Accurate prediction of myopic progression and high myopia by machine learning.

Background: Myopia is a leading cause of visual impairment in Asia and worldwide. However, accurately predicting the progression of myopia and the high risk of myopia remains a challenge. This study aims to develop a predictive model for the development of myopia. Methods: We first retrospectively gathered 612 530 medical records from five independent cohorts, encompassing 227 543 patients ranging from infants to young adults. Subsequently, we developed a multivariate linear regression algorithm model to predict the progression of myopia and the risk of high myopia. Result: The model to predict the progression of myopia achieved an R2 value of 0.964 vs a mean absolute error (MAE) of 0.119D [95% confidence interval (CI): 0.119, 1.146] in the internal validation set. It demonstrated strong generalizability, maintaining consistent performance across external validation sets: R2 = 0.950 vs MAE = 0.119D (95% CI: 0.119, 1.136) in validation study 1, R2 = 0.950 vs MAE = 0.121D (95% CI: 0.121, 1.144) in validation study 2, and R2 = 0.806 vs MAE = -0.066D (95% CI: -0.066, 0.569) in the Shanghai Children Myopia Study. In the Beijing Children Eye Study, the model achieved an R2 of 0.749 vs a MAE of 0.178D (95% CI: 0.178, 1.557). The model to predict the risk of high myopia achieved an area under the curve (AUC) of 0.99 in the internal validation set and consistently high area under the curve values of 0.99, 0.99, 0.96 and 0.99 in the respective external validation sets. Conclusion: Our study demonstrates accurate prediction of myopia progression and risk of high myopia providing valuable insights for tailoring strategies to personalize and optimize the clinical management of myopia in 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.

Association between body stature with ocular biometrics and refraction among Chinese preschoolers.

PURPOSE: To evaluate the association of body stature with ocular biometrics and refraction in preschool children. METHODS: A cross-sectional, school-based study was conducted in Shenzhen, China. Preschool children aged 3 to 6 from 10 randomly-selected kindergartens were recruited. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), corneal radius curvature (CR), axial length to corneal radius ratio (AL-to-CR ratio) and lens thickness (LT) were measured using non-contact partial-coherence laser interferometry. Cycloplegic refractions were obtained by a desktop autorefractor. Body height and weight were measured using standard procedures. The association between body stature and ocular biometrics were analyzed with univariable and multivariable regression model. RESULTS: A total of 373 preschoolers were included. AL, ACD, VCD, CR, and AL-to-CR ratio, were positively associated with height and weight (p < 0.05), whereas LT was negatively associated with height and weight (p < 0.01). No association was observed between stature and central cornea thickness and refraction. After adjusted for age and gender in a multivariable regression model, AL had positive associations with height (p < 0.01) and weight (p < 0.01). However, refraction had no significant association with stature parameters. CONCLUSION: Taller and heavier preschoolers had eyes with longer AL, deeper vitreous chamber, and flatter cornea. The significant associations between body stature and ocular biometric parameters reveal the driving influence of body development on the growth of eyeballs in preschoolers.

Longitudinal Changes in Choroidal Thickness Varied With Refractive Progression in Myopic and Non-Myopic Children: A Two-Year Cohort Study.

Purpose: To evaluate the longitudinal changes in subfoveal choroidal thickness (SFCT) in children with different refractive status. Methods: A total of 2290 children 3 to 14 years old who attended the first year of kindergarten (G0), first year of primary school (G1), fourth year of primary school (G4), or first year of junior high school (G7) in Guangzhou, China, were recruited and followed up for 2 years. All participants received cycloplegic autorefraction, axial length measurement and SFCT measurement using a CIRRUS HD-OCT device. Children were divided into groups of persistent non-myopia (PNM), persistent myopia (PM), or newly developed myopia (NDM). Children in the PNM and PM groups were further divided into subgroups of stable refraction (absolute mean annual spherical equivalent refraction [SER] change < 0.5 D) and refractive progression (absolute mean annual SER change ≥ 0.5 D). Results: The mean ± SD ages for the G1 to G7 cohorts were 3.89 ± 0.30, 6.79 ± 0.47, 9.71 ± 0.34, and 12.54 ± 0.38, years, respectively. SFCT consistently decreased in the NDM group across the G1 to G7 cohorts (all P < 0.001) and exhibited variability across different age cohorts in the PNM and PM groups. Further subgroup analysis revealed significant thickening of SFCT in the PNM-stable group among the G0, G1, and G7 cohorts (all P < 0.05), whereas it remained stable among all cohorts in the PM-stable group (all P > 0.05). Conversely, SFCT exhibited thinning in the G4 and G7 cohorts in the PM-progressive group (both P < 0.01) and for the entire cohort of children in the PNM-progressive group (P = 0.012). Conclusions: SFCT increased in nonmyopic children with stable refraction, remained stable in myopic children maintained stable refraction, and decreased in those with refractive progression, whether they were myopic or not.

Long-Term Axial Length Shortening in Myopic Orthokeratology: Incident Probability, Time Course, and Influencing Factors.

Purpose: Long-term axial length (AL) shortening in myopia is uncommon but noteworthy. Current understanding on the condition is limited due to difficulties in case collection. The study reported percentage, probability, and time course of long-term AL shortening in myopic orthokeratology based on a large database. Methods: This study reviewed 142,091 medical records from 29,825 subjects in a single-hospital orthokeratology database that were collected over 10 years. Long-term AL shortening was defined as a change in AL of -0.1 mm or less at any follow-up beyond 1 year. Incident probability was calculated based on multivariate logistic regression. Time course was estimated using mixed-effect regression model. Results: A total of 10,093 subjects (mean initial age, 11.70 ± 2.52 years; 58.8% female) with 80,778 visits were included. The number of subjects experienced long-term AL shortening was 1,662 (16.47%; 95% confidence interval, 15.75%-17.21%). Initial age showed significant impact on the incident occurrence (OR, 1.37; 95% confidence interval, 1.34-1.40; P < 0.001). The estimated probability of AL shortening was approximately 2% for subjects with initial age of 6 years and 50% for those aged 18. Among the 1662 AL shortening cases, the median magnitude of the maximum AL reduction was 0.19 mm. The shortening process mostly occurred within the initial 2 years. Subject characteristics had limited associations with the shortening rate. Conclusions: Long-term AL shortening is possible in subjects receiving myopic orthokeratology. Although age notably affect the incident probability, the time course seems to not vary significantly.

Effect of Extracurricular After-School Physical Activities on Academic Performance of Schoolchildren: A Cluster Randomized Clinical Trial.

Importance: The beneficial effects of increasing outdoor physical activity time on children's myopia onset and physical well-being are widely acknowledged. However, in countries with competitive educational systems, such as China, parents and school administrators may be relatively reluctant to increase the extracurricular physical activity time for children due to concerns that this action will compromise children's academic performance. Objective: To investigate whether additional extracurricular physical activity time after school compromises the academic performance of schoolchildren. Design, Setting, and Participants: This cluster randomized clinical trial was conducted from October 2020 to June 2021 in Yudu, Jiangxi, China. Eligible children in grades 3 and 4 from 24 elementary schools were randomized to the intervention or control group. Primary analysis was conducted in the full sample using the intention-to-treat principle. Interventions: The intervention group received 2 hours of after-school physical activity time outdoors on school days. The control group was free to arrange their after-school activity. Main Outcomes and Measures: The primary outcome was the between-group mean difference in mathematics test scores at the end of 1 academic year, with a noninferiority margin of -3.3 points. Standardized mathematics tests, physical fitness assessments (in reference to the 2018 National Physical Fitness Survey Monitoring Programme in China), and cycloplegic autorefraction were performed at baseline and the end of 1 academic year. Myopia was defined as a cycloplegic spherical equivalent refraction of -0.5 diopters or less in either eye. Results: A total of 2032 children (mean [SD] age, 9.22 [0.62] years; 1040 girls [51.2%]) from 24 schools were randomized to the intervention group (12 schools; 1012 children) or control group (12 schools; 1020 children). The mean (SD) mathematics score at the end of 1 academic year was 78.01 (17.56) points in the intervention group and 77.70 (17.29) points in the control group. The adjusted between-group mean difference was 0.65 points (95% CI, -2.85 to 4.15). The adjusted between-group mean difference in physical fitness score was 4.95 points (95% CI, 3.56-6.34; P < .001) and -1.90% (95% CI, -18.72% to 14.91%; P > .99) in myopia incidence. Conclusions and Relevance: Results of this trial indicate that, compared with the control practice of free play after school, adding 2 hours of extracurricular physical activity outdoors after school was noninferior in academic performance and had superior efficacy in improving physical fitness. Trial Registration: ClinicalTrials.gov Identifier: NCT04587765.

Impact of Cataract Surgery on Income in Rural Southern China: The SUCCESS Randomized Controlled Trial.

PURPOSE: Visual impairment from cataracts is closely associated with low income, but trial evidence regarding the impact of surgery on income is lacking. We investigated whether cataract surgery could increase personal income. DESIGN: A 2-arm, parallel-group, open-label, randomized controlled trial (ClinicalTrials.gov, NCT03020056). METHODS: Persons aged 50 years or older in rural Guangdong, China, with best-corrected visual acuity <6/19 in both eyes due to cataracts were randomly assigned (1:1) to receive surgery within 4 weeks (intervention group), or 1 year later (control group). All participants were interviewed at baseline and end-line regarding demographic characteristics, income, and quality of life. RESULTS: Among the 292 eligible persons (5.40%, mean age = 74.0 y, 61.0% women) randomly assigned to intervention (n = 146) or control (n = 146) groups, 12 participants (8.22%) in the intervention group and 1 (0.68%) in the control did not receive the allocated intervention. By study closeout, 18 participants (6.16%) were lost to follow-up. The mean 1-year income increase of the intervention group ($2469-$3588; change = $1119) was significantly larger than that of the controls ($2258-$2052; change = $-206), a between-group difference of $1325 (relative increase = 54.0%; 95% CI = $739 to $1911; P < 0.001). In multivariable modeling, intervention group membership was associated with greater income increase (ß = 1143.2; 95% CI = 582.0 to 1704.3; P < 0.001). Greater improvement in best-corrected visual acuity was associated with income increase in univariable modeling (ß = 1626.9; 95% CI = 1083.6 to 2170.1; P < 0.001). CONCLUSIONS: Cataract surgery substantially increases personal income in rural China, offering a strategy for poverty alleviation. The strong association between increased income and change in visual acuity enhances the biological plausibility of the result.

Longitudinal Changes in Lens Thickness and Lens Power Among Persistent Non-Myopic and Myopic Children.

Purpose: To assess the longitudinal changes in crystalline lens in persistent non-myopic and myopic children. Methods: Four cohorts of children were recruited from Guangzhou, China, from first year of kindergarten (G0, n = 1129), first year of primary school (G1, n = 1324), fourth year of primary school (G4, n = 1854), and first year of junior high school (G7, n = 867) in 2018 and followed up annually for 2 years. All children received cycloplegic autorefraction and ocular biometry measurement. Children were classified into categories of persistent non-myopia (PNM; spherical equivalent refraction [SER] ≥-0.5 diopter [D] at baseline and during follow-up), persistent myopia (PM; SER <-0.5 D at baseline and during follow-up), or newly developed myopia (NDM: SER ≥-0.5 D at baseline and <-0.5 D during follow-up). Results: The mean (SD) age was 3.69 (0.34) years for children in G0, 6.79 (0.35) years in G1, 9.52 (0.42) years in G4, and 12.56 (0.38) years in G7. A LOWESS plot showed a three-stage pattern of change in lens thickness (LT) in PNM children including a rapid decrease from 3 to 7 years of age and a slower decrease from 7 to 11 years, followed by an increase thereafter. Similar trends were observed in the PM and NDM groups, although there was less change in LT. In contrast, lens power (LP) decreased consistently in all cohorts during the follow-up. No significant changes in LT or LP were observed around myopia onset. Conclusions: The lens showed a three-stage pattern of change in LT, whereas there was continuous loss of LP in children ages 3 to 15 years.

Axial Growth Driven by Physical Development and Myopia among Children: A Two Year Cohort Study.

Background: The physical process of axial length growth among children and its role in the occurrence of myopia remain insufficiently explored. In this study, we investigate the patterns of ocular axial growth among persistent myopia (PM) and persistent non-myopia (PNM) children aged 3 to 15 years. Methods: A group of 6353 children aged 3 to 15 years, selected from rural schools in China, were followed up annually for 2 years. Biometric measurements including axial length (AL) and spherical equivalent refraction (SER) were obtained. Body height was recorded. Children were divided into two groups: PM group defined as SER of −0.50 D or less; PNM group defined as −0.50 D < SER < +3.0 D during follow-up. Results: Annual AL growth was fairly consistent for PNM eyes of children aged 3 to 11 years and then reduced significantly (independent t test, p < 0.001) for children aged 12 years and older. This pattern of AL changes was similar for PM children, although the AL growth was greater among them. Among children aged 6 and older, body height change was concomitant to AL growth (p < 0.01) and SER myopic shift (p < 0.001) until reaching 12 years old (p = 0.308 and p = 0.679, respectively). Conclusions: Stature growth and AL growth are both remarkable and consistent and concomitant but start to attenuate when the children reach 10 to 12 years old among emmetropic children. This observation suggests that AL growth is driven by physical development until 12 years old, whereas its excessive growth is dominated by myopia development.

Prevalence, incidence, and risk factors for myopia among urban and rural children in southern China: protocol for a school-based cohort study.

INTRODUCTION: Myopia is the common cause of reduced uncorrected visual acuity among school-age children. It is more prevalent in urban than in rural areas. Although many myopia studies have focused on the effect of urbanisation, it remains unclear how visual experience in urban regions could affect childhood myopia. This study aims to investigate the incidence and prevalence of myopia among school-age children in urban and rural settings, thereby identifying the environmental factors that affect the onset and progression of myopia. METHODS AND ANALYSIS: A school-based cohort study will be conducted. We will enroll all first-grade students from an urban (10 primary schools) and a rural (10 primary schools) regions of Zhaoqing city, China. Over 3-year follow-up period, students will receive detailed eye examinations annually and complete questionnaires about living habits and environment. In a 5% random subsample of the cohort, physical activity, light intensity and eye-tracking data will be obtained using wearable devices, and high-resolution macular images will be obtained by optical coherence tomography (OCT). The primary outcome is incident myopia, defined as myopia (spherical equivalent refractive of at least -0.5D) detected during follow-up among those without myopia at baseline. ETHICS AND DISSEMINATION: Ethics approval was obtained from the ethics committee of the Zhongshan Ophthalmic Center (number: 2019KYPJ171). Study findings will be published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT04219228.

Prevalence of Ocular Demodex Infestation in Children: An Epidemiological Survey in South China.

OBJECTIVES: To investigate the prevalence of and risk factors for Demodex mite infestation of the eyelashes in Chinese children. METHODS: A total of 1,575 children were surveyed from June 2017 to January 2019 and stratified into two age groups: 3 to 6 and 7 to 14 years. All subjects underwent routine eye examination and lash epilation for Demodex mite identification and counting using microscopy. Demographic data and lifestyle habits were also recorded. RESULTS: Demodex mites were detected in 189 of 1,575 (12.0%) children, including Demodex folliculorum (D. folliculorum) in 180 (11.4%), Demodex brevis (D. brevis) in 11 (0.7%), and both mites in 2 (0.1%). The median number of D. folliculorum mites was 1 (interquartile range [IQR], 1-2) and that of D. brevis was 1 (IQR, 1-1). Children with Demodex infestation did not exhibit more ocular discomfort than those without (21.2% vs. 23.1%; P=0.56). However, lash abnormalities, including trichiasis, cylindrical dandruff, or scaly discharge at the lash root, were more prevalent in children with Demodex infestation (24.9% vs. 12.8%; P<0.001) and in the 7 to 14-year subgroup (33.7% vs. 12.8%; P<0.001). Multiple logistic regression revealed that autumn-winter was associated with a higher detection rate of Demodex infestation (all P<0.05). In the 3-6-year subgroup, children residing in rural regions exhibited a higher prevalence of Demodex infestation (P=0.03). CONCLUSIONS: Ocular Demodex infestation, with a low Demodex mite count, was found in healthy Chinese children aged 3 to 14 years.

Effect of a complex intervention to improve post-vision screening referral compliance among pre-school children in China: A cluster randomized clinical trial.

BACKGROUND: We investigated whether specific appointments for quality-assured care could increase referral uptake, often low in China, in children's vision screening. METHODS: We randomized children aged 4-7 years in Yudu, Jiangxi, China, by school to Control (free school-based eye screening, parents of children failing screening recommended for further examination [usual practice]) or Intervention (identical examinations, with parents additionally provided with specific appointments for further examinations by quality-assured doctors at a designated local hospital). Both groups could select any hospital for referral exams, which were not free. Six months after screening, parents were interviewed on referral compliance at any hospital (primary outcome) and potential determinants. This trial is registered at the ClinicalTrials.gov, number NCT03251456. FINDINGS: Among 9936 children at 63 schools randomized to Intervention (32 schools, 5053 [50·9%] children) or Control (31 schools, 4883 [49·1%] children), 1114 children (11·2%) failed screening. Among 513 referred Intervention children (46·1%, 32 schools, mean age 5·36 years, 53·0% boys) and 601 referred Control children (53·9%, 31 schools, mean age 5·30 years, 57·7% boys), 104 (20·3%) and 135 (22·5%) were lost to follow-up respectively. Under Intention to Treat analysis, assuming children lost to follow-up were non-compliant, Intervention children had significantly higher compliance than Controls (308/513 = 60·0% vs. 225/601 = 37·4%, P < 0·001). In regression models, Intervention group membership (Relative risk [RR] 1·53, 95% confidence interval, 1·36-1·72), travel time to hospital (RR: 0·97, 0·95-0·999), baseline glasses wear (RR: 1·37, 1·17-1·60), strabismus (RR: 1·17, 1·01-1·36) and worse uncorrected vision (RR: 1·41, 1·03-1·92) were associated with compliance. INTERPRETATION: Providing specific appointments for quality-assured eye care improved referral compliance in this setting.

Significant Axial Elongation with Minimal Change in Refraction in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study.

PURPOSE: To document the distribution of ocular biometry and to evaluate its associations with refraction in a group of Chinese preschoolers. DESIGN: Population-based cross-sectional study. PARTICIPANTS: A total of 1133 preschoolers 3 to 6 years of age from 8 representative kindergartens. METHODS: Biometric measurements including axial length (AL), anterior chamber depth (ACD), and corneal radius of curvature (CR) were obtained from partial-coherence laser interferometry (IOL Master; Carl Zeiss Meditec, Oberkochen, Germany) before cycloplegia. Lens power (LP) and AL-to-CR ratio were calculated. Cycloplegic refraction (3 drops of 1% cyclopentolate) was measured using an autorefractor (KR8800; Topcon Corp., Tokyo, Japan), and spherical equivalent refraction (SER) was calculated. Biometric and refractive parameters were assessed as a function of age and gender. Multiple regression analysis was performed to explore the associations between refraction and ocular biometry. MAIN OUTCOME MEASURES: Ocular biometric distributions and their relationships to refraction. RESULTS: Among the 1127 children (99.5%) with successful cycloplegic refraction, mean SER was 1.37±0.63 diopters (D). Prevalence of myopia increased from 0% at 3 years of age to 3.7% (95% confidence interval, 1.0%-6.5%) at 6 years of age. Biometric parameters followed Gaussian distributions with means of 22.39±0.68 mm for AL, 7.79±0.25 mm for CR, and 24.61±1.42 D for calculated LP; and non-Gaussian distributions with means of 3.34±0.24 mm for ACD and 2.88±0.06 for AL-to-CR ratio. Axial length, ACD, and AL-to-CR ratio increased from 3 to 6 years of age, CR remained stable, whereas LP declined. Overall, SER declined slightly. For the SER variance, AL explained 18.6% and AL-to-CR ratio explained 39.8%, whereas AL, CR, and LP accounted for 80.0% after adjusting for age and gender. CONCLUSIONS: Young Chinese children are predominantly mildly hyperopic, with a low prevalence of myopia by the age of 6 years. An increase of 1 mm in AL was associated with only 0.45 D of myopic change. Decreases in LP reduce the myopic shifts that normally would be associated with increases in AL, and thus play a key role in refractive development in this age group.

Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China: A Randomized Clinical Trial.

IMPORTANCE: Myopia has reached epidemic levels in parts of East and Southeast Asia. However, there is no effective intervention to prevent the development of myopia. OBJECTIVE: To assess the efficacy of increasing time spent outdoors at school in preventing incident myopia. DESIGN, SETTING, AND PARTICIPANTS: Cluster randomized trial of children in grade 1 from 12 primary schools in Guangzhou, China, conducted between October 2010 and October 2013. INTERVENTIONS: For 6 intervention schools (n = 952 students), 1 additional 40-minute class of outdoor activities was added to each school day, and parents were encouraged to engage their children in outdoor activities after school hours, especially during weekends and holidays. Children and parents in the 6 control schools (n = 951 students) continued their usual pattern of activity. MAIN OUTCOMES AND MEASURES: The primary outcome measure was the 3-year cumulative incidence rate of myopia (defined using the Refractive Error Study in Children spherical equivalent refractive error standard of ≤-0.5 diopters [D]) among the students without established myopia at baseline. Secondary outcome measures were changes in spherical equivalent refraction and axial length among all students, analyzed using mixed linear models and intention-to-treat principles. Data from the right eyes were used for the analysis. RESULTS: There were 952 children in the intervention group and 951 in the control group with a mean (SD) age of 6.6 (0.34) years. The cumulative incidence rate of myopia was 30.4% in the intervention group (259 incident cases among 853 eligible participants) and 39.5% (287 incident cases among 726 eligible participants) in the control group (difference of -9.1% [95% CI, -14.1% to -4.1%]; P < .001). There was also a significant difference in the 3-year change in spherical equivalent refraction for the intervention group (-1.42 D) compared with the control group (-1.59 D) (difference of 0.17 D [95% CI, 0.01 to 0.33 D]; P = .04). Elongation of axial length was not significantly different between the intervention group (0.95 mm) and the control group (0.98 mm) (difference of -0.03 mm [95% CI, -0.07 to 0.003 mm]; P = .07). CONCLUSIONS AND RELEVANCE: Among 6-year-old children in Guangzhou, China, the addition of 40 minutes of outdoor activity at school compared with usual activity resulted in a reduced incidence rate of myopia over the next 3 years. Further studies are needed to assess long-term follow-up of these children and the generalizability of these findings. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00848900.

Normative distribution of visual acuity in 3- to 6-year-old Chinese preschoolers: the Shenzhen kindergarten eye study.

PURPOSE: To document the distribution of uncorrected visual acuity (UCVA) in a defined population of Chinese preschoolers and to discuss its implications for vision referral. METHODS: Preschoolers aged 3 to 6 years old were recruited from kindergartens in Shenzen. Uncorrected visual acuity was estimated by using Early Treatment Diabetic Retinopathy Study Tumbling E charts, followed by cycloplegic refraction and ocular examination. The reference population was defined as children without clinically significant ocular abnormalities, with spherical equivalent refraction greater than -0.50 to less than +2.00 diopters (D), astigmatism less than 0.75 D, and anisometropia less than 2.00 D. The age-specific UCVA cutoffs were defined by the line where the single-sided 95th percentile of the reference population fell. RESULTS: A total of 483 of the 1255 children enrolled were considered the reference population. The monocular UCVA cutoff fell on the line of 20/63 at age 3, 20/50 at age 4, and 20/40 at ages 5 and 6. Using no better than these lines as criteria generated referral rates of 9.4% to 27.8% in the general population at different ages, and detected 83.3% and more than 90.0% of those with myopia and amblyopia, respectively. Using uncorrected interocular difference of two or more lines referred 3.6% to 4.3% of the population but identified only approximately 20.0% of those with amblyopia. CONCLUSIONS: Visual acuity is still developing in preschoolers even at age 6. Most children with myopia and amblyopia can be identified with age-specific, monocular UCVA cutoffs in vision screening using Tumbling E charts, with tolerable false-positive rates. Further studies are needed to define the age at which children without significant refractive errors reach 20/20 UCVA.

Comparison of the Educational Effect upon Myopia Prevention and Treatment between Video Demonstration and Traditional Teaching.

PURPOSE: To compare the education effect of video demonstrations and conventional teaching on the prevention and control of myopia. METHODS: Eighty students were randomly divided into an experimental (n = 40) and a control (n = 40) group, and each group was split into two classes of 40 students. The students in the experimental group attended classes mainly based on video demonstration and those in the control group received conventional teaching. All students then undertook a test and the examination scores were statistically compared between the two groups. RESULTS: The educational background, age, and gender did not differ between the two groups (all P > 0.05). The experimental group had a mean test score of 8.25 ± 1.45, which was slightly lower than the mean of 8.58 ± 1.11 in the control group, but the difference was not statistically significant (t = -1.589, P = 0.114). CONCLUSION: The educational effect of video demonstrations was almost identical to that of traditional teaching. In addition, video classes reduced the training time and financial costs, indicating that they deserve widespread application.

Two-year changes in refractive error and related biometric factors in an adult Chinese population.

IMPORTANCE: This article provides, to our knowledge, the first longitudinal population-based data on refractive error (RE) in Chinese persons. OBJECTIVE: To study cohort effects and changes associated with aging in REs among Chinese adults. DESIGN, SETTING, AND PARTICIPANTS: A 2-year, longitudinal population-based cohort study was conducted in southern China. Participants, identified using cluster random sampling, included residents of Yuexiu District, Guangzhou, China, aged 35 years or older who had undergone no previous eye surgery. METHODS: Participants underwent noncycloplegic automated refraction and keratometry in December 2008 and December 2010; in a random 50% sample of the participants, anterior segment ocular coherence tomography measurement of lens thickness, as well as measurement of axial length and anterior chamber depth by partial coherence laser interferometry, were performed. MAIN OUTCOMES AND MEASURES: Two-year change in spherical equivalent refraction (RE), lens thickness, axial length, and anterior chamber depth in the right eye. RESULTS: A total of 745 individuals underwent biometric testing in both 2008 and 2010 (2008 mean [SD] age, 52.2 [11.5] years; 53.7% women). Mean RE showed a 2-year hyperopic shift from -0.44 (2.21) to -0.31 (2.26) diopters (D) (difference, +0.13; 95% CI, 0.11 to 0.16). A consistent 2-year hyperopic shift of 0.09 to 0.22 D was observed among participants aged 35 to 64 years when stratifying by decade, suggesting that a substantial change in RE with aging may occur during this 30-year period. Cross-sectionally, RE increased only in the cohort younger than 50 years (0.11 D/y; 95% CI, 0.06 to 0.16). In the cross-sectional data, axial length decreased at -0.06 mm/y (95% CI, -0.09 to -0.04), although the 2-year change in axial length was positive and thus could not explain the cross-sectional difference. These latter results suggest a cohort effect, with greater myopia developing among younger persons. CONCLUSIONS AND RELEVANCE: This first Chinese population-based longitudinal study of RE provides evidence for both important longitudinal aging changes and cohort effects, most notably greater myopia prevalence among younger persons.

Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy for iris parameter measurements in patients with primary angle closure glaucoma.

PURPOSE: To compare the repeatability and consistency of anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in measuring iris parameters in patients with primary angle closure glaucoma. METHODS: Twenty-two patients (38 eyes) with primary angle closure glaucoma, including 5 eyes with acute angle closure glaucoma, 10 fellow eyes of acute angle closure glaucoma, and 23 eyes with chronic angle closure glaucoma, were recruited consecutively in our hospital. All subjects underwent anterior scanning by AS-OCT and UBM. Peripheral iris thickness (PIT) and iris curvature (IC) in the anterior segment image obtained by AS-OCT and UBM were measured twice. The reproducibility of these two scans was evaluated by the intraclass correlation coefficient (ICC). A paired t-test was used to compare the difference between the two scans and the 95% limits of agreement (LoA) were calculated. RESULTS: The ICCs of PIT and IC measured by UBM were 0.892 and 0.936 respectively, while for AS-OCT these values were 0.629 and 0.859, respectively. UBM had a higher reproducibility in both PIT and IC measurements as compared with AS-OCT. Differences in PIT measurement between AS-OCT and UBM (P = 0.331) were not statistically significant, the 95% LoA (-0.178-0.156) mm was 36.1-41.2% of the mean. The IC was 0.053 mm smaller when measured by UBM than by AS-OCT (P = 0.017), with the 95% LoA (-0.100-0.206) mm, or 36.2-74.6% of the mean. CONCLUSION: UBM had a higher reproducibility in measuring iris parameters than AS-OCT. The consistency between AS-OCT and UBM in measuring iris parameters was low in primary angle closure glaucoma patients.

Determinants and two-year change in anterior chamber angle width in a Chinese population.

OBJECTIVE: To study the population distribution and longitudinal changes in anterior chamber angle width and its determinants among Chinese adults. DESIGN: Prospective cohort, population-based study. PARTICIPANTS: Persons aged 35 years or more residing in Guangzhou, China, who had not previously undergone incisional or laser eye surgery. METHODS: In December 2008 and December 2010, all subjects underwent automated keratometry, and a random 50% sample had anterior segment optical coherence tomography with measurement of angle-opening distance at 500 µm (AOD500), angle recess area (ARA), iris thickness at 750 µm (IT750), iris curvature, pupil diameter, corneal thickness, anterior chamber width (ACW), lens vault (LV), and lens thickness (LT) and measurement of axial length (AL) and anterior chamber depth (ACD) by partial coherence laser interferometry. MAIN OUTCOME MEASURES: Baseline and 2-year change in AOD500 and ARA in the right eye. RESULTS: A total of 745 subjects were present for full biometric testing in both 2008 and 2010 (mean age at baseline, 52.2 years; standard deviation [SD], 11.5 years; 53.7% were female). Test completion rates in 2010 varied from 77.3% (AOD500: 576/745) to 100% (AL). Mean AOD500 decreased from 0.25 mm (SD, 0.13 mm) in 2008 to 0.21 mm (SD, 13 mm) in 2010 (difference, -0.04; 95% confidence interval [CI], -0.05 to -0.03). The ARA decreased from 21.5 ± 3.73 10(-2) mm(2) to 21.0 ± 3.64 10(-2) mm(2) (difference, -0.46; 95% CI, -0.52 to -0.41). The decrease in both was most pronounced among younger subjects and those with baseline AOD500 in the widest quartile at baseline. The following baseline variables were significantly associated with a greater 2-year decrease in both AOD500 and ARA: deeper ACD, steeper iris curvature, smaller LV, greater ARA, and greater AOD500. By using simple regression models, we could explain 52% to 58% and 93% of variation in baseline AOD500 and ARA, respectively, but only 27% and 16% of variation in 2-year change in AOD500 and ARA, respectively. CONCLUSIONS: Younger persons and those with the least crowded anterior chambers at baseline have the largest 2-year decreases in AOD500 and ARA. The ability to predict change in angle width based on demographic and biometric factors is relatively poor, which may have implications for screening. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Correlation between lens thickness and central anterior chamber depth.

PURPOSE: To investigate gender differences in lens thickness (LT) and central anterior chamber depth (ACD) in normal subjects, and to assess age associated changes in these measures. METHODS: The anterior chamber depth (ACD), and lens thickness (LT), of 150 normal subjects (150 eyes) was measured by anterior segment optical coherence tomography (AS- OCT). Gender differences were assessed by independent t-test, and correlation analysis was used to examine the effect of age. RESULTS: The mean values of ACD and LT were 0.69±0.32 mm and 4.85±0.43 mm, respectively. Women had a significantly lower Mean ACD as compared to men (2.56±0.33mm vs 2.85±0.29 mm; P﹤0.05). No statistically significant difference was found in LT between male and female subjects (P＞0.05). Correlation analysis findings suggest that LT increases with age (r =0.83, P﹤0.05), and that ACD decreases with age (r=- 0.57, P﹤0.05). After controlling for LT, no significant correlation was observed between age and ACD (P＞0.05). CONCLUSION: The ACD of female subjects was, on average, shallower than that of their male counterparts. Aging was associated with increasing LT, and the observed narrowing of ACD with age, might be partially mediated by the increasing LT.