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.

Eye Size and Shape in Relation to Refractive Error in Children: A Magnetic Resonance Imaging Study.

Purpose: The purpose of this study was to determine the association between eye shape and volume measured with magnetic resonance imaging (MRI) and optical biometry and with spherical equivalent (SE) in children. Methods: For this study, there were 3637 10-year-old children from a population-based birth-cohort study that underwent optical biometry (IOL-master 500) and T2-weighted MRI scanning (height, width, and volume). Cycloplegic refractive error was determined by automated refraction. The MRI images of the eyes were segmented using an automated algorithm combining atlas registration with voxel classification. Associations among optical biometry, anthropometry, MRI measurements, and RE were tested using Pearson correlation. Differences between refractive error groups were tested using ANOVA. Results: The mean volume of the posterior segment was 6350 (±680) mm3. Myopic eyes (SE ≤ -0.5 diopters [D]) had 470 mm3 (P < 0.001) and 970 mm3 (P < 0.001) larger posterior segment volume than emmetropic and hyperopic eyes (SE ≥ +2.0D), respectively. The majority of eyes (77.1%) had an oblate shape, but 47.4% of myopic eyes had a prolate shape versus 3.9% of hyperopic eyes. The correlation between SE and MRI-derived posterior segment length (r -0.51, P < 0.001) was stronger than the correlation with height (r -0.30, P < 0.001) or width of the eye (r -0.10, P < 0.001). Conclusions: In this study, eye shape at 10 years of age was predominantly oblate, even in eyes with myopia. Of all MRI measurements, posterior segment length was most prominently associated with SE. Whether eye shape predicts future myopia development or progression should be investigated in longitudinal studies.

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.

Myopia control in Mendelian forms of myopia.

PURPOSE: To study the effectiveness of high-dose atropine for reducing eye growth in Mendelian myopia in children and mice. METHODS: We studied the effect of high-dose atropine in children with progressive myopia with and without a monogenetic cause. Children were matched for age and axial length (AL) in their first year of treatment. We considered annual AL progression rate as the outcome and compared rates with percentile charts of an untreated general population. We treated C57BL/6J mice featuring the myopic phenotype of Donnai-Barrow syndrome by selective inactivation of Lrp2 knock out (KO) and control mice (CTRL) daily with 1% atropine in the left eye and saline in the right eye, from postnatal days 30-56. Ocular biometry was measured using spectral-domain optical coherence tomography. Retinal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured using high-performance liquid chromatography. RESULTS: Children with a Mendelian form of myopia had average baseline spherical equivalent (SE) -7.6 ± 2.5D and AL 25.8 ± 0.3 mm; children with non-Mendelian myopia had average SE -7.3 ± 2.9 D and AL 25.6 ± 0.9 mm. During atropine treatment, the annual AL progression rate was 0.37 ± 0.08 and 0.39 ± 0.05 mm in the Mendelian myopes and non-Mendelian myopes, respectively. Compared with progression rates of untreated general population (0.47 mm/year), atropine reduced AL progression with 27% in Mendelian myopes and 23% in non-Mendelian myopes. Atropine significantly reduced AL growth in both KO and CTRL mice (male, KO: -40 ± 15; CTRL: -42 ± 10; female, KO: -53 ± 15; CTRL: -62 ± 3 µm). The DA and DOPAC levels 2 and 24 h after atropine treatment were slightly, albeit non-significantly, elevated. CONCLUSIONS: High-dose atropine had the same effect on AL in high myopic children with and without a known monogenetic cause. In mice featuring a severe form of Mendelian myopia, atropine reduced AL progression. This suggests that atropine can reduce myopia progression even in the presence of a strong monogenic driver.

Myopia risk behaviour related to the COVID-19 lockdown in Europe: The generation R study.

PURPOSE: To battle the spreading of the COVID-19 virus, nationwide lockdowns were implemented during 2020 and 2021. Reports from China revealed that their strict home confinements led to an increase in myopia incidence. The Netherlands implemented a more lenient lockdown, which allowed children to go outside. We evaluated the association between COVID-19 restrictions, myopia risk behaviour and myopia progression in Dutch teenagers. METHOD: A total of 1101 participants (mean age 16.3 ± 3.65 yrs) completed questionnaires about their activities before, during and after lockdown (March-October 2020). We used a repeated-measures ANOVA to compare time use between these time periods. Ocular measurements were acquired before the COVID-19 pandemic when participants were 13 years old; only 242 participants had ocular measurements at 18 years of age at the time of this analysis. Linear regression analyses were used to evaluate the association between lifestyle factors and myopia progression. RESULTS: Children were on average 16.2 (1.03) years of age during lockdown. Total nearwork increased from 8.11 h/day to 11.79 h/day, and remained higher after lockdown at 9.46 h/day (p < 0.001). Non-educational nearwork increased by 2.22 h/day (+49%) during lockdown and was associated with faster axial length progression (B 0.002 mm/h/year; SE 0.001 p = 0.03). Before and during lockdown, the mean time spent outdoors was similar (1.78 h/day and 1.80 h/day, respectively). After lockdown, time spent outdoors decreased to 1.56 h/day (p < 0.001). CONCLUSION: The Dutch lockdown significantly increased digitised nearwork in adolescents but did not affect outdoor exposure. The changes in time spent performing nearwork remained after the lockdown measures had ended. We expect that the COVID-19 pandemic may lead to an increase in myopia prevalence and progression in European children.

Whole exome sequencing of known eye genes reveals genetic causes for high myopia.

High myopia [refractive error ≤ -6 diopters (D)] is a heterogeneous condition, and without clear accompanying features, it can be difficult to pinpoint a genetic cause. This observational study aimed to evaluate the utility of whole exome sequencing (WES) using an eye disorder gene panel in European patients with high myopia. Patients with high myopia were recruited by ophthalmologists and clinical geneticists. Clinical features were categorized into isolated high myopia, high myopia with other ocular involvement or with systemic involvement. WES was performed and an eye disorder gene panel of ~500 genes was evaluated. Hundred and thirteen patients with high myopia [mean (SD) refractive error - 11.8D (5.2)] were included. Of these, 53% were children younger than 12 years of age (53%), 13.3% were aged 12-18 years and 34% were adults (aged > 18 years). Twenty-three out of 113 patients (20%) received a genetic diagnosis of which 11 patients displayed additional ocular or systemic involvement. Pathogenic variants were identified in retinal dystrophy genes (e.g. GUCY2D and CACNA1F), connective tissue disease genes (e.g. COL18A1 and COL2A1), non-syndromic high myopia genes (ARR3), ocular development genes (e.g. PAX6) and other genes (ASPH and CNNM4). In 20% of our high myopic study population, WES using an eye gene panel enabled us to diagnose the genetic cause for this disorder. Eye genes known to cause retinal dystrophy, developmental or syndromic disorders can cause high myopia without apparent clinical features of other pathology.

Myopia progression from wearing first glasses to adult age: the DREAM Study.

PURPOSE: Data on myopia progression during its entire course are scarce. The aim of this study is to investigate myopia progression in Europeans as a function of age and degree of myopia from first prescription to final refractive error. METHODS: The Drentse Refractive Error and Myopia Study assessed data from a branch of opticians in the Netherlands from 1985 onwards in a retrospective study. First pair of glasses prescribed was defined as a spherical equivalent of refraction (SER) ≤-0.5 D to ≥-3.0 D. Subjects with prescriptions at an interval of at least 1 year were included in the analysis. RESULTS: A total of 2555 persons (57.3% female) met the inclusion criteria. Those with first prescription before the age of 10 years showed the strongest progression (-0.50 D; IQR: -0.75 to -0.19) and a significantly (p<0.001) more negative median final SER (-4.48 D; IQR: -5.37 to -3.42). All children who developed SER ≤-3 D at 10 years were highly myopic (SER ≤-6D) as adults, children who had SER between -1.5 D and -3 D at 10 years had 46.0% risk of high myopia, and children with SER between -0.5 D and -1.5 D had 32.6% risk of high myopia. Myopia progression diminished with age; all refractive categories stabilised after age 15 years except for SER ≤-5 D who progressed up to -0.25 D annually until age 21 years. CONCLUSION: Our trajectories of the natural course of myopia progression may serve as a guide for myopia management in European children. SER at 10 years is an important prognostic indicator and will help determine treatment intensity.

Physical Activity Spaces Not Effective against Socioeconomic Inequalities in Myopia Incidence: The Generation R Study.

SIGNIFICANCE: Our findings show that non-Dutch background, lower maternal education, and lower net household income level may be new risk factors for myopia development in the Netherlands. Newly introduced physical activity spaces may not be effective enough in increasing outdoor exposure in children to reduce eye growth. PURPOSE: The aims of this study were to evaluate socioeconomic inequalities in myopia incidence, eye growth, outdoor exposure, and computer use and to investigate if newly introduced physical activity spaces can reduce eye growth in school-aged children. METHODS: Participants (N = 2643) from the Dutch population-based birth cohort Generation R were examined at ages 6 and 9 years. Socioeconomic inequalities in myopia incidence, eye growth, and lifestyle were determined using regression analyses. Information on physical activity spaces located in Rotterdam was obtained. Differences in eye growth between those who became exposed to new physical activity spaces (n = 230) and those nonexposed (n = 1866) were evaluated with individual-level fixed-effects models. RESULTS: Myopia prevalence was 2.2% at age 6 years and 12.2% at age 9 years. Outdoor exposure was 11.4 h/wk at age 6 years and 7.4 h/wk at age 9 years. Computer use was 2.1 h/wk at age 6 years and 5.2 h/wk at age 9 years. Myopia incidence was higher in children with non-Dutch background, and families with lower household income and lower maternal education (odds ratio [OR], 1.081 [95% confidence interval, 1.052 to 1.112]; OR, 1.035 [95% confidence interval, 1.008 to 1.063]; OR, 1.028 [95% confidence interval, 1.001 to 1.055], respectively). Children living <600 m of a physical activity space did not have increased outdoor exposure, except those from families with lower maternal education (ß = 1.33 h/wk; 95% confidence interval, 0.15 to 2.51 h/wk). Newly introduced physical activity spaces were not associated with reduction of eye growth. CONCLUSIONS: Children from socioeconomically disadvantaged families became more often myopic than those from socioeconomically advantaged families. We did not find evidence that physical activity spaces protect against myopia for the population at large, but subgroups may benefit.

Smartphone Use Associated with Refractive Error in Teenagers: The Myopia App Study.

PURPOSE: To investigate the association between smartphone use and refractive error in teenagers using the Myopia app. DESIGN: Cross-sectional population-based study. PARTICIPANTS: A total of 525 teenagers 12 to 16 years of age from 6 secondary schools and from the birth cohort study Generation R participated. METHODS: A smartphone application (Myopia app; Innovattic) was designed to measure smartphone use and face-to-screen distance objectively and to pose questions about outdoor exposure. Participants underwent cycloplegic refractive error and ocular biometry measurements. Mean daily smartphone use was calculated in hours per day and continuous use as the number of episodes of 20 minutes on screen without breaks. Linear mixed models were conducted with smartphone use, continuous use, and face-to-screen distance as determinants and spherical equivalent of refraction (SER) and axial length-to-corneal radius (AL:CR) ratio as outcome measures stratified by median outdoor exposure. MAIN OUTCOME MEASURES: Spherical equivalent of refraction in diopters and AL:CR ratio. RESULTS: The teenagers on average were 13.7 ± 0.85 years of age, and myopia prevalence was 18.9%. During school days, total smartphone use on average was 3.71 ± 1.70 hours/day and was associated only borderline significantly with AL:CR ratio (ß = 0.008; 95% confidence interval [CI], -0.001 to 0.017) and not with SER. Continuous use on average was 6.42 ± 4.36 episodes of 20-minute use without breaks per day and was associated significantly with SER and AL:CR ratio (ß = -0.07 [95% CI, -0.13 to -0.01] and ß = 0.004 [95% CI, 0.001-0.008], respectively). When stratifying for outdoor exposure, continuous use remained significant only for teenagers with low exposure (ß = -0.10 [95% CI, -0.20 to -0.01] and ß = 0.007 [95% CI, 0.001-0.013] for SER and AL:CR ratio, respectively). Smartphone use during weekends was not associated significantly with SER and AL:CR ratio, nor was face-to-screen distance. CONCLUSIONS: Dutch teenagers spent almost 4 hours per day on their smartphones. Episodes of 20 minutes of continuous use were associated with more myopic refractive errors, particularly in those with low outdoor exposure. This study suggested that frequent breaks should become a recommendation for smartphone use in teenagers. Future large longitudinal studies will allow more detailed information on safe screen use in youth.

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.

Randomized Controlled Trial of a Spectacle Lens for Macular Degeneration.

SIGNIFICANCE: E-Scoop, a spectacle lens, provides no clinically relevant improvements on quality of life, visual acuity, and contrast sensitivity for patients with AMD. Because patients' burden is high and therapeutic options are scarce, the incentive to develop effective vision rehabilitation interventions remains. PURPOSE: Patients with AMD experience low quality of life due to vision loss, despite angiogenesis inhibitor interventions that slow down progression for some patients. E-Scoop, which includes low-power prisms, 6% magnification, yellow tint, and antireflection coating, might aid in daily activities by improving distance viewing. Separately, these features have little proven effectiveness. E-Scoop has not been formally tested. This study aimed to determine the impact of E-Scoop on quality of life and the effect on visual acuity and contrast sensitivity. METHODS: In this randomized controlled, open-label trial, 190 of 226 eligible patients were included. The primary outcome was quality of life measured with the 25-item National Eye Institute Visual Function Questionnaire. Secondary outcomes were visual acuity and contrast sensitivity. The follow-up for quality of life was after 6 weeks for controls and after 3 weeks of use for E-Scoop wearers. The visual measures were repeated after 6 weeks, with optimal refractive correction, with and without E-Scoop. RESULTS: Randomization resulted in 99 E-Scoop and 86 control group patients for intention-to-treat analysis. No differential change was found between the E-Scoop and control groups on the 25-item National Eye Institute Visual Function Questionnaire using Rasch analysis (Cohen d = -0.07, P = .53). Statistically significant but small effects were found in favor of E-Scoop on binocular visual acuity (mean difference, 0.05 logMAR [2.5 letters, P < .001]) and contrast sensitivity (mean difference, 0.10 logCS [2 letters, P < .001]). CONCLUSIONS: No effect of E-Scoop on quality of life was found. E-Scoop showed effects that were statistically significant, although not clinically meaningful and within typical variability, on visual measures.

A 3-year follow-up study of atropine treatment for progressive myopia in Europeans.

BACKGROUND: Atropine is the most powerful treatment for progressive myopia in childhood. This study explores the 3-year effectiveness of atropine in a clinical setting. METHODS: In this prospective clinical effectiveness study, children with progressive myopia ≥ 1D/year or myopia ≤ -2.5D were prescribed atropine 0.5%. Examination, including cycloplegic refraction and axial length (AL), was performed at baseline, and follow-up. Outcome measures were spherical equivalent (SER) and AL; annual progression of SER on treatment was compared with that prior to treatment. Adjustments to the dose were made after 1 year in case of low (AL ≥ 0.3 mm/year) or high response (AL < 0.1 mm/year) of AL. RESULTS: A total of 124 patients were enrolled in the study (median age: 9.5, range: 5-16 years). At baseline, median SER was -5.03D (interquartile range (IQR): 3.08); median AL was 25.14 mm (IQR: 1.30). N = 89 (71.8%) children were persistent to therapy throughout the 3-year follow-up. Median annual progression of SER for these children was -0.25D (IQR: 0.44); of AL 0.11 mm (IQR: 0.18). Of these, N = 32 (36.0%) had insufficient response and were assigned to atropine 1%; N = 26 (29.2%) showed good response and underwent tapering in dose. Rebound of AL progression was not observed. Of the children who ceased therapy, N = 9 were lost to follow-up; N = 9 developed an allergic reaction; and N = 17 (19.1%) stopped due to adverse events. CONCLUSION: In children with or at risk of developing high myopia, a starting dose of atropine 0.5% was associated with decreased progression in European children during a 3-year treatment regimen. Our study supports high-dose atropine as a treatment option for children at risk of developing high myopia in adulthood.

Myopia management in the Netherlands.

PURPOSE: A trend that myopia is becoming gradually more common is shown in studies worldwide. Highest frequencies have been found in East Asian urban populations (96.5%) but also a study in Europe shows that nearly half of the 25-29 year olds has myopia. With the increase in prevalence, high myopia, i.e. a spherical equivalent of -6 or more and an axial length of 26 mm or more is also on the rise. High myopia particularly carries a significant risk of ocular pathology related to the long axial length. This highlights the need for myopia management in children with progressive myopia, in particular progression to high myopia. RECENT FINDINGS: During the last decade, many intervention studies for myopia progression have emerged. Although lifestyle adjustments are effective, pharmacological and optical interventions have shown the highest efficacy on reduction of eye growth. High concentration atropine (0.5%-1.0%) shows the most reduction in axial length progression, but has drawbacks of light sensitivity and loss of accommodation. Nevertheless, when these side effects are mitigated by multifocal photochromatic glasses, the long-term adherence to high dose atropine is high. Lower concentrations of atropine are less effective, but have less side effects. Studies on optical interventions have reported reduction of progression for Ortho-K and multifocal contact lenses, but are in need for replication in larger studies with longer duration. SUMMARY: The field of myopia management is rapidly evolving, and a position on the best approach for daily clinics is desirable. Over the last 10 years, our team of clinical researchers has developed a strategy which involves decision-making based on age, axial length, position on the axial length growth chart, progression rate, risk of high myopia, risk profile based on lifestyle and familial risk, side effects, and individual preference. This personalised approach ensures the most optimal long-term myopia control, and helps fight against visual impairment and blindness in the next generations of elderly.

Evidence That Emmetropization Buffers Against Both Genetic and Environmental Risk Factors for Myopia.

Purpose: To test the hypothesis that emmetropization buffers against genetic and environmental risk factors for myopia by investigating whether risk factor effect sizes vary depending on children's position in the refractive error distribution. Methods: Refractive error was assessed in participants from two birth cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC) (noncycloplegic autorefraction) and Generation R (cycloplegic autorefraction). A genetic risk score for myopia was calculated from genotypes at 146 loci. Time spent reading, time outdoors, and parental myopia were ascertained from parent-completed questionnaires. Risk factors were coded as binary variables (0 = low, 1 = high risk). Associations between refractive error and each risk factor were estimated using either ordinary least squares (OLS) regression or quantile regression. Results: Quantile regression: effects associated with all risk factors (genetic risk, parental myopia, high time spent reading, low time outdoors) were larger for children in the extremes of the refractive error distribution than for emmetropes and low ametropes in the center of the distribution. For example, the effect associated with having a myopic parent for children in quantile 0.05 vs. 0.50 was as follows: ALSPAC: age 15, -1.19 D (95% CI -1.75 to -0.63) vs. -0.13 D (-0.19 to -0.06), P = 0.001; Generation R: age 9, -1.31 D (-1.80 to -0.82) vs. -0.19 D (-0.26 to -0.11), P < 0.001. Effect sizes for OLS regression were intermediate to those for quantiles 0.05 and 0.50. Conclusions: Risk factors for myopia were associated with much larger effects in children in the extremes of the refractive error distribution, providing indirect evidence that emmetropization buffers against both genetic and environmental risk factors.

The impact of computer use on myopia development in childhood: The Generation R study.

Environmental factors are important in the development of myopia. There is still limited evidence as to whether computer use is a risk factor. The aim of this study is to investigate the association between computer use and myopia in the context of other near work activities. Within the birth cohort study Generation R, we studied 5074 children born in Rotterdam between 2002 and 2006. Refractive error and axial length was measured at ages 6 and 9. Information on computer use and outdoor exposure was obtained at age 3, 6 and 9 years using a questionnaire, and reading time and reading distance were assessed at age 9 years. Myopia prevalence (spherical equivalent ≤-0.5 dioptre) was 11.5% at 9 years. Mean computer use was associated with myopia at age 9 (OR = 1.005, 95% CI = 1.001-1.009), as was reading time and reading distance (OR = 1.031; 95% CI = 1.007-1.055 (5-10 h/wk); OR = 1.113; 95% CI = 1.073-1.155 (>10 h/wk) and OR = 1.072; 95% CI = 1.048-1.097 respectively). The combined effect of near work (computer use, reading time and reading distance) showed an increased odds ratio for myopia at age 9 (OR = 1.072; 95% CI = 1.047-1.098), while outdoor exposure showed a decreased odds ratio (OR = 0.996; 95% CI = 0.994-0.999) and the interaction term was significant (P = 0.036). From our results, we can conclude that within our sample of children, increased computer use is associated with myopia development. The effect of combined near work was decreased by outdoor exposure. The risks of digital devices on myopia and the protection by outdoor exposure should become widely known. Public campaigns are warranted.

Subfoveal choroidal thickness at age 9 years in relation to clinical and perinatal characteristics in the population-based Generation R Study.

PURPOSE: To assess the association between clinical and perinatal characteristics and subfoveal choroidal thickness in 9-year-old children. METHODS: The study included data from the population-based Generation R cohort, whose participants underwent cycloplegic refractometry, ocular biometry, height, weight and subfoveal choroidal thickness measurements using a swept-source optical coherence tomography (SS-OCT) instrument. Birth parameters were obtained using medical records. Statistical analyses were performed using multivariate regression models adjusted for age, ethnicity and sex. RESULTS: A total of 1018 children (52.5% girls, 47.5% boys) with a mean age of 9.9 ± 0.3 years and a mean cycloplegic spherical equivalent refraction of 0.80 ± 1.1 D in boys and 0.81 ± 1.4 in girls were eligible for analysis. The subfoveal choroid was 17 µm thicker in girls (298 ± 60.6 µm) than in boys (281 ± 55.0 µm; p < 0.001), a difference of 9.1 µm persisting after adjustment for age, ethnicity and axial length (p = 0.017). Subfoveal choroidal thickness decreased with increasing ocular axial length (-16.2 µm/mm, 95% CI -21.2 to -12.4, p < 0.001) and with increasing myopic refraction (-10.0 µm/D, 95% CI 6.8-13.1; p < 0.001, adjusted for age, ethnicity, axial length and sex) while it increased with increasing body height (1.3 µm/cm, 95% CI 0.8 to 1.9, p < 0.001). Additionally, choroidal thickness increased with increasing birthweight (13.0 µm/kg; 95% CI 0.006-0.020; p < 0.001) and increasing size for gestational age (8.2 µm/kg; 95% CI 4.6-11.8; p < 0.001). Smoking up until the time that pregnancy became known was associated with a thinner choroid (p = 0.016). There was no detectable effect of alcohol consumption. The distributions of axial length, refraction and choroidal thickness were narrower than in older populations. CONCLUSION: The subfoveal choroid was thicker in girls than in boys, and higher body height, higher birthweight and larger size for gestational age were associated with a thicker subfoveal choroid. The implications of these findings for myopia development need further evaluation in longitudinal studies.