Qianyun Chen

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.

Effect of providing free glasses on children’s educational outcomes in China: cluster randomized controlled trial

Objective To assess the effect of provision of free glasses on academic performance in rural Chinese children with myopia. Design Cluster randomized, investigator masked, controlled trial. Setting 252 primary schools in two prefectures in western China, 2012-13. Participants 3177 of 19 934 children in fourth and fifth grades (mean age 10.5 years) with visual acuity <6/12 in either eye without glasses correctable to >6/12 with glasses. 3052 (96.0%) completed the study. Interventions Children were randomized by school (84 schools per arm) to one of three interventions at the beginning of the school year: prescription for glasses only (control group), vouchers for free glasses at a local facility, or free glasses provided in class. Main outcome measures Spectacle wear at endline examination and end of year score on a specially designed mathematics test, adjusted for baseline score and expressed in standard deviations. Results Among 3177 eligible children, 1036 (32.6%) were randomized to control, 988 (31.1%) to vouchers, and 1153 (36.3%) to free glasses in class. All eligible children would benefit from glasses, but only 15% wore them at baseline. At closeout glasses wear was 41% (observed) and 68% (self reported) in the free glasses group, and 26% (observed) and 37% (self reported) in the controls. Effect on test score was 0.11 SD (95% confidence interval 0.01 to 0.21) when the free glasses group was compared with the control group. The adjusted effect of providing free glasses (0.10, 0.002 to 0.19) was greater than parental education (0.03, −0.04 to 0.09) or family wealth (0.01, −0.06 to 0.08). This difference between groups was significant, but was smaller than the prespecified 0.20 SD difference that the study was powered to detect. Conclusions The provision of free glasses to Chinese children with myopia improves children’s performance on mathematics testing to a statistically significant degree, despite imperfect compliance, although the observed difference between groups was smaller than the study was originally designed to detect. Myopia is common and rarely corrected in this setting. Trial Registration Current Controlled Trials ISRCTN03252665.

Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects: The Zhongshan Angle-Closure Prevention Trial

OBJECTIVE To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. DESIGN Longitudinal cohort study. PARTICIPANTS Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. METHODS Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. MAIN OUTCOME MEASURES Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. RESULTS No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001). CONCLUSIONS Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period.

Compliance with follow-up after cataract surgery in rural China.

Purpose: To evaluate reasons for non-compliance with post-cataract surgical follow-up in rural China, and assess the impact of incentives on improving compliance. Methods: Patients having undergone cataract surgery more than 3 months previously at cataract surgery training hospitals in Guangdong were invited by telephone and advertisements to a hospital-based study examination, with compensation for travel costs (US

Visual outcomes of cataract surgery performed by supervised novice surgeons during training in rural China

7). Information on prior post-surgical follow up was collected by questionnaire at the hospital or by telephone. Logistic regression was used to assess predictors of post-operative attendance with or without compensation. Results: Among 518 eligible patients, 426 (82.2%) underwent interviews and 342 (66.0%) attended the compensated study examination. Ninety nine participants (23.2%) reported previously returning for uncompensated follow-up ≥ 3 months post-operatively, and 225 (52.8%) had returned for any prior post-operative examination. Uncompensated follow-up at ≥ 3 months was associated with higher income (P = 0.037), and recalling instruction by a doctor to follow-up (P = 0.001), while age, gender, travel cost, and post-operative satisfaction and vision were not associated. Younger (P = 0.002) patients and those reporting being instructed to follow up (P = 0.008) were more likely to return for the compensated research examination. Among all interviewed subjects, only 170 (39.9%) reported knowing they were to return to hospital. Conclusions: Modest compensation, advertisements and telephone contact can increase medium-term follow-up rates after cataract surgery by three-fold. Better communication of specific targets for follow-up may improve follow-up compliance.

Factors Underlying Different Myopia Prevalence between Middle- and Low-income Provinces in China

To assess the outcomes of cataract surgery performed by novice surgeons during training in a rural programme.

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

Currently available data on myopia and spectacle wear are drawn largely from China’s richer and middle-income areas, and little is known about refractive error and spectacle wear in the lowest income provinces. Studies from China and elsewhere suggest that large differences in myopia prevalence may exist between areas of different socioeconomic status within countries, but reasons for these differences are not well understood. The current report details the prevalence and predictors of myopia measured using the identical protocols and equipment in 2 adjoining provinces of western China, middle-income Shaanxi and low-income Gansu. Study methods including institutional review board approvals and consent have been described elsewhere. The study was carried out in Yulin prefecture, Shaanxi, and Tianshui prefecture, Gansu Province, which are nearby areas. Shaanxi’s gross domestic product per capita is

Disordered sleep and myopia risk among Chinese children

US6108 and was ranked 14th among China’s 31 administrative regions in 2012, while Gansu is the second-poorest province in the country (per capita gross domestic product of

Association Between Body Composition and Retinal Vascular Caliber in Children and Adolescents

US3100). Yulin is a relatively wealthy region in a middle-income province and Tianshui constitutes a poor region of one of China’s lowest-income provinces. A complete list of primary schools was obtained, and 1 school from each township in the 2 prefectures was selected at random (Yulin, Shaanxi n 1⁄4 132; Tianshui, Gansu n 1⁄4 120). Within each school, 1 class was randomly chosen in each of the 4th and 5th grades. The following data were collected in September 2012: children’s age, sex, boarding at school, parental schooling and migration for work, family wealth, classroom blackboard use, and visual acuity. Children with uncorrected visual acuity of 6/12 in either eye underwent cycloplegic refraction. A study-specific mathematics test was administered as an index of academic achievement. In May and June 2013, we collected data on parental spectacle wear, children’s time spent outdoors and in near/middle distance work using validated instruments. Clinically significant myopia was defined as uncorrected visual acuity of 6/12 in either eye and a spherical equivalent of 0.5 diopter in both eyes. Characteristics were compared between children in the 2 prefectures, accounting for sampling weight and school clustering. Relative risk (RR) estimation using general linear modeling with Poisson regression and robust error variance was used to determine the association between potential risk factors and myopia for the 2 provinces separately and for the total study population. Subjects with missing myopia data (n 1⁄4 306 [1.5%]) were excluded. Among 9489 children in Shaanxi (mean age, 10.4 1.03 years; 53.1% boys), the prevalence of clinically significant myopia (22.9%; 95% CI, 21.2%e24.7%) was nearly twice that of 10 137 children (mean age, 10.7 1.24 years; 49.1% boys) in Gansu (12.7%; 95% CI, 11.3%e14.1%; RR for Shaanxi vs Gansu 1.81 [95% CI, 1.58e2.07; P < 0.001]). Parents out-migrating for work were less common in the Shaanxi cohort (8.10%) than in the Gansu cohort (16.8%; P < 0.001), and families were less likely to be in the lowest wealth tertile for the total sample in Shaanxi (17.2% vs 38.7%; P < 0.001). One-half of our Shaanxi cohort (49%) versus 3.6% in Gansu lived in low population density areas (P < 0.001). Mathematics scores were higher in Shaanxi (P 1⁄4 0.03), and the blackboard was used less in Shaanxi than in Gansu (26.7% of classes spending the majority of classtime directed at the blackboard in Shaanxi vs 45.5% in Gansu; P < 0.001; Table 1, available at www.aaojournal.org). Differences in outdoor activity and near and middle distance work were minimal between Shaanxi and Gansu, and between children with and without myopia (Table 2, available at www.aaojournal.org). Older age (RR, 1.07; 95% CI, 1.02e1.13), parental glasses wear (RR, 1.57; 95% CI, 1.39e1.77), and higher math score (RR, 1.20 [95% CI, 1.13e1.28] per increase of 1 standard deviation in score) were associated with increased risk for myopia in both provinces separately and in the total study population (above RRs are for the total study population). Male sex (RR, 0.81; 95% CI, 0.73e0.91) was associated with lower risk and near work (RR, 1.02 [95% CI, 1.00e1.03] per hour/week increase), with greater risk in the total study population and in Shaanxi alone, but not in Gansu alone. Blackboard use and family wealth were not associated with myopia risk in the multivariate model and no clear linear pattern was found for population density across quartiles (Table 3). Residence in Shaanxi was associated with a 69% increased risk of myopia (RR, 1.69; 95% CI, 1.39; 2.06) after adjusting for other risk factors. The likelihood ratio test (P < 0.001) and pseudo R (<20%) both suggest that the current model fits the data well, and that the conclusion is valid that real, as-yet-unexplained differences exist between myopia prevalence in Shaanxi and Gansu. Even after adjusting for differences in factors associated with myopia, such as near work, school achievement, and outdoor activity, we could not explain much of the large variation in prevalence of clinically significant myopia between middleincome Shaanxi and low-income Gansu. The current study is among the first to compare known myopia risk factors between nearby areas with large differences in myopia rates. It is possible that the low near work demand in the current cohort (8 hours in both Gansu and Shaanxi vs 23e30 hours in Singapore and Australia) might explain the lack of large effects of near work and outdoor activity. Greater blackboard use was protective against myopia in univariate analyses (data not shown), perhaps owing to lower near work demands: weekly near work was lower with highest (6.7 hours) versus lowest (7.6 hours; P < 0.05) blackboard use. Greater blackboard use was also associated with less wealth here (data not shown), because schools in low-income areas could not afford textbooks, which may confound the association with myopia. More research is needed on myopia risk and classroom use of near and distance teaching tools. Our definition of myopia included visual acuity, which limits comparisons with other studies, although not internal comparison between Shaanxi and Gansu. Primary school attendance rates are >95% in the area; thus, this school-based sample is likely representative of the population. It is unlikely that genetic factors

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