Prevalence of Myopia and Its Associated Factors Among Japanese Preschool Children

Global burden of blindness and vision loss among children and adolescents: A systematic analysis for the global burden of disease study 2021

AIM

This study investigates the global burden of vision impairment caused by refraction disorders, near vision loss, and other vision loss among children and adolescents from 1990 to 2021. The analysis is categorized globally by sex, age, and socio-demographic index (SDI), with a focus on predicting trends to 2035.

METHODS

Data weas obtained from the Global Burden of Disease Study 2021. We reported the prevalence and disability-adjusted life-years (DALYs) of vision impairment due to refraction disorders, near vision loss, and other vision loss globally. Then, we described the prevalence and DALYs numbers and rates by sex, SDI and age. Next, we analyzed the relationship between rate and SDI. Finally, bayesian age-period-cohort (BAPC) analysis model was used to predict the trends from 2022 to 2035 globally by sex and age.

RESULTS

The prevalence and DALYs rates for refraction disorders had a statistically significant trend of reduction in four age groups globally and were positively associated with SDI. The prevalence and DALYs rates for near vision loss were increasing in four age groups, and were negatively associated with SDI. The BAPC model indicates that the age-specific prevalence and DALYs rates of refraction disorders and other vision loss in both men and women will remain on a downward trend until 2035, while near vision loss continues to rise.

CONCLUSIONS

The findings underscore that there are extensive variations based on the type of vision impairment, age group, sex and SDI. Policies should be tailored to specific types in order to effectively alleviate the burden.

Relationship between the axial length/corneal radius of curvature ratio and hyperopia reserve in preschool children aged 3 - 6 years

PURPOSE

This study aimed to investigate the association between the axial length (AL) to average corneal curvature (CR) ratio and hyperopia reserve in preschool children.

METHODS

AL, CR, horizontal and vertical meridians of the corneal radius (CR1, CR2), and 1% atropine cycloplegic refraction were measured in preschool children aged 3 - 6 years. The corneal curvatures were then used to calculate the AL/CR1, AL/CR2, and AL/CR ratios.

RESULTS

A total of 338 children were included, comprising 178 boys (52.7%) and 160 girls (47.3%). The mean values for AL, CR, AL/CR1, AL/CR2, AL/CR, and spherical equivalent refractive error (SER) were 22.11 ± 0.88 mm, 7.77 ± 0.26 mm, 2.80 ± 0.09, 2.90 ± 0.09, 2.85 ± 0.09, and + 2.13 ± 1.46 D, respectively. AL, AL/CR1, AL/CR2, and AL/CR increased with age, showing significant differences among age groups (P < 0.001). Conversely, SER moved from higher hyperopia toward lesser hyperopia with age, also showing significant differences among age groups (P < 0.001). Linear regression equations were established, with Y representing hyperopia reserve and X representing AL/CR: Age 3: Y = 44.67 - 15.02X; Age 4: Y = 33.96 - 11.19X; Age 5: Y = 42.11 - 13.98X; Age 6: Y = 44.94 - 15.00X. These results suggest that the AL/CR ratio could be used to assess hyperopia reserve insufficiency. The optimal cut-off point for the receiver operating characteristic (ROC) curve was ≥ 2.91, with a sensitivity, specificity, and Youden index of 0.84, 0.88, and 0.73, respectively. The critical value of the ROC curve increased with age in children aged 3 - 6 years.

CONCLUSION

This cross-sectional study found that the hyperopia reserve in children of different ages can be estimated using the hyperopia reserve equation. Additionally, the AL/CR ratio can serve as an effective index for detecting hyperopia reserve insufficiency, with an optimal ROC curve cut-off point of ≥ 2.91 in preschool children aged 3 - 6 years, and the critical value increasing with age.

Social behavioral analysis of the influence of residential area and grade on pupils' myopia rate: a cross-sectional survey in Nanjing, China

Objective

This study aims to examine the prevalence of myopia among pupils in different residential areas (city center, nearby suburbs, and far suburbs) and grade levels (lower, middle, and upper), analyzing social behaviors and risk factors to guide early intervention.

Methods

A cross-sectional survey was conducted with elementary students across various regions in Nanjing. A total of 2,342 valid questionnaires were collected. Univariate and multivariate logistic regression analyses were used to identify and assess risk factors for myopia and their variations across regions and grade levels.

Results

The survey revealed an overall myopia prevalence of 35.65% (95% CI = 33.71-37.59) among pupils in Nanjing, with the highest rate observed in nearby suburbs (41.34, 95% CI = 38.37-44.31). Myopia prevalence increased with grade level. Multivariate logistic regression analysis identified 8 significant risk factors for myopia, including visual fatigue, frequent eye rubbing, late bedtimes, heavy study burdens, insufficient time spent outdoors, insufficient device breaks, mobile phone use, and infrequent vision checks. Risk factors for myopia varied by region and grade level. Common risk factors across all groups included visual fatigue and infrequent vision checks. City center exhibited unique risk factors, such as late bedtimes and insufficient time spent outdoors. Nearby suburbs displayed unique risk factors, including heavy study burdens and entertainment-oriented electronic device use. Far suburbs displayed a unique risk factor in the prevalent use of mobile phones. Besides, lower grade students showed notably higher entertainment-oriented electronic device use, while upper grade students were more likely to have late bedtimes and insufficient device breaks.

Conclusion

Different social behavioral factors play a key role in the occurrence of myopia among pupils in different regions and grades, and targeted intervention measures need to be developed based on regional characteristics and grade level features.

Digital Screen Time and Myopia: A Systematic Review and Dose-Response Meta-Analysis

Importance

The association of digital screen time with myopia has been documented, but the dose-response association and safe exposure threshold remain unclear.

Objective

To evaluate the dose-response association of time spent on digital screens with myopia risk.

Data Sources

PubMed, EMBASE, Cochrane Library databases, CINAHL, and ClinicalTrials.gov were searched for full-length articles from peer-reviewed journals without restrictions on study design, publication date, or language from inception to November 25, 2024.

Study Selection

Primary research articles investigating the association of exposure to digital screen devices (ie, smartphones, tablets, game consoles, computers, or television) with myopia-related outcomes (ie, prevalent or incident myopia and the rate of myopia progression) were identified by reviewers.

Data Extraction and Synthesis

Two independent reviewers extracted data using a standardized procedure in accordance with the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. A random-effects, dose-response meta-analysis (DRMA) was utilized to examine the pattern of the association of screen time with myopia.

Main Outcome and Measures

Increased odds of myopia per hour of daily screen time.

Results

In the linear DRMA of 45 studies with 335 524 participants (mean [SD] age, 9.3 [4.3] years), an additional hour of daily screen time was associated with higher odds of myopia (odds ratio [OR], 1.21; 95% CI, 1.13-1.30). The nonlinear DRMA of 34 studies with 314 910 participants also indicated higher odds of myopia with increasing screen time, ranging from 1 hour of daily exposure (OR, 1.05; 95% CI, 1.01-1.09) to 4 hours (OR, 1.97; 95% CI, 1.56-2.40). The dose-response curve showed myopia risk increasing significantly between 1 to 4 hours of daily screen time, and then rising more gradually after 4 hours.

Conclusions and Relevance

In this systematic review and DRMA, a daily 1-hour increment in digital screen time was associated with 21% higher odds of myopia and the dose-response pattern exhibited a sigmoidal shape, indicating a potential safety threshold of less than 1 hour per day of exposure, with an increase in odds up to 4 hours. These findings can offer guidance to clinicians and researchers regarding myopia risk.

Weight Status and Myopia in Children and Adolescents: A Nationwide Cross-Sectional Study of China

BACKGROUND/OBJECTIVES

The prevalence of both myopia and obesity is increasing among children and adolescents around the world. We aimed to examine the association between weight status and myopia in Chinese children and adolescents.

METHODS

The analysis included 35,108 participants aged 6-17 from a nationwide cross-sectional survey.

RESULTS

Our results indicated that girls with overweight and obesity had higher odds ratio (OR) of myopia and mild myopia: ages 6-8 (OR = 1.33, 95% CI: 1.01-1.76; OR = 1.71, 95% CI: 1.14-2.55) and 9-11 (OR = 1.22, 95% CI: 1.03-1.44; OR = 1.31, 95% CI: 1.06-1.62). Myopic boys had higher body fat percentages (BFP) at ages 6-8 (β = 1.18, 95% CI: 0.38-1.98), 9-11 (β = 0.58, 95% CI: 0.08-1.07), and 15-17 (β = 0.42, 95% CI: 0.03-0.80), and higher body mass index (BMI) at ages 9-11 (β = 0.30, 95% CI: 0.12-0.48) and 12-14 (β = 0.19, 95% CI: 0.02-0.38). Girls had higher BFP at ages 9-11 (β = 0.62, 95% CI: 0.19-1.05) and 12-14 (β =0.53, 95% CI: 0.19-0.88) and higher BMI at 9-11 (β = 0.53, 95% CI: 0.34-0.73). Furthermore, the dose-response curves revealed a significant gender- and age-specific association between BMI, BFP, and myopia odds ratio.

CONCLUSIONS

the study found an association between overweight or obesity and myopia in girls aged 6-11, and indicated that high BFP and BMI are associated with myopia, varying by sex and age.

Axial length to corneal curvature radius ratio is negatively correlated with choroidal blood flow in myopic children

Background

The pathophysiologic mechanisms underlying early-onset myopia remain unclear; in this study, we investigate the pathogenesis by examining the interrelationships between axial length to corneal curvature radius ratio ( AL / CR ) and choroidal blood flow.

Methods

This cross-sectional study included 202 eyes from myopic children, categorized into 141 eyes with mild myopia, 47 eyes with moderate myopia, and 14 eyes with high myopia. Optical coherence tomography angiography (OCTA) was used to measure choroidal blood flow perfusion within a 6 mm × 6 mm area of the macular region, divided into nine subareas based on ETDRS partitioning: macular fovea, nasal side 1, superior 1, temporal side 1, inferior 1, nasal side 2, superior 2, temporal side 2, and inferior 2. Data on corneal curvature and ocular axial length were collected to calculate the AL / CR , with equivalent spherical lens power, gender, and age gathered for group comparisons, and the correlation between AL/CR and choroidal blood flow perfusion volume was analyzed.

Results

AL / CR was significantly negatively correlated with choroidal blood flow perfusion ( P < 0.001 ). Linear regression and mediation analyses indicated that for each unit increase in choroidal blood perfusion volume in nasal region 1, AL / CR decreased by an average of 0.421 units. This relationship is mediated by several factors, with axial length serving as a key mediator.

Conclusion

AL / CR correlates with choroidal blood flow perfusion, indicating a link between refractive biological parameters and ocular blood circulation. Myopia is an ischemic eye condition that warrants attention to fundus microcirculation changes in myopic children.

Role of lens in early refractive development: evidence from a large cohort of Chinese children

AIMS

To document longitudinal changes in spherical equivalent refraction (SER) and related biometric factors during early refractive development.

METHODS

This was a prospective cohort study of Chinese children, starting in 2018 with annual follow-ups. At each visit, children received cycloplegic autorefraction and ocular biometry measurements. Lens power (LP) was calculated using Bennett's formula. Children were divided into eight groups based on baseline age: the 3-year-old (n=426, 49.77% girls), 4-year-old (n=834, 47.36% girls), 6-year-old (n=292, 46.58% girls), 7-year-old (n=964, 43.46% girls), 9-year-old (n=981, 46.18% girls), 10-year-old (n=1181, 46.32% girls), 12-year-old (n=504, 49.01%) and 13-year-old (n=644, 42.70%) age groups.

RESULTS

This study included right-eye data from 5826 children. The 3-year-old and 4-year-old age groups demonstrated an inflection point in longitudinal SER changes at a mild hyperopic baseline SER (+1 to +2 D), with children with more myopic SER showing hyperopic refractive shifts while those with more hyperopic SER showing myopic shifts. The hyperopic shift in SER was mainly attributed to rapid LP loss and was rarely seen in the older age groups. Axial elongation accelerated in the premyopia stage, accompanied by a partially counter-balancing acceleration of LP loss. For children aged 3-7 years, those with annual SER changes <0.25 D were all mildly hyperopic at baseline (mean: 1.23 D, 95% CI 1.20 to 1.27 D).

CONCLUSION

Our findings suggest that during early refractive development, refractions cluster around or above +1.00 D. There is a pushback process in which increases in the rate of LP occur in parallel with increases in axial elongation.

Myopic shift in female mice after ovariectomy

Myopia is a global public health concern, with a higher prevalence in women than that in male. As the relationship between sex hormone and myopia remains unclear, we aimed to reveal the relationship between sex hormone and myopia by removing the ovaries of mice and measuring changes in ocular parameters related to myopia. Lens-induced myopia (LIM) surgeries were performed on 3-week-old male mice and age-matched female mice to evaluate the effects of sex on myopia development, which indicated a high degree of myopia and rapid progression of axial elongation in male mice. Bilateral ovariectomy (OVX) performed on 4-week-old female mice induced myopic refraction status in ovariectomized mice. Although axial length elongation was larger in ovariectomized mice than that in sham control mice, the result was insignificant. To further reveal the relationship between female sex hormones and myopia, LIM combined with OVX was performed, which revealed a magnified myopic refraction status in ovariectomized mice. Nevertheless, elongation of the anterior chamber depth in the - 30 D lens-treated eyes significantly increased in LIM + OVX mice compared with the frame-treated eyes in LIM + OVX mice and - 30 D lens-treated eyes in LIM + Sham surgery mice. Sex hormones play a role in regulating myopia development in female mice.

Epidemiology of Myopia: Prevalence, Risk Factors and Effects of Myopia

Myopia is the most common cause of visual impairment in children and young adults. In order to assess the consequences for society, it is necessary to know temporal trends in prevalence, incidence and associated factors in childhood and adolescence, as well as the rate of myopia progression, as based on epidemiological research. This paper presents a literature review of publications from 2020 up to March 2024, supplemented by other relevant publications. The prevalence of myopia in children and adolescents in Germany is almost stable and is significantly lower than in Asia. The development of myopia is influenced by outdoor activity, parental myopia, genetics and near work, while insufficient time spent outdoors in childhood is a significant and controllable risk factor for myopia-related complications such as myopic maculopathy, glaucoma, and retinal detachment.

Interdependence of Nutrition, Physical Activity, and Myopia

Background: Myopia (also known as nearsightedness), a prevalent refractive error, occurs when parallel rays of light converge in front of the retina, resulting in blurry distance vision. Recently, there has been a marked rise in myopia among the global population. The absence of effective methods of controlling the progression of this visual defect prompts the search for new preventive and therapeutic options. The impact of diet and lifestyle on the progression of myopia is still not fully understood. Therefore, our aim was to examine how these factors might affect the advancement of myopia, based on the existing literature. Methods: This manuscript was prepared through an extensive literature review conducted from June 2022 to September 2024. We searched for pertinent research articles using reputable databases, including PubMed, Scopus, and Web of Science. We included all types of publications, with a special focus on the newest ones. Results: Despite far-reaching examination, the relationship between these factors and myopia control remains inconclusive with varying degrees of evidence supporting their roles. Conclusions: However, promoting a healthy lifestyle, particularly increasing physical activity and outdoor time, is essential. Additionally, emerging research suggests that maintaining a balanced diet is important due to the potential impact of certain nutrients on myopia development. Ophthalmologists should also guide parents on the alternative correction methods beyond single vision glasses, especially for rapidly progressing cases. With the rising prevalence of myopia in children, further research is necessary.

Link between parental myopia and early-onset high myopia: Insights from a clinical retrospective analysis

INTRODUCTION

Genetic aetiology is suspected in the development of early-onset high myopia (spherical equivalent refractive error [SER] ≤-6.00 D at ≤6 years of age), considering that the role of environmental factors in inducing high myopia is improbable at an early age. Therefore, we aimed to understand if early-onset high myopia is associated with parental myopia in a clinical setting.

METHODS

A retrospective study was conducted in which information about demographics, age of apparent onset of myopia, refractive error, axial length, number of myopic parents, time spent outdoors and time spent on near-work was obtained from electronic medical records (EMR). It included 195 myopic individuals categorised into (1) Early-onset high myopes (EOHM): SER ≤ -6.00 D with age of presentation ≤6 years, (2) Early-onset low myopes (EOLM): SER > -6.00 D with age of apparent onset ≤6 years, (3) Late-onset high myopes (LOHM): SER ≤ -6.00 D with age of presentation and age of apparent onset >6 years and (4) Late-onset low myopes (LOLM): SER > -6.00 D with age of apparent onset >6 years.

RESULTS

Overall, 63% of individuals were found to have parental myopia. The proportion of individuals with EOHM, EOLM, LOHM and LOLM with parental myopia was 57%, 74%, 53% and 64%, respectively. After adjustment for age, gender and environmental factors, the odds of development of EOHM (Odds ratio: 0.78, 95% confidence interval: 0.25-2.48), EOLM (1.54, 0.65-3.67) or LOHM (0.70, 0.30-1.65) were similar in the presence of myopic parents, when compared with LOLM. The SER and axial length did not differ based on the number of myopic parents in any of these categories.

CONCLUSION

This retrospective analysis reveals that the presence of parental myopia, which was self-reported, did not induce additional risk for early-onset high myopia.

Regional disparities in the prevalence and correlated factors of myopia in children and adolescents in Gansu, China

Background

Myopia is a significant public health problem across the globe. This study aimed to examine the regional disparity in prevalence and correlated factors of myopia in children and adolescents in two typical regions, Gannan Tibetan Autonomous Prefecture (Gannan Prefecture for short, a Tibetan residential area) and Wuwei City (a Han residential area) in Gansu Province, China, and to provide a reference for the prevention and control of regional myopia.

Methods

The study was a cross-sectional study of children and adolescents in Gansu Province, China. A total of 6,187 (Wuwei City: 3,266, Gannan Tibetan Autonomous Prefecture: 2,921) students were selected by stratified cluster sampling. Eye examinations and questionnaires were administered to the participants. Myopia is defined as a condition in which the spherical equivalent refractive error of an eye is less than or equal to -0.50 D when ocular accommodation is relaxed. The χ2 test and multivariate logistic regression analysis were used to analyze the correlated factors of myopia.

Results

The myopia rate of 6,187 students was 71.4%, and students had a higher rate of myopia (77.5%) in Wuwei City compared to Gannan Prefecture (64.6%) (p < 0.001). The results of multivariate analysis in Wuwei City showed that girls (odds ratio (OR) = 1.325), junior students (OR = 2.542), senior students(OR = 4.605), distance between eyes and book less than one foot (OR = 1.291), and parents with myopia (one, OR = 2.437; two, OR = 4.453) had higher risks of myopia (all, p < 0.05). For Gannan Prefecture, girls (OR = 1.477), senior students (OR = 1.537), daily time spent doing homework ≥2 h (OR = 1.420), the distance between eyes and book less than one foot (OR = 1.205), mean time continuous eye use (0.25-<0.5 h, OR = 1.345, 0.5-<1 h, OR = 1.317, ≥1 h, OR = 1.313), average daily sleep duration <8 h (OR = 1.399), and parents with myopia (one, OR = 1.852; two, OR = 2.913) had higher risks of myopia (all, p < 0.05).

Conclusion

The prevalence of myopia is at a relatively high level in Gansu Province. The prevalence and risk factors for myopia vary by region.

Myopia Control: Are We Ready for an Evidence Based Approach?

INTRODUCTION

Myopia and its vision-threatening complications present a significant public health problem. This review aims to provide an updated overview of the multitude of known and emerging interventions to control myopia, including their potential effect, safety, and costs.

METHODS

A systematic literature search of three databases was conducted. Interventions were grouped into four categories: environmental/behavioral (outdoor time, near work), pharmacological (e.g., atropine), optical interventions (spectacles and contact lenses), and novel approaches such as red-light (RLRL) therapies. Review articles and original articles on randomized controlled trials (RCT) were selected.

RESULTS

From the initial 3224 retrieved records, 18 reviews and 41 original articles reporting results from RCTs were included. While there is more evidence supporting the efficacy of low-dose atropine and certain myopia-controlling contact lenses in slowing myopia progression, the evidence about the efficacy of the newer interventions, such as spectacle lenses (e.g., defocus incorporated multiple segments and highly aspheric lenslets) is more limited. Behavioral interventions, i.e., increased outdoor time, seem effective for preventing the onset of myopia if implemented successfully in schools and homes. While environmental interventions and spectacles are regarded as generally safe, pharmacological interventions, contact lenses, and RLRL may be associated with adverse effects. All interventions, except for behavioral change, are tied to moderate to high expenditures.

CONCLUSION

Our review suggests that myopia control interventions are recommended and prescribed on the basis of accessibility and clinical practice patterns, which vary widely around the world. Clinical trials indicate short- to medium-term efficacy in reducing myopia progression for various interventions, but none have demonstrated long-term effectiveness in preventing high myopia and potential complications in adulthood. There is an unmet need for a unified consensus for strategies that balance risk and effectiveness for these methods for personalized myopia management.

Impact of ophthalmic clinical service use in mitigating myopia onset and progression in preschool children: a retrospective cohort study

BACKGROUND

Although school screenings identify children with vision problems and issue referrals for medical treatment at an ophthalmic hospital, the effectiveness of this approach remains unverified.

OBJECTIVE

To investigate the impact of ophthalmic clinical services on the onset and progression of myopia in preschool children identified with vision impairment.

METHODS

Using data from the Shanghai Child and Adolescent Large-scale Eye Study (SCALE), this retrospective cohort study evaluated the visual development of children from three districts-Jing'an, Minhang, and Pudong-which are representative of geographic diversity and economic disparity in Shanghai's 17 districts. Initially, in 2015, the study encompassed 14,572 children aged 4-6 years, of whom 5,917 needed a referral. Our cohort consisted of 5,511 children who had two or more vision screenings and complete personal information over the follow-up period from January 2015 to December 2020. We divided these children into two groups based on their initial spherical equivalent (SE): a High-risk group (SE > -0.5 D) and a Myopia group (SE ≤ -0.5 D). Within each of these groups, we further categorized children into Never, Tardily, and Timely groups based on their referral compliance to compare the differences in the occurrence and progression of myopia. Cox proportional models were applied to estimate hazard ratios (HRs) for myopia incidence per person-years of follow-up in High-risk group. Generalized additive models(GAM) was used to calculating the progression for annual spherical equivalent changes in all children.

RESULTS

Of the 5,511 preschool children (mean age, 5.25 years; 52.24% male) who received a referral recommendation, 1,327 (24.08%) sought clinical services at an ophthalmic hospital. After six years of follow-up, 65.53% of children developed myopia. The six-year cumulative incidence of myopia in the Never, Tardily, and Timely groups was 64.76%, 69.31%, and 57.14%, respectively. These percentages corresponded to hazard ratios (HRs) of 1.31 (95% CI, 1.10-1.55) for the Tardily group and 0.55 (95% CI, 0.33-0.93) for the Timely group, compared with the Never group. The HRs were adjusted for age, sex, and SE at study entry. Interestingly, the Timely group showed significantly less SE progression than the other groups (P < 0.001), and SE progression was higher in the High-risk group (-0.33 ± 0.37D/year) than in children with myopia (-0.08 ± 0.55D/year).

CONCLUSION

Timely utilization of ophthalmic clinical services among children aged 4 to 6 years who fail school vision screenings can significantly reduce the incidence of myopia and slow SE progression.

Refraction and ocular biometric parameters in 3-to 6-year-old preschool children : a large-scale population-based study in Chengdu, China

PURPOSE

To understand the ocular biometric parameters characteristics and refractive errors in 3-to 6-year-old preschool children in Chengdu, China, and to investigate the prevalence of refractive errors.

METHOD

A school-based cross-sectional study was conducted in Chengdu from 2020 to2022 with a total of 666 kindergartens. All children were measured by non-cycloplegic autorefraction and uncorrected visual acuity (UCVA) and ocular biometric parameters. Finally, univariate linear regression models were used to analyze the relationship between ocular biometric parameters and refraction.

RESULTS

A total of 108,578 preschool children aged 3-6 underwent examinations, revealing a myopia prevalence of 6.1%. The mean axial length (AL), keratometry (K), corneal radius (CR), axial length/corneal radius (AL/CR) Ratio, central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were 22.35 ± 0.69 mm, 43.35 ± 1.58 D, 7.80 ± 0.28 mm, 2.87 ± 0.08, 533.31 ± 32.51 μm, 2.70 ± 0.28 mm, 3.91 ± 0.27 mm, and 15.20 ± 0.68 mm, respectively. With increasing age, AL, CR, AL/CR ratio, CCT, ACD, LT, and VCD also increased. Regardless of age, males consistently exhibited longer AL, flatter corneal curvature, shallower ACD, thicker CCT, thinner LT, and longer VCD compared to females. AL, K, CR, LT, and VCD all showed significant linear relationships with SE (all P < 0.001) in univariate linear regression analysis after adjusting for gender and age.

CONCLUSION

The prevalence of myopia among preschool children aged 3-6 in Chengdu is relatively low. Ocular biometric parameters affecting refractive errors include AL, K, CR, LT, and VCD. The preschool period serves as a critical phase for myopia prevention and control.

Association between Axial Length to Corneal Curvature Radius Ratio and Myopia in Adult Patients

Purpose

To analyze the distribution characteristics of axial length to corneal curvature radius ratio (AL/CR) and other ocular biometric parameters in adult myopia patients and their association with myopia.

Methods

A cross-sectional study was conducted among patients with no eye diseases except ametropia who attended the optometry clinic of the First Affiliated Hospital of Hainan Medical College from January 2022 to June 2022. In total, 187 eyes (right eye) of 187 myopic patients aged 18-35 years were selected by random sampling. Based on the results of spherical equivalent (SE, (D)) obtained by postdilation optometry, all subjects were divided into three groups: mild myopia (≤-0.50D and >-3.00D, 42 eyes), moderate myopia (≤-3.00D and >-6.00D, 80 eyes), and high myopia (≤-6.00D, 65 eyes). The axial length (AL), corneal curvature radius (CR), and AL/CR were measured and compared between the three groups. The association between AL and AL/CR of the eye and SE was analyzed by multiple linear regression. Also, the predictive ability of AL/CR for high myopia was investigated by ROC curve.

Results

There were no statistically significant differences in age, gender, or intraocular pressure between the three groups. The mean values of AL/CR in mild, moderate, and high myopia groups were 3.17 ± 0.06, 3.31 ± 0.08, and 3.43 ± 0.10, respectively, and the difference between the groups was statistically significant (P < 0.001). Linear regression analysis showed that both AL and AL/CR were strongly negatively correlated with SE (P < 0.05), while CR had a weak positive correlation with SE without statistically significant differences (P > 0.05). The adjusted linear regression equation shows that for every 0.1 unit increase in AL/CR, SE increases by 1.54 D. Compared with 0.830 (95% confidence interval: 0.769 to 0.900) for AL, the area under ROC curve of AL/CR was 0.896 (95% confidence interval: 0.851 to 0.941), indicating that the diagnostic value of AL/CR for high myopia was higher than that of AL (P <  0.01). When the Youden index reached its maximum (0.626), the AL/CR cutoff point was 3.309, and the sensitivity and specificity were 0.954 and 0.672, respectively.

Conclusion

This study showed that AL and AL/CR in adult myopia patients were significantly negatively correlated with SE, and the corralation between AL/CR and SE is greater than that between AL and SE. Therefore, AL/CR can be used to analyze the dynamic changes of SE in the development of adult myopia independently of optometry on a certain basis, and it is especially suitable for the diagnosis of high myopia in adults. This trial is registered with ChiCTR2300069070.

Axial length to corneal radius of curvature ratio and refractive error in Chinese preschoolers aged 4-6 years: a retrospective cross-sectional study

OBJECTIVE

This study aims to investigate the associations of axial length to corneal radius of curvature (AL/CRC) ratio with refractive error and to determine the effect of AL/CRC ratio on hyperopia reserve and myopia assessment among Chinese preschoolers.

METHODS

This was a retrospective cross-sectional study that evaluated subjects aged 4-6 years. AL and CRC were obtained using a non-contact ocular biometer. Correlation analysis was performed to explore the associations of AL/CRC ratio with spherical equivalent refractive error (SER). The accuracy of AL/CRC ratio for hyperopia reserve and myopia assessment was analysed using cycloplegic refraction by drawing receiver operating characteristic (ROC) curves.

RESULTS

The analysis included 1024 participants (537 boys, 52.4%). The mean AL/CRC ratios in hyperopes, emmetropes and myopes were 2.90±0.06, 2.95±0.05 and 3.08±0.07, respectively. The SER was found to be more strongly correlated with AL/CRC ratio (ρ=-0.66, p<0.001) than either AL or CRC alone (ρ=-0.52, p<0.001; ρ=-0.03, p=0.33, respectively). AL/CRC was correlated with SER in hyperopes (ρ=-0.54, p<0.001), emmetropes (ρ=-0.33, p<0.001) and myopes (r=-0.67, p<0.001). For low hyperopia reserve assessment, the area under the ROC curves of AL/CRC ratio was 0.861 (95% CI 0.829 to 0.892), the optimal cut-off value of the AL/CRC ratio was ≥2.955. For myopia assessment, the area under the ROC curves of AL/CRC ratio was 0.954 (95% CI 0.925 to 0.982), the optimal cut-off value of the AL/CRC ratio was ≥2.975.

CONCLUSIONS

The SER showed a better correlation with AL/CRC ratio than either AL or CRC alone, especially in myopes, among children aged 4-6 years. These findings indicate that when cycloplegic refraction is unavailable, AL/CRC ratio could be used as an alternative indicator for identifying low hyperopia reserve and myopia among preschoolers, helping clinicians and parents screen children with low hyperopia reserve before primary school in a timely manner.

Orthokeratology in controlling myopia of children: a meta-analysis of randomized controlled trials

BACKGROUND

Delaying the development and lowering the progression of myopia in children is the focus of current ophthalmology researches. We aimed to evaluate the role of orthokeratology in controlling myopia of children, to provide insights to the clinical treatment and care of children with myopia.

METHODS

Two investigators searched the The Cochrane Library, Embase, Pubmed, China national knowledge infrastructure, China biomedical literature database, WanFang and Weipu databases for randomized controlled trials(RCTs) on the role of orthokeratology in controlling myopia of children up to November 5, 2022. Two researchers independently searched, screened and extracted the studies according to the inclusion and exclusion standards. RevMan5.3 software was used for statistical analysis.

RESULTS

A total of 14 RCTs involving 2058 children were included in this meta-analysis. Synthesized outcomes indicated that orthokeratology improved the uncorrected visual acuity(MD = 0.40, 95%CI: 0.05 ~ 0.74), reduced the diopter change(MD=-3.19, 95%CI: -4.42~-1.95), changes of corneal curvature(MD=-3.21, 95%CI: -3.64~-2.79), the length of ocular axis (MD=-0.66, 95%CI: -1.27~-0.06) and amount of ocular axis change(MD=-0.42, 95%CI: -0.64~-0.21) after 1 year of wearing orthokeratology(all P < 0.05). Besides, orthokeratology reduced the diopter change (MD=-3.22, 95%CI: -4.86~-1.58), the length of ocular axis (MD=-1.15, 95%CI: -2.25~-0.06) and the amount of ocular axis change after 2 year of wearing orthokeratology (MD=-0.53, 95%CI: -0.96~-0.11) after 2 year of wearing orthokeratology (all P < 0.05). No publication biases were found amongst the synthesized outcomes (all P > 0.05).

CONCLUSIONS

Orthokeratology delays the progression of myopia in children, the long-term effects of orthokeratology need further investigations in future studies.

Dietary Patterns and Associations with Myopia in Chinese Children

Dietary shifts in populations undergoing rapid economic transitions have been proposed as partly contributing toward the rapid intergenerational rise in myopia prevalence; however, empirical evidence of the effect of dietary factors on myopia is limited. This study investigated the association between dietary factors and incident myopia in Chinese children aged 10-11 years. We evaluated dietary habits using a 72-item food frequency questionnaire (FFQ) among 7423 children. Myopic status was assessed using the "General Personal Information Questionnaire". Principal component analysis was used to extract dietary patterns and investigate their association with myopia. After adjusting for potential confounders, participants with the highest adherence to dietary pattern A (95% confidence interval (CI): 0.66-0.92, p for trend = 0.007) and dietary pattern C (95% CI: 0.58-0.80, p for trend < 0.001) had a lower risk of myopia than participants with the least adherence. Both of these dietary patterns are characterized by high consumption of meats, aquatic product, dairy and its products, eggs, legumes, vegetables, fruits, grains, and potatoes. Our findings suggest that other environmental factors, such as those related to the dietary environment, may contribute to the development of myopia. These findings can serve as a reference for diet-related primary prevention of myopia.

The Incidence and Severity of Myopia in the Population of Medical Students and Its Dependence on Various Demographic Factors and Vision Hygiene Habits

(1) Background: Myopia is one of the leading causes of visual impairment. Visual work and usage of electronic devices are known risk factors of myopia. Many education systems were forced to apply online and hybrid teaching methods, to reduce the number of new cases of COVID-19. Medical students are a population well-known for intense visual work in the form of learning; (2) Methods: Visual acuity and refractive error were measured in the population of medical students. Participants also filled out the survey that included their population characteristic and their habits related to the hygiene of vision; (3) Results: We found a correlation between the age of the first diagnosis of myopia and current values of refractive error. The majority of participants believe that the COVID-19 pandemic had an impact on the health of their vision. Among methods of studying, usage of the computer screen was less preferred by myopic students; (4) Conclusions: In the population of medical school students in Eastern Poland, visual acuity was lower than 1.0 in 232 (52.97%) in the right eye and 234 (53.42%) in the left eye. Early recognition of refractive error has influenced its current values. Among methods of studying, usage of the computer screen was less preferred by myopic students. More population-based studies should focus on the impact of the COVID-19 pandemic on the health of vision.