Environmental Factors and Myopia: Paradoxes and Prospects for Prevention

Slowing of Greater Axial Length Elongation Stemming from the Coronavirus Disease 2019 Pandemic with Increasing Time Outdoors: The Tokyo Myopia Study

Purpose

To investigate the changes in axial length (AL) elongation and other ocular parameters before and during the coronavirus disease 2019 pandemic.

Design

A longitudinal school-based study.

Participants

Public elementary schoolchildren in Tokyo (grades 1-6; age, 6-12 years) participated in this study from 2018 to 2021.

Methods

All participants underwent eye examinations and provided written consent to measurements of the noncycloplegic refraction and ocular biometry including AL, among others. The students' parents also completed a questionnaire about the students' lifestyles. We included the right eye in our analysis and compared the changes in the ocular parameters among the periods using a linear mixed-effects model for repeated measures and examined the univariate and step-wise multiple regression analyses to evaluate the associations between myopia and other covariates.

Main Outcome Measures

Changes in AL elongation and other ocular parameters from 2018 to 2019 (prepandemic), that of 2019 to 2020 (immediately after the pandemic onset), and that of 2020 to 2021 (during the pandemic).

Results

A total of 578 students before the pandemic period, 432 immediately after the pandemic onset, and 457 during the pandemic period were evaluated. The changes in the ALs and spherical equivalents (SEs) a year before, immediately after onset, and during the pandemic were 0.31 mm/-0.20 diopter, 0.38 mm/-0.27 diopter, and 0.28 mm/-0.47 diopter, respectively (ALs, P < 0.001; SEs, P = 0.014). The results of the questionnaire showed that time spent outdoors daily had changed during the 3 years to 79, 63, and 77 minutes/day, respectively (P < 0.001). Time spent using smartphones or tablets increased year by year to 41, 52, and 62 minutes/day (P < 0.001). The greatest AL elongation occurred during the period when the shortest amount of time was spent outdoors during the 3 years.

Conclusions

These results suggested that the school closures and decreasing time spent outdoors might have caused greater AL elongation among schoolchildren in Tokyo; however, it is possible that, although the time spent in near work still increased, the return to the time spent outdoors to the prepandemic levels may have affected the slowing of AL elongation after lockdown.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Influence of eye-related behavior on myopia among junior middle school students under the background of double reduction during the COVID-19 pandemic

BACKGROUND

To investigate the changes in the unhealthy eye-related behaviors of junior middle school students during the COVID-19 pandemic and the double reduction policy and its relationship with myopia.

METHODS

Data were obtained from the 2019-2022 Tianjin Children and Youth Myopia, Common Diseases and Health Influencing Factors Survey. Latent profile analysis (LPA) and a generalized linear model (GLM) were applied to analyze the effect of eye-related behavior classes on myopia.

RESULTS

A total of 2508 junior middle school students were included. The types of eye-related behavior were categorized into the medium-healthy behavior group, heavy academic burden and near-eye behavior group, insufficient lighting group and high-healthy behavior group. Students with heavy academic burdens and near-eye behavior were more likely to develop myopia than were those in the high-healthy group (OR = 1.466, 95% CI = 1.203-1.787; P < 0.001).

CONCLUSIONS

The dual reduction policy has a positive effect on improving unhealthy eye-related behaviors, and the prevention and control of myopia through the use of different combinations of eye-related behaviors are heterogeneous among junior middle school students. In the post-COVID-19 period, we should continue to implement a double reduction policy and formulate targeted eye-related behavior strategies to provide an important reference for the prevention and control of myopia among children and adolescents during public health emergencies in the future.

The Myopia Prevalence and Association With Physical Activity Among Primary School Students Aged 6-12 Years: A Cross-Sectional Study in Tianjin, China

Purpose

This study aimed to investigate the prevalence of myopia and determine the association between physical activity and risk of myopia among primary school students in Tianjin, China.

Methods

A cross-sectional study was conducted among subjects from nine primary schools. All of the subjects underwent visual acuity and spherical equivalent (SE) with noncycloplegic autorefraction measurement. Myopia was defined as an SE refraction ≤-0.50D and an uncorrected visual acuity <5.0 in either eye. Physical activity was measured via the Physical Activity Questionnaire for Children. Data were analyzed using the Pearson χ2 test and binary logistic regression. Stratification analysis by sex was also performed.

Results

A total of 2976 participants (1408 boys and 1568 girls) aged six to 12 years (mean age 8.82 years) were included in this study. The overall prevalence of myopia was 52.92%. When stratified according to physical activity, myopia prevalence significantly decreased with increasing physical activity levels (χ2 trend test = 127.63, P < 0.001). In the binary logistic regression analysis, after adjusting for age, sex, and school region, the odds ratio for the association between physical activity and myopia was 0.762 (95% confidence interval, 0.675-0.862, P < 0.001). When stratified by sex, the significant statistical association between physical activity and myopia both can be found in two groups (P < 0.05).

Conclusions

Higher levels of physical activity were independently associated with decreased risk of myopia. The significant reverse statistical association between physical activity and myopia can be found in male or female groups.

Translational Relevance

Taking part in physical activities may be an effective way to reduce the prevalence of myopia.

Association Between Serum Vitamin D Levels and Myopia in the National Health and Nutrition Examination Survey (2001-2006)

PURPOSE

To assess the relationship between serum vitamin D levels and myopia in people aged 12-50 years using the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

Demographics, vision, and serum vitamin D levels from NHANES (2001-2006) were analyzed. Multivariate analyses were performed to examine the relationship between serum vitamin D levels and myopia while controlling for sex, age, ethnicity, education level, serum vitamin A, and poverty status. The main outcome was presence or absence of myopia, defined as a spherical equivalent of -1 diopters or more.

RESULTS

Of the 11669 participants, 5,310 (45.5%) had myopia. The average serum vitamin D concentration was 61.6 ± 0.9 nmol/L for the myopic group and 63.1 ± 0.8 nmol/L for the non-myopic group (p = .01). After adjusting for all covariates, having higher serum vitamin D was associated with lower odds of having myopia (odds ratio 0.82 [0.74-0.92], p = .0007). In linear regression modeling that excluded hyperopes (spherical equivalent > +1 diopters), there was a positive relationship between spherical equivalent and serum vitamin D levels. Specifically, as serum vitamin D doubled, spherical equivalent increased by 0.17 (p = .02) indicating a positive dose-response relationship between vitamin D and myopia.

CONCLUSIONS

Participants with myopia, on average, had lower serum concentrations of vitamin D compared to those without myopia. While further studies are needed to determine the mechanism, this study suggests that higher vitamin D levels are associated with lower incidence of myopia.

The Relationship between Selected Parameters and the Occurrence of Premyopia in a Group of 1155 Children Aged 8 in Northwestern Poland

Background: Determination of the number of pupils at risk of developing pre-myopia and selected ophthalmic parameters in a group of 1155 children aged 8. Material: Ophthalmic examinations were performed in Polish 8-year-old, /1518 individuals/; 1155 of whom presented complete data for analysis. There was a total of 554 (47.9%) girls and 602 (52.1%) boys. Examination of the anterior and posterior segment of the eye, evaluation of accommodation, convergence, heterophoria, alignment of the eyeball, muscular balance with ocular mobility in 9 directions of gaze, and spatial vision were tested. Refraction was obtained under cycloplegia. Refractions (spherical equivalent, SE). were categorized as pre-myopia (-0.50 D-+0.75 D), myopia (≤-0.5 D), emmetropia (>-0.5 D to ≤+0.5 D), mildly hyperopia (>+0.5 D to ≤+2.0 D) and hyperopia (>+2.0 D). Data analysis was performed using Statistica 13.5 software: chi-squared, Pearson's, t-Student, and U Mann-Whitney tests. p-values of <0.05 were considered statistically significant. Results: Pre-myopia was diagnosed in as many as 704 subjects (60.9%) with a similar frequency among both girls-328 (46.6%)-and boys with 376 (53.4%). Conclusions: Current data indicates that the growing group of myopic individuals in many industrialized countries is the sixth most common cause of blindness. Further research is crucial to understand the factors underlying accommodative and binocular mechanisms for myopia development and progression and to make recommendations for targeted interventions to slow the progression of myopia in a group of early school children.

The etiology, diagnostics, and treatment of the spasm of the near reflex - a narrative review

Physiological adaptation of the eye to the visual perception of near objects consists of the "near triad": convergence, accommodation, and pupil miosis. Normally, these tend to revert when one stops fixating on a near object. Spasm of the near reflex (SNR) is a pathological phenomenon, which manifests itself by the persistence of the above-mentioned adjustments, which prevents the eye from returning to its relaxed state. In this narrative review, we aim to summarize the etiology, diagnostics, treatment, and prevention of SNR. The literature review was performed by searching online databases. The clinical presentation of SNR is diverse; it presents as isolated accommodative spasm more frequently than impairment of all three components of the near triad. Patients usually present with fluctuations in visual acuity, blurred vision, diplopia, and asthenopia. The etiology is not fully understood. Potential causes include neuroanatomic, organic, and psychogenic disorders. The diagnosis is clinical, based on the constellation of symptoms and assessment of the near triad. The diagnostic golden standard is a cycloplegic examination of refraction, preferably using cyclopentolate hydrochloride (1%, 0.5%, or 0.1% solution). The first-line treatment requires the administration of a cycloplegic drug in combination with plus lenses, flipper lenses, optical fogging, or miotics. For secondary cases, causal treatment should be implemented. Prevention of SNR should be based on eliminating modifiable risk factors. We propose including screening for SNR symptoms in every ophthalmic examination, especially among patients with psychogenic or neural disorders, after brain trauma, or young adults spending much time in front of computer screens.

Combined Effect of Outdoor Time and Other Modifiable Factors on Myopia Incidence Among Children and Adolescents - 9 PLADs, China, 2020

What is already known about this topic?

Myopia has been identified as a significant emerging challenge and policy priority among children and adolescents in China by the Ministry of Education and seven other departments. Limited research has been conducted to investigate the collective impact of outdoor time and other modifiable factors on the incidence of myopia.

What is added by this report?

This study provides support for the protective effect of combining increased outdoor time with other prevention strategies in reducing the incidence of myopia. The results indicate the presence of a dose-response relationship.

What are the implications for public health practice?

To effectively prevent myopia, it is important to implement comprehensive interventions that encompass various aspects such as outdoor time, eye-use habits, eye-use environments, and lifestyle modifications.

CCDC66 mutations are associated with high myopia through affected cell mitosis

BACKGROUND

High myopia (HM) refers to an eye refractive error exceeding -5.00 D, significantly elevating blindness risk. The underlying mechanism of HM remains elusive. Given the extensive genetic heterogeneity and vast genetic base opacity, it is imperative to identify more causative genes and explore their pathogenic roles in HM.

METHODS

We employed exome sequencing to pinpoint the causal gene in an HM family. Sanger sequencing was used to confirm and analyse the gene mutations in this family and 200 sporadic HM cases. Single-cell RNA sequencing was conducted to evaluate the gene's expression patterns in developing human and mouse retinas. The CRISPR/Cas9 system facilitated the gene knockout cells, aiding in the exploration of the gene's function and its mutations. Immunofluorescent staining and immunoblot techniques were applied to monitor the functional shifts of the gene mutations at the cellular level.

RESULTS

A suspected nonsense mutation (c.C172T, p.Q58X) in CCDC66 was found to be co-segregated with the HM phenotype in the family. Additionally, six other rare variants were identified among the 200 sporadic patients. CCDC66 was consistently expressed in the embryonic retinas of both humans and mice. Notably, in CCDC66-deficient HEK293 cells, there was a decline in cell proliferation, microtube polymerisation rate and ace-tubulin level. Furthermore, the mutated CCDC66 failed to synchronise with the tubulin system during Hela cell mitosis, unlike its wild type counterpart.

CONCLUSIONS

Our research indicates that the CCDC66 variant c.C172T is associated with HM. A deficiency in CCDC66 might disrupt cell proliferation by influencing the mitotic process during retinal growth, leading to HM.

Research on an artificial intelligence-based myopic maculopathy grading method using EfficientNet

PURPOSE

We aimed to develop an artificial intelligence-based myopic maculopathy grading method using EfficientNet to overcome the delayed grading and diagnosis of different myopic maculopathy degrees.

METHODS

The cooperative hospital provided 4642 healthy and myopic maculopathy color fundus photographs, comprising the four degrees of myopic maculopathy and healthy fundi. The myopic maculopathy grading models were trained using EfficientNet-B0 to EfficientNet-B7 models. The diagnostic results were compared with those of the VGG16 and ResNet50 classification models. The leading evaluation indicators were sensitivity, specificity, F1 score, area under the receiver operating characteristic (ROC) curve area under curve (AUC), 95% confidence interval, kappa value, and accuracy. The ROC curves of the ten grading models were also compared.

RESULTS

We used 1199 color fundus photographs to evaluate the myopic maculopathy grading models. The size of the EfficientNet-B0 myopic maculopathy grading model was 15.6 MB, and it had the highest kappa value (88.32%) and accuracy (83.58%). The model's sensitivities to diagnose tessellated fundus (TF), diffuse chorioretinal atrophy (DCA), patchy chorioretinal atrophy (PCA), and macular atrophy (MA) were 96.86%, 75.98%, 64.67%, and 88.75%, respectively. The specificity was above 93%, and the AUCs were 0.992, 0.960, 0.964, and 0.989, respectively.

CONCLUSION

The EfficientNet models were used to design grading diagnostic models for myopic maculopathy. Based on the collected fundus images, the models could diagnose a healthy fundus and four types of myopic maculopathy. The models might help ophthalmologists to make preliminary diagnoses of different degrees of myopic maculopathy.

Association between body mass index and myopia in the United States population in the National Health and Nutrition Examination Surveys 1999 to 2008: a cross-sectional study

BACKGROUND

This study investigated the association between body mass index (BMI) and myopia in the United States.

METHODS

This cross-sectional study included 8,000 participants from the 1999 to 2008 National Health and Nutrition Examination Survey (NHANES). BMI was classified into four groups: < 18.5, 18.5 - 24.9, 25-29.9, and > 29.9. Three diagnostic thresholds were used for myopia A\B\C: spherical equivalent ≤ -0.5\-0.75\-1 diopters in the right eye. Multivariate logistic regression analysis and smooth curve fitting were performed to evaluate the association between BMI and myopia.

RESULTS

The incidence of myopia was 39.4%. BMI was correlated with myopia, with each 1 kg/m2 increase in BMI associated with a 1% increase in the risk of myopia (OR, 1.01; 95% CI 1.01 1.02; p < 0.05). In myopia B, after adjusting for confounding factors, compared with the reference group (BMI 18.5-24.9), participants with a BMI of 25-29.9 and greater than 29.9 had a 14% and 25% increased risk of myopia, respectively (OR 1.14; 95% CI 1.01 1.29; p = 0.037, OR 1.25; 95% CI 1.08 1.44; p = 0.003), which was similar to the results for myopic A (OR, 1.15; 95% CI 1.02 1.3; p = 0.027, OR 1.19; 95% CI 1.03 1.37; p = 0.018) and myopia C (OR 1.15; 95% CI 1.01 1.31; p = 0.035, OR 1.18; 95% CI 1.01 1.37; p = 0.032). Moreover, there was a linear relationship between myopia and BMI (p for nonlinearity = 0.767).

CONCLUSIONS

Myopia using all three diagnostic thresholds was positively associated with higher BMI. This suggests a potential association between myopia and higher BMI in the American population, warranting further investigations.

Acupuncture modulates development of myopia by reducing NLRP3 inflammasome activation via the dopamine-D1R signaling pathway

BACKGROUND

Dopamine has been suggested to be a stop signal for eye growth and affects the development of myopia. Acupuncture is known to increase dopamine secretion and is widely used to treat myopia clinically.

OBJECTIVE

The aim of this study was to determine if acupuncture inhibits myopia progression in form deprived Syrian hamsters by inducing rises in dopamine content that in turn suppress inflammasome activation.

METHODS

Acupuncture was applied at LI4 and Taiyang every other day for 21 days. The levels of molecules associated with the dopamine signaling pathway, inflammatory signaling pathway and inflammasome activation were determined. A dopamine agonist (apomorphine) was used to evaluate if activation of the dopaminergic signaling pathway suppresses myopia progression by inhibiting inflammasome activation in primary retinal pigment epithelial (RPE) cells. A dopamine receptor 1 (D1R) inhibitor (SCH39166) was also administered to the hamsters.

RESULTS

Acupuncture inhibited myopia development by increasing dopamine levels and activating the D1R signaling pathway. Furthermore, we also demonstrated that nucleotide-binding oligomerization domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome activation was inhibited by activation of the D1R signaling pathway.

CONCLUSION

Our findings suggest that acupuncture inhibits myopia development by suppressing inflammation, which is initiated by activation of the dopamine-D1R signaling pathway.

Prevalence Trend of Myopia during the Post-COVID-19 Epidemic Period among Preschoolers: A Prospective School-based Study

SIGNIFICANCE

Changes in behavior and lifestyle during the post-coronavirus disease 2019 (COVID-19) epidemic may have some impact on myopia rates in preschoolers, and exploring the changes in myopia rates in preschool children may inform the formulation of myopia prevention and control policies.

PURPOSE

This study aimed to investigate the prevalence of myopia in preschool children during the post-COVID-19 epidemic period in Xuzhou, China.

METHODS

A series of cross-sectional school-based studies was conducted. A total of 117,632 preschool children aged 3 to 6 years were subjected to annual vision screening from 2019 to 2021. Spot photo screening was used to record the spherical equivalent refraction for each child and to analyze the prevalence of myopia by age, sex, and region during the post-COVID-19 epidemic period.

RESULTS

A total of 113,979 preschool children were included in the analysis, of whom 60,784 (53.3%) were male and 53,195 (46.7%) were female. For all children, the mean ± standard deviation spherical equivalent refraction in 2019, 2020, and 2021 was +0.32 ± 0.50, +0.34 ± 0.55, and +0.34 ± 0.54 D, respectively (all P < .05), indicative of a very slight hyperopic shift. In all age groups, the change in mean spherical equivalent refraction and its distribution were relatively stable. From 2019 to 2021, the overall prevalence of myopia in preschool children was 3.1, 3.3, and 3.5%, respectively. The rise in myopia rates was minimal. The largest increase in the annual prevalence of myopia was seen among children aged 6 years, at 0.5%, followed by those aged 5 years (0.4%) and aged 3 years (0.4%). The prevalence was higher in boys than girls and in urban versus rural areas.

CONCLUSIONS

During the post-COVID-19 epidemic period, the refractive status of Xuzhou preschool children remained stable.

Global risk factor analysis of myopia onset in children: A systematic review and meta-analysis

INTRODUCTION

This work aimed to comprehensively assess the risk factors affecting myopia in children to develop more effective prevention and treatment strategies. To this end, data from database were employed to assess the relationship between the incidence of myopia and its risk factors.

METHODS

We searched eight databases online in June 2022. Cohort studies were included that measured the connection between risk factors and myopia. Eligibility was not restricted by language. The Newcastle-Ottawa Scale (NOS) was used to measure the risk of bias and conducted GRADE evaluation to determine the certainty of evidence. Potential risk factors with positive or negative results were seen. Inplasy Registration: https://inplasy.com/inplasy-2022-4-0109/.

RESULTS

Evidence that risk factors for myopia are mixed, comprising both positive (20) and null (17) findings. In 19 cohort studies on 3578 children, girls were more likely to develop myopia (RR: 1.28 [1.22-1.35]). Myopia can occur at any age, from early childhood to late adulthood. Children whose parents had myopia were more likely to develop myopia. Longer outdoor activities time (RR: 0.97 [0.95-0.98]) and less near-work time (RR: 1.05 [1.02-1.07]) appeared to be significantly decrease the incidence of myopia. Children with lower SE, longer AL, a lower magnitude of positive relative accommodation, worse presenting visual acuity, deeper anterior chamber, and thinner crystalline lens may be related to myopia onset. The burden of myopia in underprivileged countries is higher than in developed countries (RR: 5.28 [2.06-13.48]). The quality of evidence for the evaluated factors was moderate to low or very low.

CONCLUSIONS

Genetic factors, environmental factors (such as excessive use of electronic products, and poor study habits) and lifestyle factors (such as lack of outdoor activities, poor nutrition, etc.) are the main risk factors for myopia in children. Myopia prevention strategies should be designed based on environmental factors, gender, parental myopia and eye indicators in order to explore a lifestyle that is more conducive to the eye health of children.

Effects of school myopia management measures on myopia onset and progression among Chinese primary school students

BACKGROUND

Schools play an organizational role in managing myopia-related behavioral habits among students. We evaluated the effects of school myopia management measures on myopia onset and progression in a school-based prospective 1-year observational study.

METHODS

In total, 8319 children from 26 elementary schools were included. Online questionnaire completed by a parent, in which school myopia management experience including outdoor activities in recess or physical education class, teachers' supervision, and teaching facilities. Variables were defined as implemented well or poorly, according to the Comprehensive Plan to Prevent Myopia among Children and Teenagers. Children underwent ophthalmic examinations, and the incidence and progression of myopia from 2019 to 2020 were estimated. Multilevel logistic regression models were constructed to analyze the association between school management measures and myopia development in 8,9 years and 10,11 years students.

RESULTS

From 2019 to 2020, the incidence of myopia among primary school students was 36.49%; the mean difference of spherical equivalent in myopic children was - 0.29 ± 1.22 diopters. The risk of incident myopia was reduced by 20% in 8,9 years participants with well-implemented class recess compared with those with poorly implemented class recess (adjusted odds ratio [aOR]: 0.80, p = 0.032). PE outdoor time was significantly associated with myopia incidence in 10,11 years students (aOR: 0.76, p = 0.043). Compared with poorly implemented reading and writing posture, desk and chair height, 10,11 participants with well-implemented desk and chair height were less likely to have rapid myopic progression (p = 0.029, p = 0.022).

CONCLUSION

In Shanghai, children's myopia is associated with better implementation of school myopia management measures. The present findings suggest that outdoor activities during class recess or PE class, providing suitable desks and chairs, and adequate instruction in reading and writing postures might protect against pathological eye growth. An age-specific myopia prevention and control programs in school is of primary importance.

A retinoscopic survey of donkeys and goats

PURPOSE

Assess the refractive states of donkeys and goats.

METHODS

Forty-two donkeys and 28 goats were enrolled. The mean ± SD ages were 7.68 ± 7.33 years for donkeys and 4.26 ± 2.33 years for goats. Seven donkeys and one goat were <6 months old. Retinoscopy was performed in alert animals, following cycloplegia in goats but not in donkeys. Normality was determined using the Kolmogorov-Smirnov test. The two primary meridians and two eyes were compared using Pearson's correlation and paired Student's t-tests. The association between refractive states and age was examined using one-way ANOVA in donkeys and a paired Student's t-test in goats. One-sample t-tests were conducted to assess if the refractive error distributions were significantly different from "0".

RESULTS

The mean ± SD spherical equivalent (SE) refractive errors of the right and left donkey eyes were -0.80 ± 1.03 D and -0.35 ± 0.95 D, respectively. The majority (86%) of the donkeys had an astigmatic refraction and eight (19%) had anisometropia. The mean SE refractive errors of the right and left goat eyes were -0.15 ± 1.1 D and -0.18 ± 1.2 D, respectively. The majority (54%) of the goat eyes had an astigmatic refraction and five (18%) had anisometropia. The right and left eye SE refractive errors were positively correlated in both species (both p = .9). Age was not correlated with refractive error in both donkeys (p = .09) and goats (p = .6).

CONCLUSIONS

Both goats and donkeys are emmetropic.

High Myopia and Thickness of Extraocular and Masticatory Muscles-7T MRI, Preliminary Study

(1) Background: Myopia is one of the most common refractive errors in the world. The aim of this study was to evaluate the transverse dimensions of selected masticatory muscles (temporalis muscle and masseter muscle) versus the transverse dimensions of selected extraocular muscles (superior rectus, inferior rectus, medial rectus and lateral rectus) in emmetropic and high myopic subjects. (2) Methods: Twenty-seven individuals were included in the analysis, resulting in 24 eyeballs of patients with high myopia and 30 eyeballs of emmetropic subjects. A 7 Tesla resonance was used to analyze the described muscles. (3) Results: Statistical analysis showed differences in all analyzed extraocular muscles and all analyzed masticatory muscles between emmetropic subjects and high myopic subjects. In the high myopic subject group, statistical analysis showed four correlations. The three negative correlations were between the lateral rectus muscle and an axial length eyeball, refractive error and an axial length eyeball, and the inferior rectus muscle and visual acuity. The positive correlation was between the lateral rectus muscle and the medial rectus muscle. (4) Conclusions: The high myopic subjects are characterized by a larger cross-sectional area of extraocular muscles and masticatory muscles compared to the emmetropic subjects. Correlations were observed between the thickness of the extraocular muscles and the masticatory muscles. The lateral rectus muscle was related to the length of the eyeball. The phenomenon requires further study.

Association of educational environment with the prevalence of myopia: a cross-sectional study in central China

Purposes

This study was to estimate the prevalence of myopia among primary school students in Hefei, China, and evaluate the association of educational environment with myopia.

Methods

This study was a cross-sectional study, and recruited primary school students in grades 1-6. Children underwent a stepwise ophthalmic examination, which included visual acuity and objective cycloplegic refraction to identify children with myopia. Under the guidance of parents, children completed a questionnaire, including gender, region, grade and several indicators related to education. The study analyzed the risk factors by using a logistic regression and assessed feature importance by using a random forest algorithm.

Results

A total of 3,596 primary school students were involved in this analysis, and the overall prevalence of myopia was 27.1%. Gender, grade, education level of the father, education level of the mother, academic level of children, hours of homework per day on weekends, number of after-school tutoring per week and frequency of extracurricular reading were significantly associated with myopia. There was no significant association between the amount of homework per day on school days and myopia after adjusting for covariates. In terms of educational environment, the top 3 factors were academic level of children, homework on weekends and after-school tutoring.

Conclusions

Educational environment with high educational loads was associated with the high prevalence of myopia. Reducing the burden of studying, especially that after class, was an effective way to prevent myopia.

Myopia among children and adolescents: an epidemiological study in Fuzhou City

Objective

To provide a reference for the prevention and control of myopia by analyzing and discussing the findings of an epidemiological survey of the prevalence of myopia among children and adolescents in Fuzhou City from 2019 to 2021.

Methods

Participants for this cross-sectional study were drawn from Gulou District and Minqing County in Fuzhou City using cluster random sampling to account for differences in population density, economic development, and other environmental variables.

Results

Myopia was more prevalent in 2020 than in 2019, but by 2021 it had dropped to about the same level as in 2019. Myopia was more prevalent among girls than boys during the course of the study period, with a three-year prevalence of 44.72% for boys and 52.16% for girls. Mild myopia accounted for 24.14% of all cases, followed by moderate myopia at 19.62%, and severe myopia at 4.58%. Students in urban regions had a prevalence of myopia equivalent to that of students in the suburbs, and this prevalence rose with age.

Conclusion

Myopia was quite prevalent among children and adolescents in Fuzhou City, and was shown to be steadily rising as students progressed through the school system. This suggests that all levels of government, educational institutions, medical facilities, and concerned parents in Fujian Province should focus on the issue of myopia and collaborate to reduce the risk factors for the development of myopia in school-aged participants.

The outdoor environment affects retinal and choroidal thickness

PURPOSE

Accumulating evidence suggests that time outdoors is protective against myopia development and that the choroid may be involved in this effect. The goal of this study was to examine the effect of 2 h of time outdoors in sunlight on retinal and choroidal thickness in adults.

METHODS

Twenty adults, ages 23-46 years, each participated in three experimental sessions on different days, consisting of 2 h of exposure to (1) indoor illumination (350 lux), (2) darkness (<0.1 lux) or (3) outdoor environment (6000-50,000 lux). Spectral-domain optical coherence tomography (SD-OCT) imaging was conducted at baseline, after 1 and 2 h of exposure, and after 1 and 2 h of follow-up. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE) and photoreceptor inner segment thicknesses were determined.

RESULTS

At 2 h, the choroid was significantly thinner during the outdoor compared with the indoor and dark conditions (p < 0.01) but was not significantly different at follow-up. Total retinal thickness was significantly thicker during and after the outdoor compared with the indoor and dark conditions. The outer segment + RPE was significantly thinner during the outdoor compared with the indoor condition but was not significantly different at follow-up. The inner segment was significantly thicker during the outdoor compared with the indoor and dark conditions during exposure and follow-up.

CONCLUSIONS

Spending 2 h outdoors under high-intensity sunlight resulted in an unexpected thinning of the choroid, which recovered post-exposure. Retinal thickness showed different responses to the outdoor and indoor environments and was sensitive to the duration of exposure.

Myopia Management in Daily Routine - A Survey of European Pediatric Ophthalmologists

PURPOSE

Assessment of diagnostic and therapeutic strategies currently used in routine practice for myopia management in Europe.

METHODS

Online survey study including 11 main questions. The questionnaire was sent to members of the European Paediatric Ophthalmology Society (EPOS). The following items and questions were surveyed: I. Profession and workplace of the survey participants. II. Preventive measures and recommendations for myopia management, a) regarding reading distance and near work, b) optical tools, i.e., application of Defocus Incorporated Multiple Segments (DIMS) glasses, near additions, or contact lenses, and c) the application of atropine eye drops. III. Application of additional diagnostic tools.

RESULTS

Forty-eight individuals completed the survey. Of the respondents, 88% (n = 42) affirmed that they generally gave advice on strategies for myopia prevention and management strategies. Almost all study participants (n = 41; 85%) recommend outdoor time as a preventive measure. The recommendation on near distance is given less frequently, with 28 (58%) participants confirming that they do recommend a "safe" reading distance, and 15 (31%) negating this. Eight (17%) survey participants recommend using near addition glasses, while 36 (75%) do not. Similarly, 35 (73%) respondents do not apply DIMS glasses and 8 (17%) apply them. Fourteen (29%) participants recommend myopia-reducing contact lenses while 30 (63%) do not, and 29 (60%) confirmed that they applied atropine eye drops to slow myopia progression while 14 (29%) do not prescribe these eye drops. The majority of respondents (n = 25; 86%) who prescribe atropine eye drops use atropine 0.01% eye drops.

CONCLUSIONS

Prevention and therapeutic management of childhood myopia is an essential part in the daily routine of pediatric ophthalmologists. Substantial agreement was found for the protective role of outdoor time (85%). The only common therapeutic approach is the administration of atropine eye drops (60%).

Flash Electroretinography as a Measure of Retinal Function in Myopia and Hyperopia: A Systematic Review

Refractive errors (myopia and hyperopia) are the most common visual disorders and are severe risk factors for secondary ocular pathologies. The development of refractive errors has been shown to be associated with changes in ocular axial length, suggested to be induced by outer retinal elements. Thus, the present study systematically reviewed the literature examining retinal function as assessed using global flash electroretinograms (gfERGs) in human clinical refractive error populations. Electronic database searching via Medline, PubMed, Web of Science, Embase, Psych INFO, and CINAHL retrieved 981 unique records (last searched on the 29 May 2022). Single case studies, samples with ocular comorbidities, drug trials, and reviews were excluded. Demographic characteristics, refractive state, gfERG protocol details, and waveform characteristics were extracted for the eight studies that met the inclusion criteria for the review and were judged to have acceptable risk of bias using the OHAT tool (total N = 552 participants; age 7 to 50). Study synthesis suggests that myopia in humans involves attenuation of gfERG photoreceptor (a-wave) and bipolar cell (b-wave) function, consistent with the animal literature. Meaningful interpretation of the overall findings for hyperopia was limited by inconsistent reporting, highlighting the need for future studies to report key aspects of gfERG research design and outcomes more consistently for myopic and hyperopic refractive errors.

The association between time spent on screens and reading with myopia, premyopia and ocular biometric and anthropometric measures in 6- to 7-year-old schoolchildren in Ireland

PURPOSE

More time spent on near tasks has consistently been associated with the promotion of myopia. The World Health Organization advises limiting daily screentime to less than 2 h for children aged five and over. This study explored the relationship between time spent on screens and reading/writing with refractive status, ocular biometric and anthropometric factors in 6- to 7-year-olds in Ireland.

METHODS

Participants were 723 schoolchildren (377 boys [51.8%]), mean age 7.08 (0.45) years. The examination included cycloplegic autorefraction (1% cyclopentolate hydrochloride), ocular biometry (Zeiss IOLMaster), height (cm) and weight (kg). Screentime and reading/writing time were reported by parents/legal guardians by questionnaire. Myopia (≤-0.50D) and premyopia (>-0.50D ≤ 0.75D) risk assessments were performed using logistic regression, and multivariate linear regression was used to analyse continuous variables.

RESULTS

Reported daily screentimes were 31% <1 h, 49.5% 1-2 h, 15.6% 2-4 h and 3.9% >4 h. Reading/writing times were 42.2% frequently, 48.0% infrequently and 9.8% seldom/never. Linear regression, controlling for age and ethnicity, revealed >2 h/day on screens was associated with a more myopic spherical equivalent [β = -1.15 (95% confidence intervals {CIs}: 1.62-0.69, p < 0.001)], increased refractive astigmatism (β = 0.29, CI: 0.06-0.51, p = 0.01), shorter corneal radius (β = 0.12, CI: 0.02-0.22, p = 0.02), higher axial length/corneal radius (β = 0.06, CI: 0.03-0.09, p < 0.001), heavier weight (β = 1.60, CI: 0.76-2.45, p < 0.001) and higher body mass index (BMI) (β = 1.10, CI: 0.28-1.12, p < 0.001). Logistic regression, controlling for age and ethnicity, revealed daily screentime >2 h was associated with myopia (OR = 10.9, CI: 4.4-27.2, p = 0.01) and premyopia (OR = 2.4, CI: 1.5-3.7, p < 0.001). Frequent reading/writing was associated with screentime ≤2 h/day (OR = 3.2, CI: 1.8-5.8, p < 0.001).

CONCLUSION

Increased screentime was associated with a more myopic refraction, higher axial length/corneal radius ratio, increased odds of myopia, premyopia, higher degrees of astigmatism, increased weight, BMI and decreased reading/writing time. Dedicated education programmes promoting decreased screentime in children are vital to prevent myopia and support eye and general health.

Epidemiological Characteristics and Influencing Factors of Myopia Among Primary School Students in Southern China: A Longitudinal Study

Objectives: To study the epidemiological characteristics and influencing factors of myopia to provide a scientific basis for the prevention and control of myopia. Methods: 7,597 students studying in grades 1-3 were followed up. Eye examinations and questionnaire surveys were conducted annually from 2019 to 2021. The influencing factors of myopia were analyzed by logistic regression model. Results: The prevalence of myopia among students in grades 1-3 in 2019 was 23.4%, which increased to 41.9% and 51.9% after the 1-and 2-year follow-up, respectively. The incidence of myopia and change in the spherical equivalent refraction (SER) were higher in 2020 than in 2021. The 2-year cumulative incidences of myopia were 2.5%, 10.1%, 15.5%, 36.3%, and 54.1% in students with a baseline SER >+1.50D, +1.00D to +1.50D, +0.50D to +1.00D, 0.00D to +0.50D, and -0.50D to 0.00D, respectively. Outdoor activities, sex, age, baseline SER, parental myopia, sleep time, and digital device exposure were associated with myopia. Conclusion: The prevalence of myopia demonstrated a rapid increase; thus, healthy habits and outdoor activities should be promoted for the prevention and control of myopia.

Prevalence and Risk Factors of Refractive Errors and Effective Spectacle Coverage in Emiratis and Non-Emiratis Aged 40 Years or Older: the Dubai Eye Health Survey

PURPOSE

The aim was to investigate the prevalence and risk factors of refractive errors (REs) and the effective spectacle coverage in Emiratis and non-Emiratis in Dubai.

DESIGN

The Dubai Eye Health Survey was a population-based cross-sectional study of participants aged 40 years or older.

METHODS

Distance and near visual acuity (VA), and noncycloplegic automated refraction were tested according to a standardized protocol. Distance VA was tested using the Early Treatment Diabetic Retinopathy Study (ETDRS) logMAR chart at 3 m and near VA was measured using the near vision logMAR chart at 40 cm under ambient lighting. Myopia was defined as spherical equivalent of refraction of less than -0.50 diopters (D), and hypermetropia as spherical equivalent of more than +0.50 D. Astigmatism was defined as cylinder power of 0.5 D or greater. Effective spectacle coverage for distance vision was computed as met need/(met need+unmet need+under-met need)×100%. Multivariable logistic regression models were used to examine associations between sociodemographic factors and RE.

RESULTS

The authors included 892 participants (446 Emiratis and 446 non-Emiratis) in the analysis. The prevalence of hypermetropia was 20.4% [95% confidence interval (CI): 16.8%-24.4%] in Emiratis and 20.6% (95% CI: 20.0%-24.7%) in non-Emiratis. The prevalence of myopia and high myopia was 27.4% (95% CI: 23.3%-31.7%) and 1.8% (95% CI: 0.8%-3.5%) in Emiratis, and 19.5% (95% CI: 15.9%-23.5%) and 0.9% (95% CI: 0.2%-2.3%) in non-Emiratis, respectively. High education (P=0.02) and not currently working (P=0.002) were risk factors of myopia in non-Emiratis only. The prevalence of astigmatism was 7.4% (95% CI: 5.1%-10.2%) in Emiratis and 1.6% (95% CI: 0.6%-3.2%) in non-Emiratis. This prevalence was higher in individuals aged over 60 years (P<0.001) and men (P=0.014) among Emiratis. The prevalence of anisometropia and uncorrected presbyopia was 11.4% (95% CI: 8.6%-14.8%) and 0.7% (95% CI: 0.1%-2.0%) in Emiratis, and 9.2% (95% CI: 6.7%-12.3%) and 0.4% (95% CI: 0.05%-1.6%) in non-Emiratis, respectively. The effective spectacle coverage was 62.3% (95% CI: 54.0%-70.6%) and 69% (95% CI: 60.5%-77.5%) in Emiratis and non-Emiratis, respectively.

CONCLUSIONS

A high proportion of Emiratis and non-Emiratis was affected by RE without optimal effective spectacle coverage, highlighting the imperativeness of intervention to alleviate the burden. The findings may help facilitate evidence-based policymaking concerning the delivery of eye care services and allocation of medical resources in Dubai.

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.

Comparisons of Three Methods for Myopia Control in Adolescents

Objective

A rising trend in electronic use has increased the prevalence of myopia in adolescents, but the optimal approach to controlling myopia remains undetermined. Here, we explored the effects of common single vision (SV) spectacle lenses combined with 0.01% atropine eye drops (SV + A), orthokeratology (OK) lenses, and peripheral defocus (PD) spectacle lenses on myopia control in adolescents.

Methods

Totally 150 myopic adolescent patients (300 eyes) receiving treatment at The First People's Hospital of Chenzhou City were enrolled. According to doctors' advice and guardians' wishes, the patients were divided into SV + A group, OK group, and PD group, with each group consisting of 50 cases (100 eyes). The spherical equivalent, axial length, accommodative response index (accommodative sensitivity and accommodative lag), and intraocular pressure were compared before and after 12 months of wearing lenses, and the complications were recorded.

Results

Before wearing lenses, there was no statistical significance in baseline characteristics such as age, gender, and spherical equivalent among the three groups (P > 0.05). After wearing lenses, the increase in spherical equivalent and axial length in the SV + A and OK groups were lower than in the PD group (P < 0.05), and the SV + A group had the lowest axial length growth. Compared with the SV + A group, accommodative sensitivity was much higher and accommodative lag was significantly lower in the OK and PD groups (P < 0.01). In addition, there was no significant difference in intraocular pressure before and after wearing lenses among the three groups (P > 0.05). Though the OK group patients had more complications, the difference was not statistically significant (P > 0.05).

Conclusion

SV + A, OK, and PD lenses can effectively control the progression of myopia in adolescents, but SV + A and OK lenses exhibited more significant effects.

Influence of parental behavior on myopigenic behaviors and risk of myopia: analysis of nationwide survey data in children aged 3 to 18 years

Background

Preventive parental behavior may play an important role in the outcomes of children’s myopia. We investigated associations between parental behavior and children’s myopia status and daily activities using data from the most recent myopia survey in Taiwan.

Methods

In total, 3845 children aged 3 to 18 years who completely responded to the questionnaire were included (total score ranging from 0 to 75). A score of ≥ 50 was considered to indicate beneficial parental behavior. Time allocation data for near-work activities, using electronic devices, and outdoor activities were collected using a separate self-reported questionnaire. Associations between beneficial parental behavior and children’s myopia status and activity patterns were analyzed and stratified by school level.

Results

Beneficial parental behavior was positively associated with children’s myopia in the overall samples [adj. odds ratio (OR): 1.31, 95% confidence interval (CI): 1.08–1.59, p = 0.006)] and at the elementary school level (adj. OR: 1.43, 95% CI: 1.11–1.83, p = 0.005). However, a negative association with high myopia was observed in the overall samples (adj. OR: 0.71, 95% CI: 0.50–0.99, p = 0.049) and high school level (adj. OR: 0.62, 95% CI: 0.41–0.92, p = 0.02). Beneficial parental behavior was associated with less time spent on near work (≥ 180 min/day) and electronic device use (≥ 60 min/day), but not with outdoor activities.

Conclusion

In Taiwan, children’s myopia is associated with higher rate of parents’ beneficial behaviors, which suggests that regular vision surveillance is necessary to promote better parental behavior toward children’s eye care. Certain parental practices may influence children’s behavior pattern and reduce the risk of children’s high myopia development in the long run.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14036-5.

Comparison of Factors Associated with Myopia among Middle School Students in Urban and Rural Regions of Anhui, China

SIGNIFICANCE

The prevention and control of myopia have become a major public health task throughout the world. The analysis of the modifiable factors associated with myopia will help in planning concrete strategies that can be widely implemented by schools and families.

PURPOSE

This study assessed the modifiable factors associated with myopia and compared them between rural and urban regions.

METHODS

Data were collected from December 2020 to March 2021. A multi-stage stratified cluster sampling method was used to select 6154 middle school students. All children underwent an eye examination, including visual acuity and cycloplegic refraction. Data on near work, sleep and outdoor activities were collected in questionnaires.

RESULTS

The myopia prevalence values in urban and rural regions were 68.1% and 63.7%, respectively (χ2 = 15.57, P < .001). More than 3 hours homework per day(OR in urban and rural region: 1.36, 95% CI = 1.07-1.75 vs. 1.72, 95% CI = 1.43-2.07), 36-40 core subjects per week(1.30, 95% CI = 1.04-1.57 vs. 1.42, 95% CI = 1.24-1.64) and going to sleep before 10 o'clock (0.56, 95% CI = 0.32-0.93 vs. 0.50, 95% CI = 0.28-0.90) were significantly associated with myopia in both regions. In contrast, taking breaks during near work was a significant factor in the rural region (less than 1 hour: OR = 0.57, 95% CI = 0.42-0.76; 1-2 hours: OR = 0.63, 95% CI = 0.46-0.86), but not in the urban region. More time outdoors per day was associated with a reduced prevalence of myopia only for urban children (2-3 hours: OR = 0.55, 95% CI = 0.31-0.97; more than 3 hours: OR = 0.38, 95% CI = 0.19-0.75).

CONCLUSIONS

Homework loads and the time of going to sleep were associated with myopia for children in both urban and rural regions. However, time outdoors was only associated with myopia in urban regions and taking breaks during near work only associated with myopia in rural regions.

The G allele of the IGF1 rs2162679 SNP is a potential protective factor for any myopia: Updated systematic review and meta-analysis

Background

The insulin-like growth factor 1 (IGF1) gene is located within the myopia-associated MYP3 interval, which suggests it may play an important role in the progression of myopia. However, the association between IGF1 SNPs and any myopia is rarely reported.

Methods

A comprehensive literature search was conducted on studies published up to July 22, 2021 in PubMed, EMBASE, CBM, COCHRANE, CNKI, WANFANG and VIP databases. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for single-nucleotide polymorphisms (SNPs) that have been evaluated in at least three studies.

Results

Nine studies involving 4596 subjects with any myopia and 4950 controls examined 25 SNPs in IGF1 gene, among which seven SNPs were included in this meta-analysis. Significant associations were not found in any genetic models between rs6214, rs12423791, rs5742632, rs10860862, rs5742629 and any myopia. Rs2162679 was suggestively associated with any myopia in the codominant model (GA vs. AA: OR = 0.87, 95% CI: 0.76–1.00) and the dominant model (GG+GA vs. AA: OR = 0.88, 95% CI = 0.78–1.00).

Conclusion

Meta-analysis of updated data reveals that the G allele of the IGF1 rs2162679 SNP is a potential protective factor for any myopia, which is worth further researches.

The Evolution and the Impact of Refractive Errors on Academic Performance: A Pilot Study of Portuguese School-Aged Children

The relationship between vision and academic performance has been discussed for a long time, with special emphasis on visual factors associated with learning problems. The objective of this pilot study is to obtain an initial idea about the evolution and the impact of refractive errors on school-aged children. A visual examination was performed on 252 children between the ages of 6 and 11 years, which consisted of objective refraction, subjective refraction, and accommodative and binocular tests. No significant differences were observed regarding the refractive state when taking academic performance into account (p > 0.05). However, it was determined that academic performance was better among children with a negative spherical equivalent. Studies with a larger sample size must be conducted to verify the results that were attained in this present pilot study, and these must likewise look at possible ways in which strategies can be implemented in schools to reduce myopia progression.

Trends in Myopia Development Among Primary and Secondary School Students During the COVID-19 Pandemic: A Large-Scale Cross-Sectional Study

Objectives

To evaluate myopia development among primary and secondary school students during the coronavirus 2019 (COVID-19) pandemic.

Methods

A cross-sectional study was conducted to evaluate the development of myopia among students in Shenzhen, China during the COVID-19 outbreak.

Results

The study included 1,472,957 and 1,573,824 students in 2019 and 2020, respectively. The prevalence of myopia was 46.9 and 50.5% in 2019 and 2020, respectively. The prevalence of myopia among students in the former Shenzhen Special Economic Zone (SEZ) was higher than that in areas outside the former Shenzhen SEZ (2019: 47.0 vs. 43.7%; 2020: 50.5 vs. 47.3%). The prevalence of myopia among girls was higher than that among boys (2019: 50.4 vs. 44.0%; 2020: 54.0 vs. 47.6%). The 50th percentile (P50) of spherical equivalent refraction (SER) in the right eye among girls was lower than that in boys. The prevalence of myopia continued to increase as the grade increased, with the greatest annual increase observed in Grades 2–5 (3.4–3.9%). The P50 of SER in the right eye of students decreased as the grade increased.

Conclusions

The prevalence of myopia among students increased during the COVID-19 pandemic, especially in primary school Grades 2–5.

The influence of alcohol intake in myopia development or progression: The SUN cohort study

BACKGROUND

Myopia is a highly prevalent disorder, and one of the first causes of blindness. In turn, alcohol consumption has been shown to be a risk factor for many diseases and a main contributor to the global burden of disease. However, no studies have investigated the relationship between alcohol intake and myopia. Our aim was to prospectively assess the association between alcohol intake and the development or progression of myopia.

METHODS

In a Spanish dynamic prospective cohort (the SUN Project) we assessed 15,642 university graduates, recruited between 1999 and 2018 and followed up biennially through mailed questionnaires. Alcohol intake was assessed with a validated 136-item food frequency questionnaire. Development or progression of myopia was collected in subsequent questionnaires during follow-up every two years.

RESULTS

Alcohol intake was linearly and significantly associated with a higher risk of myopia development or progression: the OR for 10-year incidence/progression of myopia was 1.05, 95% CI 1.01-1.09 per each 10-grams increase in alcohol intake.

CONCLUSIONS

Alcohol consumption might lead to the development or progression of myopia, although confirmation is needed for the mechanisms through which this association may occur, thus further research is needed to verify these findings.

Prevalence and risk factors for myopia and high myopia: A cross-sectional study among Han and Uyghur students in Xinjiang, China

PURPOSE

This study aimed to investigate the prevalence and risk factors for myopia and high myopia among Han and Uyghur students in Xinjiang, China.

METHODS

This cross-sectional study with a multistage, stratified cluster sampling method was completed in Xinjiang, China. Visual acuity and noncycloplegic refraction were measured. The crude and sex- and age-adjusted prevalence of myopia and high myopia in Han and Uyghur students were compared. Multivariate logistic regression analyses were applied to identify risk factors associated with myopia and high myopia.

RESULTS

In total, 84,033 participants were included in the final analysis, comprising 64,110 Han and 19,923 Uyghur participants. The overall age- and sex-adjusted prevalence of myopia and high myopia were 47.70% (95% CI: 47.67-47.74) and 2.55% (95% CI: 2.54-2.56), respectively. Compared to the Uyghur population, the Han population had a higher prevalence of myopia (63.59% vs. 21.34%, p < 0.0001) and high myopia (4.68% vs. 0.6%, p < 0.0001). Han ethnicity, age, female sex, higher education level and living in urban areas were found to be positively associated with myopia and high myopia. Living in northern Xinjiang was found to be positively associated with myopia but negatively associated with high myopia.

CONCLUSIONS

Our study investigated the prevalence of myopia and high myopia among Han and Uyghur students aged 4-23 years in Xinjiang, China. The Han population had a higher prevalence of myopia and high myopia than the Uyghur population. However, the prevalence of myopia among the Uyghur population showed a more remarkable increasing trend than that among the Han population in Xinjiang.

Dietary ω-3 polyunsaturated fatty acids are protective for myopia

Myopia is a leading cause of visual impairment and blindness worldwide. However, a safe and accessible approach for myopia control and prevention is currently unavailable. Here, we investigated the therapeutic effect of dietary supplements of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on myopia progression in animal models and on decreases in choroidal blood perfusion (ChBP) caused by near work, a risk factor for myopia in young adults. We demonstrated that daily gavage of ω-3 PUFAs (300 mg docosahexaenoic acid [DHA] plus 60 mg eicosapentaenoic acid [EPA]) significantly attenuated the development of form deprivation myopia in guinea pigs and mice, as well as of lens-induced myopia in guinea pigs. Peribulbar injections of DHA also inhibited myopia progression in form-deprived guinea pigs. The suppression of myopia in guinea pigs was accompanied by inhibition of the "ChBP reduction-scleral hypoxia cascade." Additionally, treatment with DHA or EPA antagonized hypoxia-induced myofibroblast transdifferentiation in cultured human scleral fibroblasts. In human subjects, oral administration of ω-3 PUFAs partially alleviated the near-work-induced decreases in ChBP. Therefore, evidence from these animal and human studies suggests ω-3 PUFAs are potential and readily available candidates for myopia control.

Impact of the Pressure-Free Yutori Education Program on Myopia in Japan

This study aimed to investigate the influence of educational pressure on myopia. A less-intense school curriculum was introduced nationally in Japan beginning in 2012 based on a pressure-free education policy. In this retrospective observational study, a total of 1025 Japanese medical students of Asahikawa Medical University underwent measurements of the cycloplegic refractive error and axial length (AL), from 2011 to 2020. The spherical equivalent (SE) and AL were correlated significantly with the fiscal year of births (p = 0.004 and p = 0.034, respectively) only during enforcement of the system of high-pressure education. The SE and AL regression rates during the two educational approaches differed significantly (p = 0.004 and p = 0.037, respectively). The prevalence of high myopia was correlated significantly (p < 0.001) only during the system of high-pressure education. The regression of the prevalence rate of high myopia during the two education approaches differed significantly (p = 0.010). The progression rates of myopia and increased prevalence of high myopia were observed only during high-pressure education, suggesting that not only ophthalmologists but also educators and the government should work on together to control the progression of myopia.

Survey on the Progression of Myopia in Children and Adolescents in Chongqing During COVID-19 Pandemic

Background: The Covid-19 pandemic restricts children and adolescents from doing normal daily activities such as playing outdoors and going to school. The incidence and prevalence of myopia have increased during the COVID-19 pandemic. The aim of this study was to investigate and evaluate the impact of the home confinement during the COVID-19 pandemic on the progression of myopia among children and adolescents in Chongqing, China. Methods: The survey was conducted by using stratified samplings. Samples were randomly selected from the 2019 National Student Physique and Health Survey database, and their visual function and refractive data were compared with those in 2020. Vision-related behavior questionnaire including digital screen exposure was applied to investigate the correlation between eye parameter and eye health-related behavior. Results: A total of 1,733 and 1,728 students were enrolled in 2020 and 2019, respectively. The percentage of myopia students was 55.02% in 2020, which was higher than that in 2019 (44.62%). The mean uncorrected visual acuity (UCVA, LogMAR, 0.35 ± 0.42) in 2020 was higher than that in 2019 (0.27 ± 0.36, P < 0.001). The mean spherical equivalent (SE) refraction (-1.94 ± 2.13 D) in 2020 was lower than that in 2019 (-1.64 ± 5.49 D, P < 0.001). For students who used digital devices for online courses, the mean SE in the television group (-1.10 ± 1.49 D) was better than that in the computer group (-2.03 ± 2.37 D, P = 0.0017) and in the cell phone group (-2.02 ± 2.09 D, P = 0.0028). The average duration of online classes (r = -0.27, P < 0.0001), the number of online classes per day (r = -0.33, P < 0.0001), as well as digital screen exposure time (r = -0.20, P < 0.0001) were negatively correlated with SE, and the average time of outdoor activity (r = 0.20, P < 0.0001) was positively correlated with SE. Conclusions: Increased digital screen exposure contributes to myopic progression in children and adolescents of Chongqing during the COVID-19 pandemic. Suitable digital devices should be provided for online classes and outdoor activity should be advocated to prevent myopic pandemic.

IMI Accommodation and Binocular Vision in Myopia Development and Progression

The role of accommodation in myopia development and progression has been debated for decades. More recently, the understanding of the mechanisms involved in accommodation and the consequent alterations in ocular parameters has expanded. This International Myopia Institute white paper reviews the variations in ocular parameters that occur with accommodation and the mechanisms involved in accommodation and myopia development and progression. Convergence is synergistically linked with accommodation and the impact of this on myopia has also been critiqued. Specific topics reviewed included accommodation and myopia, role of spatial frequency, and contrast of the task of objects in the near environment, color cues to accommodation, lag of accommodation, accommodative-convergence ratio, and near phoria status. Aspects of retinal blur from the lag of accommodation, the impact of spatial frequency at near and a short working distance may all be implicated in myopia development and progression. The response of the ciliary body and its links with changes in the choroid remain to be explored. Further research is critical to understanding the factors underlying accommodative and binocular mechanisms for myopia development and its progression and to guide recommendations for targeted interventions to slow myopia progression.

IMI Risk Factors for Myopia

Risk factor analysis provides an important basis for developing interventions for any condition. In the case of myopia, evidence for a large number of risk factors has been presented, but they have not been systematically tested for confounding. To be useful for designing preventive interventions, risk factor analysis ideally needs to be carried through to demonstration of a causal connection, with a defined mechanism. Statistical analysis is often complicated by covariation of variables, and demonstration of a causal relationship between a factor and myopia using Mendelian randomization or in a randomized clinical trial should be aimed for. When strict analysis of this kind is applied, associations between various measures of educational pressure and myopia are consistently observed. However, associations between more nearwork and more myopia are generally weak and inconsistent, but have been supported by meta-analysis. Associations between time outdoors and less myopia are stronger and more consistently observed, including by meta-analysis. Measurement of nearwork and time outdoors has traditionally been performed with questionnaires, but is increasingly being pursued with wearable objective devices. A causal link between increased years of education and more myopia has been confirmed by Mendelian randomization, whereas the protective effect of increased time outdoors from the development of myopia has been confirmed in randomized clinical trials. Other proposed risk factors need to be tested to see if they modulate these variables. The evidence linking increased screen time to myopia is weak and inconsistent, although limitations on screen time are increasingly under consideration as interventions to control the epidemic of myopia.

TuYou-County Pediatric Eye (TYPE) study, design issues, baseline demographic characteristics, and implications: Report number 1

To report the rationale, design, and baseline demographic characteristics of TuYou-County Pediatric Eye study, which mainly aimed to determine the retinal microvascular changes with optical coherence tomography angiography (OCTA) and its association with eye abnormalities in school aged children and adolescents at suburban location in Northern China.TuYou-County Pediatric Eye study was a school-based survey conducted in TuYou-County. Multi-ethnic (Mongol, Han, and Hui) participants will be followed up for 5 years. Standardized ophthalmological examinations include visual acuity, ocular biometry, retinal photography, and OCTA. A questionnaire survey was conducted to collect variables regarding to eye disease such as parental history of eye diseases, near work, outdoor activities, living and eating habits, etc.After sampling, 687 participants were eligible for investigation, and 20 students did not attend the investigation, living 667 (response rate, 97.1%) students completed questionnaires and all ocular examinations. The average age of all participants was 14.9 ± 5.11.TYPE study is the first large-scale school-based multi-ethnic survey in suburban site of Northern China. Continuous identification of retinal microvascular changes with eye diseases will provide new insights into the control related diseases in school-age children and adolescents.

Naturally-occurring myopia and loss of cone function in a sheep model of achromatopsia

Achromatopsia is an inherited retinal disease characterized by loss of cone photoreceptor function. Day blind CNGA3 mutant Improved Awassi sheep provide a large animal model for achromatopsia. This study measured refractive error and axial length parameters of the eye in this model and evaluated chromatic pupillary light reflex (cPLR) testing as a potential screening test for loss of cone function. Twenty-one CNGA3 mutant, Improved Awassi, 12 control Afec-Assaf and 12 control breed-matched wild-type (WT) Awassi sheep were examined using streak retinoscopy and B-mode ocular ultrasonography. Four CNGA3 mutant and four Afec-Assaf control sheep underwent cPLR testing. Statistical tests showed that day-blind sheep are significantly more myopic than both Afec-Assaf and WT Awassi controls. Day-blind sheep had significantly longer vitreous axial length compared to WT Awassi (1.43 ± 0.13 and 1.23 ± 0.06 cm, respectively, p < 0.0002) and no response to bright red light compared to both controls. Lack of response to bright red light is consistent with cone dysfunction, demonstrating that cPLR can be used to diagnose day blindness in sheep. Day-blind sheep were found to exhibit myopia and increased vitreous chamber depth, providing a naturally occurring large animal model of myopia.

Effectiveness of a novel mobile health (Peek) and education intervention on spectacle wear amongst children in India: Results from a randomized superiority trial in India

BACKGROUND

Uncorrected refractive errors can be corrected by spectacles which improve visual functioning, academic performance and quality of life. However, spectacle wear can be low due to teasing/bullying, parental disapproval and no perceived benefit.Hypothesis: higher proportion of children with uncorrected refractive errors in the schools allocated to the intervention will wear their spectacles 3-4 months after they are dispensed.

METHODS

A superiority, cluster-randomised controlled trial was undertaken in 50 government schools in Hyderabad, India using a superiority margin of 20%. Schools were the unit of randomization. Schools were randomized to intervention or a standard school programme. The same clinical procedures were followed in both arms and free spectacles were delivered to schools. Children 11-15 years with a presenting Snellen visual acuity of <6/9.5 in one or both eyes whose binocular acuity improved by ≥2 lines were recruited.In the intervention arm, classroom health education was delivered before vision screening using printed images which mimic the visual blur of uncorrected refractive error (PeekSim). Children requiring spectacles selected one image to give their parents who were also sent automated voice messages in the local language through Peek. The primary outcome was spectacle wear at 3-4 months, assessed by masked field workers at unannounced school visits. www.controlled-trials.com ISRCTN78134921 Registered on 29 June 2016.

FINDINGS

701 children were prescribed spectacles (intervention arm: 376, control arm: 325). 535/701 (80%) were assessed at 3-4 months: intervention arm: 291/352 (82.7%); standard arm: 244/314 (77.7%). Spectacle wear was 156/291 (53.6%) in the intervention arm and 129/244 (52.9%) in the standard arm, a difference of 0.7% (95% confidence interval (CI), -0.08, 0.09). amongst the 291 (78%) parents contacted, only 13.9% had received the child delivered PeekSim image, 70.3% received the voice messages and 97.2% understood them.

INTERPRETATION

Spectacle wear was similar in both arms of the trial, one explanation being that health education for parents was not fully received. Health education messages to create behaviour change need to be targeted at the recipient and influencers in an appropriate, acceptable and accessible medium.

FUNDING

USAID (Childhood Blindness Programme), Seeing is Believing Innovation Fund and the Vision Impact Institute.

Analysis of parental decisions to use orthokeratology for myopia control in successful wearers

PURPOSE

To investigate factors that influence parental decisions to use orthokeratology (ortho-k) as a myopia control method for their children, and parents' perspectives during children's ortho-k treatment in a hospital setting.

METHODS

Parents/guardians of children wearing ortho-k lenses for at least six months were required to complete a face-to-face survey to investigate the reasons for choosing ortho-k and their experience of the treatment.

RESULTS

Parents/guardians of 128 ortho-k wearers were recruited from the West China Hospital, Sichuan, China. The majority of the participants (74%) were mothers. Wearers' mean age at the time of the survey was 12.0 ± 2.0 years, with a mean history of ortho-k lens wear of 20.3 ± 8.0 months. Most participants had learned about ortho-k through word of mouth (56%) or from ophthalmologists (40%); in China, only ophthalmologists may prescribe ortho-k. The highest ranked motivation was the rapid progression of their children's myopia (54%), followed by ophthalmologists' advice (17%) or participants' who felt they had obtained enough knowledge (17%) of ortho-k (Kruskal-Wallis test, p = 0.002). 'Effectiveness' was the most common reason that participants decided to use ortho-k (81%), and potential injury was their major concern (75%). Itchy/sore eye was the most common initial adverse effect experienced with lens wear (22%), while a lost or broken ortho-k lens was the most frequently reported problem (34%). Parents of older lens wearers were significantly less involved in all procedures (Spearman rank correlation test, all p < 0.001). Most wearers, according to either the participants or the wearers themselves, were willing to wear ortho-k lenses at treatment commencement (80%), and the most common reason was 'to avoid having to wear spectacles in the daytime'.

CONCLUSIONS

The most powerful motivation for parents to enrol their children in ortho-k treatment was the rapid progression of myopia. The main reason why participants chose ortho-k, which most participants learned of by word of mouth, was the effectiveness of the treatment. During use, the most common symptom reported was itchy or sore eyes, but only initially. Children's willingness to participate is very important for successful ortho-k treatment; however, their motivation can be quite different from that of their parents. Ortho-k is a well-accepted option for myopia control in children.

Prenatal and neonatal factors for the development of childhood visual impairment in primary and middle school students: a cross-sectional survey in Guangzhou, China

OBJECTIVES

In this cross-sectional survey, we sought to determine the prevalence of and the influence of prenatal and neonatal factors on childhood visual impairment without correction (VIUC) in a paediatric population from Guangzhou, China.

SETTING

The health survey covered 11 administrative districts in Guangzhou, including 991 schools.

PARTICIPANTS

All of the primary and middle school students in Guangzhou were invited to complete an online questionnaire with the help of their parents. The results of physical examinations were reported by school medical departments. The results of the questionnaire were collected by the researchers. In total, 253 301 questionnaires were collected.

PRIMARY OUTCOME MEASURES

The students' uncorrected visual acuity (UCVA) was examined by trained optometrists by standard logarithmic visual acuity charts. VIUC was defined by UCVA (of the better eye) (UCVA <6/12) with three levels: light VIUC (UCVA ≥6/18 to <6/12), mild VIUC (UCVA ≥6/60 to <6/18) and severe VIUC (UCVA <6/60).

RESULTS

A total of 39 768 individuals (15.7%) had VIUC, and the rate was much higher among grade 10 to 12 students (51.4%) than among grade 1 to 6 students (6.71%). The following factors were significantly associated with an increased risk of VIUC: female gender, high birth weight, formula feeding, not having siblings, higher level of parents' education, parental myopia, much homework time and little outdoor activity. Delivery mode was not associated with the risk of VIUC.

CONCLUSIONS

This study validates known major prenatal/genetic, perinatal and postnatal factors for childhood VIUC. In conclusion, prenatal and perinatal factors can affect the onset of childhood VIUC, but parental myopia and postnatal factors are the main factors.

Neonatal vitamin D status and myopia in young adult men

PURPOSE

The prevalence of myopia is increasing worldwide, and modifiable risk factors are thus important to identify. Season of birth has been associated with later myopia risk. Neonatal vitamin D status is highly dependent on season of birth due to maternal sun exposure late in gestation. We hypothesize that prenatal exposure to low levels of vitamin D can interfere with visual development in term-born infants and that this might contribute to adult visual dysfunction. The aim of this study was thus to compare neonatal vitamin D levels from stored dried blood spots taken shortly after birth among young term-born men with myopia (cases) and random controls with emmetropia.

METHODS

In this case-control study, we analysed neonatal 25(OH)D₃ levels of 457 myopic male cases and 1280 emmetropic male controls assessed for myopia at the mandatory Danish conscript examination. Data were analysed using logistic regression analysis and results presented as crude and adjusted for potential confounders namely maternal age, maternal ethnicity, maternal and paternal education and season of birth.

RESULTS

We did not observe a seasonal variation in myopia risk, neither did we observe increased odds of myopia in relation to low neonatal 25(OH)D₃ levels.

CONCLUSION

The rapid increase in myopia does not seem related to neonatal vitamin D status.

Accommodation is unrelated to myopia progression in Chinese myopic children

This study shows accommodative accuracy and distance accommodation facility in myopic children do not play a role in myopia progression. In 144 subjects, the monocular distance accommodative facility (DAF) and continuous accommodative stimulus-response curves (ASRCs) were measured at the enrolment. Retrospective and prospective refraction with regard to the enrolment visit were obtained from the outpatient database system based on noncycloplegic subjective spherical equivalent refraction (SER). The rate of myopic progression at enrolment was the first derivative of the Gompertz function, which was fitted with each subject's longitudinal refractive error data, including at least four records of SER with an interval of more than 6 months between each visit. A mixed linear model for multilevel repeated-measures data was used to explore the associations between the rate of myopia progression and accommodative parameters. The mean rate of myopia progression at enrolment was -0.61 ± 0.31 D/y with a mean age of 12.27 ± 1.61 years. By adjusting for age and SER, it was shown that the myopic progression rate was not associated with the accommodative lag (F = 0.269, P = 0.604), accommodative lag area (F = 0.086, P = 0.354), slope of ASRC (F = 0.711, P = 0.399), and DAF (F = 0.619, P = 0.432).

The Role of Time Exposed to Outdoor Light for Myopia Prevalence and Progression: A Literature Review

Purpose

The development of myopia as a refractive disorder seems to hold multifactorial causes. Among others, increased time exposed to natural light outdoors is regarded as possible effective preventive measure against myopia development. The objective of this review is to analyse and summarize the evidence investigating the association between time outdoors and myopia prevalence and progression.

Methods

A review, restricted to articles published in the last ten years, was conducted. The literature search for the included articles was performed in the following databases: PubMed, the Cochrane Library, Web of Science and Scopus. If predefined inclusion criteria were met, the studies were further categorized and data were summarized and individually evaluated.

Results

Two cross-sectional studies, 7 prospective cohort studies and 3 intervention studies were reported in this review, representing the data of a total of 32,381 participants. The majority of the studies found an inverse association between myopia incidence/prevalence and increased time outdoors. The association between time outdoors and myopia progression on the other hand remains debatable; one recent randomized controlled trial indicating a protective value of increased time outdoors for further progression in myopic children.

Conclusion

In summary, increasing time exposed to outdoor light seems to be a simple and effective preventive measure to decrease myopia prevalence. Also, contrasting previous review work, it may represent a potential strategy for myopia progression control. Future investigation is necessary to better define and quantify outdoor time and its effects on myopia.

Myopia in school-aged children with preterm birth: the roles of time spent outdoors and serum vitamin D

AIMS

To analyse the factors associated with myopia in school-aged children with preterm birth and with or without retinopathy of prematurity (ROP).

METHODS

Children born prematurely between January 2010 and December 2011 were enrolled in this cross-sectional study when they reached school age between April 2017 and June 2018 in a referral centre. The main parameters were cycloplegic refraction, time spent outdoors and serum 25-hydroxyvitamin D (25(OH)D) concentration.

RESULTS

A total of 99 eyes from 99 children with a mean age of 6.8 years underwent analysis. The average time spent outdoors was significantly higher in the non-myopic group (0.9 ± 0.5 hours/day) than in the myopic group (0.7 ± 0.3 hours/day) (p = 0.032). After adjustment for age, sex, number of myopic parents, ROP severity, near-work time and serum 25(OH)D concentration, more time spent outdoors was correlated with a lower odds of myopia (OR, 0.13 per additional hour per day; 95% CI, 0.02-0.98; p = 0.048). Mean serum 25(OH)D concentrations were similar between the myopic and non-myopic groups (49.7 ± 13.6 and 48.8 ± 14.0 nmol/mL; p = 0.806) and were not correlated with spherical equivalence power (r = -0.09; p = 0.418). Vitamin D insufficiency was present in 57% of the participants.

CONCLUSIONS

Among preterm children with or without ROP, more time spent outdoors was associated with lower odds of myopia. The serum 25(OH)D concentration was not associated with myopia, but a high proportion of the participants had insufficient levels.

Performance of Topological Perception in the Myopic Population

Purpose: Discriminating objects' topological property (TP) is a primitive function of visual representation, which is reported to be associated with magnocellular (M) visual pathway, temporal lobe (TL), and superior colliculus (SC)-pulvinar subcortical pathway. Previous studies have shown that M pathway and TL were affected in high myopia (HM) subjects. The study was accordingly designed to explore whether topological perception performance was abnormal in HM subjects. Methods: 30 mildly myopic, 25 moderately myopic, 35 highly myopic, and 20 emmetropic subjects were enrolled. All participants underwent a comprehensive ophthalmological assessment including automated refraction, intraocular pressure, Humphrey 10-2 standard automated perimetry, ocular fundus photography and swept-source optical coherence tomography. Defined by differences in hole, TP and non-TP discrimination with letters "E", "S", "P", "d" as stimuli in the central and peripheral regions was performed using the MATLAB 2017 software. d-primes extracted from the software were analyzed within each group. The correlation of peripheral TP/non-TP deficit with spherical equivalent (SE), axial length (AL) and average peripapillary retinal nerve fiber layer (RNFL) thickness was performed. Results: The patterns of topological perception performance were similar among the groups. TP discrimination peripherally was significantly better than that centrally in the mild myopia (P < .001), moderate myopia (P < .001), high myopia (P < .001) and emmetropia groups (P = .001). In the peripheral region, TP d-prime scores were significantly better than non-TP d-prime scores (all P < .001). The main and interaction effects of eccentricity and stimulus type were statistically significant(P < .05). There was no statistically significant correlation between peripheral TP/non-TP deficit and SE, AL or average RNFL thickness (P > .05). Conclusions: The current study first showed that patterns of topological perception among the myopic population were similar and not affected by the severity of myopia.

The Prevalence of Myopia and Factors Associated with It Among Secondary School Children in Rural Vietnam

Purpose

To assess the prevalence of myopia and associated factors among secondary school children in a rural area of Vietnam.

Methods

A school-based cross-sectional study of children in grades six to nine was conducted in four secondary schools in Hoang Mai town, Nghe An Province, Vietnam, during December 2018 and January 2019. The status of myopia was defined as a spherical equivalent objective refractive error of −0.50 D or worse in either eye. A case–control study was conducted to explore factors associated with myopia, where children with myopia were considered to be cases, and children without myopia were considered to be controls. Factors associated with myopia were analyzed using univariate and multivariate logistic regression.

Results

The prevalence of myopia among secondary school children was 14.2% (95% CI: 12.7–15.7%) and tended to increase with grade, from 10.5% in grade six to 17.7% in grade nine. Myopia prevalence in girls was significantly higher than in boys. Factors associated with myopia were a mother with a college/university education (OR = 2.5, 95% CI = 1.2–5.3), parents who wore spectacles (OR = 2.0, 95% CI = 1.1–3.8), distance from near work (OR = 5.2, 95% CI = 3.5–7.9), and taking breaks after 30 minutes of continued reading (OR = 1.6, 95% CI = 1.1–2.5). However, there were inverse associations with myopia for children belonging to the wealthiest households (OR = 0.2, 95% CI = 0.1–0.5) and time spent performing outdoor activities (OR = 0.6, 95% CI = 0.4–0.9).

Conclusion

Our study showed that the prevalence of myopia is considerable among secondary children in rural areas of Vietnam. The prevalence of myopia tended to increase among children in higher grade levels. Thus, appropriate interventions should be developed and conducted to deal with the issue of school-age myopia.