Mean cycloplegic refractive error in emmetropic adults – The Tehran Eye Study / Error refractivo ciclopléjico medio en adultos emétropes: estudio ocular de Teherán

Purpose: In children under 20 years, refractive development targets a cycloplegic refractive error of +0.5 to +1.5D, while presbyopes over 40 years generally have non-cycloplegic errors of ≥ +1D. Some papers suggest these periods are separated by a period of myopic refractive error (i.e., ≤ –0.50D), but this remains unclear. Hence, this work investigates the mean cycloplegic refractive error in adults aged between 20 – 40 years. Methods: In 2002 a cross-sectional study with stratified cluster sampling was performed on the population of Tehran, providing cycloplegic and non-cycloplegic refractive error data for the right eyes of 3,576 participants, aged 30.6 ± 18.6 years (range: 1–86 years). After grouping these data into age groups of 5 years, the refractive error histogram of each group was fitted to a Bigaussian function. The mean of the central, emmetropized peak was used to estimate the mean refractive error without the influence of myopia. Results: The mean cycloplegic refractive error at the emmetropized peak decreased from +1.10 ± 0.11D (95 % confidence interval) to +0.50 ± 0.04D before 20 years and remains stable at that value until the age of 50 years. The non-cycloplegic refractive error also sees a stable phase at 0.00 ± 0.04D between 15 – 45 years. After 45 – 50 years both cycloplegic and non-cycloplegic refractive error become more hypermetropic over time, +1.14 ± 0.12D at 75 years. Conclusions: The cycloplegic refractive error in adults is about +0.50D between 20 – 50 years, disproving the existence of the myopic period at those ages.(AU)

A pilot study of axial length changes associated with myopia control spectacles in subjects reading under mesopic conditions.

PURPOSE: To investigate whether axial length changes in subjects wearing myopia control spectacles under mesopic conditions. METHODS: Young users of monofocal spectacles with myopic spherical equivalent ranging from -1.00 D to -5.00 D were enrolled prospectively. Subjects were tested while using a pair of special defocus spectacles with a central zone including the distance myopic correction and a peripheral zone with an addition of +3.50 D. Subjects first read an online book with black letters on white background on a desktop computer with their monofocal spectacles for 20 minutes and then read with special defocus spectacles for another 20 minutes. Reading took place in a darkened room under 20 lux illumination. Before and after these periods, axial length of the right eye was measured ten times using the Lenstar, and average measurements were recorded. RESULTS: The 11 subjects in this pilot study had a mean age of 20.9 ± 7.7 years, and 1 was female. Their mean spherical equivalent of the right eyes was -3.20 ± 2.29 D. As expected, axial length increased by 8.2 ± 9.4 µm (P < 0.01) after 20 minutes of reading with monofocal spectacles in low light. When reading with defocus spectacles under the same conditions, the axial length saw an additional, nonsignificant change of 2.2 ± 12.2 µm (P = 0.56). CONCLUSIONS: When reading in mesopic conditions, the axial length in study subjects did not return to baseline values with myopia control spectacles.

Mean cycloplegic refractive error in emmetropic adults - The Tehran Eye Study.

PURPOSE: In children under 20 years, refractive development targets a cycloplegic refractive error of +0.5 to +1.5D, while presbyopes over 40 years generally have non-cycloplegic errors of ≥ +1D. Some papers suggest these periods are separated by a period of myopic refractive error (i.e., ≤ -0.50D), but this remains unclear. Hence, this work investigates the mean cycloplegic refractive error in adults aged between 20 - 40 years. METHODS: In 2002 a cross-sectional study with stratified cluster sampling was performed on the population of Tehran, providing cycloplegic and non-cycloplegic refractive error data for the right eyes of 3,576 participants, aged 30.6 ± 18.6 years (range: 1-86 years). After grouping these data into age groups of 5 years, the refractive error histogram of each group was fitted to a Bigaussian function. The mean of the central, emmetropized peak was used to estimate the mean refractive error without the influence of myopia. RESULTS: The mean cycloplegic refractive error at the emmetropized peak decreased from +1.10 ± 0.11D (95 % confidence interval) to +0.50 ± 0.04D before 20 years and remains stable at that value until the age of 50 years. The non-cycloplegic refractive error also sees a stable phase at 0.00 ± 0.04D between 15 - 45 years. After 45 - 50 years both cycloplegic and non-cycloplegic refractive error become more hypermetropic over time, +1.14 ± 0.12D at 75 years. CONCLUSIONS: The cycloplegic refractive error in adults is about +0.50D between 20 - 50 years, disproving the existence of the myopic period at those ages.

Accommodative-vergence disorders in a paediatric ophthalmology clinical setting in Argentina.

PURPOSE: To determine the frequency of potential non-strabismic accommodative-vergence anomalies (NSAVA) and investigate associations between NSAVA, refractive errors and age among children attending a paediatric ophthalmology clinic. METHODS: This study included children and adolescents aged 5-19 years attending an ophthalmology clinic with at least two follow-up visits. At their first visit, children had a comprehensive ophthalmic examination, including refractive error measurement by cycloplegic autorefraction and spectacles were prescribed if necessary. At the second visit, children had an examination of best-corrected visual acuity, convergence and accommodation to identify potential NSAVA. The relationship between age, sex, heterophoria and refractive error and potential NSAVA was assessed by a multivariable logistic regression model. RESULTS: A total of 384 children and adolescents were evaluated. Their mean age was 10.97 ± 3.07 years and 58.9% were females. Forty-two per cent of children failed the NSAVA tests and 34.1% had myopia (≤-0.50 D). Children who failed NSAVA tests self-reported a higher proportion of reading problems (73.7%) compared to those who passed the tests (26.3%; p < 0.001). Children with self-reported reading problems were more likely to have accommodative infacility (57.9%) compared with children without (42.1%; p < 0.001). Refractive error and age were not associated with failure in NSAVA tests (p > 0.05). CONCLUSIONS: NSAVA was a frequent cause of vision problems found in a sample of children from an ophthalmology paediatric clinic. Thus, further research is necessary to understand the potential of public health policies to prevent, refer, diagnose and treat those conditions.

Longitudinal changes in crystalline lens thickness and power in children aged 6-12 years old.

OBJECTIVES: To determine the three-year changes in crystalline lens power (LP) and thickness (LT) in children and their associated factors. METHODS: Schoolchildren aged 6-12 years living in Shahroud, northeast Iran were examined in 2015 and 2018. The Bennett formula was used to calculate LP. Multiple generalized estimating equations (GEE) analysis was used for data analysis. RESULTS: Among the 8089 examined eyes, the mean LP in Phase 1 and 2, and the three-year change were 21.61 ± 1.47D, 21.00 ± 1.42D, and -0.61 ± 0.52D, respectively. The GEE model showed that negative shifts in LP were less pronounced with increasing age (ß = 0.176; p < 0.001), and were also less noticeable in hyperopes compared to emmetropes (ß = 0.120; p < 0.001). The changes in LP decreased when outdoor activity increased among urban residents (ß = 0.013; p = 0.039), while it increased in rural area (ß = -0.020; p = 0.047). Mean three-year change in LT was 0.002 ± 0.13 mm. Female sex and aging by one year increased the LT by 0.022 mm (P < 0.001). However, LT decreased in 6-8-year-olds, while it increased in 10-12-year-old children, both in a linear fashion. The change in LT was less in myopes than in emmetropes (ß = -0.018, P-value = 0.010). CONCLUSION: LP decreases after three years in 6 to 12-year-old children. LT increases slightly after three years in 6 to 12-year-old children. The changes in LP and LT were associated with the refractive errors, place of residence, age and gender and outdoor activity time.

Retinal shadows produced by myopia control spectacles.

PURPOSE: To analyse ocular coherence tomography (OCT) images of the retinal shadows caused by defocus and diffusion optics spectacles. METHODS: One eye was fitted successively with the Hoya Defocus Incorporated Multiple Segments (DIMS) spectacle lens, two variations of the +3.50 D peripheral add spectacle (DEFOCUS) and the low-contrast dot lens (Diffusion Optics Multiple Segments, DOMS); each at a vertex distance of 12 mm. Simultaneously, a retinal image of the macular region with central fixation was obtained using infrared OCT. The corneal power and intraocular distances were determined using an optical biometer. RESULTS: The retinal images for the DIMS and DOMS lenses showed patterns of obvious retinal shadows in the periphery, while the central 10-11° remained clear. The DEFOCUS lens produced a darkened peripheral area. Dividing the size of the retinal pattern, measured with the calliper of the OCT software, by the actual size on the spectacle lens gave a magnification of -0.57 times. This is consistent with the incoming OCT beam being imaged to a position approximately 31 mm beyond the front of the eye. [Correction added on 26 October 2023 after first online publication: The preceding paragraph was corrected.] CONCLUSION: With device-specific correction, retinal OCT images can help visualise the regions affected by the defocus or lowered contrast induced by myopia control spectacles. This is of potential value for improving myopia therapies.

Preservatives and pH in low-dose atropine formulations for clinical trials.

Over a century ago, atropine has been tested to arrest myopia progression with good results. In recent years, many randomized clinical trials have tested different concentrations against placebo. Three recent such studies with low-dose atropine showed that it was less effective than previous studies, even the last one showing no difference in myopia progression between the treated and control group. Previous randomized studies had been performed in Asian populations, and these last three were extended to Western Caucasian populations, based on the initial observation that differences in iris pigmentation could be a factor for a difference in effectiveness. We have noticed that the three last studies in the West have used the same patented formulation, while previous studies have preferred compounded low-dose atropine. Here we review how the power of hydrogen (pH) and preservatives could account for differences in drug penetration to the eye, possibly explaining the differences between studies.

Effect of low-dose atropine (0.01%) on crystalline lens power among school-aged children with progressive myopia.

PURPOSE: To evaluate the change in crystalline lens power (LP) in a cohort of Indian children with progressive myopia receiving atropine (0.01%) compared with an untreated control group. DESIGN: Nonrandomised clinical trial. METHODS: The study included 120 children (70 in the atropine group; 50 in the control group) with progressive myopia (≥0.5 D/year) with a 1-year follow-up. The atropine group received 0.01% atropine eye drops once daily in both eyes, whereas the control group received no treatment. Changes in cycloplegic spherical equivalent, axial length (AL), keratometry (KER), anterior chamber depth (ACD) and lens thickness (LT) were recorded. LP was calculated using the formula proposed by Bennett. RESULTS: Mean myopia progression at year 1 was significantly less in the atropine group (-0.18 D [0.2]) than in the control group (-0.59 [0.21]; p < 0.001). The increase in AL was significantly different between the two groups (atropine: 0.21 mm [0.12]; control: 0.29 mm [0.11], p < 0.001). A significantly greater loss of LP was noted in the atropine group (-0.67 D [0.34]) than in the placebo group (-0.28 D [0.42]; p < 0.001). The change in LT was significantly different between the atropine and control groups (p = 0.02), whereas the change in ACD and KER was similar in the two groups. CONCLUSION: The greater loss of LP could contribute to the anti-myopia effect of atropine and should therefore be evaluated in studies reporting the efficacy of atropine on myopia to assess its actual effect on myopic progression.

IMI-Onset and Progression of Myopia in Young Adults.

Myopia typically starts and progresses during childhood, but onset and progression can occur during adulthood. The goals of this review are to summarize published data on myopia onset and progression in young adults, aged 18 to 40 years, to characterize myopia in this age group, to assess what is currently known, and to highlight the gaps in the current understanding. Specifically, the peer-reviewed literature was reviewed to: characterize the timeline and age of stabilization of juvenile-onset myopia; estimate the frequency of adult-onset myopia; evaluate the rate of myopia progression in adults, regardless of age of onset, both during the college years and later; describe the rate of axial elongation in myopic adults; identify risk factors for adult onset and progression; report myopia progression and axial elongation in adults who have undergone refractive surgery; and discuss myopia management and research study design. Adult-onset myopia is common, representing a third or more of all myopia in western populations, but less in East Asia, where onset during childhood is high. Clinically meaningful myopia progression continues in early adulthood and may average 1.00 diopters (D) between 20 and 30 years. Higher levels of myopia are associated with greater absolute risk of myopia-related ocular disease and visual impairment, and thus myopia in this age group requires ongoing management. Modalities established for myopia control in children would be options for adults, but it is difficult to predict their efficacy. The feasibility of studies of myopia control in adults is limited by the long duration required.

Emmetropization and nonmyopic eye growth.

Most eyes start with a hypermetropic refractive error at birth, but the growth rates of the ocular components, guided by visual cues, will slow in such a way that this refractive error decreases during the first 2 years of life. Once reaching its target, the eye enters a period of stable refractive error as it continues to grow by balancing the loss in corneal and lens power with the axial elongation. Although these basic ideas were first proposed over a century ago by Straub, the exact details on the controlling mechanism and the growth process remained elusive. Thanks to the observations collected in the last 40 years in both animals and humans, we are now beginning to get an understanding how environmental and behavioral factors stabilize or disrupt ocular growth. We survey these efforts to present what is currently known regarding the regulation of ocular growth rates.

Non-Miotic Improvement in Binocular Near Vision with a Topical Compound Formula for Presbyopia Correction.

INTRODUCTION: The aim of this case series was to examine the association between unaided binocular visual acuity for near vision and pupil change after the instillation of a special topical formulation for presbyopia treatment. METHODS: This was a case series consisting of consecutive participants with presbyopia aged 40-70 years who were tested for visual acuity and pupil diameter before and 2 h after instillation of a formulation of pilocarpine and phenylephrine drops (FOV Tears) for presbyopia. Participants underwent subjective refraction, photopic and scotopic pupil diameter measurement and unaided monocular and binocular visual acuity testing by logMAR for distance and near vision both pre- and post-instillation of eye drops. RESULTS: The study enrolled 363 subjects (n = 176 women, 48%) with a mean (± standard deviation) age of 50.4 ± 5.8 years. Mean spherical equivalent (SE) changed significantly (- 0.17 Diopters) after instillation of the FOV Tears formulation (p < 0.001). Post-instillation of eye drops, the scotopic pupil diameter decreased by 0.97 ± 0.98 mm, and the near visual acuity by logMAR improved significantly by nearly two lines (p < 0.01). In the linear regression analyses, age (p < 0.001) and SE pre-drop instillation (p < 0.001) were associated with unaided binocular visual acuity. The changes in photopic pupil diameter and the scotopic pupil diameter were not associated with unaided binocular visual acuity. CONCLUSIONS: The use of the pilocarpine and phenylephrine formulation (FOV Tears) improved binocular visual acuity for near vision in presbyopic patients, and the effect was independent of pupil change.

Refractive Errors and Their Associated Factors in Schoolchildren: A Structural Equation Modeling.

PURPOSE: To determine the prevalence of myopia and hyperopia in Shahroud schoolchildren and their risk factors. METHODS: Optometric examinations including the measurement of uncorrected and corrected visual acuity as well as non-cycloplegic and cycloplegic refraction using retinoscopy were done for students. Generalized Structural Equation Modeling (GSEM) was used to determine direct and indirect effects of independent variables on myopia and hyperopia. RESULTS: The data of 5581 students with a mean age of 9.24 ± 1.7 years were used in this study. The prevalence of myopia was 5.0% (95%CI: 4.3-5.7) and the prevalence of hyperopia was 4.8% (95%CI: 4.0 - 5.5) in all schoolchildren. According to the GSEM results, the odds of myopia in rural areas were 0.55 compared to urban areas. A one-unit increase in the ocular AL increased the odds of myopia by 4.91 times. The interaction of sex and age on myopia was significant such that in girls, the odds of myopia increased by 20% for every one-year increase in age while no significant change was seen in boys. A one-unit increase in the ocular AL decreased the odds of hyperopia by 0.49 times. Moreover, the interaction of outdoor activity hours and sex on the prevalence of hyperopia was significant such that increased outdoor activity reduced the odds of hyperopia in girls while no significant correlation was found in boys. CONCLUSION: Myopia and hyperopia had moderate prevalence. Axial Length had the largest direct association on myopia and hyperopia. Age and outdoor activity had weak associations on refractive errors.

Role of tutorial classes and full day schooling on self-reported age of myopia onset: findings in a sample of Argentinian adults.

PURPOSE: To investigate the effect of tutorial classes and schooling schedule in childhood on age of myopia onset. METHODS: Refractive data for subjects ≥18 years of age were collected from 8 dispensing opticians or refractive ophthalmologists' offices in Argentina. Age of myopia onset, spherical equivalent (SE), and risk factors were determined using questionnaires. Multiple linear regression models were applied to assess possible factors associated with age of myopia onset or final adult SE. RESULTS: A total of 274 adults (61.3% females) with myopia between -0.50 and -6.00 D were included. Mean age was 36.9 ± 14.5 years. The mean adult SE was -2.95 ± 1.45 D, and the mean age of myopia onset was 14.2 ± 5.4 years. Subjects that attended after-school tutorial classes (ß = -2.23; P = 0.005) or a full day schedule in primary school (ß = -1.07; P = 0.035) or that spent more time on near work (ß = -0.70; P = 0.010) in childhood, had younger age of myopia onset. CONCLUSIONS: In our study cohort, adults that had attended tutorial classes and/or full-day schooling during childhood had younger age of myopia onset.

Rapid progression of myopia at onset during home confinement.

PURPOSE: To determine whether the myopic shift at myopia onset was faster than usual during home confinement associated with the COVID-19 pandemic. METHODS: Data on refractive error in consecutive children who presented for their first myopic spectacle prescription from September 2020 to May 2021 (new-onset myopia during the pandemic) were collected. Inclusion criteria were age 5-18 years and cycloplegic spherical equivalent in both eyes in the emmetropic range in the pre-pandemic years as recorded 1 year and 2 years before the actual visit. Annualized mean myopic shifts over the two previous periods were calculated. RESULTS: A total of 39 subjects (59% girls) were enrolled. Mean age at the visit after confinement was 10.79 ± 2.83 years. The mean refractive error for the right eyes in 2018 was +0.29 ± 0.56 D. The year after (2019), these children had a mean spherical equivalent of -0.12 ± 0.70 D. At the enrollment visit after myopia onset in the pandemic period, they had myopia of -1.33 ± 0.73 D. The mean annualized myopic shift for the right eyes was -0.37 ± 0.43 D before the pandemic and -1.12 ± 0.70 D during the pandemic period that included home confinement (P < 0·001 [Wilcoxon text]). CONCLUSIONS: Previous pre-pandemic prospective studies have reported myopic shift at onset of approximately -0.80 D. The period of strict pandemic home confinement saw higher rates of myopic shift.

Light Intensity in Nursery Schools: A Possible Factor in Refractive Development.

PURPOSE: Increased levels of outdoor light have been found to be associated causally with decreased rates of myopia. The goal of this study was to measure the effect of indoor nursery school light intensity on refraction of preschool children in Israel. METHODS: A total of 1596 children aged 4 to 5 years from 27 nursery schools were examined. Light intensity was tested with a luxmeter device (Lux) inside and outside the nursery school. Noncycloplegic refractions were measured with the PlusOptix vision A09 screening device. Data analysis was performed using Pearson coefficients, chi-square tests for proportions and ANOVA tests by tertiles of illuminance. RESULTS: This study included 1131 kindergarten children with a mean age of 4.87 ±â€Š0.33 years, of which 571 were female (50.5%). The mean light intensity of the low, medium, and high intensity groups differed significantly (ANOVA P < 0.001) at 359 ±â€Š2.64 lux (range 264-431), 490 ±â€Š2.21 lux (range 432-574), and 670.76 ±â€Š3.73 lux (range 578-804), respectively. Mean spherical equivalent (SE) was +0.56 ±â€Š0.03D for the low-intensity group, +0.73 ±â€Š0.03D for the medium-intensity group, and +0.89 ±â€Š0.03D for the high-intensity group (ANOVA P < 0.001). The low-intensity group had 42.1% of children with zero refraction or less, while the high-intensity group had 19.3%. CONCLUSIONS: In the nursery schools, lower amounts of illumination were associated with less hyperopic refractive error. As the low hyperopic reserve is a risk factor for developing myopia, this finding needs to be followed up to establish whether this association reflects a causal relationship, which could be modulated for the prevention of myopia.

Analysis of visual disability in Buenos Aires, Argentina. Pathologic myopia is the leading cause in working age.

This study assessed the causes of visual impairment over a decade in Buenos Aires City. This is a retrospective case series where we reviewed the database of visual disability certificates issued by the Buenos Aires City Ministry of Health between 2009 and 2017. In Argentina, visual disability is defined as a visual acuity = 20/200 in the better eye, or a corresponding visual field of less than 20 degrees in the less impaired eye. The database included the following variables: year of issue, age, gender, and cause of visual disability. Between 2009 and 2017 a total of 7656 subjects were certified as legally blind. The mean age of the sample was 57 ± 21 years and 52.1% were females. The emission was near 700 certificates per year. The age distribution showed that 62.8% of certificates were from patients older than 50 years and that only 6.6% were given to subjects under 20. The leading causes of visual disability in Buenos Aires City were age-related macular degeneration (ARMD) with a rate of 15.5%, degenerative myopia (14.4%), primary open-angle glaucoma (11.3%) and diabetic retinopathy (6.6%). In subjects younger than 50, degenerative myopia was the first cause of visual disability. Interestingly in Argentina, where the prevalence of myopia is low, degenerative myopia is found to be the major cause of visual disability in middle-aged adult subjects. Population and clinical methods to avoid this preventable disease should need to be implemented as a matter of urgency.

Este trabajo estudia las causas de la discapacidad visual durante una década en la Ciudad de Buenos Aires. Se presenta una serie de casos retrospectiva donde se revisó la base de datos de certificados de discapacidad visual emitidos por el Ministerio de Salud de la Ciudad de Buenos Aires entre 2009 y 2017. En Argentina, la discapacidad visual se define como una agudeza visual = 20/200 en el mejor ojo, o un campo visual correspondiente de menos de 20 grados en el ojo menos deteriorado. La base de datos incluyó las siguientes variables: año de emisión, edad, sexo y causa de la discapacidad visual. Entre 2009 y 2017 se certificaron un total de 7656 sujetos con ceguera legal. La edad media de la muestra fue de 57 ± 21 años y el 52.1% fueron mujeres. La distribución por edades mostró que el 62.8% de los certificados fueron dados a pacientes mayores de 50 años y que solo el 6.6% se otorgó a menores de 20 años. Las principales causas de discapacidad visual fueron la degeneración macular asociada a la edad (DMAE) (15.5%), la miopía degenerativa (14.4%), el glaucoma primario de ángulo abierto (11.3%) y la retinopatía diabética (6.6%). En los menores de 50 años, la miopía degenerativa fue la primera causa de discapacidad visual. Resulta interesante que, en Argentina, donde la prevalencia de miopía es baja, la miopía degenerativa sea la principal causa de discapacidad visual en adultos de mediana edad.

Analysis of visual disability in Buenos Aires, Argentina. Pathologic myopia is the leading cause in working age / Análisis de discapacidad visual en Buenos Aires, Argentina. La miopía patológica es la principal causa en edad laboral

Abstract This study assessed the causes of visual impairment over a decade in Buenos Aires City. This is a retrospective case series where we reviewed the database of visual disability certificates issued by the Buenos Aires City Ministry of Health between 2009 and 2017. In Argentina, visual disability is defined as a visual acuity ≤ 20/200 in the better eye, or a corresponding visual field of less than 20 degrees in the less impaired eye. The database included the following variables: year of issue, age, gender, and cause of visual disability. Between 2009 and 2017 a total of 7656 subjects were certified as legally blind. The mean age of the sample was 57 ± 21 years and 52.1% were females. The emission was near 700 certificates per year. The age distribution showed that 62.8% of certificates were from patients older than 50 years and that only 6.6% were given to subjects under 20. The leading causes of visual disability in Buenos Aires City were age-related macular degeneration (ARMD) with a rate of 15.5%, degenerative myopia (14.4%), primary open-angle glaucoma (11.3%) and diabetic retinopathy (6.6%). In subjects younger than 50, degenerative myopia was the first cause of visual disability. Interestingly in Argentina, where the prevalence of myopia is low, degenerative myopia is found to be the major cause of visual disability in middle-aged adult subjects. Population and clinical methods to avoid this preventable disease should need to be implemented as a matter of urgency.

Resumen Este trabajo estudia las causas de la discapacidad visual durante una década en la Ciudad de Buenos Aires. Se presenta una serie de casos retrospectiva donde se revisó la base de datos de certificados de discapacidad visual emitidos por el Ministerio de Salud de la Ciudad de Buenos Aires entre 2009 y 2017. En Argentina, la discapacidad visual se define como una agudeza visual ≤ 20/200 en el mejor ojo, o un campo visual correspondiente de menos de 20 grados en el ojo menos deteriorado. La base de datos incluyó las siguientes variables: año de emisión, edad, sexo y causa de la discapacidad visual. Entre 2009 y 2017 se certificaron un total de 7656 sujetos con ceguera legal. La edad media de la muestra fue de 57 ± 21 años y el 52.1% fueron mujeres. La distribución por edades mostró que el 62.8% de los certificados fueron dados a pacientes mayores de 50 años y que solo el 6.6% se otorgó a menores de 20 años. Las principales causas de discapacidad visual fueron la degeneración macular asociada a la edad (DMAE) (15.5%), la miopía degenerativa (14.4%), el glaucoma primario de ángulo abierto (11.3%) y la retinopatía diabética (6.6%). En los menores de 50 años, la miopía degenerativa fue la primera causa de discapacidad visual. Resulta interesante que, en Argentina, donde la prevalencia de miopía es baja, la miopía degenerativa sea la principal causa de discapacidad visual en adultos de mediana edad.

Reappraisal of the historical myopia epidemic in native Arctic communities.

PURPOSE: This study was developed to explain the extraordinary rise in myopia prevalence beginning after 1950 in Indigenous Arctic communities considering recent findings about the risk factors for school myopia development. Myopia prevalence changed drastically from a historical low of less than 3% to more than 50% in new generations of young adults following the Second World War. At that time, this increase was attributed to concurrent alterations in the environment and way of life which occurred in an aggressive programme of de-culturalization and re-acculturation through residential school programmes that introduced mental, emotional and physical stressors. However, the predominant idea that myopia was genetic in nature won the discussion of the day, and research in the area of environmental changes was dismissed. There may have also been an association between myopia progression and the introduction of extreme mental, emotional and physical stressors at the time. RECENT FINDINGS: Since 1978, animal models of myopia have demonstrated that myopiagenesis has a strong environmental component. Furthermore, multiple studies in human populations have shown since 2005 how myopia could be produced by a combination of limited exposure to the outdoors and heavy emphasis on academic subjects associated with intense reading habits. This new knowledge was applied in the present study to unravel the causes of the historical myopia epidemics in Inuit communities. SUMMARY: After reviewing the available published data on myopia prevalence in circumpolar Inuit populations in the 20th century, the most likely causes for the Inuit myopia epidemic were the combination of increased near work (from almost none to daily reading) and the move from a mostly outdoor to a much more indoor way of life, exacerbated by fewer hours of sunshine during waking hours, the lower illuminance in the Arctic and the extreme psychophysical stress due to the conditions in the Residential Schools.