ArticleLiterature Review

The complex interactions of retinal, optical and environmental factors in myopia aetiology

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... Earlier onset and faster progression expose higher numbers of adults to the risk of suffering permanent loss of vision and blindness from myopiarelated complications [4,5]. Specifically, the prevalence of myopic retinopathy increases from 0.42% in people with myopia less than 5 diopters to 25.3% in those with myopia of 5 diopters or more [6]. This increased risk of myopia-associated complications is commonly expressed as Odds Ratio (OR): the OR of myopic macular degeneration, compared with people without myopia, is 2.2 for those with myopia of −1.0 to −2.99D, 9.7 for those with myopia of −3.0 to −4.99D, 40.6 for −5.0 to −6.99D of myopia, 126.8 for −7.0 to −8.99D, and 348.6 for myopia of −9.00D and greater [6]. ...
... Specifically, the prevalence of myopic retinopathy increases from 0.42% in people with myopia less than 5 diopters to 25.3% in those with myopia of 5 diopters or more [6]. This increased risk of myopia-associated complications is commonly expressed as Odds Ratio (OR): the OR of myopic macular degeneration, compared with people without myopia, is 2.2 for those with myopia of −1.0 to −2.99D, 9.7 for those with myopia of −3.0 to −4.99D, 40.6 for −5.0 to −6.99D of myopia, 126.8 for −7.0 to −8.99D, and 348.6 for myopia of −9.00D and greater [6]. For retinal detachment, the OR is 3.1 for those with myopia of −0.75 for −2.75D, 9.0 for −3.0D to −5.75D, 21.5 for −6 to −8.75D, 44.2 for −9 to 14.75D, and 88.2 for −15D and higher [6]. ...
... This increased risk of myopia-associated complications is commonly expressed as Odds Ratio (OR): the OR of myopic macular degeneration, compared with people without myopia, is 2.2 for those with myopia of −1.0 to −2.99D, 9.7 for those with myopia of −3.0 to −4.99D, 40.6 for −5.0 to −6.99D of myopia, 126.8 for −7.0 to −8.99D, and 348.6 for myopia of −9.00D and greater [6]. For retinal detachment, the OR is 3.1 for those with myopia of −0.75 for −2.75D, 9.0 for −3.0D to −5.75D, 21.5 for −6 to −8.75D, 44.2 for −9 to 14.75D, and 88.2 for −15D and higher [6]. For myopic optic neuropathy, which is often grouped under glaucomatous optic nerve damage, the OR is 1.6 for those with myopia up to −3.00D, and 2.5 for those with −3.00D or higher degrees of myopia [6]. ...
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Purpose Myopia (short-sightedness) is an emerging WHO priority eye disease. Rise in prevalence and severity are driven by changes in lifestyle and environment of children and young people (CYP), including less time spent in bright daylight and more time spent on near-vision activities. We aimed to systematically map the literature describing direct, objective measurements of the visual environment of CYP. Methods We conducted searches in Ovid Medline 1946, Ovid Embase and The Cochrane Central Register of Controlled Trials in November 2024. We included primary research written in English on environmental/behavioural factors and myopia onset/progression in CYP 3–18 years. Two reviewers independently screened titles/abstracts/full texts. Results We included 34 articles: 21 explored the association of indoor and/or outdoor light exposure and myopia and included light measurements, two near-vision activities, four both light and near-work, four time outdoors without illuminance measurements, and three light exposure based on meteorological data. Most measurements were carried out at the level of individual children, rather than the surrounding environment alone. Conclusion Despite limitations in measurement techniques, there is evidence that reduced illuminance, less time spent in bright light and increased daily duration/sustained episodes of near-vision activities and reduced working distance are associated with increased myopia prevalence/progression.
... In addition, more outdoor activities and less time spent using electronic screens can also delay the progression of myopia in children (Resnikoff et al., 2008;Lv et al., 2015;Huang et al., 2016;Tay et al., 2017). According to research reports, there is no safe threshold for myopia refractive error, which indicates that there is no "physiological myopia" (Flitcroft, 2012). Once myopia has formed, it can continue to worsen throughout childhood and, in high myopia, even into adulthood (Fricke et al., 2012). ...
... Once myopia has formed, it can continue to worsen throughout childhood and, in high myopia, even into adulthood (Fricke et al., 2012). Accompanied by high myopia and pathological myopia, changes in the sclera, choroid and retina cannot be prevented by optical correction (Flitcroft, 2012;Morgan et al., 2012;Holden et al., 2016;Morgan et al., 2018). Progressive high myopia has been proven to be a significant risk factor for open-angle glaucoma, cataract, myopic macular degeneration, rhegmatogenous retinal detachment, and myopic choroidal neovascularization, thereby causing irreversible damage to visual acuity (Tideman et al., 2016). ...
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Background Atropine is an effective medicine for myopia prevention and control. This meta-analysis was conducted to investigate the effects of atropine on choroidal thickness (ChT) in children with myopia. Methods Between its inception and 1 June 2023, Medline, Embase, and Web of Science were all searched, and only English literature was included. The choroidal thickness was the primary study outcome. Axial length, standardized equivalent refraction were examined as secondary outcomes. STATA 12.0 was used for data extraction and analysis. Results A total of 307 eyes were involved in this study to evaluate the effect of atropine on ChT, axial length (AL) and standardized equivalent refraction (SER) in myopic children. Choroidal thickening was significantly higher in the atropine group than in the control group at 1 month (WMD, 6.87 mm, 95% CI, 0.04 to 13.10, P = 0.049), whereas it was significantly higher in the atropine group than in the control group at months 6 (WMD, 10.37 mm, 95% CI, −3.21 to 23.95, P = 0.135), 12 (WMD, 15.10 mm, 95% CI, −5.08 to 35.27, P = 0.143) and at final follow-up (WMD, 11.52 mm, 95% CI, −3.26 to 26.31, P = 0.127), the differences were not statistically significant. At months 1 (WMD, −0.03 mm, 95% CI, −0.04 to −0.01, P = 0.003), 6 (WMD, −0.07 mm, 95% CI, −0.01 to −0.03, P = 0.000), 12 (WMD, −0.13mm, 95% CI, −0.15 to −0.11, P = 0.843), and at final follow-up (WMD, −0.08 mm, 95% CI, −0.16 to −0.01, P = 0.127), atropine treatment was able to delay the axial elongation. At 1-month follow-up, there was no significant difference in the effect of atropine on SER in myopic children compared with the control group (WMD, 0.01D, 95% CI, −0.07 to 26.31, P = 0.127), whereas it was able to control the progression of refractive status at final follow-up (WMD, 11.52 mm, 95% CI, −3.26 to 26.31, P = 0.127). Conclusion Limited evidence suggests that 0.01% atropine causes choroidal thickening in myopic children at 1 month of treatment. In the short term, choroidal thickness may be a predictor of the effectiveness of atropine in controlling myopia in children. 0.01% atropine is effective in controlling myopic progression in terms of SER and AL. Systematic Review Registration http://www.crd.york.ac.uk/prospero, identifier, CRD42022381195.
... However, this condition is associated with potential complications such as myopic macular degeneration, retinal detachment, cataracts, and open-angle glaucoma. These complications lead to permanent vision loss in later stages of life [9,10]. In patients with mild-to-moderate myopia, whose axial length is less than 26.0 mm, the size of the optic disc remains comparable to that in nonmyopic eyes [6]. ...
... A recent study confirmed a link between the severity of myopia and the risk of open-angle glaucoma. This was based on a dose-response meta-analysis that analyzed 24 studies involving 514,265 individuals from 11 countries [6,9,19]. The findings revealed a progressively greater risk of open-angle glaucoma with increasing myopia severity. ...
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Plain language summary Glaucoma is a significant cause of permanent blindness worldwide. This causes damage to the visual nerve that worsens over time. The primary way to treat open-angle glaucoma and its many causes is to lower eye pressure. Further research is being conducted to determine the relationship between nearsightedness and glaucoma. Increased nearsightedness is significantly linked to higher rates of glaucoma, especially in people with severe nearsightedness. This review aimed to examine the link between myopia and glaucoma in greater depth, focusing on structural and functional effects, risk factors, and assessment methods, especially optical coherence tomography (OCT), in very nearsighted people. We conducted a thorough search of several databases between 2012 and 2024. Individuals aged 18 years or older with myopia greater than six diopters or an axial length greater than 26 mm and a diagnosis of chronic glaucoma were eligible. Randomized controlled trials, prospective cohort studies, and observational studies were some of the methods used in this study. The quality of the work and statistical methods were used to summarize the features and results of the study. Of the 350 articles initially published, only 15 met the inclusion criteria. These studies mostly used different optical tomography tests to detect structural changes, such as ocular nerve fiber layer damage, before functional loss. According to meta-analyses, the risk of chronic glaucoma increases as myopia worsens, indicating a solid nonlinear relationship. Myopia and glaucoma are linked, demonstrating the importance of thorough evaluation. Severe myopia is strongly associated with damage to the visual nerve. Over the past few years, optical tomography has become a vital imaging tool for identifying early damage to the optic nerve. However, further research is needed on the sex-related tendencies of glaucoma patients. This study provides data that reveal a link between nearsightedness and glaucoma, highlighting the importance of optical tomography and other imaging techniques for early detection and monitoring. To better manage glaucoma in highly myopic individuals, we need to understand how the severity of myopia, changes in structure, and changes in function affect each other. Supplementary Information The online version contains supplementary material available at 10.1007/s10792-024-03321-4.
... Patologías como: glaucoma, catarata, desprendimiento de retina o maculopatía miópica aumentan considerablemente la posibilidad de que aparezcan cuanto mayor es la miopía. (5). Estas patologías son más incapacitantes que la mayoría de las que pueden provocar el uso de LC. ...
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Relevancia: Podemos encontrarnos con casos en los que sea necesario un conocimiento superior en contactología. No es lo habitual, pero no por ello debemos olvidar o dejar de aprender en esta rama de la óptica. Las lentes de contacto rígidas van a ayudar a mejorar la calidad de vida del paciente, provocando el menor daño posible. Además de la satisfacción obtenida, cuando le devuelves una buena agudeza visual a un post-LASIK o reduces la miopía de manera diurna a una adolescente disgustada por sus gafas.Propósito: Una buena formación con el uso de lentes de contacto es imprescindible para poder hacer frente a los casos un poco mas complicados que precisen de nuestra ayuda. Estar actualizado en este tema nos convertirá en mejores profesionales de lo que ahora somos y nos otorgara mayor prestigio.Informes de casos: El primer caso clínico trata de un varón de mediana edad que cansado del uso de gafas y en los comienzos de la presbicia, no quiere usarlas mas, que es por ello por lo que se operó. Al no dar resultado la solución sencilla, lentes de contacto blandas, se colocan unas lentes de contacto rígidas. La agudeza visual mejora considerablemente aunque se reduce la comodidad en el porte. Es interesante como con la lente rígida somos capaces de dar buena agudeza visual en visión lejana y cercana a nuestro paciente. En el segundo caso podemos estar orgullosos de que una adolescente pueda prescindir de sus gafas en el hogar y estar de nuevo contenta con su uso fuera de casa, además de intentar ralentizar el crecimiento de su ametropía, que como veremos puede aumentar la probabilidad de sufrir algunas patologías oculares.Conclusiones: Podemos ver dos claros ejemplos en los que las lentes de contacto rígidas nos abren una gran cantidad de opciones para mejorar la agudeza visual y con ello la calidad de vida de nuestros pacientes. No reciclarnos en el tema de la contactología puede no dar la mejor solución a los problemas de nuestros pacientes.
... In our recent work analysing over 30,000 fundus photographs in the UK Biobank, a wide range of retinal parameters were found to vary in a highly nonlinear fashion across refractive error, 18 tying in with the observation that the odds of myopic complications increase exponentially, or quasi-exponentially, with increasing myopia. 19 Variations in eye shape patterns across refractive error were postulated to be one important reason behind this non-linearity. For example, in myopia, an increasingly non-uniform expansion of the posterior eye (increasing tendency towards prolateness) may result in increasing rates of mechanical stretching at the posterior pole and, consequently, increasing rates of fundus changes as myopia increases. ...
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Purpose: To determine whether imaging features derived from fundus photographs contain 3D eye shape information beyond that available from spherical equivalent refraction (SER). Methods: We analysed 99 eyes of 68 normal adults in the UK Biobank. An ellipsoid was fitted to the entire volume of each posterior eye (vitreous chamber without the lens)—segmented from magnetic resonance imaging of the brain. Asphericity was computed based on the semidiameters of the ellipsoid's axes to describe posterior eye shape along the horizontal (temporal–nasal) and vertical (superior–inferior) meridians, while volume was calculated as the total number of foreground voxels. Mixed-effects linear regression models were used to test the association of SER with asphericity and volume, controlling for age and sex. Then, the association between various fundus features and asphericity was tested—both before and after controlling for SER, age and sex. Results: Posterior eyes were generally oblate (asphericity > 0), but the degree of oblateness reduced as SER decreased, with the shape tending towards prolateness in high myopia. Neither sex nor age influenced asphericity. However, males had larger posterior eyes on average (this difference disappeared after height was additionally controlled for). Optic disc (OD) orientation, OD-fovea angle, vessel tortuosity, vessel fractal dimension and central retinal arteriolar or venular equivalent (CRAE or CRVE) showed significant univariable associations with asphericity along at least one meridian. After controlling for SER, age and sex, a more negative OD-fovea angle (larger OD-fovea angular separation) remained significantly associated with reduced horizontal oblateness (p = 0.01). Similarly, decreasing CRAE (narrower arterioles) remained significantly associated with reduced oblateness along both the horizontal (p = 0.04) and vertical (p < 0.01) meridians. Conclusions: Variations in OD-fovea angle and CRAE are associated with differences in ocular asphericity—even in eyes with similar SER—suggesting that fundus imaging provides eye shape information beyond what is available from refractive error alone.
... Refractive errors are the leading cause of reversible visual impairment globally [1]. Over the past three decades, the prevalence of refractive errors has significantly increased [2,3], and it is estimated that by 2050, almost half of the global population will be affected by myopia [2]. ...
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Introduction Infectious keratitis is a rare but devastating complication following photorefractive keratectomy (PRK) that may lead to visual impairment. This study assessed the clinical features, treatment strategies, and outcomes of post-PRK infectious keratitis. Methods This retrospective study was conducted on patients with post-PRK infectious keratitis presenting to Khalili Hospital, Shiraz, Iran, from June 2011 to March 2024. The study was conducted in two stages: the first stage assessed the incidence of post-PRK infectious keratitis among patients who underwent PRK at our center, while the second stage included all patients with post-PRK infectious keratitis, regardless of where their PRK was performed. The following data were collected: demographics, post-surgery presentation time, risk factors, culture results, treatments, follow-up duration, complications, and corrected distance visual acuity (CDVA) at admission and the last follow-up. Results Forty-two patients (42 eyes) with a mean age of 28.74 years (male-to-female ratio of 1.2:1) were included. Among 38,938 PRK procedures performed at our center, the incidence of keratitis was estimated to be 0.018% (7/38,938). The odds of keratitis during the COVID-19 pandemic were 7.05 times higher (95% CI: 1.58 to 31.52, p-value = 0.015) than outside this timeframe (February 2020 to August 2023). Gram-positive bacteria were the most commonly isolated pathogens in microbiological studies, accounting for 45.2% (19/42) of cases. Early-onset infections were primarily caused by Staphylococcus aureus (9/26, 34.6%), Staphylococcus epidermidis (4/26, 15.4%), and Pseudomonas aeruginosa (4/26, 15.4%), whereas all of the cases with fungi (4/4, 100% (and Acanthamoeba (3/3, 100%) infections caused late-onset infections. All patients received broad-spectrum antibiotic therapy, followed by adjusted treatment based on microbial results. Cases developing endophthalmitis and those not responding to treatment or having non-resolving corneal scars required further interventions, such as penetrating keratoplasty and deep vitrectomy. The mean follow-up duration was 40.81 months, and 97.6% (41/42) of cases experienced CDVA improvement at follow-up. Conclusion This long-term study found a post-PRK keratitis rate of 0.018%, with gram-positive bacteria as the most common pathogens. Prompt management and regular follow-up assessments are essential for achieving satisfactory outcomes.
... With the global rise in myopia there has been a subsequent rise in retinal tears (RTs) retinal detachments (RDs). The severity of axial elongation impacts outcome; for example, RD is five or six times more likely in highly myopic (odds ratio > 20) as compared to low myopic (odds ratio < 4) patients (Flitcroft, 2012;Williams and Hammond, 2019). Ocular biometric measurements may serve as key features in the prediction of RDs. ...
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Given close relationships between ocular structure and ophthalmic disease, ocular biometry measurements (including axial length, lens thickness, anterior chamber depth, and keratometry values) may be leveraged as features in the prediction of eye diseases. However, ocular biometry measurements are often stored as PDFs rather than as structured data in electronic health records. Thus, time-consuming and laborious manual data entry is required for using biometry data as a disease predictor. Herein, we used two separate models, PaddleOCR and Gemini, to extract eye specific biometric measurements from 2,965 Lenstar, 104 IOL Master 500, and 3,616 IOL Master 700 optical biometry reports. For each patient eye, our text extraction pipeline, referred to as Ocular Biometry OCR, involves 1) cropping the report to the biometric data, 2) extracting the text via the optical character recognition model, 3) post-processing the metrics and values into key value pairs, 4) correcting erroneous angles within the pairs, 5) computing the number of errors or missing values, and 6) selecting the window specific results with fewest errors or missing values. To ensure the models’ predictions could be put into a machine learning-ready format, artifacts were removed from categorical text data through manual modification where necessary. Performance was evaluated by scoring PaddleOCR and Gemini results. In the absence of ground truth, higher scoring indicated greater inter-model reliability, assuming an equal value between models indicated an accurate result. The detection scores, measuring the number of valid values (i.e., not missing or erroneous), were Lenstar: 0.990, IOLM 500: 1.000, and IOLM 700: 0.998. The similarity scores, measuring the number of equal values, were Lenstar: 0.995, IOLM 500: 0.999, and IOLM 700: 0.999. The agreement scores, combining detection and similarity scores, were Lenstar: 0.985, IOLM 500: 0.999, and IOLM 700: 0.998. IOLM 500 was annotated for ground truths; in this case, higher scoring indicated greater model-to-annotator accuracy. PaddleOCR-to-Annotator achieved scores of detection: 1.000, similarity: 0.999, and agreement: 0.999. Gemini-to-Annotator achieved scores of detection: 1.000, similarity: 1.000, and agreement: 1.000. Scores range from 0 to 1. While PaddleOCR and Gemini demonstrated high agreement, PaddleOCR offered slightly better performance upon reviewing quantitative and qualitative results.
... Yet, increases in myopia prevalence have been observed in Europe as well (1). As myopia can cause substantial individual and public financial burden (6,7), and high myopia is associated with an increased risk of severe secondary pathologies (8), this global increase in myopia prevalence requires immediate attention. ...
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Introduction The increasing prevalence of myopia worldwide is problematic because myopia can result in severe secondary pathologies, and is associated with considerable financial burden. With plenty of prevalence data available for some regions, current data for Europe remain sparse. Yet, information on myopia prevalence and associations is essential for monitoring, preventive and interventive purposes. Likewise, uncorrected refractive errors are also critical, as they can, e.g., affect educational outcomes, making information on uncorrected myopia valuable for diagnostics and health education. Methods We performed non-cycloplegic autorefraction on two samples in Germany. The younger sample included 489 primary school students (grades 3–4, mean age: 9.30 ± 0.78 years), the older sample 1,032 secondary school students (grades 8–10, mean age 14.99 ± 1.12 years). These samples mark the limits of the age range during which school myopia usually emerges. Results Myopia (spherical equivalent ≤ −0.75D) prevalence was 8.4% in the younger sample and 19.5% in the older sample. The prevalence was generally higher in higher grade levels, with the most notable difference between grades 8 and 9. Females were more myopic than males in all grades except grade 3, with the largest gender difference in grade 10. The older sample also exhibited a more myopic spherical equivalent than the younger sample. In the older sample, spherical equivalent was more myopic in females than in males, and in grade 9 and 10 participants more than in grade 8 participants. Rates of uncorrected myopia were extremely high: 51.2% in the younger sample and 43.3% in the older sample. Discussion The obtained myopia prevalence rates are generally consistent with other European studies, as is the higher prevalence in female than male adolescents, accelerating with age. The high rates of uncorrected myopia warrant further investigation and should inform public health policies, including the implementation of regular refractive screenings.
... Myopia progresses over time and is linked to severe ocular complications, including cataracts, glaucoma, retinal detachment, and myopic maculopathy, which can lead to vision loss [13][14][15][16]. The study by Nti et al. [10] indicates that eye care practitioners in Africa are aware of the growing prevalence of myopia but lack comprehensive data on its progression and associated factors. ...
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Background and Aim To investigate the pattern of progression of myopia among a Ghanaian clinical cohort. Methods A retrospective cohort analysis of a clinical data set of all healthy myopic participants attending a tertiary eye care center was performed. Participants' biennial refraction examinations were tracked for refractive changes 4 years after the date of the first visit. This covered the period from January 2015 to December 2019. Myopia progression was defined as a difference in spherical equivalent between consecutive biennial visits equal to, or greater than −0.50 D of myopia. Results The medical records of 169 myopic participants were reviewed, with the majority (53.8%) being female. Most of the participants (51.4%) were younger than 36 years, and at the end of the study period, 96 participants (56.8%), who made up the majority, showed progression of myopia Univariate regression revealed that the 36–59‐year‐old age range is associated with a 60% [cOR = 0.40, 95% CI: –0.17, 0.97; p = 0.04] reduced likelihood compared to those belonging to the 0–17‐year‐old age group, and the Mole‐Dagbon ethnicity is associated with an almost fourfold [cOR = 3.80; 95% CI: –1.40, 10.316; p = 0.01] increased likelihood of experiencing myopia progression compared to those of Ga‐Adangbe ethnicity. Multivariate regression revealed that the Mole‐Dagbon ethnicity is associated with an increased likelihood of experiencing myopia progression 4 years after their initial visit [aOR = 3.49; 95% CI: –1.27, 9.63; p = 0.02] compared to those of Ga‐Adangbe ethnicity. Conclusion Our study provides important insights into myopia progression in Ghana, with findings that are consistent with global trends. The association of myopia progression with age, place of residence, degree of myopia, and ethnicity highlights the need for tailored interventions to manage this growing public health concern in African populations.
... Myopia (nearsightedness) represents a major public health challenge due to its increased risk of developing associated eye complications such as myopic maculopathy and glaucoma among others, which are related to the degree of myopia experienced [1]. Myopia has structural and functional consequences on the retina, possibly due to the sustained mechanical stress that myopic eye growth has on the retinal tissue [2]. ...
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Myopic eye growth induces mechanical stretch, which can lead to structural and functional retinal alterations. Here, we investigated the effect of lens-induced myopic growth on the distribution of retinal ganglion cells (RGCs), glial fibrillary acidic protein (GFAP) expression and intensity, and peripapillary retinal nerve fiber layer (ppRNFL) thickness in common marmosets (Callithrix jacchus) induced with myopia continuously for six months, using immunohistochemistry and spectral-domain optical coherence tomography. We also explored the relationship between cellular structural parameters and the photopic negative response (PhNR) using full-field electroretinography. Marmosets induced with myopia for six months developed axial myopia, had a thinner ppRNFL, reduced peripapillary ganglion cell (≈20%) and astrocyte density (≈42%), increased panretinal GFAP expression (≈42%) and nasal mid-periphery staining intensity (≈81%) compared to age-matched controls. Greater degrees of myopia and vitreous elongation were associated with reduced peripapillary RGCs and astrocyte density, and increased GFAP expression and intensity. These cellular structural changes did not show a significant relationship with the features of the PhNR, which remained unchanged. The outcomes of this study suggest that myopia induces a reorganization of the peripapillary inner retina at the cellular level that may not result in measurable functional repercussions at this stage of myopia development.
... Myopia is a common yet complex ophthalmic condition. Once regarded as a benign refractive error, it is now recognized that even low levels of myopia are associated with an increased risk of various ocular disorders [1]. Researchers have highlighted a global myopia pandemic, underscoring its widespread prevalence [2,3]. ...
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Purpose: Scleral cross-linking (SXL) with ultraviolet A (UVA) and riboflavin has already been used in laboratory studies for scleral stiffness increase as a potential treatment for progressive myopia and scleral ectasia. This study aims to investigate whether the regional application of scleral cross-linking (SXL) with ultraviolet A (UVA) and riboflavin in fresh porcine eye globes affects the ocular rigidity as well as its impact on intraocular pressure after an induced acute increase in the volume of intraocular fluid. Methods: The study included two groups of fresh porcine eyes: an experimental group (n=20) that underwent scleral cross-linking (SXL) with riboflavin and UVA applied to the posterior sclera and a control group (n=20) that did not receive SXL treatment. Subsequently, a balanced salt solution (volumes 50, 100, 150, and 200 μL) was administered into porcine globes via a syringe, and, at the same time, the intraocular pressure (IOP) was continuously monitored by a pressure sensor that was cannulated to the vitreous chamber. The relationship between volume and pressure was obtained, and the ocular rigidity coefficient (K) was calculated according to Friedenwald's law. Finally, scleral strips were dissected from the globes and were examined macroscopically. Results: In the control group, the mean IOP observed entails gradual, statistically significant increases for higher volumes. Specifically, the mean IOP at 0 μL equals 10 mmHg (SD=0), whereas at 200 μL the mean IOP equals 33.83 mmHg (SD=4.060). The differences were statistically significant with p-values <0.001 in all cases. Similarly, the observed gradual IOP increases in the SXL group were statistically significant with p < 0.001 in all cases except for the comparison of volume 0 μL measurements to volume 50 μL, where the p-value equaled 0.003. Specifically in the SXL group, the mean IOP at 0 μL equals 10.00 mmHg (SD=0.000), the mean IOP at 50 μL equals 13.31 mmHg (SD=2.011), whereas the mean IOP at 200 μL equals 32.06 mmHg (SD=3.078). At no additional injected volume, the differences between the control and the SXL groups were statistically significant. The analysis regarding ocular rigidity indicated significantly higher scores in the control group (K50=0.00812, SD=0.03) compared to the SXL group (K50=0.00552, SD=0.027), t=2.844; p=0.007. The difference regards measures of volumes 0 to 50 μL, while all other rigidity measures were found to be non-significant. Interestingly, the ocular rigidity coefficient in the SXL-treated group did not show changes with an increase in IOP. The macroscopic appearance of the scleral strips showed a significantly increased stiffness of the SXL scleras against the control ones. Conclusion: This study showed that stiffened scleras did not induce substantial change in ocular rigidity and significant IOP elevations. Studying the biomechanical ocular response of laboratory scleral crosslinking applications supports the development of next-generation crosslinking procedures that may constitute potential therapeutic options for severe ophthalmic diseases like pathologic myopia.
... The relationship between myopia and various diseases has been studied extensively. 30 Myopia is commonly known to be associated with RD and glaucoma in previous research. [32][33][34] In this study, it was found that late adolescent men with high myopia have a 1 in 1000 chance of developing RD, which is about 3.4 times higher than those without high myopia (online supplemental table 5). ...
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Objective This study aims to provide updated prevalence estimates of myopia and high myopia among late adolescent men in Seoul, South Korea, and predict future trends up to 2050. Methods and analysis This cross-sectional and population-level study includes late adolescent men of the same age who underwent a series of medical examinations at the Seoul Regional Military Manpower Administration between 2013 and 2022. The population with myopia and high myopia was estimated, and the prevalence for 2050 was forecasted. Associated risk factors and ocular disease status of the high myopia population were investigated. Results Over the 10-year period, the prevalence of myopia and high myopia among late adolescent men in Seoul was 70.67% and 20.29%, respectively. Between 2013 and 2022, the prevalence of the myopia and high myopia has increased significantly (p<0.001 and 0.006, respectively). The annual growth rate for the prevalence of myopia and high myopia was 0.61% and 0.33%, respectively. Regression analyses predicted that by 2050, myopia and high myopia prevalence will reach 90.90% and 31.26% by linear regression, and 90.75% and 31.17% by non-linear regression, respectively. Risk factor analysis identified that a high education level was associated with a higher prevalence of high myopia. Retinal detachment was significantly more common among those with high myopia, while retinal dystrophy was less common. Conclusion This study highlights a concerning trend of increasing myopia and high myopia prevalence, which is likely to reach 90.90% and 31.26% by 2050, with significant future burden for public health and society.
... It is estimated that the prevalence of myopia is rapidly increasing with forecasts for approximately half of the world population being myopic in 2050 (Fricke et al., 2018). High myopia has been documented to be associated with ocular diseases such as glaucoma, cataract, myopic macular degeneration (Flitcroft, 2012). The risk of ocular complications raises interest in investigating the methods to hinder myopia onset and slow the myopia progression rate. ...
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Purpose This study evaluates differences in the visual field performance when wearing the Defocus Incorporated Multiple Segments (DIMS) spectacle lens compared to wearing a conventional single vision (SV) spectacle lens. Methods Twenty-one children aged 9–14 years with spherical equivalent refraction (SER) between −1.13D to −4.75D were recruited. Mid-peripheral near visual acuity (NVA) under room lighting condition (500 lux ±10%) was measured using DIMS and SV lenses, respectively. Automated static perimetry (Zeiss, Humphrey Visual Field HFA 750i) with SITA Fast 30–2 protocol was used to investigate the visual field sensitivity. During the test, the study lens (Plano DIMS or SV lens) were inserted into the lens holder in front of the trial lenses with each child’s compensated prescription. Results Three children were not able to complete the reliable visual tests due to fixation losses (>20%) or high false positive rate (>15%) while 18 children successfully completed the test. The mean visual field sensitivity was 29.2 ± 3.7 decibels (dB) and 29.3 ± 3.5 dB when wearing DIMS and SV lens, respectively. The mean sensitivity differences between DIMS and SV lens among 76 locations ranged from −2.4 ± 3.9 dB to 1.6 ± 3.9 dB. No statistically significant difference in sensitivity was observed across 76 locations within the central 30o between DIMS and SV lens (Wilcoxon signed rank test with bonferroni correction for multiple comparisons, p > 0.00065). Compared to SV lens, 0.05 logarithm of minimal angle of resolution (logMAR) reduction in mid-peripheral NVA in all 4 quadrants (Superior, Temporal, Inferior and nasal, p < 0.05) was noted with the DIMS lens (N = 18). However, no statistically significant correlation was found between the mid-peripheral NVA and visual sensitivity at the specific locations. Conclusion Although the mid-peripheral NVA was slightly reduced using DIMS lens, wearing DIMS lens did not change the children’s visual sensitivity to detect the static stimulus within 30o visual field when compared to wearing SV lens.
... 19 One study reported that the strongest associations with myopia prevalence were homework on weekends and after-school tutoring. 45 Maps of the dioptric field, 46 while informative, have not clarified the specific mechanisms. Screen time remains a controversial factor. ...
... Eyes with myopia, especially high myopia characterized by longer axial lengths, are likelier to enable pathologic changes such as myopic maculopathy, retinal detachment, myopic choroidal neovascularization, and myopic optic neuropathy. These diseases are closely associated with exacerbated myopia [2,3]. Although the underlying pathogenesis of myopia remains elusive, numerous studies have indicated the significant role of the sclera (particularly at the posterior pole) in the development of myopia. ...
... [2][3][4] Contrary to the common belief that only high myopia (≤−6 D) amplifies the risk of ocular diseases, recent research indicates that even low levels of myopia (≤−3 D) can double the risk of myopic maculopathy and posterior subcapsular cataract and triple the risk of retinal detachment compared to the emmetropic eye. 5 In response to the global epidemic of childhood myopia, leading optometric and ophthalmologic professional organisations around the world have issued resolutions, statements or consensus documents. These bodies unanimously agree that no level of myopia can be considered entirely safe, and assert that current evidence sufficiently justifies the initiation of myopia prevention and control strategies for children at risk of progressive myopia. ...
Article
Purpose The Predicting Myopia Onset and progression (PreMO) risk indicator, developed using data generated from white children in the UK, incorporates age, spherical equivalent refraction (SER), axial length (AL) and parental myopia to stratify the likelihood of developing myopia. This study evaluated the PreMO's predictive accuracy using prospective datasets from independent samples of children in Hong Kong (HK) and an ethnically diverse cohort of children in the United Kingdom. Methods Non‐myopic children (SER > –0.50 D) aged 6–8 and 9–10 years were scored using the PreMO risk indicator framework, integrating baseline cycloplegic SER, AL and parental myopia data. Scores were assigned risk categories as follows: 0 = no risk, 1–3 = low risk, 4–6 = moderate risk and 7–9 = high risk. SER at ≥15 years of age was used to define refractive outcomes as ‘myopic’ or ‘not myopic’. PreMO's predictive accuracy was analysed via Receiver Operator Characteristic curves, with Youden's J ‐Index identifying the optimal risk score threshold. Sensitivity, specificity and area under the curve were determined and compared with those of singular predictors, that is, SER < +0.75 D and AL ≥ 23.07 mm at 6–8 years. Results In the cohort of children aged 6–8 years, a PreMO risk score ≥ 4 exhibited high sensitivity in predicting myopia onset in UK (0.97) and HK (0.94) children, with high specificity in UK (0.96) and moderate specificity in HK (0.64) children. In UK children aged 6–8 years, the PreMO outperformed singular predictors such as SER and AL. Among HK children aged 9–10 years, the PreMO score maintained high sensitivity (0.90) and moderate specificity (0.72). Conclusions A PreMO risk score ≥ 4 is a strong predictive indicator for future myopia onset, particularly in UK children. Despite high sensitivity in both UK and HK cohorts, specificity varied, indicating the need for contextual application of the tool, particularly in pre‐myopic Asian children.
... From 1983 to 2000, the incidence of myopia in 7-year-old school children has increased significantly, from approximately 6% to around 21.0% in Taiwan, China [17] . In East Asia metropolitan areas, up to 90% of secondary school children have suffered from myopia, in which approximately 20% of those children have suffered high myopia [19] . Overall, the prevalence of myopia has elevated from 80% to 88%, including increase of moderate myopia from 39% to 46%, severe myopia from 8% to 17%, and terminal myopia from 0.1% to 0.9% [20] . ...
Article
Myopia is a huge health problem due to its high frequency, vision losses and public health cost. According to the World Health Organization, at least 2.2 billion people have vision impairment. Although myopia can be controlled at its early and middle stages, unfortunately, no cure can be achieved so far. Among the methods to control myopia, atropine, a muscarinic receptor antagonist, is the oldest but still the most effective for retardation of myopia progression. Despite such a fact, standard protocols have not been established for clinicians to use atropine for treatment of myopia. In this article, a concise and up to date summary of myopia epidemiology and pathogenesis and summarized therapeutic effects and side effects, possible mechanisms and application methods of atropine were provided in hope for clinical doctors to effectively control this problematic disease. At present, the protocol is recommend: use higher dose (1%) of atropine intermittently to effectively slowdown myopia progression in schoolchildren for 2y, and to significantly reduce side effects of atropine by decrease of atropine frequency for 1y and inhibit myopic rebound by withdrawal of topical atropine gradually for 1y. Application of a lower dose (0.05%) atropine regime should also be considered due to its effectiveness and application at regular basis.
... For example, combining the U-net architecture with geometric models such as the ellipsoid and non-linear models has shown promise in improving the precision of segmentation and providing more detailed anatomical representations [14]. These hybrid approaches leverage the strengths of both deep learning and traditional methods, offering a robust framework for eye model extraction that is both accurate and interpretable [15]. ...
Article
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Abstracting eye models from MRI images is critical in advancing medical imaging, particularly for clinical diagnostics. Current methods often struggle with accuracy and efficiency, highlighting a gap this research aims to fill. This study investigates the application of machine learning methods, focusing on the U-net-based deep learning framework, to improve the accuracy of eye model extraction. The objectives include fitting measured eye data to models such as the Ellipsoid model, evaluating automated segmentation tools, and assessing the usability of machine learning-based extractions in clinical scenarios. We employed point cloud data of 202,872 points to fit eye models using ellipsoid, non-linear, and spherical fitting techniques. The fitting processes were optimized to ensure precision and reliability. We compared the performance of these models using mean squared error (MSE) as the primary metric. The non-linear model emerged as the most accurate, with a significantly lower MSE (1.186562) compared to the ellipsoid (781.0542) and spherical models. This finding indicates that the non-linear model provides a more detailed and precise representation of the eye’s geometry. These results suggest that machine learning methods, particularly non-linear models, can significantly enhance the accuracy and usability of eye model extraction in clinical diagnostics, offering a robust framework for future advancements in medical imaging.
... It is advised for individuals to ensure compliance with regular eye exam recommendations, especially in individuals with nearsightedness, as myopia is a major risk factor for RRD. [37][38][39][40] Furthermore, current recommendations advise that maintenance of overall health and well-being as well as utilization of ocular safety equipment when participating in risky activities. 40,41 However, the most important risk factor in developing RRD still appears to be related to age. ...
Article
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Purpose Does weather affect the rate of developing rhegmatogenous retinal detachment (RRD)? This comprehensive review investigates the findings of the most recent studies on the relationship between RRD and climatic or seasonal factors. Methods An extensive search across PubMed, Embase, and Google Scholar databases resulted in 112 initial results, from which 18 studies published between 1980 and 2024 were selected. The selection criteria were based on the studies’ relevance to our topic. We analyzed their methodology, geographic scope, and key findings. Data extraction encompassed study design, sample size, sex ratio, incidence rates, results, and identified limitations. Results Eight studies found no statistically significant relationship between seasonal variations and the incidence of RRD. Conversely, seven studies reported an increased incidence of RRD during the summer months. Additionally, secondary analyses of factors, such as ambient temperature, atmospheric pressure, and daylight hours, showed varied and sometimes conflicting results. A summary of common limitations and biases was synthesized into a table, providing guidelines for future research exploring this topic. Conclusion This comprehensive review highlights the complex interaction between environmental factors and RRD incidence. The conflicting results across different studies suggest a need for further research in this area. Future studies should address the identified limitations and biases to provide a clearer understanding of the relationship between climate and RRD. By utilizing the guidelines from our review, future research could aim to minimize confounding factors and improve the robustness of their findings. Understanding these interactions can be used to develop preventive strategies and enhance clinical practices to reduce the burden of RRD.
... The threshold for what constitutes a meaningful reduction can vary depending on factors such as the duration of treatment, sample population, and study design considerations. We believe that any reduction in myopia progression, as long as a causal effect is evident, is clinically significant, as even a small reduction can be beneficial by decreasing the risk of ocular morbidities in children later in life [7]. ...
... 12 Abundant human data indicate a strong correlation between myopia and eye growth. [13][14][15] As myopia progresses, the structure of the eye undergo abnormal changes. Excessive elongation in axial length (AL) is accompanied by decreased choroidal thickness (ChT) and scleral tissue remodeling. ...
Article
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Purpose To investigate the changes in choroidal thickness (ChT), refractive status, and ocular dimensions in the mouse eye in vivo using updated techniques and instrumentation. Methods High-resolution swept-source optical coherence tomography (SS-OCT), eccentric infrared photoretinoscopy, and custom real-time optical coherence tomography were used to analyze choroidal changes, refractive changes and ocular growth in C57BL/6J mice from postnatal day (P) 21 to month 22. Results The ChT gradually increased with age, with the thickest region in the para-optic nerve head and thinning outward, and the temporal ChT was globally thicker than the nasal ChT. Retinal thickness remained stable until 4 months and subsequently decreased. The average spherical equivalent refraction error was −4.81 ± 2.71 diopters (D) at P21, which developed into emmetropia by P32, reached a hyperopic peak (+5.75 ± 1.38 D) at P82 and returned to +0.66 ± 1.86 D at 22 months. Central corneal thickness, anterior chamber depth, lens thickness, and axial length (AL) increased continuously before 4 months, but subsequently exhibited subtle changes. Vitreous chamber depth decreased with lens growth. ChT was correlated significantly with the ocular parameters (except for retinal thickness) before the age of 4 months, but these correlations diminished after 4 months. Furthermore, for mice younger than 4 months, the difference in the ChT, especially temporal ChT, between the two eyes contributed most to that of axial length and spherical equivalent refraction error. Conclusions Four months could be a watershed age in the growth of mouse eyes. Large-span temporal recordings of refraction, ocular dimensions, and choroidal changes provided references for the study of the physiological and pathological mechanisms responsible for myopia.
... Myopia is linked to a spectrum of sightthreatening complications, including but not limited to macular degeneration, retinal detachment, and cataracts. High myopia, which has the highest risk of complications [2] , is particularly noteworthy. Onset at a younger age is a predictive factor for developing high myopia [3] . ...
Article
AIM: To elucidate whether differences exist in the impact on retarding the elongation of axial length (AL) among children with myopia when utilizing orthokeratology (ortho-k) lenses employing the corneal refractive therapy (CRT) design versus those employing the vision shaping treatment (VST) design. METHODS: This retrospective clinical trial aimed to collect and analyze AL data from individuals who wore ortho-k lenses for three years. A total of 654 subjects were enrolled and prescribed one of the three specific brands of ortho-k lenses: CRT, Euclid, and Mouldway. The study’s primary focus was to compare the rates of AL elongation and myopic progression across these three brands of ortho-k lenses. RESULTS: In the 3-year follow-up, the AL elongation exhibited variations of 0.73±0.36 mm in the CRT lens group, 0.59±0.37 mm in the Euclid lens group, and 0.63±0.38 mm in the Mouldway lens group. A noteworthy disparity emerged between the CRT and Mouldway groups (P<0.01), as well as between the CRT and Euclid groups (P<0.001). Additionally, it was observed that 32.1% of participants who wore CRT lenses experienced a decelerated progression of myopia, in contrast to 47.2% in the Euclid group and 44.4% in the Mouldway group. Statistical analyses revealed a statistically significant distinction between the CRT and Euclid groups (P<0.01), and similarly, the CRT group demonstrated a statistically significant difference when compared to the Mouldway group (P<0.05). CONCLUSION: Ortho-k lenses represent a pragmatic strategy for mitigating the advancement of myopia. In contradistinction to ortho-k lenses utilizing the CRT design, those employing the VST design exhibited a more favorable impact regarding retarding AL elongation.
... When uncorrected, myopia results in blurred distant vision, a by-product of the relative increase in axial length compared to the eye's optical (refracting) power [5]. While such mismatching errors can be corrected with optical aides, including spectacles and contact lenses, or refractive surgery, to restore clear vision, on the other hand, myopia is associated with increased risks of visual impairments tied to a variety of pathologies, including glaucoma, myopic maculopathy, retinal detachment, and cataracts [6]. While clinical treatment strategies to prevent and/or slow the progression of myopia are under investigation, with some multifocal contact lens options already in use [7], improved understanding of the underlying disease process is key to improving treatment efficacy, potentially via the development of novel therapies, including gene-based ones. ...
Article
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Purpose This study investigated the differential gene expression of BMPs in chick retinal pigment epithelium (RPE) during recovery from short term exposure to optical defocus and form-deprivation (FD) treatments. Methods 14-day old White-Leghorn chicks wore either monocular +10 or -10 D lenses, or diffusers for 2 or 48 h, after which eyes were allowed unobstructed vision for up to 96 h. Over this recovery period, refractive errors and choroidal thickness (ChT) were tracked using retinoscopy and high-frequency A-scan ultrasonography. Real-time PCR was used to examine the expression of BMP2, 4, and 7 genes in RPE samples collected 0, 15 min, 2, 24, 48, and 96 h after the termination of treatments. Expression levels in treated eyes and their contralateral control eyes were compared. Results After the termination of the lens and diffuser treatments, eyes gradually recovered from induced shifts in refractive error. With all three treatments, ChT changes reached statistical significance after 48 h of treatment, be it thinning with the -10 D lens and diffuser treatments (-0.06 ± 0.03mm, p < 0.05; -0.11 ± 0.04 mm, p < 0.05, resp.), or thickening with the +10 D lens (0.31 ± 0.04 mm, p < 0.001). BMP2 gene expression was rapidly upregulated in eyes wearing the +10 D lens, being statistical significance after 2 h, as well as 48 h of treatment. With the 2 h treatment, the latter gene expression pattern persisted for 15 min into the recovery period, before decreasing to the same level as that of contralateral control eyes, with a short-lived rebound, i.e., upregulation, 24 h into the recovery period. With the longer, 48 h treatment, BMP2 gene expression decreased more gradually, from 739 ± 121% at the end of the treatment period, to 72 ± 14% after 48 h of recovery. Two and 48 h of both -10 D and FD treatments resulted in BMP2 gene expression downregulation, with the time taken for gene expression levels to fully recover varying with the duration of initial treatments. In both cases, BMP2 gene expression downregulation persisted for 15 min into the recovery period, but reversed to upregulation by 2 h. Similar gene expression patterns were also observed for BMP4, although the changes were smaller. Conclusions The observed changes in BMP gene expression in chick RPE imply dynamic, albeit complex regulation, with the duration of exposure and recovery being critical variables for all three types of visual manipulations. This study provides further evidence for a role of the RPE as an important signal relay linking the retina to the choroid and sclera in eye growth regulation.
... Retinal alterations in myopia are generally attributed to the stretching of ocular tissues during axial elongation. 1 Our recent work, analyzing >20 000 healthy adults in the UK Biobank, further demonstrated that changes in a wide range of retinal landmarks occurred in a highly nonlinear fashion across refractive error. 2 Specifically, the magnitude of retinal changes induced by each diopter (D) increase in refractive error increased as myopia became more severe, tying in with observations that the odds of myopia-related complications increase exponentially (or quasi-exponentially), not linearly, with higher myopia. 3 One intriguing observation from this study was that the initially positive association between spherical equivalent refraction (SER) and retinal vessel caliber, as captured by the measurements of central retinal arteriolar or venular equivalent (CRAE or CRVE), was no longer evident but changed direction after the optical influence of ocular magnification was accounted for. However, one limitation of the study was the lack of axial length (AL) information, which is a more direct measure of ocular dimensions. ...
Article
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Purpose: Dimensional measures of retinal features are subject to the optical influence of ocular magnification. We examined the impact of ocular magnification on the association between axial length (AL) and measurements of retinal vessel calibre in fundus photographs. Design: Cross-sectional study. Participants: Eighty-two normal right eyes from healthy participants aged 16-31 years. Methods: Central retinal arteriolar and venular equivalents (CRAE and CRVE) were derived from colour fundus photographs using semi-automated software. Ordinary least squares linear regression was used to assess the influence of AL (independent variable) on CRAE and CRVE, controlling for age, sex and ethnicity, both before and after magnification correction using different formulae. These formulae estimate magnification based on different ocular parameters: AL only (Bennnett’s formula), refractive error only (Bengtsson’s formula) and refractive error combined with keratometry (Littmann’s formula). Previous research has primarily relied on Bengtsson’s formula, which is less accurate than Bennett’s formula. We also examined the impact of treating the non-telecentric fundus camera used in this study as telecentric when applying these magnification correction formulae. Main Outcome Measures: Central retinal arteriolar and venular equivalents (in pixels). Results: Before magnification correction, increasing AL was associated with decreasing CRAE (β: -0.49, 95% CI: -0.89 to -0.09, p=0.02) and CRVE (β: -0.91, 95% CI: -1.62 to -0.20, p=0.01). After magnification correction, this observation was no longer evident, regardless of the correction formula applied. When inappropriately assuming the fundus camera to be telecentric, we observed a bias towards increasing magnification-corrected CRAE and CRVE with increasing AL (β coefficients were positive or became more positive), reaching statistical significance (p<0.05) for CRAE corrected using Bennett’s or Littmann’s formula, and for CRVE corrected using Bennett’s formula. Conclusions: Failing to correct for ocular magnification results in apparent narrowing of vessels in longer eyes, while inappropriate assumptions about telecentricity during magnification correction introduce an optical artifact that causes apparent widening of vessels. These findings suggest that myopic changes in retinal vessel calibre are optical (not biological) in nature. Proper correction of this effect to accurately derive dimensional measures is a crucial—yet often overlooked—methodological consideration in “oculomics” research investigating retinal biomarkers of systemic conditions.
... Current theory proposes that myopia develops ultimately because the sclera loses its biomechanical strength 37,42,43 , while the role of the retina and other intervening layers is generally thought of in terms of chemical signal initiation and relay 6,[44][45][46] . However, it is possible that changes in the structural integrity of the eyeball during myopia development and progression may not be restricted to only the sclera. ...
Article
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Retina-derived growth signals relayed from the choroid to the sclera cause remodeling of the extracellular scleral matrix, resulting in myopic ocular elongation. However, to the best of our knowledge, no studies have assessed changes in choroidal stromal biomechanical properties during myopia progression. Here we utilized 7 µm-resolution scanning acoustic microscopy (SAM) to assess biomechanical properties (bulk modulus (K) and mass density (rho)) of choroidal stroma from guinea pig eyes with form-deprivation (FD) induced myopia. The choroidal stroma had considerable intrinsic strength arising from its biomechanical properties and these were differentially affected by myopia in central and peripheral regions. Choroidal stromal biomechanical values were also highly correlated with those in adjacent scleral regions, and the choroidal stromal-scleral association was stronger in myopic eyes. Biomechanical changes observed in the choroidal stroma of myopic eyes were mirrored to those observed in the adjacent sclera. These findings suggest that choroidal stromal remodeling may accompany myopia and open the door to the source of the signals that cause scleral remodeling in myopia.
... The global prevalence of myopia has increased remarkably in recent decades, especially in East Asian countries such as China, Japan, and Singapore, where its prevalence can reach up to 80-90% in young people [4][5][6][7] . Individuals with high myopia are at significantly increased risk of developing a range of secondary pathologies 8 , such as cataracts 9 , glaucoma 10 , retinal detachment 11 , and myopic macular degeneration (MMD) 12 . Moreover, high myopia can progress to pathologic myopia (PM)-often accompanied by MMD and/or myopic traction maculopathy (MTM)-which is a major cause of low vision and permanent vision loss 13 . ...
Article
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The mechanisms underlying myopia pathogenesis are not well understood. Using publicly-available human and animal datasets, we expound on the roles of known, implicated proteins, and new myopia-related signaling pathways were hypothesized. Proteins identified from human serum or ocular fluids, and from ocular tissues in myopic animal models, were uploaded and analyzed with the QIAGEN Ingenuity Pathway Analysis (IPA) software (March 2023). With each IPA database update, more potentially-relevant proteins and signaling pathways previously unavailable during data acquisition are added, allowing extraction of novel conclusions from existing data. Canonical pathway analysis was used to analyze these data and calculate an IPA activation z-score—which indicates not only whether an association is significant, but also whether the pathway is likely activated or inhibited. Cellular immune response and cytokine signaling were frequently found to be affected in both human and animal myopia studies. Analysis of two publicly-available proteomic datasets highlighted a potential role of the innate immune system and inflammation in myopia development, detailing specific signaling pathways involved such as Granzyme A (GzmA) and S100 family signaling in the retina, and activation of myofibroblast trans-differentiation in the sclera. This perspective in myopia research may facilitate development of more effective and targeted therapeutic agents.
... Furthermore, predictions suggest this number is expected to increase to 50% by 2050 [1]. Although myopia can be corrected by spectacles, contact lenses, or surgery, the rapid increase in its prevalence has raised alarming concerns regarding its association with high myopia (typically defined as −5.00D or −6.00D or below), where eyes with high myopia are more susceptible to sight-threatening ocular diseases, such as retinal detachments and glaucoma, due to the excessive elongation of the eyeball [2][3][4]. The onset of myopia has been suggested to be affected by multiple factors, such as genetics [5] and the environment [6,7]. ...
Article
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The vitreous humor (VH) is a transparent gelatin-like substance that occupies two-thirds of the eyeball and undergoes the most significant changes during eye elongation. Quantitative proteomics on the normal growth period in the VH could provide new insights into understanding its progression mechanism in the early stages of myopia. In this study, a data-independent acquisition (SWATH-MS) was combined with targeted LC-ESI-MS/MS to identify and quantify the relative protein changes in the vitreous during the normal growth period (4, 7, 14, 21 and 28 days old) in the chick model. Chicks were raised under normal growing conditions (12/12 h Dark/light cycle) for 28 days, where ocular measurements, including refractive and biometric measurements, were performed on days 4 (baseline), 7, 14, 21 and 28 (n = 6 chicks at each time point). Extracted vitreous proteins from individual animals were digested and pooled into a left eye pool and a right pool at each time point for protein analysis. The vitreous proteome for chicks was generated using an information-dependent acquisition (IDA) method by combining injections from individual time points. Using individual pool samples, SWATH-MS was employed to quantify proteins between each time point. DEPs were subsequently confirmed in separate batches of animals individually on random eyes (n = 4) using MRMHR between day 7 and day 14. Refraction and vitreous chamber depth (VCD) were found to be significantly changed (p < 0.05, n = 6 at each time point) during the period. A comprehensive vitreous protein ion library was built with 1576 non-redundant proteins (22987 distinct peptides) identified at a 1% false discovery rate (FDR). A total of 12 up-regulated and 26 down-regulated proteins were found across all time points compared to day 7 using SWATH-MS. Several DEPs, such as alpha-fetoprotein, the cadherin family group, neurocan, and reelin, involved in structural and growth-related pathways, were validated for the first time using MRMHR under this experimental condition. This study provided the first comprehensive spectral library of the vitreous for chicks during normal growth as well as a list of potential growth-related protein biomarker candidates using SWATH-MS and MRMHR during the emmetropization period.
Article
Purpose To assess longitudinal changes in optical quality across the periphery (horizontal meridian, 60°) in young children who are at high (HR) or low risk (LR) of developing myopia, as well as a small subgroup of children who developed myopia over a 3‐year time frame. Methods Aberrations were measured every 6 months in 92 children with functional emmetropia at baseline. Children were classified into HR or LR based on baseline refractive error and parental myopia. Zernike polynomials were calculated for 4 mm pupils, accounting for the elliptical shape of the pupil in the periphery. Various metrics were computed, including Strehl Ratios with only high‐order aberrations (HO‐SR). Primary spherical aberration (SA), horizontal coma and defocus were also analysed given their relevance in emmetropisation. The areas under the image quality metrics for various regions of interest were computed. Results HO‐SR were higher in children at HR and children with myopia, even when SA was removed from the Strehl Ratio (SR) calculation. SA was less positive in children at HR and children with myopia. Defocus was more negative in children at HR and children with myopia at all eccentricities and was even more negative when computed relative to the fovea, an effect that increased in the mid periphery. Relative peripheral defocus also became more negative over time in children at HR and children with myopia at the mid temporal retina. The other aberrations showed no significant changes in time overall. Conclusions This longitudinal study showed differences in HO‐SR, SA and defocus in the central and near‐peripheral retina (±20°) of young children at HR before they develop myopia compared with children at LR for myopia. The results may indicate these eccentricities are significant in providing signals for emmetropisation. The small changes noted over time may indicate that the differences are a cause of myopia development.
Article
Purpose The purpose of this study was to compare the perception and understanding of the information provided by ChatGPT regarding myopia among optometry students, optometrists undertaking a Master degree and practicing optometrists. Methods This was a cross‐sectional descriptive study using a structured questionnaire distributed via Wooclap to 225 participants (125 optometry students, 21 Masters students and 79 practicing optometrists). All participants evaluated the responses generated by ChatGPT Version 4.0 using a five‐point scale: very poor, poor, acceptable, good and very good. Data were analysed using SPSS, applying descriptive analysis and chi‐squared tests to assess the significance of differences observed between the groups. Results Practicing optometrists, with an average age of 39.7 ± 11.0 and 15.2 ± 7.5 years of professional experience, rated the information provided by ChatGPT on myopia complications more positively than the optometry and Masters students, highlighting the importance of clinical experience ( p < 0.001). Alternatively, this may indicate a difference in awareness, knowledge and training, with younger students potentially being more speculative in their evaluations. The perceptions about myopia prevention among the groups were similar ( p = 0.28). At the same time, the perceptions of the effectiveness of treatments such as contact lenses and pharmaceutical agents showed differences, with optometrists rating these treatments more positively ( p < 0.001 and p = 0.004, respectively). Conclusions This study showed differences in the perception and interpretation of the information provided by ChatGPT about myopia depending on the level of education. While AI plays an important role in education, practicing optometrists trust the information extracted by ChatGPT more than optometry students.
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Purpose Prolonged exposure to broadband light with a short-wavelength (blue) or long-wavelength (orange/red) bias is known to impact eye growth and refraction, but the mechanisms underlying this response are unknown. Thus, the present study investigated the effects of broadband blue and orange lights with well-differentiated spectrums on refractive development and global flash electroretinography (gfERG) measures of retinal function in the chick myopia model. Methods Chicks were raised for 4 days with monocular negative lenses, or no lens, under blue, orange, or white light. Chick weight, eye dimensions, and refraction were measured at the conclusion of rearing. In a separate cohort of chicks, the effect of 4 days of colored light rearing on retinal responses to orange, blue, or white light flashes was assessed using gfERG. Results Chicks reared under orange light for 4 days exhibited a significantly larger myopic shift in response to negative lenses compared to those reared under blue light. Orange light rearing for 4 days increased the gfERG d-wave amplitude and implicit time in response to orange light flashes but did not alter responses to white or blue flashes. Blue and white light rearing did not affect the retina's response to light flashes of any color. Conclusions Orange light rearing exacerbated defocus-induced myopia relative to blue light rearing. The gfERG recordings revealed that prolonged orange light exposure increased retinal responsivity to the offset of long wavelength light flashes, suggesting a potential role for ON/OFF pathway balance in generating the refractive response that requires further electrophysiological and molecular investigation.
Article
Importance Additional data are required regarding atropine treatment regimens for control of myopia progression. Objective To investigate the efficacy and safety of different atropine regimens for myopia in children. Design, Setting, and Participants This was a secondary analysis of the 3-year results of the 24-Month Myopia Outcome Study of Atropine in Children (MOSAIC) trial, called the MOSAIC2 trial. The MOSAIC trial was an investigator-led, double-masked, randomized clinical trial of different atropine concentrations and regimens. The MOSAIC2 study took place at the Centre for Eye Research Ireland, in Dublin, Ireland, and included children and adolescents with myopia from the MOSAIC trial. Data analysis was conducted from November 2023 to February 2024. Interventions Participants were randomly assigned to the following cohorts: group 1, nightly placebo for 2 years then 0.05% atropine eye drops for 1 year and group 2, nightly 0.01% atropine eye drops for 2 years then rerandomization to placebo nightly, tapering placebo, or tapering of 0.01% atropine eye drops for 1 year. Main Outcomes and Measures Observed changes in cycloplegic spherical equivalent refraction and axial length from month 24, or baseline, to month 36. Results A total of 199 children with myopia (mean [SD] age, 13.9 [2.4] years; 121 female [60.8%]) of the 250 children and adolescents from the MOSAIC trial were included in the MOSAIC2 trial analysis. Of 83 participants assigned to group 1, 66 (79.5%) reconsented to year 3, and 61 (73.5%) completed the trial. Of 167 participants assigned to group 2, 133 (79.6%) continued to year 3, and 121 (72.5%) completed the trial (0.01% atropine, then nightly placebo: n = 31 and n = 29 [93.5%]; 0.01% atropine, then tapering placebo: n = 29 and n = 25 [86.2%]; 0.01% atropine then tapering 0.01% atropine: n = 73 and n = 67 [91.8%], respectively). Compared with the group taking placebo then 0.05% atropine, the combined atropine then placebo groups had more spherical equivalent progression (adjusted difference, −0.13 diopters [D]; 95% CI, −0.22 to −0.04 D; P = .01) and axial elongation (adjusted difference, 0.06 mm; 95% CI, 0.02-0.09 mm; P = .008), and the group taking 0.01% atropine then tapering 0.01% atropine had more axial elongation (adjusted difference, 0.04 mm; 95% CI, 0.009-0.07 mm; P = .04). In the group taking placebo then 0.05% atropine, 15% (n = 10) and 8% (n = 5) reported blurred near vision and photophobia, respectively, during year 3, compared with 3% (n = 2) and 0%, respectively, in the group taking 0.01% atropine then tapering 0.01% atropine, and no reports in both placebo groups. Conclusions and Relevance Despite more adverse events, participants using 0.05% atropine during year 3 had no differences in treatment completion rates and exhibited 0.13-D less myopia progression and 0.06-mm less axial elongation, compared with participants using placebo, supporting consideration of treatment as given to the group taking 0.05% atropine in this European population. Trial Registration isrctn.org Identifier: ISRCTN36732601
Article
Orthokeratology lenses are effective methods for controlling myopia progression. This paper describes the principles and effects of orthokeratology lenses, focusing on randomized controlled trials investigating their ability to prevent myopia progression. While the short-term effects are widely accepted, further well-designed studies are required to assess the persistence of long-term benefits and the possibility of a rebound phenomenon after lens discontinuation. Additionally, both physicians and patients should prioritize safety, particularly in preventing complications such as infectious keratitis.
Article
Purpose The purpose of the study was to evaluate and compare the changes in axial length and refractive profile in myopic patients exposed with different illumination. Methodology A cross-sectional study among 15 myopic subjects was conducted in the tertiary eye care institute. Before participating in the study, individuals underwent comprehensive ocular examinations to ensure their suitability. For each participant, the experiment was conducted in two phases: Phase I procedures occurring at the initial visit and Phase II procedures taking place 1 week later. In Phase I, baseline measurements of axial length and refractive profiles were taken for all participants, followed by exposure to illumination below 500 Lux for 30 min. Phase II replicated the baseline measurements, followed by exposure to lighting above 1000 Lux for the same duration. Axial length measurements were performed using Lenstar LS-500, and refractive profiles were determined using an autorefractometer, both administered by experienced optometrists. Three consecutive measurements were taken for each eye, and the average value was recorded for both axial length and refractive parameters. Paired t -test was used to compare axial length measurements at baseline and after exposure to different illumination levels. Linear regression was used to determine the association between axial length and illumination levels. Statistical significance was considered if P < 0.05. Results Mean axial length measurements varied across the two illumination groups: 23.62 ± 0.18 mm in the high illumination group (>1000 lux) and 23.96 ± 0.23 mm in the low illumination group (<500 lux). Paired t -test revealed a significant difference in axial length among the groups ( P = 0.01). Similarly, the mean spherical equivalent refractive error also varied significantly across the illumination groups: −1.52 ± 0.60 Diopter (D) in the high illumination group, and − 2.01 ± 0.16 D in the low illumination group. There was a significant negative correlation between axial length and refractive error for high illumination group. Conclusion Higher levels of illumination were associated with shorter axial length and less myopic refractive error in individuals.
Article
INTRODUCTION: Patients of cataract with hypermetropic eye usually have a thick lens that boosts pupillary block and consequent angle closure. Its removal allows for expansion of anterior chamber dimensions and angle width, promoting aqueous humour outflow and intraocular pressure reduction. AIM: To study pre operative and post operative changes in intraocular pressure and anterior chamber depth after phacoemulsification with intraocular lens implantation in eye greater than 23.5D intraocular lens. MATERALAND METHODS: This research was a prospective interventional study conducted among patients underwent for phacoemulsification with intraocular lens implantation in eye greater than 23.5D intraocular lens. Atotal 48 eyes of 48 patients were included in the study. Anterior chamber depth was measured by IOLMaster 500 and IOP was measured by Goldmann applanation tonometer. Data analysis was done using licensed SPSS software version 21.0 (Chicago, Illinois). RESULTS: In the present study, mean age of study participants was 62.7±11.3 years. Out of the 48 participants, 27 (56.3%) were female and 21 (43.8%) were male, 30 (62.5%) were operated for left eye. Pre and post -op anterior chamber depth was 3.8±0.73 mm and 4.1±0.67 mm respectively (p<0.001). Pre and post -op IOP was 15.7±2.9 mm Hg and 13.6 ±2.6 mm Hg respectively (p<0.001). CONCLUSION: Our study concluded that anterior chamber depth was statistically significant increases and IOP was statistically significant decreases after phacoemulsification with intraocular lens implantation in eye greater than 23.5D intraocular lens.
Article
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Myopia is a type of clinical refraction, a form of spherical refractive anomaly in which the eye has a relatively stronger refractive power for the corresponding length of the anteroposterior axis. The focus of this optical system is far in front of the retina. Myopia can be congenital or manifest later, most often at school age. It can be stationary or progressive. Progresive myopia is sight-threatening. The article discusses results from a screening program for myopia progression in Bulgarian schools between 2018-2023. The risk factors for myopia development have been outlined, and the ways of prophylaxis have been pointed out.
Article
To investigate the incidence of microbial keratitis among Japanese patients wearing orthokeratology (ortho-k) lenses Retrospective multicenter study This study was conducted at 4 hospitals in Japan and involved 1438 patients who had been prescribed ortho-k lenses and had worn them for at least 3 months. Data on patient demographics, lens characteristics, lens care systems, and presence of microbial keratitis were extracted from the medical records. Duration of ortho-k lens wear was calculated from the original fitting date to the patient's last visit, with the total years of lens wear used as person-years of lens wear. The incidence of microbial keratitis was calculated by dividing the number of infected cases by the total person-years of lens wear for all enrolled participants. Among the 1438 patients, 753 were male and 685 were female, with a mean age of 12.7 ± 5.4 years. The mean duration of ortho-k lens wear was 5.2 ± 4.5 years, and the mean lens power was -3.52 ± 1.41 D. The total person-years of lens wear for all enrolled patients was 7415. Four cases of microbial keratitis were identified, resulting in an overall incidence of microbial keratitis of 5.4 (95% CI: 1.0–9.8) per 10,000 patient-years among ortho-k lens wearers. This study represents the largest sample size to date for estimating the incidence of microbial keratitis associated with ortho-k lenses. The incidence was similar to or slightly lower than that of previous studies on ortho-k-related microbial keratitis and also comparable to that of daily wear soft contact lenses.
Article
Professor Debbie Jones and Professor Nicola Logan take a close look at what can be learned from the results of the MiSight 1 day clinical study after seven years and how this might influence our clinical practice. (C105432, suitable for logging as one distance learning CPD point for optometrists, contact lens opticians and dispensing opticians)
Article
Evidence from human studies of ocular accommodation and studies of animals reared in monochromatic conditions suggest that chromatic signals can guide ocular growth. We hypothesized that ocular biometric response in humans can be manipulated by simulating the chromatic contrast differences associated with imposition of optical defocus. The red, green, and blue (RGB) channels of an RGB movie of the natural world were individually incorporated with computational defocus to create two different movie stimuli. The magnitude of defocus incorporated in the red and blue layers was chosen such that, in one case, it simulated +3 D defocus, referred to as color-signed myopic (CSM) defocus, and in another case it simulated -3 D defocus, referred to as color-signed hyperopic (CSH) defocus. Seventeen subjects viewed the reference stimulus (unaltered movie) and at least one of the two color-signed defocus stimuli for ∼1 hour. Axial length (AL) and choroidal thickness (ChT) were measured immediately before and after each session. AL and subfoveal ChT showed no significant change under any of the three conditions. A significant increase in vitreous chamber depth (VCD) was observed following viewing of the CSH stimulus compared with the reference stimulus (0.034 ± 0.03 mm and 0 ± 0.02 mm, respectively; p = 0.018). A significant thinning of the crystalline lens was observed following viewing of the CSH stimulus relative to the CSM stimulus (-0.033 ± 0.03 mm and 0.001 ± 0.03 mm, respectively; p = 0.015). Differences in the effects of CSM and CSH conditions on VCD and lens thickness suggest a directional, modulatory influence of chromatic defocus. On the other hand, ChT responses showed large variability, rendering it an unreliable biomarker for chromatic defocus-driven responses, at least for the conditions of this study.
Article
This study aimed to investigate the choroidal thickness (ChT) distribution in adult myopic eyes, focusing on the macular, nasal midperiphery, and temporal midperiphery regions, and to explore its relationship with axial length (AL) and refractive error. A cross-sectional, observational study. Twenty-nine eyes of 29 adult volunteers were examined. ChT was measured using high-speed swept-source optical coherence tomography covering an area of 50 degrees in three different regions: centered at macular, nasal side at 33 degrees, and temporal side at 33 degrees. Statistical analyses were performed to assess differences in ChT between regions and correlations with AL and spherical equivalent (SE). ChT was found to be thickest in the macular region, followed by the nasal and temporal midperiphery regions. Significant correlations were observed between AL/SE and ChT in the macular and temporal regions, but not in the nasal region. The temporal midperiphery showed the strongest correlation with AL and SE. This study revealed a nasal-temporal asymmetry in ChT distribution in myopic eyes, with the temporal midperiphery showing the thinnest ChT. The strong correlations between ChT in the temporal midperiphery and AL/SE suggest a role for the temporal choroid in axial elongation and myopia progression. These findings highlight the importance of considering peripheral ChT in understanding ocular growth and myopia management.
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Myopia is a global pandemic, with significant adverse effects on visual health, it is essential to excavate a more comprehensive and inclusive myopia defence that can address the lack of myopia defences due to age, refractive error and astigmatism range. In this study, the multifocal rigid gas-permeable contact lens (MF-RGPCL) was employed as a myopic intervention, the efficacy of MF-RGPCL were observed by the changes in axial length (AL) and best-corrected visual acuity (BCVA) , and the safety was evaluated by monitoring the changes in corneal endothelial cells. Additionally, analyse the subjects' ocular parameters, genetic characteristics, lens’ fit, growth and development and which affect the development of AL in the MF-RGPCL group. After one year, the axial growth of the MF-RGPCL group was significantly slower than that of the SVL group. Similarly, the BCVA of the MF-RGPCL group was significantly better than that of the SVL group. And the AL progression in the MF-RGPCL group was significantly correlated with onset age of myopia, parental myopia, lens decentration, pupil distance, and corneal curvature. No significant alterations were observed in the corneal endothelial cells. MF-RGPCL has been demonstrated to provide effective myopia control and good safety, and can be used as an alternative for myopia defence in adolescents. Complementary clinical indications for orthokeratology lenses (OK lenses) and multifocal soft contact lenses (MF-SCL)
Article
This month, in our series looking at common myths concerning contact lenses, Dr Aman Mahil and Monica Jong look at the risks of myopia on vision loss
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Myopia is the most common refractive error worldwide, contributing not only to visual impairment but also serving as a potential risk factor for various severe ocular diseases. Its impact on patients’ quality of life and health is significant and imposes substantial socioeconomic burdens. In this study, we analyzed the top 100 most cited articles related to myopia published in the Web of Science Core Collection database from January 2000 to February 2024. Using data visualization tools CiteSpace, VOSviewer, and Scimago Graphica, we identified the most influential research papers and academic journals in the field of myopia. The top 100 most influential articles were published in 25 renowned journals across 30 countries, with Investigative Ophthalmology & Visual Science being the most prolific. Ophthalmology had the highest total citation frequency, while The Lancet had the highest average citation frequency. The United States and the National University of Singapore were the top countries and institutions with the most published papers. The 3 major research directions are Ophthalmology, Medicine, General & Internal, and Genetics & Heredity. The top 5 co-occurring keywords were refractive error, risk factors, prevalence, eye growth, and form-deprivation myopia. Cluster analysis results highlighted focal points such as retinal detachment, high myopia, and contrast sensitivity, indicating potential future research trends. Prospective research directions include investigating the pathogenesis of myopia, updating diagnostic technologies, and identifying risk genes for myopia and its complications.
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Purpose In the past few decades, the prevalence of myopia, where the eye grows too long, has increased dramatically. The visual environment appears to be critical to regulating the eye growth. Thus, it is very important to determine the properties of the environment that put children at risk for myopia. Researchers have suggested that the intensity of illumination and range of distances to which a child's eyes are exposed are important, but this has not been confirmed. Methods We designed, built, and tested an inexpensive, child-friendly, head-mounted device that can measure the intensity and spectral content of illumination approaching the eyes and can also measure the distances to which the central visual field of the eyes are exposed. The device is mounted on a child's bicycle helmet. It includes a camera that measures distances over a substantial range and a six-channel spectral sensor. The sensors are hosted by a light-weight, battery-powered microcomputer. We acquired pilot data from children while they were engaged in various indoor and outdoor activities. Results The device proved to be comfortable, easy, and safe to wear, and able to collect very useful data on the statistics of illumination and distances. Conclusions The designed device is an ideal tool to be used in a population of young children, some of whom will later develop myopia and some of whom will not. Translational Relevance Such data would be critical for determining the properties of the visual environment that put children at risk for becoming myopic.
Article
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The eyes of neonates grow from ametropia (refractive error) toward emmetropia. Whether or not this 'emmetropization' is visually guided is controversial. I describe experiments which demonstrate that in the chick refractive state is used to regulate the growth of the eye's vitreous chamber in order to achieve emmetropia from hyperopia or myopia that is induced by different visual deprivations. I discuss several studies that begin to examine the neural pathways that might be involved in the control of eye growth. Optic nerve section was used to examine the level of visual processing necessary for the control of eye growth. Eyes in which the optic nerve has been cut can still grow in the appropriate direction to correct induced hyperopia or myopia. Nevertheless, an intact optic nerve is necessary for normal refractions to be achieved; eyes with optic nerve section overshoot control levels and reverse the sign of the initial refractive error. These findings suggest that eye growth in chicks is controlled by an intraocular mechanism and possibly by a brain-mediated mechanism as well. The hypothesis that ocular accommodation is integral to the control of eye growth was also tested. Complete recovery from induced refractive errors was achieved even when accommodation had been abolished by lesions of the Edinger-Westphal nucleus. The elimination of accommodation did not prevent the ability of chick eyes to compensate for the defocus of spectacle lenses. These results suggest that accommodation is not necessary for the control of eye growth.
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The relationship between a history of hypertension and the quality of its control in routine clinical practice and the risk of acute myocardial infarction was examined in a multicenter, case-control study conducted in Argentina between November 1991 and August 1994, within the framework of the FRICAS study. The cases were 939 patients with acute myocardial infarction and without a history of ischemic heart disease. The controls were 949 subjects identified in the same centers as the cases and admitted with a wide spectrum of acute disorders unrelated to known or suspected risk factors for acute myocardial infarction. The odds ratios and the 95% confidence intervals were derived from multiple logistic regression equations, including terms for age, gender, education, social status, exercise, smoking status, cholesterolemia, history of diabetes, body mass index, and family history of myocardial infarction. The quality of hypertension control was assessed with the most recent blood pressure reading reported by the subjects. Seventy-two percent of hypertensive cases and 62.6% of hypertensive controls had a history of antihypertensive therapy by self-report, when admitted to the medical center. The adjusted odds ratio for acute myocardial infarction due to hypertension was 2.58 (95% confidence interval, 2.08-3.19). The odds ratio was 2.42 (95% confidence interval, 1.88-3.11) when hypertensives reported that their greatest systolic value was below 200 mm Hg (moderate status) and 4.12 (95% confidence interval, 2.87-5.89) when it was above 200 mm Hg (severe status). When the highest diastolic blood pressure value was below 120 mm Hg (moderate status), the risk increased to 2.48 (95% confidence intervals, 1.90-3.24) and to 4.12 (95% confidence interval, 2.83-5.99) when it was above 120 mm Hg (severe status). If the most recent systolic blood pressure was ≤140 mm Hg, the odds ratio was 2.59 (95% confidence interval, 1.96-3.41), and it was 3.42 (95% confidence interval, 2.40-4.87) when the value was >140 mm Hg. If the most recent diastolic blood pressure was ≤90 mm Hg, the risk increased more than two fold (odds ratio =2.48; 95% confidence interval, 1.91-3.22), and if it was >90 mm Hg, it increased nearly four-fold (odds ratio =3.72; 95% confidence interval, 2.33-5.96). In smokers, the odds ratio was 2.28 in the absence of hypertension and increased to 7.51 when hypertension was present. In this Argentine population, hypertension is a strong and independent risk factor for acute myocardial infarction. In routine clinical practice, the control of blood pressure to levels below 140/90 seems to be required in order to reduce part (but not all) of the risk of acute myocardial infarction in hypertensive patients.
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Several lines of evidence suggest that the pigeon is near-sighted for stimuli located in front of its beak and far-sighted for stimuli located to the sides of its head.
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The presence of lower-field myopia (described in chickens, pigeons, quail and amphibians) allows these animals to keep the ground in focus while performing other visual tasks. A relationship has also been reported between the eye height and the degree of myopia observed. All of the animals reported in the literature to date are ground-foraging species. Using infrared neutralizing video retinoscopy and static photoretinoscopy we found a lower-field myopia to be absent in the barn owl (Tyco alba), Swainson's hawk (Buteo swainsonii), Cooper's hawk (Accipiter cooperi) and American kestrel (Falco sparverius). These findings suggest that the presence or absence of a lower-field myopia is a function of the visual ecology of the animal.
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Neuronal types contributing to the inner plexiform layer of the cat retina are described based primarily on light microscopy of Golgi-impregnated retinal whole-mounts. Cells have been characterized on morphological criteria that include dendritic branching patterns, dendritic tree sizes, cell body sizes and stratification of processes in the inner plexiform layer. Nine different types of bipolar cell, 22 different types of amacrine cell and 23 different types of ganglion cell can be distinguished using one or more of these morphological criteria. The significance of the different morphological types of cells is discussed, particularly in relationship to the functional bisublamination of the cat inner plexiform layer.
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High myopia caused primarily due to abnormal emmetropization and excessive axial ocular elongation is associated with sight-threatening ocular pathology. Muscular dysfunction of ocular ciliary muscles due to altered intracellular calcium levels can result in defective mechanotransduction of the eye and retinal defocus. The vitamin D3 receptor (VDR; a intracellular hormone receptor) is known to mediate calcium homeostasis, influencing the development of myopia. In the present study, a total of 206 high myopia, 98 low myopia and 250 control samples were analyzed for VDR gene Fok1 (exon 2 start codon) polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. High myopia patients revealed decrease in the frequency of ff homozygotes (8.3%) as compared to control group (14.0%), with a corresponding increase in frequency of FF homozygotes (68.9% in high myopia vs. 62.8% in controls). The frequency of f allele carriers (Ff and ff) was increased in females of high myopia (35.6%) and low myopia cases (45.4%). Elevated frequency of f allele was found only in early age at onset cases of high myopia (0.227) and later age at onset (10-20 years) cases of low myopia (0.273) as well as in low myopia cases with parental consanguinity (0.458) (P 0.035; χ(2) = 6.692*). The results suggest that VDR gene might not be playing a direct role in the development of myopia, but might contribute indirectly to the risk conferred by mechanical stress factors or growth/development related factors through its role in calcium homeostasis and regulation of ciliary muscle function.
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The study of peripheral refractive error is of growing interest as degradation of the retinal image quality in the periphery is known to affect central refractive error development and ocular shape in animal models. The purpose of this study was to measure peripheral refraction across the horizontal, vertical, and two oblique meridians in a group of myopic and emmetropic adults and to investigate retinal asymmetry in the human retina. Thirty-one myopes (spherical equivalent between -2.00 and -9.62 D) and 20 emmetropes (spherical equivalent between -0.50 and +0.50 D) with astigmatism less than -0.75 D, participated in the project. Noncycloplegic peripheral refraction measurements were captured with an autorefractor (NVision K-5001; Shin-Nippon, Tokyo, Japan) at the fovea and up to 30° eccentricity in the horizontal, vertical, and two oblique meridians in 10° steps. RPR was calculated by subtracting the foveal spherical equivalent refraction from that obtained at each eccentric location. Along all measured meridians, myopic eyes showed a relative hyperopic shift in the periphery, with the superior-temporal portion of the retina exhibiting the smallest shift. Emmetropic eyes, however, exhibited a relatively consistent refractive profile across all meridians and eccentricities, confirming a spherical retinal shape for this group. In addition, off-axis astigmatism increased with eccentricity in all meridians. These results suggest that the myopic eye tends toward an ellipsoid shape, rather than the globular shape of an emmetropic eye.
Article
The objective of this case-control study of idiopathic retinal detachment was to evaluate previously suggested hypotheses about risk factors for retinal detachment and to investigate whether new ocular or systemic risk factors could be identified. Between 1986 and 1990, data were obtained at five US clinical centers on 253 patients with idiopathic retinal detachment and 1,138 controls. Patients with pathologic myopia were excluded. Data were collected from interviews, clinical examinations, and laboratory analyses of blood samples. Only one clearly relevant risk factor, myopia, emerged from the analyses. An eye with a spherical equivalent refractive error of −1 to −3 diopters had a fourfold increased risk of retinal detachment compared with a nonmyopic eye; if the refractive error was greater than −3 diopters, the risk was increased 10-fold. The data suggest that almost 55% of nontraumatic detachments in eyes without previous surgery are attributable to myopia. The etiology of retinal detachment appears to be related to the architecture of the eye. The study found no evidence that systemic factors, particularly cardiovascular factors, play a role.
Article
Objective: To investigate the risk factors for rhegmatogenous retinal detachment (RRD), including myopia, blunt trauma, cataract extraction and family history of RRD. Methods: 1:1 case control study was performed on 200 cases with RRD and 200 without RRD (control group). The criteria of controls included: without the history of RRD and a good match with cases in age, sex and residential area. The odds ratio (ORs) and population attributed risk proportion (PARPs) of the risk factors were calculated and tested. Results: The ORs of blunt trauma, myopia, cataract extraction and family history of RRD were 6.55 (95% CI, 2.65 ∼ 25.32, P < 0.001), 5.34 (95% CI, 2.27 ∼ 6.69, P < 0.001), 21 (95% CI, 3.35 ∼ 99, P < 0.001) and 3 (95% CI, 0.24 ∼ 0.99, P > 0.05), respectively. The PARPs of blunt trauma, myopia and cataract extraction were 12%, 62% and 9.1%, respectively. Conclusion: Myopia, blunt trauma, and cataract extraction are risk factors for RRD, and family history of RRD is not found to be related to RRD.
Article
Purpose. To determine if optical correction of induced axial myopia prevents the refractive and structural recovery from myopia towards emmetropia. Methods. Tree shrews were monocularly deprived (MD) of pattern vision using translucent goggles for a period of 5 days (n=15). At the end of 5 days MD, in vivo measurements of refraction and axial ocular dimensions were taken using retinoscopy and A-scan ultrasonography respectively. One group of tree shrews then had the translucent occluder removed from the treated eye and replaced with a negative lens that corrected their induced axial myopia (n=5). Another group of tree shrews had the translucent occluder removed and replaced with a plano powered lens over the treated eye (n= 5). A further group of tree shrews had the translucent occluder removed and was left to recover without any lens in front of the treated eye. After a further 5 days tree shrews had their ocular refraction and axial dimensions measured again. Results. All three groups developed similar degrees of myopia after a 5 day period of MD (-6.5 ± 0.4 D) which was due to elongation of the vitreous chamber (133 ± 13 microns). The group of tree shrews whose induced myopia was corrected with a negative lens showed no significant recovery from myopia (-6.8 ± 1.0 D vs. -6.3 ± 0.8 D, p=0.6) or vitreous chamber elongation. The group of tree shrews who had the translucent occluder replaced with a plano lens showed a similar degree of emmetropization after 5 days as the normal recovery group, with the myopia reduced to -1.4 D and -1.7 D respectively, which was due mainly to a reduction in vitreous chamber elongation relative to the control eye (140 vs 30 microns). Both groups had significantly less myopia (p<0.001) and vitreous chamber elongation (p< 0.01) than the optically corrected group of tree shrews. Conclusions. Optical correction of induced axial myopia prevents emmetropization in tree shrews. These results may have implications for the correction of refractive errors in human infants where emmetropization is not complete.
Article
Objectives: To examine familial relationships for myopia among siblings and the distribution of myopia in an adult population aged 23 to 78 years. Methods and participants: Eye examinations were conducted in a cross-sectional study on the offspring of the Framingham Eye Study cohort. Between 1989 and 1991, 1585 persons, the offspring of 1319 parents, underwent refraction and were tested for best corrected visual acuity. A person was considered myopic if at least one eye had a spherical equivalent refractive error of at least -1.00 diopter. Results: For both sexes, prevalence of myopia decreased with increasing age, from about 60% for ages 23 to 34 years to about 20% for ages 65 years and older. Among men, both age and years of education were related to myopia. Among women, age was related to myopia, but years of education were not. Age-, sex-, and education-adjusted analyses, using the second-order generalized estimating equations approach, showed a strong association of myopia between siblings. The association between siblings decreased with increasing between-siblings age difference: the estimated odds ratio was about 5 for an age difference of 2 years and half that for an age difference of 10 years. Conclusions: The relative importance of genetic and environmental factors in explaining familial relationships for myopia remains unclear. Nevertheless, the large increase in myopia prevalence for more recent birth cohorts and the decrease in the strength of the between-siblings association for myopia with increasing between-siblings age difference suggest an important role for environmental factors in the cause of myopia.
Article
Background Visual impairment and blindness are common in older people in Britain. It is important to know the causes of visual impairment to develop health service and research priorities. The authors aimed to identify the causes of visual impairment in people aged 75 years and older in Britain. Methods In the MRC Trial of the Assessment and Management of Older People in the Community, trial nurses tested visual acuity in everyone aged 75 years and older in 53 general practices. For all visually impaired patients in 49 of the 53 medical practices, data regarding the cause of vision loss were extracted from the general practice medical notes. Additional follow up questionnaires were also sent to the hospital ophthalmologist to confirm the cause of vision loss. Visual impairment was defined as a binocular acuity of less than 6/18. Results There were 1742 (12.5%) people visually impaired in the 49 participating practices. Of these, 450 (26%) achieved a pinhole visual acuity in either eye of 6/18 or better. In these people, the principal reason for visual loss was considered to be refractive error. The cause of visual loss was available for 976 (76%) of the remaining 1292 visually impaired people identified. The main cause of visual loss was age related macular degeneration (AMD); 52.9% (95% confidence interval 49.2 to 56.5) of people had AMD as a main or contributory cause. This was followed by cataract (35.9%), glaucoma (11.6%), myopic degeneration (4.2%), and diabetic eye disease (3.4%). Conclusions A substantial proportion of visual impairment in our sample of older people in Britain can be attributed to remediable causes—refractive error and cataract. There is considerable potential for visual rehabilitation in this age group. For the large proportion with macular degeneration, low vision services will be important.
Article
The National High Blood Pressure Education Program (NHBPEP) was launched 20 years ago based on data from population studies and clinical trials that showed high blood pressure (HBP) was a major unsolved—but soluble—mass public health problem. The present review summarizes recent data from US prospective population studies on blood pressure—systolic (SBP), diastolic (DBP)—and cardiovascular risk. The outcome variables include blood pressure-related risks, primarily incidence and mortality from coronary heart disease, stroke, other and all cardiovascular diseases (CVD); also cardiac abnormalites (roentgenographic, electrocardiographic, echocardiographic); also, all-cause mortality and life expectancy. Data accrued during the past 20 years confirm that SBP and DBP have continuous, graded, strong, independent, etiologically significant relationships to the outcome variables. These relationships are documented for young, middle-aged, and older men and for middle-aged and older women of varying socioeconomic backgrounds and ethnicity. Among persons aged 35 years or more, most have SBP/DBP above optimal (<120/<80 mm Hg); hence, they are at increased CVD risk, ie, the blood pressure problem involves most of the population, not only the substantial minority with clinical HBP. For middleaged and older persons, SBP relates even more strongly to risk than DBP; at every DBP level, higher SBP results in greater CVD risk and curtailment of life expectancy. A great potential exists for improved health and increased longevity through control of the blood pressure problem. Its realization requires a strategy combining populationwide and high-risk approaches, the former to prevent rise of blood pressure with age and to achieve primary prevention of HBP by nutritional-hygienic means; the latter to enhance detection, treatment, and control of HBP. The newly expanded goals of the NHBPEP, aimed at implementing this broader strategy for the solution of the blood pressure problem, merit active support from physicians and all health professionals.(Arch Intern Med. 1993;153:598-615)
Article
purpose. The chemical coding of intrinsic choroidal neurons (ICNs) has features in common with extrinsic fibers (e.g., from the pterygopalatine ganglion) making it impossible to assess whether a neuronal nitric oxide synthase (nNOS)/vasoactive intestinal polypeptide (VIP)–immunoreactive nerve fiber is of intrinsic or extrinsic origin. Neurobiotin injections into single neurons allow the visualization of projections of these cells and the determination of the origin of target innervation. Thus, this technique was used in the present study to help characterize the organization of the ICN in the human eye. methods. ICNs were visualized with the fluorescent vital dye 4-Di-2-ASP. Electrophysiological properties were determined by means of intracellular recordings. The impaled neurons were iontophoretically filled with neurobiotin. After fixation, immunohistochemistry for neuronal nitric oxide synthase (nNOS), α-smooth muscle actin, and calcitonin gene-related peptide (CGRP) was conducted. results. ICN processes were traced over distances of up to 2.612 μm. They were found in the immediate vicinity of other nNOS-positive or -negative ICNs and were also found apposed to smooth muscle fibers (vascular and stromal nonvascular). CGRP-positive fibers forming boutons were observed closely associated with ICNs. Electrophysiological recording showed phasic firing without slow afterhyperpolarization, no spontaneous activity, an input resistance of 136 ±73 MΩ, and a membrane time constant of 7 ± 1 ms. conclusions. Apart from the first functional characterization of ICNs, this study provided more precise evidence of reciprocal ICN-to-ICN contacts and innervation of both choroidal nonvascular and vascular smooth muscle. The presented technique offers promising perspectives to further investigate the function of ICNs in ocular homeostasis.
Article
purpose. Although astigmatism is prevalent during early infancy, the influence of astigmatism on early refractive development is unclear. This study was undertaken to determine the effects of astigmatism on emmetropization in monkeys. methods. Infant rhesus monkeys (n = 39) were exposed to optically simulated astigmatism in one or both eyes from approximately 1 to 4 months of age. With-the-rule, against-the-rule, and oblique astigmatisms were optically simulated by appropriately orienting the principal meridians of the spherocylindrical treatment lenses (+1.50 −3.00 D × 90°, 180°, 45°, or 135°; i.e., +1.50 and −1.50 D powers in the two principal meridians). Refractive development was assessed every 2 to 3 weeks by cycloplegic retinoscopy, keratometry and corneal videotopography, and A-scan ultrasonography. Data from 19 control monkeys, including 3 animals that were reared with binocular plano lenses, were used for comparison purposes. results. Most of the cylinder-lens-reared monkeys, regardless of the orientation of the imposed astigmatism, showed clear signs of either hyperopic or myopic growth compared with control monkeys. The distributions of refractive error and vitreous chamber depth both showed bimodal patterns that differed from normal by amounts equivalent to the optical powers of the principal meridians of the treatment lenses. More frequently, refractive development was biased toward the eye’s least-hyperopic focal plane. The refractive changes were mainly axial. After lens removal, the lens-reared monkeys recovered and as a group exhibited refractive errors and axial dimensions similar to those in control monkeys. conclusions. In the presence of significant amounts of astigmatism, emmetropization is directed toward one of the two focal planes associated with the astigmatic principal meridians and not the circle of least confusion. These results suggest that the mechanisms responsible for emmetropization are insensitive to stimulus orientation and the global form of the retinal image. It appears that emmetropization seeks out the image plane that contains the maximum effective contrast integrated across spatial frequency and stimulus orientation.
Article
purpose. Previous studies have shown that chick eyes compensate for positive or negative lenses worn for brief periods if the chicks are in darkness the remainder of the time. This study was undertaken to determine whether chicks can compensate for brief periods of lens wear if given unrestricted vision the remainder of the time. Previous studies have also shown that chick eyes alternately wearing positive and negative lenses for brief periods compensate for the positive lenses. The current study sought to determine whether brief periods of positive lens wear can outweigh daylong wearing of negative lenses. methods. Chicks wore +6 D or +10 D lenses for between 8 and 60 min/d, in two to six periods and wore either no lenses or negative lenses for the remainder of the 12-hour daylight period. Refraction and ultrasound biometry were performed before and after the 3-day-long experiments. results. Wearing positive lenses for as little as 12 min/d (six periods of 2 minutes) with unrestricted vision the remainder of the time caused eyes to become hyperopic and reduced the rate of ocular elongation. These effects also occurred when the scene viewed was beyond the far point of the lens-wearing eye and thus was myopically blurred. Even when chicks wore negative lenses for the entire day except for 8 minutes of wearing positive lenses, the eyes compensated for the positive lenses, as though the negative lenses had not been worn. When chicks wore binocular negative lenses for the entire day except for 8 minutes of wearing a positive lens on one eye and a plano lens on the other, the eye wearing the positive lens became less myopic than the eye wearing the plano lens. conclusions. Brief periods of myopic defocus imposed by positive lenses prevent myopia caused by daylong wearing of negative lenses. This implies that periods of myopic and hyperopic defocus do not add linearly. If children are like chicks and if the hyperopic defocus of long daily periods of reading predisposes a child to myopia, regular, brief interruptions of reading might have use as a prophylaxis against progression of myopia.
Article
The accommodation stimulated by convergence, CA/ C, was measured under laboratory and clinical conditions. There was a small nonlinearity to the CA/C ratios measured under laboratory conditions for three of six subjects. We found that convergence accommodation decreases with decreasing accommodative amplitude but not as rapidly as has been reported in the literature. Our results suggest that convergence accommodation can contribute substantially to the near accommodative response for many patients.
Article
BACKGROUND—The safety and predictability of refractive surgery for all degrees of myopia is now becoming established. It is therefore appropriate to evaluate whether there is a patient driven demand for such treatments and, if so, to establish guidelines for its provision within the National Health Service (NHS). METHODS—A comparative study was designed to assess the effect of degree of myopia on quality of life ("high" (n = 30) -10.00D, worse eye; "moderate" (n = 40) -4.00 to -9.75D, worse eye; "low" (n = 42) <-4.00D, worse eye) compared with a group of patients with keratoconus (n = 30) treated by optical correction. Data collection included binocular logMAR visual acuity, Pelli-Robson low contrast letter sensitivity, questionnaires to assess subjective visual function (VF-14) and effect on quality of life (VQOL), and semi-structured interviews. RESULTS—There were no significant differences in any of the measures between patients with a high degree of myopia and those with keratoconus, or between those with a low and those with a moderate degree of myopia. However, those with a high degree of myopia had highly significantly poorer logMAR, VF-14, and VQOL scores than those with low and moderate myopia (p<0.001). Interview data supported these findings with patients with a high degree of myopia and those with keratoconus reporting that psychological, cosmetic, practical, and financial factors affected their quality of life. CONCLUSION—Compared with low and moderate myopia, patients with a high degree of myopia experience impaired quality of life similar to that of patients with keratoconus. Criteria should therefore be identified to enable those in sufficient need to obtain refractive surgical treatment under the NHS.
Article
• The Lens Opacities Case-Control Study evaluated risk factors for age-related nuclear, cortical, posterior subcapsular, and mixed cataracts. The 1380 participants were ophthalmology outpatients, aged 40 to 79 years, classified into the following groups: posterior subcapsular only, 72 patients; nuclear only, 137 patients; cortical only, 290 patients; mixed cataract, 446 patients; and controls, 435 patients. In polychotomous logistic regression analyses, low education increased risk (odds ratio [OR]= 1.46) and regular use of multivitamin supplements decreased risk (OR =0.63) for all cataract types. Dietary intake of riboflavin, vitamins C, E, and carotene, which have antioxidant potential, was protective for cortical, nuclear, and mixed cataract; intake of niacin, thiamine, and iron also decreased risk. Similar results were found in analyses that combined the antioxidant vitamins (OR =0.40) or considered the individual nutrients (OR =0.48 to 0.56). Diabetes increased risk of posterior subcapsular, cortical, and mixed cataracts (OR =1.56). Oral steroid therapy increased posterior subcapsular cataract risk (OR = 5.83). Females (OR =1.51) and nonwhites (OR = 2.03) were at increased risk only for cortical cataract. Risk factors for nuclear cataract were a nonprofessional occupation (OR =1.96), current smoking (OR = 1.68), body mass index (OR = 0.76), and occupational exposure to sunlight (OR =0.61). Gout medications (OR =2.48), family history (OR =1.52), and use of eyeglasses by age 20 years, which is an indicator of myopia (OR = 1.44), increased risk of mixed cataract. The results support a role for the nutritional, medical, personal, and other factors in cataractogenesis. The potentially modifiable factors suggested by this study merit further evaluation.
Article
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Article
To determine whether developing primate eyes are capable of growing in a manner that eliminates astigmatism, we reared infant monkeys with cylindrical spectacle lenses in front of one or both eyes that optically simulated with-the-rule, against-the-rule, or oblique astigmatism (+1.50-3.00x90, x180, x45 or x135). Refractive development was assessed by retinoscopy, keratometry and A-scan ultrasonography. In contrast to control monkeys, the cylinder-lens-reared monkeys developed significant amounts of astigmatism. The astigmatism was corneal in nature, bilaterally mirror symmetric and oblique in axis, and reversible. The ocular astigmatism appeared to be due to a reduction in the rate of corneal flattening along the steeper meridian while the other principal meridian appeared to flatten at a more normal rate. However, regardless of the orientation of the optically imposed astigmatism, the axis of the ocular astigmatism was not appropriate to compensate for the astigmatic error imposed by the treatment lenses. Our results indicate that visual experience can alter corneal shape, but there was no evidence that primates have an active, visually regulated "sphericalization" mechanism.
Article
The relationship between a history of hypertension and the quality of its control in routine clinical practice and the risk of acute myocardial infarction was examined in a multicenter, casecontrol study conducted in Argentina between November 1991 and August 1994, within the framework of the FRICAS study. The cases were 939 patients with acute myocardial infarction and without a history of ischemic heart disease. The controls were 949 subjects identified in the same centers as the cases and admitted with a wide spectrum of acute disorders unrelated to known or suspected risk factors for acute myocardial infarction. The odds ratios and the 95% confidence intervals were derived from multiple logistic regression equations, including terms for age, gender, education, social status, exercise, smoking status, cholesterolemia, history of diabetes, body mass index, and family history of myocardial infarction. The quality of hypertension control was assessed with the most recent blood pressure reading reported by the subjects. Seventy‐two percent of hypertensive cases and 62.6% of hypertensive controls had a history of antihypertensive therapy by self‐report, when admitted to the medical center. The adjusted odds ratio for acute myocardial infarction due to hypertension was 2.58 (95% confidence interval, 2.08–3.19). The odds ratio was 2.42 (95% confidence interval, 1.88–3.11) when hypertensives reported that their greatest systolic value was below 200 mm Hg (moderate status) and 4.12 (95% confidence interval, 2.87–5.89) when it was above 200 mm Hg (severe status). When the highest diastolic blood pressure value was below 120 mm Hg (moderate status), the risk increased to 2.48 (95% confidence intervals, 1.90–3.24) and to 4.12 (95% confidence interval, 2.83–5.99) when it was above 120 mm Hg (severe status). If the most recent systolic blood pressure was ≥140 mm Hg, the odds ratio was 2.59 (95% confidence interval, 1.96–3.41), and it was 3.42 (95% confidence interval, 2.40–4.87) when the value was >140 mm Hg. If the most recent diastolic blood pressure was ≤90 mm Hg, the risk increased more than two fold (odds ratio=2.48; 95% confidence interval, 1.91–3.22), and if it was >90 mm Hg, it increased nearly four‐fold (odds ratio=3.72; 95% confidence interval, 2.33–5.96). In smokers, the odds ratio was 2.28 in the absence of hypertension and increased to 7.51 when hypertension was present. In this Argentine population, hypertension is a strong and independent risk factor for acute myocardial infarction. In routine clinical practice, the control of blood pressure to levels below 140/90 seems to be required in order to reduce part (but not all) of the risk of acute myocardial infarction in hypertensive patients.
Article
Vision defects due to myopia typically appear during the school years. The comprehensive surveillance system of vision impairments in school children (ages 7 to 15 years) in the township of Kuopio, Finland (pop. 74 200) offers an opportunity to study the incidence of school myopia. In the school year 1980-81 out of 9635 school children 1383 (14%) had eye problems and were referred to the Community Health Center ophthalmologist (the author) for examination. Of the children who came for the first time to an eye examination 252 were found myopic. This gives an incidence of 2.6% per year. The incidence in different age groups as well as for boys and girls was caluclated. From the cumulative prevalences it was estimated that about 23% of the school children would be myopic at the age of 15 years.
Article
We investigated the structural basis of the physiological orientation sensitivity of retinal ganglion cells (Levick and Thibos, '82). The dendritic fields of 840 retinal ganglion cells labeled by injections of horseradish peroxidase into the dorsal lateral geniculate nucleus (LGNd) or optic tracts of normal cats, Siamese cats, and cat deprived of patterned visual experience from birth by monocular lid-suture (MD) were studied. Mathematical techniques designed to analyze direction were used to find the dendritic field orientation of each cell. Statistical techniques designed for angular data were used to determine the relationship between dendritic field orientation and angular position on the retina (polar angle). Our results indicate that 88% of retinal ganglion cells have oriented dendritic fields and that dendritic field orientation is related systematically to retinal position. In all regions of retina more than 0.5 mm from the area centralis the dendritic fields of retinal ganglion cells are oriented radially, i.e., like the spokes of a wheel having the area centralis at its hub. This relationship was present in all animals and cell types studied and was strongest for cells located close to the horizontal meridian (visual streak) of the retina. Retinal ganglion cells appear to be sensitive to stimulus orientation because they have oriented dendritic fields.
Article
Myopia has emerged as a major health issue in east Asia, because of its increasingly high prevalence in the past few decades (now 80-90% in school-leavers), and because of the sight-threatening pathologies associated with high myopia, which now affects 10-20% of those completing secondary schooling in this part of the world. Similar, but less marked, changes are occurring in other parts of the world. The higher prevalence of myopia in east Asian cities seems to be associated with increasing educational pressures, combined with life-style changes, which have reduced the time children spend outside. There are no reported major genes for school myopia, although there are several genes associated with high myopia. Any genetic contribution to ethnic differences may be small. However, to what extent many genes of small effect and gene-environment interactions contribute to variations in school myopia within populations remains to be established. There are promising optical and pharmacological interventions for preventing the development of myopia or slowing its progression, which require further validation, and promising vision-sparing treatments for pathological myopia.
Article
Recent investigations have raised the possibility that ocular diurnal rhythms might be involved in the regulation of eye growth. Specifically, the chick eye elongates with a daily rhythm, said to be absent in form-deprived eyes. The present study asks: (1) Which components of the eye have daily rhythms—only the overall eye size, or also choroidal thickness or anterior chamber depth? (2) Does the phase or amplitude of these rhythms differ in eyes growing either faster than normal (form-deprived eyes) or slower than normal (eyes recovering from form-deprivation myopia)?
Article
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.
Article
Time spent outdoors reduces the likelihood that children will develop myopia, possibly because light levels are much higher outdoors than indoors. To test this hypothesis, the effects of high ambient lighting on vision-induced myopia in monkeys were determined. Monocular form deprivation was imposed on eight infant rhesus monkeys. Throughout the rearing period (23 ± 2 to 132 ± 8 days), auxiliary lighting increased the cage-level illuminance from normal lighting levels (15-630 lux) to ∼25,000 lux for 6 hours during the middle of the daily 12-hour light cycle. Refractive development and axial dimensions were assessed by retinoscopy and ultrasonography, respectively. Comparison data were obtained in previous studies from 18 monocularly form-deprived and 32 normal monkeys reared under ordinary laboratory lighting. Form deprivation produced axial myopia in 16 of 18 normal-light-reared monkeys. In contrast, only 2 of the 8 high-light-reared monkeys developed myopic anisometropias, and in 6 of these monkeys, the form-deprived eyes were more hyperopic than their fellow eyes. The treated eyes of the high-light-reared monkeys were more hyperopic than the form-deprived eyes of the normal-light-reared monkeys. In addition, both eyes of the high-light-reared monkeys were more hyperopic than those of normal monkeys. High ambient lighting retards the development of form-deprivation myopia in monkeys. These results are in agreement with the hypothesis that the protective effects of outdoor activities against myopia in children are due to exposure to the higher light levels encountered outdoors. It is possible that therapeutic protection against myopia can be achieved by manipulating indoor lighting levels.
Article
Background: Nearsightedness (myopia) causes blurry vision when looking at distant objects. Highly nearsighted people are at greater risk of several vision-threatening problems such as retinal detachments, choroidal atrophy, cataracts and glaucoma. Interventions that have been explored to slow the progression of myopia include bifocal spectacles, cycloplegic drops, intraocular pressure-lowering drugs, muscarinic receptor antagonists and contact lenses. The purpose of this review was to systematically assess the effectiveness of strategies to control progression of myopia in children. Objectives: To assess the effects of several types of interventions, including eye drops, undercorrection of nearsightedness, multifocal spectacles and contact lenses, on the progression of nearsightedness in myopic children younger than 18 years. We compared the interventions of interest with each other, to single vision lenses (SVLs) (spectacles), placebo or no treatment. Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 11 October 2011. We also searched the reference lists and Science Citation Index for additional, potentially relevant studies. Selection criteria: We included randomized controlled trials (RCTs) in which participants were treated with spectacles, contact lenses or pharmaceutical agents for the purpose of controlling progression of myopia. We excluded trials where participants were older than 18 years at baseline or participants had less than -0.25 diopters (D) spherical equivalent myopia. Data collection and analysis: Two review authors independently extracted data and assessed the risk of bias for each included study. When possible, we analyzed data with the inverse variance method using a fixed-effect or random-effects model, depending on the number of studies and amount of heterogeneity detected. Main results: We included 23 studies (4696 total participants) in this review, with 17 of these studies included in quantitative analysis. Since we only included RCTs in the review, the studies were generally at low risk of bias for selection bias. Undercorrection of myopia was found to increase myopia progression slightly in two studies; children who were undercorrected progressed on average 0.15 D (95% confidence interval (CI) -0.29 to 0.00) more than the fully corrected SVLs wearers at one year. Rigid gas permeable contact lenses (RGPCLs) were found to have no evidence of effect on myopic eye growth in two studies (no meta-analysis due to heterogeneity between studies). Progressive addition lenses (PALs), reported in four studies, and bifocal spectacles, reported in four studies, were found to yield a small slowing of myopia progression. For seven studies with quantitative data at one year, children wearing multifocal lenses, either PALs or bifocals, progressed on average 0.16 D (95% CI 0.07 to 0.25) less than children wearing SVLs. The largest positive effects for slowing myopia progression were exhibited by anti-muscarinic medications. At one year, children receiving pirenzepine gel (two studies), cyclopentolate eye drops (one study), or atropine eye drops (two studies) showed significantly less myopic progression compared with children receiving placebo (mean differences (MD) 0.31 (95% CI 0.17 to 0.44), 0.34 (95% CI 0.08 to 0.60), and 0.80 (95% CI 0.70 to 0.90), respectively). Authors' conclusions: The most likely effective treatment to slow myopia progression thus far is anti-muscarinic topical medication. However, side effects of these medications include light sensitivity and near blur. Also, they are not yet commercially available, so their use is limited and not practical. Further information is required for other methods of myopia control, such as the use of corneal reshaping contact lenses or bifocal soft contact lenses (BSCLs) with a distance center are promising, but currently no published randomized clinical trials exist.
Article
Our previous study, Atropine for the Treatment of Myopia 1 (ATOM1), showed that atropine 1% eyedrops were effective in controlling myopic progression but with visual side effects resulting from cycloplegia and mydriasis. The aim of this study was to compare efficacy and visual side effects of 3 lower doses of atropine: 0.5%, 0.1%, and 0.01%. Single-center, double-masked, randomized study. A total of 400 children aged 6-12 years with myopia of at least -2.0 diopters (D) and astigmatism of -1.50 D or less. Children were randomly assigned in a 2:2:1 ratio to 0.5%, 0.1%, and 0.01% atropine to be administered once nightly to both eyes for 2 years. Cycloplegic refraction, axial length, accommodation amplitude, pupil diameter, and visual acuity were noted at baseline, 2 weeks, and then every 4 months for 2 years. Myopia progression at 2 years. Changes were noted and differences between groups were compared using the Huber-White robust standard error to allow for data clustering of 2 eyes per person. The mean myopia progression at 2 years was -0.30±0.60, -0.38±0.60, and -0.49±0.63 D in the atropine 0.5%, 0.1%, and 0.01% groups, respectively (P=0.02 between the 0.01% and 0.5% groups; between other concentrations P > 0.05). In comparison, myopia progression in ATOM1 was -1.20±0.69 D in the placebo group and -0.28±0.92 D in the atropine 1% group. The mean increase in axial length was 0.27±0.25, 0.28±0.28, and 0.41±0.32 mm in the 0.5%, 0.1%, and 0.01% groups, respectively (P < 0.01 between the 0.01% and 0.1% groups and between the 0.01% and 0.5% groups). However, differences in myopia progression (0.19 D) and axial length change (0.14 mm) between groups were small and clinically insignificant. Atropine 0.01% had a negligible effect on accommodation and pupil size, and no effect on near visual acuity. Allergic conjunctivitis and dermatitis were the most common adverse effect noted, with 16 cases in the 0.1% and 0.5% atropine groups, and no cases in the 0.01% group. Atropine 0.01% has minimal side effects compared with atropine at 0.1% and 0.5%, and retains comparable efficacy in controlling myopia progression.
Article
PURPOSE. Relative peripheral hyperopia has been associated with central myopia. This study was conducted to determine whether baseline relative peripheral hyperopia is associated with an increased risk of developing myopia or myopia progression in young Singapore Chinese children. METHODS. One hundred eighty-seven children who participated in the Peripheral Refraction in Preschool Children (PREP) Study at baseline underwent a follow-up examination. Autorefraction was performed at five eccentricities with an infrared autorefractor after cycloplegia: central axis and 15° and 30° eccentricities in the nasal and temporal visual fields. The primary outcomes were development of myopia among children who were nonmyopic at baseline, and myopia progression in those who were myopic at baseline. RESULTS. The mean age of the children at baseline was 7.2 ± 3.0 years, and the mean duration of follow-up was 1.26 years. At baseline, 96 children were myopic (mean central spherical equivalent [SE] -2.75 ± 1.72 D) and 91 were nonmyopic (mean central SE 0.76 ± 0.81 D). Baseline relative peripheral hyperopia was not associated with a greater likelihood of becoming myopic or myopia progression. At follow-up, children who remained nonmyopic (n = 24) retained relative peripheral myopia at all eccentricities, whereas those who became myopic (n = 67) developed relative peripheral hyperopia at the nasal (+0.44 ± 0.72 D) and temporal 30° (+0.13 ± 0.74 D). The mean change in central SE was -1.51 ± 0.63 D/y for children who developed myopia, -0.82 ± 0.76 D/y for children who were myopic at baseline, and -1.05 ± 0.80 D/y for all children. CONCLUSIONS. Baseline peripheral refraction did not predict the subsequent onset of myopia or influence the progression of myopia.
Article
In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form-deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form-deprivation) or -10 D lenses attached to the feathers with matching rings of Velcro. Each day for 4 days, 10 μl intravitreal injections of the dopamine D2/D4 antagonist spiperone (5 nmoles) or the D1 antagonist SCH-23390, were given under isoflurane anesthesia, and the diffusers (n = 16; n = 5, respectively) or lenses (n = 20; n = 6) were removed for 2 h immediately after. Saline injections prior to vision were done as controls (form-deprivation: n = 11; lenses: n = 10). Two other saline-injected groups wore the lenses (n = 12) or diffusers (n = 4) continuously. Axial dimensions were measured by high frequency A-scan ultrasonography at the start, and on the last day immediately prior to, and 3 h after the injection. Refractive errors were measured at the end of the experiment using a Hartinger's refractometer. In form-deprived eyes, spiperone, but not SCH-23390, prevented the ocular growth inhibition normally effected by the brief periods of vision (change in vitreous chamber depth, spiperone vs saline: 322 vs 211 μm; p = 0.01). By contrast, neither had any effect on negative lens-wearing eyes given similar unrestricted vision (210 and 234 μm respectively, vs 264 μm). The increased elongation in the spiperone-injected form-deprived eyes did not, however, result in a myopic shift, probably due to the inhibitory effect of the drug on anterior chamber growth (drug vs saline: 96 vs 160 μm; p < 0.01). Finally, spiperone inhibited the vision-induced transient choroidal thickening in form-deprived eyes, while SCH-23390 did not. These results indicate that the dopaminergic mechanisms mediating the protective effects of brief periods of unrestricted vision differ for form-deprivation versus negative lens-wear, which may imply different growth control mechanisms between the two.
Article
The Flitcroft (1998) emmetropization model incorporates a classical model of accommodation and convergence with blur-driven feedback control of eye growth. We have modified this model by incorporating the effects of illumination (with or without extensive near work) on accommodation, vergence, pupil diameter and emmetropization. In addition to replicating Flitcroft's results, we show that (1) decreased illumination and (2) a low convergence accommodation/convergence (CAC) ratio exacerbate the progression of near-work-induced myopia. Our model further indicates that prescription of negative lenses, under these conditions, augments the advancement of myopia.