.041).
The SER at baseline was associated with AL growth in myopic children wearing OK. The higher SER was associated with slower AL growth and control the development of myopia.
Copyright © 2015 Elsevier Ltd. All rights reserved.
To conduct a meta-analysis on the effects of orthokeratology in slowing myopia progression.
A literature search was performed in PubMed, Embase, and the Cochrane Library. Methodological quality of the literature was evaluated according to the Jadad score. The statistical analysis was carried out using RevMan 5.2.6 software.
The present meta-analysis included seven studies (two randomized controlled trials and five nonrandomized controlled trials) with 435 subjects (orthokeratology group, 218; control group, 217) aged 6 to 16 years. The follow-up time was 2 years for the seven studies. The weighted mean difference was -0.26 mm (95% confidence interval, -0.31 to -0.21; p < 0.001) for axial length elongation based on data from seven studies and -0.18 mm (95% confidence interval, -0.33 to -0.03; p = 0.02) for vitreous chamber depth elongation based on data from two studies.
Our results suggest that orthokeratology may slow myopia progression in children. Further large-scale studies are needed to substantiate the current result and to investigate the long-term effects of orthokeratology in myopia control.
Purpose
To assess the effect of different disposable soft contact lenses upon corneal thickness, and upon anterior and posterior corneal curvatures using a dual-Scheimpflug imaging based device.
Methods
Twenty-eight young, healthy subjects wore four different types of daily disposable soft contact lenses on four different days: Dailies Total1, Proclear 1 Day, Clariti 1-Day and 1-Day Acuvue Moist. The lenses had different material and water content. Pachymetry maps and keratometry values were obtained using the Galilei G4 twice a day: one before putting the lens on and one after an eight-hour period of contact-lens wear. Measurements were also recorded without any contact lenses being worn during a day.
Results
Clariti 1-Day lens caused the greatest thickening in the central (8.9 ± 2.8 μm; p < 0.01) and in the peripheral cornea (10.1 ± 4.6 μm; p < 0.01), whereas Dailies Total1 was the lens that had the most similar behaviour to the non-contact lens scenario. All the lenses caused a slight flattening in the anterior corneal curvature, except Clariti 1-Day, which induced a very slight steepening. The four lenses caused a steepening of different magnitude in the posterior corneal curvature.
Conclusions
The magnitude of the changes introduced by the use of soft contact lenses over the eight-hour wearing period was rather small. Thus it is probable it will not influence the vision nor the comfort of the subject. Also, variations on corneal parameters seem to depend on the type of contact lens used.
Purpose:To investigate changes in axial length and refractive error during overnight orthokeratology (OK) compared with conventional daily rigid gas-permeable (GP) contact lens wear in myopic children.
Methods:Twenty-six children (10.5 to 16.7 years) with progressive myopia wore an overnight OK lens in one eye and a GP lens for daily wear in the other eye for one year. After 6 months the lens-eye combinations were reversed. Axial length was monitored using the IOL Master. Spherical equivalent refractive error was measured using the Shin-Nippon NVision-K 5001 autorefractor at baseline and after a 2-week washout period of no lens wear at 6 and 12 months. Changes in axial length and refractive error were analysed separately over the two study phases, relative to baseline data collected at the beginning of each 6-month period. ANOVA and post hoc paired t-tests were used to compare changes in the two eyes. The relationship between axial length and refractive error changes was analyzed using Pearson correlation.
Results:Differences in axial length growth between OK and GP eyes were statistically significant at 6 months (GP-OK: 0.05±0.12mm, p<0.05) and 12 months (0.09±0.17mm, p<0.005). Significant interocular differences in refractive error were also found after a 2-week washout at 6 months (GP-OK: -0.32±0.45D, p<0.005) and 12 months (-0.57±0.66D, p<0.005). Increases in axial length and myopic refractive error in the GP eye were significantly correlated (r=-0.698, p<0.001), whereas correlation between these variables in the OK eye did not reach statistical significance.
Conclusions:Overnight OK lens wear inhibits axial length growth and myopia progression over a 12-month period. After 6 and 12 months the OK eye showed no change in axial length and a slight decrease in myopia compared to baseline, whereas the GP eye showed axial length growth and myopia progression. Crossover of the effects on axial length and refractive error after reversal of lens-eye combinations at 6 months reinforces the promise of this modality for myopia control.
Purpose:
To use the Gompertz function to estimate the age and the amount of myopia at stabilization and to evaluate associated factors in the Correction of Myopia Evaluation Trial (COMET) cohort, a large ethnically diverse group of myopic children.
Methods:
The COMET enrolled 469 ethnically diverse children aged 6 to younger than 12 years with spherical equivalent refraction between -1.25 and -4.50 diopters (D). Noncycloplegic refraction was measured semiannually for 4 years and annually thereafter. Right eye data were fit to individual Gompertz functions in participants with at least 6 years of follow-up and at least seven refraction measurements over 11 years. Function parameters were estimated using a nonlinear least squares procedure. Associated factors were evaluated using linear regression.
Results:
In total, 426 participants (91%) had valid Gompertz curve fits. The mean (SD) age at myopia stabilization was 15.61 (4.17) years, and the mean (SD) amount of myopia at stabilization was -4.87 (2.01) D. Ethnicity (P < 0.0001) but not sex or the number of myopic parents was associated with the age at stabilization. Ethnicity (P = 0.02) and the number of myopic parents (P = 0.01) but not sex were associated with myopia magnitude at stabilization. At stabilization, African Americans were youngest (mean age, 13.82 years) and had the least myopia (mean, -4.36 D). Participants with two versus no myopic parents had approximately 1.00 D more myopia at stabilization. The age and the amount of myopia at stabilization were correlated (r = -0.60, P < 0.0001).
Conclusions:
The Gompertz function provides estimates of the age and the amount of myopia at stabilization in an ethnically diverse cohort. These findings should provide guidance on the time course of myopia and on decisions regarding the type and timing of interventions.
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:
To determine the effect of wearing a lens with a unique peripheral optical design on the development and progression of defocus-induced myopia in newly hatched chickens.
Methods:
Eighty-five newly hatched chickens underwent bilateral retinoscopy and A-scan ultrasound to determine their refractive error and axial length. They were randomly divided into Control and two Test groups, in which each chicken was fitted with a goggle-lens over the right eye, with the left eye remaining untreated. The Control group wore a lens of power -10.00 diopters (D) of standard spherical optical design. The two Test lenses both had a central optical power -10.00 D, but used different peripheral myopia progression control (MPC) designs. For all groups, retinoscopy was repeated on days 3, 7, 10, and 14; ultrasound was repeated on day 14.
Results:
On day 0 there was no statistical difference in refractive error (mean +6.92 D) or axial length (mean 8.06 mm) between Test and Control groups or treated and untreated eyes (all P 0.05). At day 14, 37 (43.5%) of 85 chickens had not experienced goggle detachment and were included in the final analyses. in this cohort there was a significant refractive difference between the treated eyes of the control group (n = 17) and those of test 1 (n = 14) and Test 2 (N = 6) groups (both P <0.01): Control -4.65 ± 2.11 D, Test 1 +4.57 ± 3.11 D, Test 2 +1.08 ± 1.24 D (mean ± SEM). There was also a significant axial length difference (both P < 0.01): Control 10.55 ± 0.36 mm, Test 1 9.99 ± 0.14 mm, Test 2 10.17 ± 0.18 mm.
Conclusions:
Use of these unique MPC lens designs over 14 days caused a significant reduction in the development of defocus-induced myopia in chickens; the degree of reduction appeared to be design specific.
We raised chickens with defocusing lenses of differing powers in front of their eyes. For this purpose, small hoods made from soft, thin leather were carefully fitted to their heads. Lenses were attached to the hoods by velcro fasteners and could be easily removed for cleaning. The powers of the lenses were such that their optical effects could be compensated for by accommodation. It was verified by infrared (IR) photoretinoscopy that the chickens could keep their retinal images in focus. Wearing a lens resulted in a consistent shift of the non cycloplegic refractive state (measured without the lens) which was in the direction to compensate for the lens. We used a sensitive technique (precision= ± 50 μm as estimated from the variability of repeated measurements) to measure the posterior nodal distance (PND) in excised eyes of birds grown with lenses. The PND, in turn, was used to compare eyes treated with different lenses. It was found that the PND was increased in eyes which were treated with negative lenses compared to those treated with positive lenses. This effect occurs independently in both eyes and it is not due to changes in corneal curvature. We discuss our result in terms of a closed-loop feedback system for the regulation of eye growth.
To evaluate the association of symptomatic soft contact lens (SCL)-related corneal infiltrative events (CIEs) with SCL material, lens care products (LCPs), and other risk factors.
Cases with symptomatic CIEs were identified in a retrospective, multicenter case-control study at five academic eye care centers. Each case was matched to three controls each who had received eye care near the time of the case's last full examination at that center but were not matched for demographic or other factors. Infiltrate status was established by an expert panel who were masked to sponsor, SCL, and LCP brand. Stratified analyses were conducted removing all daily disposable (DD) and all extended wear (EW) cases.
Clinical records from 166 patients with symptomatic CIEs and known EW status were included. Cases used >50 SCL brands and >10 LCP brands. Increased risk in univariate analysis for LCP was not significant after adjustment for other factors. In the multivariate analysis of all cases, use of reusable SCLs (4.03×; 95% C.I. 1.12 to 14.67) and EW (3.98×; 2.32 to 6.84) increased risk and patient age (per year older) was protective (0.96×; 0.94 to 0.98). Among daily wear cases (n = 102 cases), use of reusable SCLs (12.46×; 1.54 to 100.62) and silicone hydrogel (SiHy) (1.99×; 1.06 to 3.75) and age (0.95×: 0.92 to 0.97) were associated. Without DD cases (n = 162), EW (4.42×; 2.53 to 7.70), SiHy use (1.84×; 1.03 to 3.29), and patient age (0.96× 0.94 to 0.98) were significant factors. No specific SCL or LCP brands were associated with increased risk.
In this community-based trial, younger patients were at increased risk of infiltrative events. DD lenses were protective relative to reusable lenses. Overnight use increased risk in all analyses and silicone hydrogels increased risk in daily wearers, regardless of LCP brand. Improvements in lens storage case hygiene and environment may be a mechanism for reducing risk of CIEs related to SCL use.
To review and evaluate the current literature on the incidence and risk factors for rhegmatogenous retinal detachment (RRD) following cataract surgery.
RRD is a serious complication of cataract surgery that can occur in the early or late postoperative periods. Identifying factors that increase the risk of pseudophakic retinal detachment can aid in management. Recent studies support long established risk factors for retinal detachment including intraoperative complications such as posterior capsular rupture (PCR). In addition, the current literature further defines the risk for pseudophakic retinal detachment associated with younger age at time of surgery, high myopia, and male sex in several large retrospective studies. Two recent articles also examine the state of the vitreous before and after cataract surgery and find that patients are more likely to develop posterior vitreous detachment postoperatively, possibly contributing to the increased risk of RRD.
Younger age, high myopia, and male sex continue to be associated with higher risk of pseudophakic retinal detachment. Intraoperative complications such as PCR also increase the retinal detachment risk. Given the high volume of cataract surgeries performed each year, pseudophakic retinal detachment contributes significantly to visual morbidity in the United States and Europe.
It is well established that refractive development is regulated by visual feedback. However, most optical treatment strategies designed to reduce myopia progression have not produced the desired results, primarily because some of our assumptions concerning the operating characteristics of the vision-dependent mechanisms that regulate refractive development have been incorrect. In particular, because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea determine the effects of vision on refractive development. However, experiments in laboratory animals demonstrate that ocular growth and emmetropization are mediated by local retinal mechanisms and that foveal vision is not essential for many vision-dependent aspects of refractive development. However, the peripheral retina, in isolation, can effectively regulate emmetropization and mediate many of the effects of vision on the eye's refractive status. Moreover, when there are conflicting visual signals between the fovea and the periphery, peripheral vision can dominate refractive development. The overall pattern of results suggests that optical treatment strategies for myopia that take into account the effects of peripheral vision are likely to be more successful than strategies that effectively manipulate only central vision.
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.
This prospective study was conducted to assess the influence of overnight orthokeratology (OK) on axial elongation in children, with those wearing spectacles as controls.
One hundred five subjects (210 eyes) were enrolled in the study. The OK group comprised 45 patients (90 eyes, age 12.1 ± 2.5 years, mean ± SD; OK group) who matched the inclusion criteria for OK. The control group comprised 60 patients (120 eyes, 11.9 ± 2.0 years) who also matched the inclusion criteria for OK but preferred spectacles for myopia correction. Axial length was measured at baseline and after 2 years using ocular biometry, and the changes were evaluated and compared between the groups.
Ninety-two subjects (42 and 50 in the OK and control groups, respectively) completed the 2-year follow-up examinations. At baseline, the spherical equivalent refractive error was -2.55 ± 1.82 and -2.59 ± 1.66 D, and the axial length was 24.66 ± 1.11 and 24.79 ± 0.80 mm in the OK and control groups, respectively, with no significant differences between the groups. The increase in axial length during the 2-year study period was 0.39 ± 0.27 and 0.61 ± 0.24 mm, respectively, and the difference was significant (P < 0.0001, unpaired t-test).
OK suppressed axial elongation in myopic children, suggesting that this treatment can slow the progression of myopia to a certain extent.
THE aetiology of myopia has been studied mainly by investigating the distribution of refractive errors in human populations1. No clear conclusion has emerged, however, so the prevailing clinical attitude is that myopia can neither be prevented nor cured, but only corrected with appropriate lenses. The mechanism of myopia can be rationally analysed only if a suitable animal model is found for this refractive condition. In the literature, there are only two examples of experimental myopia. Levinsohn2 claimed that a high degree of myopia develops in young monkeys when the body is kept elevated above the head for long periods of time; his results, however, have been questioned3,4. Young5 induced myopia by exposing monkeys to a restricted visual space, but the refractive error thus obtained was relatively small. During investigations on monocular visual deprivation in monkeys6 it was noted that the eye in which the lids had been closed by suture at birth developed a high degree of myopia. We report here a study of the effects of neonatal lid fusion on the refractive state and anatomy of the macaque monkey eye.
Myopia develops in macaque monkeys when their lids are surgically fused at birth and kept closed for one year. This experimental refractive error has many features in common with human myopia: It is caused by progressive axial elongation of the eye, is often accompanied by fundus changes, and can only be induced before eye growth has been completed. Myopia does not develop in animals raised in the dark; thus, it is triggered by an alteration of the visual input and is presumably mediated by the nervous system. In Macaca arctoides, atropine administration prevents abnormal eye elongation, and this suggests that lid-fusion myopia is caused by excessive accommodation. In M. mulatta, atropine is ineffective; furthermore, myopia develops when lids are sutured after interruption of the optic pathways. Thus, in this species accommodation can be ruled out as a determinant of eye elongation, and other neural mechanisms may be responsible for the refractive error. Our experiments suggest that the refractive state is largely programmed on a genetic basis, but that an abnormal visual experience can disrupt the process of postnatal eye growth and induce axial myopia.
This case series presents the first documented cases of infectious ulcers associated with overnight orthokeratology in North America and other less serious complications associated with overnight corneal reshaping.
Five cases of adverse corneal events associated with corneal refractive therapy are described: two cases of microbial keratitis, one case of infiltrates, one case of toxic keratitis, and one corneal abrasion.
Corneal compromise and poor compliance can cause adverse events with corneal reshaping. The need for ongoing patient education is important not only for pediatric contact lens patients, but also for adults.
Purpose:
Astigmatism is the most common ametropia found in humans and is often associated with large spherical ametropias. However, little is known about the etiology of astigmatism or the reason(s) for the association between spherical and astigmatic refractive errors. This study examines the frequency and characteristics of astigmatism in infant monkeys that developed axial ametropias as a result of altered early visual experience.
Methods:
Data were obtained from 112 rhesus monkeys that experienced a variety of lens-rearing regimens that were intended to alter the normal course of emmetropization. These visual manipulations included form deprivation (n = 13); optically imposed defocus (n = 48); and continuous ambient lighting with (n = 6) or without optically imposed defocus (n = 6). In addition, data from 19 control monkeys and 39 infants reared with an optically imposed astigmatism were used for comparison purposes. The lens-rearing period started at approximately 3 weeks of age and ended by 4 to 5 months of age. Refractive development for all monkeys was assessed periodically throughout the treatment and subsequent recovery periods by retinoscopy, keratometry, and A-scan ultrasonography.
Results:
In contrast to control monkeys, the monkeys that had experimentally induced axial ametropias frequently developed significant amounts of astigmatism (mean refractive astigmatism = 0.37 +/- 0.33 D [control] vs. 1.24 +/- 0.81 D [treated]; two-sample t-test, p < 0.0001), especially when their eyes exhibited relative hyperopic shifts in refractive error. The astigmatism was corneal in origin (Pearson's r; p < 0.001 for total astigmatism and the JO and J45 components), and the axes of the astigmatism were typically oblique and bilaterally mirror symmetric. Interestingly, the astigmatism was not permanent; the majority of the monkeys exhibited substantial reductions in the amount of astigmatism at or near the end of the lens-rearing procedures.
Conclusions:
In infant monkeys, visual conditions that alter axial growth can also alter corneal shape. Similarities between the astigmatic errors in our monkeys and some astigmatic errors in humans suggest that vision-dependent changes in eye growth may contribute to astigmatism in humans.
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.
Children are not offered elective contact lenses as a treatment option for refractive error nearly as often as teens are. The purpose of this report was to examine the benefits of contact lens wear for children and teens to determine whether children benefit as much as teens. If they do, children should routinely be offered contact lens wear as a treatment for refractive error.
Neophyte contact lens wearers were categorized as children (8-12 years of age) or teens (13-17 years of age). They completed the Pediatric Refractive Error Profile (PREP), a pediatric quality-of-life survey for subjects affected only by refractive error, while wearing glasses; then they were fitted with silicone hydrogel contact lenses. One week, 1 month, and 3 months after receiving contact lenses, the subjects completed the same PREP survey. Subjects also completed questions regarding wearing time and satisfaction with contact lenses during specific activities.
The study enrolled 169 subjects at three clinical centers. Ninety-three (55%) of the subjects were girls; 78 (46%) were white; and 44 (26%) were Hispanic. After wearing contact lenses for 3 months, the overall PREP score increased from 64.4 for children and 61.8 for teens while wearing glasses to 79.2 for children and 76.5 for teens. The improvement from baseline to 3 months was significant for children and teens (P<0.0001 for both groups), but there was not a significant difference in improvement between children and teens (P>0.05). The areas of most improvement were satisfaction with correction, activities, and appearance.
Contact lenses significantly improved the quality of life, as reported by children and teens using the PREP, and there was not a difference in improvement between children and teens. Contact lens wear dramatically improves how children and teens feel about their appearance and participation in activities, leading to greater satisfaction with their refractive error correction. The improvement in quality of life after contact lens wear indicates that children should be offered contact lenses as a treatment for refractive error as routinely as teens.
To determine time trends in myopia over a 20-year period in Taiwan, we conducted 5 nationwide surveys pertaining to the ocular refraction of schoolchildren in 1983, 1986, 1990, 1995 and 2000.
The sampling technique used herein involved the assessment of stratified systematic clusters, with the unweighted myopic rate being represented using data derived from different sectors of the population, such as metropolitan, city, town, and aboriginal. The mean values for the spherical equivalent of the cycloplegic refractive status and the dimension of corneal radii as determined by the autorefractometer were used for the calculation.
In our review of 5 nationwide myopia surveys, we found that the mean prevalence of myopia among 7 year olds increased from 5.8% in 1983 to 21% in 2000. At the age of 12, the prevalence of myopia was 36.7% in 1983 increasing to 61% in 2000, corresponding figures for 15-year-olds being 64.2% and 81%, respectively. The prevalence of myopia increased from 74% in 1983 to 84% in 2000 for children aged between 16 and 18 years, and, in addition, the prevalence of high myopia (over -6.0 D) increased from 10.9% in 1983 to 21% of 18-year-old students of Taiwan in 2000. The mean refractive status at the age of 12 deteriorated from -0.48 D in 1983 to -1.45 D in 2000, and from -1.49 D to -2.89 D for children aged 15, whilst for individuals aged 18, it deteriorated from -2.55 D in 1983 to -3.64 D in 2000. The mean ocular refraction began to progress to a myopic condition at the age of 11 in 1983, this becoming an age of 8 years in 2000. There appeared to be significant difference in both the prevalence and the degree of myopia between study participants residing in cities and villages.
We conclude that the cause of the relative increasing severity of myopia among the schoolchildren was due to the onset of myopia at a very young, and progressively-decreasing, age over the study period. Thus, to reduce the prevalence and severity of myopia, we should pay more attention to the eye care of pre-schoolchildren.
To assess the repeatability and reliability of IOLMaster (Carl Zeiss Meditec, Inc., Dublin, CA) axial length and keratometry measurements (K readings) with a soft contact lens on normal eyes. The method is designed for eyes with corneal irregularities or after endothelial keratoplasty.
Biometry was performed on 20 healthy right eyes of volunteer subjects with mean age, 27.3 +/- 4.9 years; axial length, 24.77 +/- 1.04 mm; and K reading, 43.48 +/- 1.69 D. Axial length and keratometry were measured and repeated with -0.5 D SofLens38 (Bausch & Lomb, Rochester, NY) and Acuvue2 (Johnson & Johnson, New Brunswick, NJ) soft contact lenses. Repeatability and reliability were evaluated. Contact lens thickness was measured directly by corneal optical coherence tomography (OCT).
Axial lengths increased 59 +/- 10 microm with SofLens38 and 134 +/- 13 microm with Acuvue2, and these changes correlated with the OCT contact lens thicknesses (P = 0.995). The axial length variability remained constant (P = 0.18), measuring 24 +/- 10 microm for SofLens38 and 23 +/- 8 microm for Acuvue2 compared with 20 +/- 7 microm with no lens. K readings of 43.08 +/- 1.66 D with SofLens38, 42.79 +/- 1.57 D with Acuvue2, and 43.48 +/- 1.69 D with no lens corresponded to differences of -0.40 +/- 0.12 D with SofLens38 and -0.69 +/- 0.19 D with Acuvue2. The K-reading variability increased slightly from 0.04 to 0.09 D with either lens.
Low-power soft contact lenses enable reliable and repeatable IOLMaster axial length and K-reading measurements. Correcting for the measurable lens thickness and lens effects, a <0.5-D error in the Sanders-Retzlaff-Kraff (SRK) II power formula is predicted.
Children's evaluation of a unique myopia progression control lens design
- Miller
Feasibility testing of a novel SCL optical design to reduce suspected risk factors for the progression of juvenile onset myopia
- Payor
Comparison of three power levels of a novel soft contact lens optical design to reduce suspected risk factors for the progression of juvenile onset myopia
- Dillehay
Lifespan refractive change in an optometric clinic population
- Irving
Prevalence of myopia in Taiwanese school children: 1983 to 2000
- Lin