The long and short of it: a comprehensive assessment of axial length estimation in myopic eyes from ocular and demographic variables.

BACKGROUND/OBJECTIVES: Axial length, a key measurement in myopia management, is not accessible in many settings. We aimed to develop and assess machine learning models to estimate the axial length of young myopic eyes. SUBJECTS/METHODS: Linear regression, symbolic regression, gradient boosting and multilayer perceptron models were developed using age, sex, cycloplegic spherical equivalent refraction (SER) and corneal curvature. Training data were from 8135 (28% myopic) children and adolescents from Ireland, Northern Ireland and China. Model performance was tested on an additional 300 myopic individuals using traditional metrics alongside the estimated axial length vs age relationship. Linear regression and receiver operator characteristics (ROC) curves were used for statistical analysis. The contribution of the effective crystalline lens power to error in axial length estimation was calculated to define the latter's physiological limits. RESULTS: Axial length estimation models were applicable across all testing regions (p ≥ 0.96 for training by testing region interaction). The linear regression model performed best based on agreement metrics (mean absolute error [MAE] = 0.31 mm, coefficient of repeatability = 0.79 mm) and a smooth, monotonic estimated axial length vs age relationship. This model was better at identifying high-risk eyes (axial length >98th centile) than SER alone (area under the curve 0.89 vs 0.79, respectively). Without knowing lens power, the calculated limits of axial length estimation were 0.30 mm for MAE and 0.75 mm for coefficient of repeatability. CONCLUSIONS: In myopic eyes, we demonstrated superior axial length estimation with a linear regression model utilising age, sex and refractive metrics and showed its clinical utility as a risk stratification tool.

Short-term effects of cyclopentolate and tropicamide eye drops on macular choroidal thickness in myopic children.

BACKGROUND: To investigate the short-term effects of cyclopentolate and tropicamide eyedrops on choroidal thickness (ChT) in myopic children using placebo or low-dose atropine eyedrops. METHODS: The analysis included 242 myopic individuals (7-19 years) enrolled in two randomised placebo-controlled clinical trials of low-dose atropine eyedrops. Cycloplegia was induced using either one drop of 1% cyclopentolate (n = 161), two drops of 1% cyclopentolate (n = 32) or two drops of 1% tropicamide (n = 49). ChT measurements were taken using swept-source optical coherence tomography before and 30 min after administering the cycloplegic eye drops. A subset of 51 participants underwent test-retest measurements prior to cycloplegia. RESULTS: Mean changes in subfoveal ChT after two drops of tropicamide and one and two drops of cyclopentolate were -2.5 µm (p = 0.10), -4.3 µm (p < 0.001) and -9.6 µm (p < 0.001), respectively. Subfoveal ChT changes after one and two drops of cyclopentolate were significantly greater than the test-retest changes (test-retest mean change: -3.1 µm; p < 0.05), while the tropicamide group was not significantly different (p = 0.64). Choroidal thinning post-cyclopentolate was not significantly different between atropine and placebo treatment groups (p > 0.05 for all macular locations). The coefficient of repeatability (CoR) in the tropicamide group (range: 8.2-14.4 µm) was similar to test-retest (range: 7.5-12.2 µm), whereas greater CoR values were observed in the cyclopentolate groups (one drop: range: 10.8-15.3 µm; two drops: range: 12.2-24.6 µm). CONCLUSIONS: Cyclopentolate eye drops caused dose-dependent choroidal thinning and increased variation in pre- to post-cycloplegia measurements compared with test-retest variability, whereas tropicamide did not. These findings have practical implications for ChT measurements when cyclopentolate is used, particularly for successive measurements.

Myopia management algorithm. Annexe to the article titled Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.

Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in later life in the near future. Because myopia can cause serious complications and vision loss, it is critical to create and prescribe effective myopia treatment solutions that can help prevent or delay the onset and progression of myopia. The scientific understanding of myopia's causes, genetic background, environmental conditions, and various management techniques, including therapies to prevent or postpone its development and slow its progression, is rapidly expanding. However, some significant information gaps exist on this subject, making it difficult to develop an effective intervention plan. As with the creation of this present algorithm, a compromise is to work on best practices and reach consensus among a wide number of specialists. The quick rise in information regarding myopia management may be difficult for the busy eye care provider, but it necessitates a continuing need to evaluate new research and implement it into daily practice. To assist eye care providers in developing these strategies, an algorithm has been proposed that covers all aspects of myopia mitigation and management. The algorithm aims to provide practical assistance in choosing and developing an effective myopia management strategy tailored to the individual child. It incorporates the latest research findings and covers a wide range of modalities, from primary, secondary, and tertiary myopia prevention to interventions that reduce the progression of myopia.

Association between Global Myopia Prevalence and International Levels of Education.

SIGNIFICANCE: The Global Myopia Prevalence and International Levels of Education study models national trends in educational performance with myopia prevalence in children; it examines the association of near work with myopia in the form of an ecologic analysis and also discusses how this may relate to educational frameworks. PURPOSE: This study aimed to investigate the relationship between myopia prevalence and national educational performance. METHODS: The prevalence of myopia in the 15- to 19-year age group in 35 regions was obtained from a meta-analysis by Holden et al. (Ophthalmology 2016;123:1036-1042) and matched with educational performance quantified by the Organisation for Economic Cooperation and Development Programme for International Student Assessment (PISA) testing from 2000 to 2018. A generalized estimating equation was used to describe the relationship between PISA scores and myopia prevalence. Clustering effects of country and chronological year were accounted for in the analysis. Linear and nonlinear terms of PISA scores using lines of best fit were further explored. RESULTS: There is a significant positive relationship between Organisation for Economic Cooperation and Development PISA educational performance and myopia prevalence in teenagers with higher PISA scores correlating with higher myopia prevalence, even after accounting for chronological year (generalized estimating equation model: P = .001, .008, and .005 for math, science, and reading, respectively). Scatterplots with cubic and logistic fits indicated that PISA math showed the strongest relationship with myopia prevalence ( r2 = 0.64), followed by science ( r2 = 0.41) and reading ( r2 = 0.31). CONCLUSIONS: These results strongly suggest that educational achievement at a national level is associated with higher myopia prevalence. Programme for International Student Assessment scores are a significant driver of many countries' education policies, and countries that have a balance between high PISA scores and lower myopia prevalence may be good models of educational policies to address the myopia public health issue.

Outdoor Scene Classrooms to Arrest Myopia: Design and Baseline Characteristics.

PURPOSE: This study aimed to investigate the impact on childhood myopia of classrooms with spatial properties of classrooms resembling those of outdoor environments. This article describes the design, baseline characteristics, and the acceptability of this strategy. METHODS: Classrooms had custom-made wallpaper installed with forest and sky scenes that had spatial frequency spectra comparable with outdoor environments (i.e., outdoor scene classrooms). Acceptability of this strategy was evaluated by questionnaires. Outcomes to access the efficacy include cumulative proportion of myopia, change of cycloplegic spherical equivalent refractive error, and axial length. RESULTS: Ten classes, comprising 520 students, were randomly assigned into outdoor scene or tradition classrooms. There was no difference in refractive status between two groups (myopia/emmetropia/hyperopia, 16.3% vs. 49.4% vs. 34.2% in outdoor scene classrooms, 18.3% vs. 49.0% vs. 32.7% in traditional classrooms; P = .83). Compared with the traditional classrooms, 88.9% of teachers and 87.5% of students felt the outdoor scene classrooms enjoyable, 22.2% of teachers and 75.3% of students reported higher concentration, and 77.8% of teachers and 15.2% of students reported no change. In addition, 44.4% of teachers and 76.0% of students reported higher learning efficiency in the outdoor scene classrooms, and 55.6% of teachers and 18.3% of students reported no change. CONCLUSIONS: Outdoor scene classrooms are appealing to teachers and students. Outcomes of the study will inform the efficacy of this strategy in Chinese children.

The future of clinical trials of myopia control.

In the field of myopia control, effective optical or pharmaceutical therapies are now available to patients in many markets. This creates challenges for the conduct of placebo-controlled, randomised clinical trials, including ethics, recruitment, retention, selective loss of faster progressors and non-protocol treatments: Ethics: It is valid to question whether withholding treatment in control subjects is ethical. Recruitment: Availability of treatments is making recruitment into clinical trials more difficult. Retention: If masking is not possible, parents may immediately withdraw their child if randomised to no treatment. Selective loss: Withdrawal of fast progressors in the control group leading to a control group biased towards low progression. Non-protocol treatment: Parents may access other myopia treatments in addition to those within the trial. We propose that future trials may adopt one of the following designs: Non-inferiority trials using an approved drug or device as the control. The choice will depend on whether a regulatory agency has approved the drug or device. Short conventional efficacy trials where data are subsequently entered into a model created from previous clinical trials, which allows robust prediction of long-term treatment efficacy from the initial efficacy. Virtual control group trials based on data relating to axial elongation, myopia progression or both, accounting for subject's age and race. Short-term control data from a cohort, for example, 1 year or less, and applying an appropriate, proportional annual reduction in axial elongation to that population and extrapolating to subsequent years. Time-to-treatment-failure trials using survival analysis; once a treated or control subject progresses or elongates by a given amount, they exit the study and can be offered treatment. In summary, the future development of new treatments in myopia control will be hampered if significant changes are not made to the design of clinical trials in this area.

Choroidal Thickness Profiles and Associated Factors in Myopic Children.

SIGNIFICANCE: This study addresses the lack of choroidal thickness (ChT) profile information available in European children and provides a baseline for further evaluation of longitudinal changes in ChT profiles in myopic children as a potential biomarker for myopia treatment and identifying children at risk of myopic progression. PURPOSE: This study aimed to investigate ChT profiles and associated factors in myopic children. METHODS: Baseline data of 250 myopic children aged 6 to 16 years in the Myopia Outcome Study of Atropine in Children clinical trial were analyzed. Choroidal thickness images were obtained using swept-source optical coherence tomography (DRI-OCT Triton Plus; Topcon Corporation, Tokyo, Japan). The macula was divided into nine Early Treatment of Diabetic Retinopathy Study locations with diameters of 1, 3, and 6 mm corresponding to the central fovea, parafoveal, and perifoveal regions. Multiple linear regression models were used to investigate determinants of ChT. RESULTS: Choroidal thickness varied across the macular Early Treatment of Diabetic Retinopathy Study locations ( P < .001): thickest in the perifoveal superior region (mean ± standard deviation, 249.0 ± 60.8 µm) and thinnest in the perifoveal nasal region (155.1 ± 50.3 µm). On average, ChT was greater in all parafoveal (231.8 ± 57.8 µm) compared with perifoveal (218.1 ± 49.1 µm) regions except superiorly where the ChT was greater in the perifoveal region. Longer axial length and higher myopic spherical equivalent refraction were consistently associated with thinner ChT at all locations in the multiple linear regression models. Asian race was significantly associated with thinner ChT only at parafoveal and perifoveal superior regions after Bonferroni correction ( P = .004 and P = .001, respectively). CONCLUSIONS: Choroidal thickness was thinnest in the nasal macular region and varied systematically across all macular locations, with axial length and spherical equivalent refraction being the strongest determinants of ChT. Longitudinal evidence will need to evaluate whether any differences in ChT profiles are predictive of myopic progression and to determine the role of ChT measurements in identifying myopic children most in need of myopia control treatment.

Prescribing patterns of myopia control contact lenses among optometrists in Ireland.

PURPOSE: This retrospective analysis of electronic medical record (EMR) data investigated the prescribing patterns of soft myopia control contact lens (MCCL) treatments since their introduction in Ireland in 2017. METHODS: Anonymised EMR data were sourced from 33 optometry practices in Ireland from 2017 to 2021 to determine the number of practices prescribing MCCLs to myopic children 5-18 years old. In MCCL-prescribing practices, the proportion of contact lens wearing children fitted with MCCLs and the proportion of progressive (≤-0.25 D/year) myopic children fitted with MCCLs were determined. Logistic regression was used to determine which factors influenced the likelihood of being prescribed a MCCL. RESULTS: Overall, just 10 practices were found to prescribe MCCLs of any type. The Coopervision MiSight contact lens was used in 85% of all MCCL fittings with most other fits being off-label multifocals. The use of MCCLs rose from 3% of contact lens fits in 2017 to 27% in 2021. Children fitted with MCCLs were on average younger (12.2 ± 2.3 years vs. 15.4 ± 2.1 years) but more myopic (-3.46 ± 1.84 D vs. -3.03 ± 1.69 D) than those fitted with standard contact lenses. The most predictive factors for being fitted with MCCLs were year of examination (OR: 2.54, 95% CI: 2.13, 3.03), younger age (OR: 1.52, 95% CI: 1.39, 1.64) and greater myopia (OR: 1.25, 95% CI: 1.11, 1.39). CONCLUSION: Clinician engagement in myopia management has increased in Ireland since the formal introduction of MCCLs, but more than two-thirds of practices included are yet to offer this form of myopia management. The proportion of children with progressive myopia that has been prescribed MCCLs has increased, but the majority of children are still managed for vision correction only. There is significant scope for improving the uptake of evidence-based myopia control treatments and for optimising the age and degree of myopia at which such interventions are initiated.

Using electronic medical record data to establish and monitor the distribution of refractive errors.

OBJECTIVE: To establish the baseline distribution of refractive errors and associated factors amongst a population that attended primary care optometry clinics. DESIGN: Retrospective cross sectional cohort study of electronic medical records (EMR). METHODS: Electronic medical record data was extracted from forty optometry clinics, representing a mix of urban and rural areas in Ireland. The analysis was confined to demographic and clinical data gathered over a sixty-month period between 2015 and 2019. Distribution rates were calculated using the absolute and relative frequencies of refractive error in the dataset, stratified for age and gender using the following definitions: high myopia ≤ -6.00 D, myopia ≤ -0.50 D, hyperopia ≥ +0.50 D, astigmatism ≤ -0.75 DC and anisometropia ≥ 1.00 D. Visual acuity data was used to explore vision impairment rates in the population. Further analysis was carried out on a gender and age-adjusted subset of the EMR data, to match the proportion of patients in each age grouping to the population distribution in the most recent (2016) Irish census. RESULTS: 153,598 clinic records were eligible for analysis. Refractive errors ranged from -26.00 to +18.50 D. Myopia was present in 32.7%, of which high myopia represented 2.4%, hyperopia in 40.1%, astigmatism in 38.3% and anisometropia in 13.4% of participants. The clinic distribution of hyperopia, astigmatism and anisometropia peaked in older age groups, whilst the myopia burden was highest amongst people in their twenties. A higher proportion of females were myopic, whilst a higher proportion of males were hyperopic and astigmatic. Vision impairment (LogMAR > 0.3) was present in 2.4% of participants. In the gender and age- adjusted distribution model, myopia was the most common refractive state, affecting 38.8% of patients. CONCLUSION: Although EMR data is not representative of the population as a whole, it is likely to provide a reasonable representation of the distribution of clinically significant (symptomatic) refractive errors. In the absence of any ongoing traditional epidemiological studies of refractive error in Ireland, this study establishes, for the first time, the distribution of refractive errors observed in clinical practice settings. This will serve as a baseline for future temporal trend analysis of the changing pattern of the distribution of refractive error in EMR data. This methodology could be deployed as a useful epidemiological resource in similar settings where primary eyecare coverage for the management of refractive error is well established.

Low-concentration atropine eyedrops for myopia control in a multi-racial cohort of Australian children: A randomised clinical trial.

BACKGROUND: To test the hypothesis that 0.01% atropine eyedrops are a safe and effective myopia-control approach in Australian children. METHODS: Children (6-16 years; 49% Europeans, 18% East Asian, 22% South Asian, and 12% other/mixed ancestry) with documented myopia progression were enrolled into this single-centre randomised, parallel, double-masked, placebo-controlled trial and randomised to receive 0.01% atropine (n = 104) or placebo (n = 49) eyedrops (2:1 ratio) instilled nightly over 24 months (mean index age = 12.2 ± 2.5 and 11.2 ± 2.8 years, respectively). Outcome measures were the changes in spherical equivalent (SE) and axial length (AL) from baseline. RESULTS: At 12 months, the mean SE and AL change from baseline were -0.31D (95% confidence interval [CI] = -0.39 to -0.22) and 0.16 mm (95%CI = 0.13-0.20) in the atropine group and -0.53D (95%CI = -0.66 to -0.40) and 0.25 mm (95%CI = 0.20-0.30) in the placebo group (group difference p ≤ 0.01). At 24 months, the mean SE and AL change from baseline was -0.64D (95%CI = -0.73 to -0.56) and 0.34 mm (95%CI = 0.30-0.37) in the atropine group, and -0.78D (95%CI = -0.91 to -0.65) and 0.38 mm (95%CI = 0.33-0.43) in the placebo group. Group difference at 24 months was not statistically significant (p = 0.10). At 24 months, the atropine group had reduced accommodative amplitude and pupillary light response compared to the placebo group. CONCLUSIONS: In Australian children, 0.01% atropine eyedrops were safe, well-tolerated, and had a modest myopia-control effect, although there was an apparent decrease in efficacy between 18 and 24 months, which is likely driven by a higher dropout rate in the placebo group.

Regional variations and temporal trends of childhood myopia prevalence in Africa: A systematic review and meta-analysis.

PURPOSE: To provide contemporary and future estimates of childhood myopia prevalence in Africa. METHODS: A systematic online literature search was conducted for articles on childhood (≤18 years) myopia (spherical equivalent [SE] ≤ -0.50D; high myopia: SE ≤ -6.00D) in Africa. Population- or school-based cross-sectional studies published from 1 Jan 2000 to 30 May 2021 were included. Meta-analysis using Freeman-Tukey double arcsine transformation was performed to estimate the prevalence of childhood myopia and high myopia. Myopia prevalence from subgroup analyses for age groups and settings were used as baseline for generating a prediction model using linear regression. RESULTS: Forty-two studies from 19 (of 54) African countries were included in the meta-analysis (N = 737,859). Overall prevalence of childhood myopia and high myopia were 4.7% (95% CI: 3.3%-6.5%) and 0.6% (95% CI: 0.2%-1.1%), respectively. Estimated prevalence across the African regions was highest in the North (6.8% [95% CI: 4.0%-10.2%]), followed by Southern (6.3% [95% CI: 3.9%-9.1%]), East (4.7% [95% CI: 3.1%-6.7%]) and West (3.5% [95% CI: 1.9%-6.3%]) Africa. Prevalence from 2011 to 2021 was approximately double that from 2000 to 2010 for all studies combined, and between 1.5 and 2.5 times higher for ages 5-11 and 12-18 years, for boys and girls and for urban and rural settings, separately. Childhood myopia prevalence is projected to increase in urban settings and older children to 11.1% and 10.8% by 2030, 14.4% and 14.1% by 2040 and 17.7% and 17.4% by 2050, respectively; marginally higher than projected in the overall population (16.4% by 2050). CONCLUSIONS: Childhood myopia prevalence has approximately doubled since 2010, with a further threefold increase predicted by 2050. Given this trajectory and the specific public health challenges in Africa, it is imperative to implement basic myopia prevention programmes, enhance spectacle coverage and ophthalmic services and generate more data to understand the changing myopia epidemiology to mitigate the expanding risk of the African population.

Will treating progressive myopia overwhelm the eye care workforce? A workforce modelling study.

PURPOSE: Treatments for myopia progression are now available, but implementing these into clinical practice will place a burden on the eye care workforce. This study estimated the full-time equivalent (FTE) workforce required to implement myopia control treatments in the UK and Ireland. METHODS: To estimate the number of 6- to 21-year-olds with myopia, two models utilising separate data sources were developed. The examination-based model used: (1) the number of primary care eye examinations conducted annually and (2) the proportion of these that are for myopic young people. The prevalence-based model used epidemiological data on the age-specific prevalence of myopia. The proportion of myopic young people progressing ≥0.25 dioptres (D)/year or ≥0.50 D/year was obtained from Irish electronic health records and the recommended review schedule from clinical management guidelines. RESULTS: Using the examination and prevalence models, respectively, the estimated number of young people with myopia was 2,469,943 and 2,235,713. The extra workforce required to provide comprehensive myopia management for this target population was estimated at 226-317 FTE at the 0.50 D/year threshold and 433-630 FTE at the 0.25 D/year threshold. Extra visits required for myopia control treatment represented approximately 2.6% of current primary eye care examinations versus 13.6% of hospital examinations. CONCLUSIONS: Implementing new myopia control treatments in primary care settings over the medium-term is unlikely to overwhelm the eye care workforce completely. Further increases to workforce, upskilling of current workforce and tools to reduce chair time will help to ensure sustainability of the eye care workforce into the future.

Is myopia prevalence related to outdoor green space?

PURPOSE: Rapid urbanisation and lifestyle changes have been associated with a huge increase in myopia across many parts of the world. There is strong evidence that environmental factors including time outdoors and urbanisation can influence the development of myopia, particularly in school-aged children. The aim of this study is to determine whether there is a relationship between the prevalence of myopia and the amount of vegetation/green spaces across different regions of the world, as a risk factor for myopia development. METHODS: The prevalence of myopia in the 15 to 19-year age group in Australia, Brazil, China, Finland, India, Iran, Japan, Oman, Singapore, South Africa and the UK was obtained from a meta-analysis by Holden et al. Normalised Difference Vegetation Index (NDVI) was used to quantify green space exposure based on Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite data. Green space was measured in locations specific to 15 studies that reported myopia prevalence. Simple linear regression was used to analyse yearly data, and a mixed effects model was applied to assess the significance of green space when study was a random effect. RESULTS: Myopia prevalence increases significantly when green space was <-0.2, but the effect was less apparent for values >-0.1. When a mixed effects model was used, the effect of green space was found to be significantly associated with myopia prevalence (p = 0.05). CONCLUSIONS: There was evidence of a weak but significant non-linear relationship between myopia and green space, with the effect most apparent at low levels of green space. A larger data sample, along with further investigations into the utilisation of green spaces, are required to understand whether increasing the amount of green space can reduce myopia incidence and progression impact.

Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.

The prevalence of myopia is increasing extensively worldwide. The number of people with myopia in 2020 is predicted to be 2.6 billion globally, which is expected to rise up to 4.9 billion by 2050, unless preventive actions and interventions are taken. The number of individuals with high myopia is also increasing substantially and pathological myopia is predicted to become the most common cause of irreversible vision impairment and blindness worldwide and also in Europe. These prevalence estimates indicate the importance of reducing the burden of myopia by means of myopia control interventions to prevent myopia onset and to slow down myopia progression. Due to the urgency of the situation, the European Society of Ophthalmology decided to publish this update of the current information and guidance on management of myopia. The pathogenesis and genetics of myopia are also summarized and epidemiology, risk factors, preventive and treatment options are discussed in details.

Smartphone use as a possible risk factor for myopia.

CLINICAL RELEVANCE: This study demonstrates an association between myopia and smartphone data usage. Youths now spend more time participating in near tasks as a result of smartphone usage. This poses an additional risk factor for myopia development/progression and is an important research question in relation to potential myopia management strategies. BACKGROUND: Children are now exposed to another possible environmental risk factor for myopia - smartphones. This study investigates the amount of time students spend on their smartphones and their patterns of smartphone usage from a myopia perspective. METHODS: Primary, secondary and tertiary level students completed a questionnaire exploring patterns of smartphone usage and assessing their attitudes toward potential myopia risk factors. Device-recorded data usage over an extended period was quantified as the primary and objective indicator of phone use. Average daily time spent using a smartphone was also quantified by self-reported estimates. Refractive status was verified by an optometrist. RESULTS: Smartphone ownership among the 418 students invited to participate was over 99-per cent. Average daily smartphone data and time usage was 800.37 ± 1,299.88-MB and 265.16 ± 168.02-minutes respectively. Myopic students used almost double the amount of smartphone data at 1,130.71 ± 1,748.14-MB per day compared to non-myopes at 613.63 ± 902.15-MB (p = 0.001). Smartphone time usage was not significantly different (p = 0.09, 12-per cent higher among myopes). Multinomial logistic regression revealed that myopic refractive error was statistically significantly associated with increasing daily smartphone data usage (odds ratio 1.08, 95% CI 1.03-1.14) as well as increasing age (odds ratio 1.09, 95% CI 1.02-1.17) and number of myopic parents (odds ratio 1.55, 95% CI 1.06-2.3). Seventy-three per cent of students believed that digital technology may adversely affect their eyes. CONCLUSION: This study demonstrates an association between myopia and smartphone data usage. Given the serious nature of the ocular health risks associated with myopia, our findings indicate that this relationship merits more detailed investigation.

The Spatial Frequency Content of Urban and Indoor Environments as a Potential Risk Factor for Myopia Development.

Purpose: To examine the hypothesis that the spatial frequency spectra of urban and indoor environments differ from the natural environment in ways that may promote the development of myopia. Methods: A total of 814 images were analyzed from three datasets; University of California Berkeley (UCB), University of Texas (UT), and Botswana (UPenn). Images were processed in Matlab (Mathworks Inc) to map the camera color characteristics to human cone sensitivities. From the photopic luminance images generated, two-dimensional spatial frequency (SF) spectra were calculated and converted to one-dimensional spectra by rotational averaging. The spatial filtering profile of a 0.4 Bangerter foil, which has been shown to induce myopia experimentally, was also determined. Results: The SF slope for natural scenes followed the recognized 1/fα relationship with mean slopes of -1.08, -0.90, and -1.04 for the UCB, UT and UPenn image sets, respectively. Indoor scenes had a significantly steeper slope (-1.48, UCB; -1.52, UT; P < 0.0001). Urban environments showed an intermediate slope (-1.29, UCB; -1.22, UT) that was significantly different from the slopes derived from the natural scenes (P < 0.0001). The change in SF content between natural outdoor scenes and indoors was comparable to that induced by a 0.4 Bangerter foil, which reduced the SF slope of a natural scene from -0.88 to -1.47. Conclusions: Compared to natural outdoor images, man-made outdoor and indoor environments have spatial frequency characteristics similar to those known to induce form-deprivation myopia in animal models. The spatial properties of the man-made environment may be one of the missing drivers of the human myopia epidemic.

IMI - Myopia Control Reports Overview and Introduction.

With the growing prevalence of myopia, already at epidemic levels in some countries, there is an urgent need for new management approaches. However, with the increasing number of research publications on the topic of myopia control, there is also a clear necessity for agreement and guidance on key issues, including on how myopia should be defined and how interventions, validated by well-conducted clinical trials, should be appropriately and ethically applied. The International Myopia Institute (IMI) reports the critical review and synthesis of the research evidence to date, from animal models, genetics, clinical studies, and randomized controlled trials, by more than 85 multidisciplinary experts in the field, as the basis for the recommendations contained therein. As background to the need for myopia control, the risk factors for myopia onset and progression are reviewed. The seven generated reports are summarized: (1) Defining and Classifying Myopia, (2) Experimental Models of Emmetropization and Myopia, (3) Myopia Genetics, (4) Interventions for Myopia Onset and Progression, (5) Clinical Myopia Control Trials and Instrumentation, (6) Industry Guidelines and Ethical Considerations for Myopia Control, and (7) Clinical Myopia Management Guidelines.

IMI - Defining and Classifying Myopia: A Proposed Set of Standards for Clinical and Epidemiologic Studies.

Purpose: We provide a standardized set of terminology, definitions, and thresholds of myopia and its main ocular complications. Methods: Critical review of current terminology and choice of myopia thresholds was done to ensure that the proposed standards are appropriate for clinical research purposes, relevant to the underlying biology of myopia, acceptable to researchers in the field, and useful for developing health policy. Results: We recommend that the many descriptive terms of myopia be consolidated into the following descriptive categories: myopia, secondary myopia, axial myopia, and refractive myopia. To provide a framework for research into myopia prevention, the condition of "pre-myopia" is defined. As a quantitative trait, we recommend that myopia be divided into myopia (i.e., all myopia), low myopia, and high myopia. The current consensus threshold value for myopia is a spherical equivalent refractive error ≤ -0.50 diopters (D), but this carries significant risks of classification bias. The current consensus threshold value for high myopia is a spherical equivalent refractive error ≤ -6.00 D. "Pathologic myopia" is proposed as the categorical term for the adverse, structural complications of myopia. A clinical classification is proposed to encompass the scope of such structural complications. Conclusions: Standardized definitions and consistent choice of thresholds are essential elements of evidence-based medicine. It is hoped that these proposals, or derivations from them, will facilitate rigorous, evidence-based approaches to the study and management of myopia.