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Nathan Congdon
Journal Articles

The Prevalence and Correlates of Vision Impairment and Glasses Ownership among Ethnic Minority and Han Schoolchildren in Rural China

Huan Wang, Brandon Barket, Sharon Du, Dimitris Friesen, Ezra Kohrman, Esther Tok, Baixiang Xiao, Wenyong Huang, Ving Fai Chan, Graeme MacKenzie, Nathan Congdon
PLOS ONE, 2021 August 30, 2021

Purpose: To determine the prevalence of visual impairment and glasses ownership among Han Chinese and Hui minority junior high school children in Ningxia Hui Autonomous Region, China. 

Design: Population-based cross-sectional study. 

Methods: Vision screening was conducted on 20,376 children (age 12–15 years) in all 124 rural junior high schools in Ningxia. Personal and family characteristics, glasses ownership, and academic performance were assessed through a survey questionnaire and standardized mathematics test, respectively. 

Results: The prevalence of visual acuity (VA) ≤6/12 in either eye was significantly higher among Han (54.5%) than Hui (45.2%) children (P<0.001), and was significantly positively associated with age, female sex, Han ethnicity, parental outmigration for work, shorter time spent outside during recess, shorter time spent watching television and higher time spent studying. Among children with VA≤6/12 in both eyes, only 56.8% of Han and 41.5% of Hui children had glasses (P<0.001). Glasses ownership was significantly associated with worse vision, greater family wealth, female sex, higher test scores, age, parental outmigration for work, understanding of myopia and glasses, higher time spent studying and Han ethnicity. 

Conclusion: One of the first of its kind, this report on Han and Hui ethnic schoolchildren confirms a high prevalence of visual impairment among both populations, but slightly higher among the Han. Both groups, especially the Hui, have low rates of glasses ownership. Future interventions and policies designed to improve glasses usage should focus on populations with lower incomes and seek to correct erroneous beliefs about the safety of glasses and efficacy of traditional eye exercises.

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Journal Articles

Visual Impairment in Rural and Migrant Chinese School-Going Children: Prevalence, Severity, Correction and Association

Yue Ma, Xinwu Zhang, Fei He, Xiaochen Ma, Hongmei Yi, Nathan Rose, Alexis Medina, Scott Rozelle, Nathan Congdon
BMJ Ophthalmology, 2020 October 11, 2020
Purpose To describe changes in the prevalence of visual impairment and glasses ownership with age and as associated with income and population density for visual impairment among rural and urban migrant Chinese students. Design Meta-analysis of 12 cross-sectional, school-based studies conducted between 2012 and 2017. Setting Rural and urban migrant schools in seven Chinese provinces. Participants A total of 83 273 rural and urban migrant Chinese students aged 6–17 years. Results Prevalence of visual impairment (uncorrected visual acuity ≤6/12 in either eye) rose from 19.0% at age 6 to 66.9% at 17, with the overall age-adjusted prevalence higher for girls (35.8%) than for boys (30.1%, p
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Journal Articles

Safety of Eyeglasses Wear for Visual Acuity among Middle School Students in Northwestern Rural China: A Cluster-randomised Controlled Trial

Yue Ma, Xinwu Zhang, Haoyang Li, Xiaochen Ma, Dimitris Friesen, Scott Rozelle, Xiaopeng Pang, Ming Zhou, Nathan Congdon
BMJ Open Ophthalmology, 2020 September 5, 2020
Objective: To assess the effect of free eyeglasses provision on visual acuity among middle school students in northwestern rural China. Methods and analysis: Among 31 middle schools randomly selected from 47 middle schools in northwestern rural China, students were randomly allocated by school to one of two interventions: free eyeglasses (intervention group), and eyeglasses prescriptions given only to the parents (control group). The main outcome of this study is uncorrected visual acuity after 9 months, adjusted for baseline visual acuity. Results: Among 2095 students from 31 middle schools, 995 (47.5%) failed the visual acuity screening, 515 (51.8%, 15 schools) of which were randomly assigned to the intervention group, with the remaining 480 students (48.2%, 16 schools) assigned to the control group. Among these, a total of 910 students were followed up and analysed. Endline eyeglasses wear in the intervention group was 44%, and 36% in the control group. Endline visual acuity of students in the intervention group was significantly better than students in the control group, adjusting for other variables (0.045 LogMAR units, 95% CI 0.006 to 0.084, equivalent to 0.45 lines, p=0.027), and insignificantly better only for baseline visual acuity (difference of 0.008 LogMAR units, 95% CI −0.018 to 0.034, equivalent to 0.08 lines). Conclusion: We found no evidence that receiving free eyeglasses worsened visual acuity among middle school students in northwestern rural China.
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Journal Articles

Impact of Spectacles Wear on Uncorrected Visual Acuity among Urban Migrant Primary School Children in China: A Cluster-Randomised Clinical Trial

Xinwu Zhang, Ming Zhou, Xiaochen Ma, Hongmei Yi, Haiqing Zhang, Xiuqing Wang, Ling Jin, Kovin Naidoo, Hasan Minto, Haidong Zou, Scott Rozelle, Nathan Congdon, Yue Ma
British Journal of Opthalmology, 2020 July 30, 2020
Objective: To estimate the effect of providing free spectacles on uncorrected visual acuity (VA) among urban migrant Chinese school children. Design Exploratory analysis from a parallel cluster-randomised clinical trial. Methods: After baseline survey and VA screening, eligible children were randomised by school to receive one of the two interventions: free glasses and a teacher incentive (tablet computer if ≥80% of children given glasses were wearing them on un-announced examination) (treatment group) or glasses prescription and letter to parents (control group). The primary outcome was uncorrected logarithm of the minimal angle of resolution (LogMAR) VA at study closeout, adjusted for baseline uncorrected VA. Results: Among 4376 randomly selected children, 728 (16.6%, mean age 10.9 years, 51.0% boys) at 94 schools failed VA screening and met eligibility criteria. Of these, 358 children (49.2%) at 47 schools were randomised to treatment and 370 children (50.8%) at 47 schools to control. Among these, 679 children (93.3%) completed follow-up and underwent analysis. Spectacle wear in the treatment and control groups was 68.3% and 29.3%(p
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Journal Articles

Effect of Chinese Eye Exercises on Change in Visual Acuity and Eyeglasses Wear among School-Aged Children in Rural China: A Propensity-Score-Matched Cohort Study

Huan Wang, Yiwei Qian, Nathan Congdon, Matthew Boswell, Scott Rozelle, Xiaochen Ma
BMC Complementary Medicine and Therapies, 2020 March 13, 2020
Background Daily “eye exercises,” massaging of periocular acupuncture pressure points, have been part of China’s national vision care policy in schools for some 50 years. However, the effect of eye exercises on myopia progression and eyeglasses wear has not been definitively investigated. This study evaluates the effectiveness of eye exercises on visual acuity and the propensity of rural children to wear eyeglasses. Methods Cohort study in 252 randomly-selected rural schools with baseline in September 2012 and follow up surveys 9 and 21 months later. Outcomes were assessed using propensity-score matching (PSM), multivariate linear regression and logistic regression to adjust for differences between children performing and not performing eye exercises. Results Among 19,934 children randomly selected for screening, 2374 myopic (spherical equivalent refractive error ≤ − 0.5 diopters in either eye) children (11.9%, mean age 10.5 [Standard Error 1.08] years, 48.5% boys) had VA in either eye ≤6/12 without eyeglasses correctable to > 6/12 with eyeglasses. Among these who completed the 21-month follow up, 1217 (58.2%) children reported practicing eye exercises on school days and 874 (41.8%) did not. After propensity-score matching, 1652 (79%) children were matched: 826 (50%) in the Eye Exercises group and 826 (50%) in the No Exercise group. Performing eye exercises was not associated with change in LogMAR uncorrected visual acuity and wear of eyeglasses, using either logistic regression or PSM at 9 or 21 months. Conclusions We found no evidence for an effect of eye exercises on change in vision or eyeglasses wear.
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Journal Articles

Visual Impairment and Spectacles Ownership among Upper Secondary School Students in Northwestern China

J Zhao, H Guan, K Du, Huan Wang, Matthew Boswell, Yaojiang Shi, Scott Rozelle, Nathan Congdon, Annie Osborn
Hong Kong Medical Journal, 2020 February 6, 2020
PURPOSE: To assess the prevalence of visual impairment and spectacles ownership among academic and vocational upper secondary school students in rural China. METHODS: This cross-sectional study included 5583 students from four academic upper secondary schools (AUSSs) and two vocational upper secondary schools (VUSSs) in Mei and Qianyang counties, Baoji Prefecture, Shaanxi Province. In March and April 2016, students underwent assessment of visual acuity (VA) and completed a questionnaire regarding spectacles use and family characteristics. Students with visual impairment (presenting VA ≤6/12 in the better eye) and students needing spectacles (uncorrected VA ≤6/12 in the better eye, which could be improved to >6/12 with refraction) were identified. RESULTS: Among 5583 students (54% boys, mean age 16.4±1.0 years) in grades 10 and grade 11 attending AUSSs (n=4549) and VUSSs (n=1034), visual impairment was detected in 4026 students. Among the AUSS students, 3425 (75%) needed spectacles; 2551 (75%) had them. Among the VUSS students, 601 (58%) needed spectacles; this proportion was significantly smaller (P=0.004), as was the proportion who had spectacles (n=212, 35%, P
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Journal Articles

Impact of Various Types of Near Work and Time Spent Outdoors at Different Times of Day on Visual Acuity and Refractive Error Among Chinese School-Going Children

Hongyu Guan, Ning Neil Yu, Huan Wang, Matthew Boswell, Yaojiang Shi, Scott Rozelle, Nathan Congdon
PLoS ONe, 2019 April 26, 2019
Background: Various types of near work have been suggested to promote the incidence and progression of myopia, while outdoor activity appears to prevent or retard myopia. However, there is a lack of consensus on how to interpret these results and translate them into effective intervention strategies. This study examined the association between visual acuity and time allocated to various activities among school-going children.
Methods: Population-based survey of 19,934 students in grade 4 and 5 from 252 randomly selected rural primary schools in Northwest China in September 2012. This survey measured visual acuity and collected self-reported data on time spent outdoors and time spent doing various types of near activities.
Results:  Prolonged (>60 minutes/day) computer usage (-0.025 LogMAR units, P = .011) and smartphone usage (-0.041 LogMAR units, P = .001) were significantly associated with greater refractive error, while television viewing and after-school study were not. For time spent outdoors, only time around midday was significantly associated with better uncorrected visual acuity. Compared to children who reported no midday time outdoors, those who spent time outdoors at midday for 31–60 minutes or more than 60 minutes had better uncorrected visual acuity by 0.016 LogMAR units (P = .014) and 0.016 units (P = .042), respectively.
Conclusions: Use of smart phones and computers were associated with declines in children’s vision, while television viewing was not. Statistically significant associations between outdoor time at midday and reduced myopia may support the hypothesis that light intensity plays a role in the protective effects of outdoor time.
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Journal Articles

Impact of a Local Vision Care Center on Glasses Ownership and Wearing Behavior in Northwestern Rural China: A Cluster-Randomized Controlled Trial

Yue Ma, Yujuan Gao, Yue Wang, Haoyang Li, Lina Ma, Jiangchao Jing, Yaojiang Shi , Hongyu Guan , Nathan Congdon
International Journal of Environmental Research and Public Health, 2018 December 8, 2018

Abstract: Visual impairment is common among rural Chinese children, but fewer than a quarter of children who need glasses actually own and use them. To study the effect of rural county hospital vision centers (VC) on self-reported glasses ownership and wearing behavior (primary outcome) among rural children in China, we conducted a cluster-randomized controlled trial at a VC in the government hospital of Qinan County, a nationally-designated poor county. All rural primary schools (n = 164) in the county were invited to participate. Schools were randomly assigned to either the treatment group to receive free vision care and eyeglasses, if needed, or control group, who received glasses only at the end of the study. Among 2806 eligible children with visiual impairment (visual acuity ≤ 6/12 in either eye), 93 (3.31%) were lost to follow-up, leaving 2713 students (45.0% boys). Among these, glasses ownership at the end of the school year was 68.6% among 1252 treatment group students (82 schools), and 26.4% (p < 0.01) among 1461 controls (82 schools). The rate of wearing glasses was 55.2% in the treatment group and 23.4% (p < 0.01) among the control group. In logistic regression models, treatment group membership was significantly associated with spectacle ownership (Odds Ratio [OR] = 11.9, p < 0.001) and wearing behavior (OR = 7.2, p < 0.001). County hospital-based vision centers appear effective in delivering childrens’ glasses in rural China.

 

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Journal Articles

The Cost-Effectiveness of Alternative Vision Screening Models among Preschool Children in Rural China

Lei Wang, Nathan Congdon, Ruth E. Hogg, Siqi Zhang, Mengjie Li, Yaojiang Shi, Ling Jin, Fei He, Huan Wang, Matthew Boswell, Mony Iyer
Acta Ophthalmologica, 2018 October 21, 2018
PURPOSE: To explore the accuracy and cost-effectiveness of three vision screening models among preschool children in rural China. METHODS: Vision screening was carried out among children aged 4-5 years in 65 preschools in two counties in Northwest China, using Crowded Single Lea Symbols to test visual acuity. Children were assigned randomly by school to one of three screening models: screening by teachers (15 schools, 1835 children), local optometrists (30 schools, 1718 children) or volunteers (20 schools, 2183 children). Children identifying ≥2 symbols incorrectly in either eye failed screening. Accuracy of screening was compared with screenings executed by experienced optometrists among 141 children selected randomly from the three screening models. Direct and indirect costs for each model were assessed. Costs to detect a true case failed screening were estimated. RESULTS: The sensitivity for three models ranged from 76.9% to 87.5%, specificity from 84.9% to 86.7% and standardized positive predictive value from 83.7% to 85.7%. None differed significantly between models. The costs per case detected were $37.53, $59.14 and $52.19 for the teachers, local optometrists and volunteers. In producing the cost estimates for teacher screening and local optometrist screening models, we used a salary payment that was identical for both models (with the salary being equal to that of the optometrist). The teacher screening model was the most cost-effective. CONCLUSION: Accuracy of screening by teachers, local optometrists and volunteers was the same in this setting, but the use of teachers was most cost-effective, reducing the cost per case detected by almost 40%.
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Journal Articles

Teachers' Influence on Purchase and Wear of Children's Glasses in Rural China: The PRICE Study

Xiuqin Wang, Yue Ma, Mi Hu, Ling Jin, Baixiang Xiao, Ming Ni, Hongmei Yi , Xiaochen Ma, Congyao Wang, Beatrice Varga, Yiwen Huang, Scott Rozelle , Nathan Congdon
Clinical & Experimental Ophthalmology, 2018 August 11, 2018
Importance:Uncorrected refractive error causes 90% of poor vision among Chinese children. Background:Little is known about teachers' influence on children's glasses wear. Design:Cohort study. Participants:Children at 138 randomly selected primary schools in Guangdong and Yunnan provinces, China, with uncorrected visual acuity (VA)≤6/12 in either eye correctable to >6/12 in both eyes, and their teachers. Methods:Teachers and children underwent VA testing and completed questionnaires about spectacles use and attitudes towards children's vision. Main Outcome Measures:Children's acceptance of free glasses, spectacle purchase and wear. Results: A total of 882 children (mean age 10.6 years, 45.5% boys) and276 teachers (mean age 37.9 years, 67.8% female) participated. Among teachers,20.4% (56/275) believed glasses worsened children's vision, 68.4% (188/275) felt eye exercises prevented myopia, 55.0% (151/275) thought children with modest myopia should not wear glasses and 93.1% (256/275) encouraged children to obtain glasses.Teacher factors associated with children's glasses-related behaviour included believing glasses harm children's vision (decreased purchase, univariate model: relative risk [RR] 0.65, 95% CI 0.43, 0.98,P
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Journal Articles

Effect of a Local Vision Care Center on Eyeglasses Use and School Performance in Rural China A Cluster Randomized Clinical Trial

Yue Ma, Nathan Congdon, Yaojiang Shi, Ruth Hogg, Alexis Medina, Matthew Boswell, Scott Rozelle, Mony Iver
JAMA Ophthalmology, 2018 May 10, 2018

Can a county-based vision center increase eyeglasses use and improve school performance among primary schoolchildren in rural China? This cluster randomized clinical trial of 31 schools and 2613 participants showed that children who received eyeglasses earlier in the school year performed significantly better on an end-of-year mathematics test than children who received eyeglasses later in the year, equivalent to half a semester. Provision of free eyeglasses also improved children's use of spectacles.

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Journal Articles

Cluster-randomized Controlled Trial of the Effects of Free Glasses on Purchase of Children's Glasses in China: The PRICE (Potentiating Rural Investment in Children's Eyecare) Study

Xiuqin Wang, Nathan Congdon, Yue Ma, Min Hu, Yuan Zhou, Weiqi Liao, Ling Jin, Xiaoyi Wu, Ming Ni, Hongmei Yi , Yiwen Huang, Beatrice Varga, Hong Zhang, Yongkang Cun, Xianshun Li, Luhua Yang, Chaoguang Liang, Wan Huang, Scott Rozelle, Xiaochen Ma
PLOS ONE, 2017 November 21, 2017
Background: Offering free glasses can be important to increase children's wear. We sought to assess whether ªUpgrade glassesº could avoid reduced glasses sales when offering free glasses to children in China. Methods: In this cluster-randomized, controlled trial, children with uncorrected visual acuity (VA)6/12 in both eyes at 138 randomly-selected primary schools in 9 counties in Guangdong and Yunnan provinces, China, were randomized by school to one of four groups: glasses prescription only (Control); Free Glasses; Free Glasses + offer of $15 Upgrade Glasses; Free Glasses + offer of $30 Upgrade Glasses. Spectacle purchase (main outcome) was assessed 6 months after randomization. Results: Among 10,234 children screened, 882 (8.62%, mean age 10.6 years, 45.5% boys) were eligibleand randomized: 257 (29.1%) at 37 schools to Control; 253 (28.7%) at 32 schools to Free Glasses; 187 (21.2%) at 31 schools to Free Glasses + $15 Upgrade; and 185 (21.0%) at 27 schools to Free Glasses +$30 Upgrade. Baseline ownership among these children needing glasses was 11.8% (104/882), and 867 (98.3%) children completed follow-up. Glasses purchase was significantly less likely when free glasses were given: Control: 59/250 = 23.6%; Free glasses: 32/252 = 12.7%, P = 0.010. Offering Upgrade Glasses eliminated this difference: Free + $15 Upgrade: 39/183 = 21.3%, multiple regression relative risk (RR) 0.90 (0.56±1.43), P = 0.65; Free + $30 Upgrade: 38/182 = 20.9%, RR 0.91 (0.59, 1.42), P = 0.69. Conclusions: Upgrade glasses can prevent reductions in glasses purchase when free spectacles are provided, providing important program income.
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Journal Articles

Impact of a Teacher Incentive on Children’s Use of Eyeglasses: A Cluster-Randomized Controlled Trial

Hongmei Yi, Haiqing Zhang, Xiaochen Ma, Linxiu Zhang, Nathan Congdon, Xiuqing Wang, Kovin Shunmugam Naidoo, Hasan Minto, Haidong Zou, Scott Rozelle
American Journal of Opthalmology, 2016 April 19, 2016

Purpose: The impact of school-time wear of glasses on children’s education has been shown to be limited by lack of regular compliance in half or more of children, even when free glasses are given. We sought to study the impact of free glasses combined with teacher incentives on in-school use of glasses among Chinese urban migrant children.

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Journal Articles

Impact of Free Glasses and a Teacher Incentive on Children's Use of Eyeglasses: A Cluster-Randomized Controlled Trial

Hongmei Yi, Xiaochen Ma, Linxiu Zhang, Scott Rozelle, Nathan Congdon
American Journal of Ophthalmology, 2015 November 25, 2015

Purpose: To study the effect of free glasses combined with teacher incentives on in-school glasses wear among Chinese urban migrant children.

Design: A cluster randomized trial.

Methods: Children with visual acuity (VA) ≤6/12 in either eye owing to refractive error in 94 randomly chosen primary schools underwent randomization by school to receive free glasses, education on their use, and a teacher incentive (Intervention), or glasses prescriptions only (Control). Intervention group teachers received a tablet computer if ≥80% of children given glasses wore them during unannounced visits 6 weeks and 6 months (main outcome) after intervention.

Results: Among 4376 children, 728 (16.7%, mean age 10.9 years, 51.0% boys) met enrollment criteria and were randomly allocated, 358 (49.2%, 47 schools) to Intervention and 370 (50.8%, 47 schools) to Control. Among these, 693 children (95.2%) completed the study and underwent analysis. Spectacle wear was significantly higher at 6 months among Intervention children (Observed [main outcome]: 68.3% vs 23.9%, adjusted odds ratio [OR] = 11.5, 95% confidence interval [CI] 5.91–22.5, P < .001; Self-reported: 90.6% vs 32.1%, OR = 43.7, 95% CI = 21.7–88.5, P < .001). Other predictors of observed wear at 6 months included baseline spectacle wear (P < .001), uncorrected VA <6/18 (P = .01), and parental spectacle wear (P = .02). The 6-month observed wear rate was only 41% among similar-aged children provided free glasses in our previous trial without teacher incentives.

Conclusions: Free spectacles and teacher incentives maintain classroom wear in the large majority of children needing glasses over a school year. Low wear among Control children demonstrates the need for interventions.

 

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Journal Articles

Population Prevalence of Need for Spectacles and Spectacle Ownership Among Urban Migrant Children in Eastern China

Hongmei Yi, Linxiu Zhang, Xiaochen Ma, Scott Rozelle, Nathan Congdon
JAMA Ophthalmology, 2015 October 1, 2015

Importance: The number of urban migrants in China is 300 million and is increasing rapidly in response to government policies. Urban migrants have poor access to health care, but little is known about rates of correction of refractive error among migrant children. This is of particular significance in light of recent evidence demonstrating the educational impact of providing children with spectacles.

Objective: To measure prevalence of spectacle need and ownership among Chinese migrant children.

Design, Setting, and Participants: Population-based, cross-sectional study among children who failed vision testing (uncorrected visual acuity ≤6/12 in either eye) between September 15 and 30, 2013, at 94 randomly selected primary schools in predominantly migrant communities in Shanghai, Suzhou, and Wuxi, China.

Main Outcomes and Measures: Refractive error by cycloplegic refraction; spectacle ownership, defined as producing glasses at school, having been told to bring them; and needing glasses, defined as uncorrected visual acuity of 6/12 or less correctable to greater than 6/12 in either eye, with myopia of −0.5 diopters (D) or less, hyperopia of +2.0 D or greater, or astigmatism of 0.75 D or greater in both eyes.

Results: Among 4409 children, 4376 (99.3%) completed vision screening (mean [SD] age, 11.0 [0.81] years; 55.3% boys; 4225 [96.5%] migrant and 151 [3.5%] local). Among 1204 children failing vision testing (total, 27.5%; 1147 migrant children [27.1%] vs 57 local children [37.7%]; P = .003), 850 (70.6%) completed refraction. Spectacle ownership in migrant children needing glasses (147 of 640 children [23.0%]) was less than among local children (12 of 34 children [35.3%]) (odds ratio = 0.55; 95% CI, 0.32-0.95; P = .03). Having uncorrected visual acuity less than 6/18 in both eyes was associated positively with baseline spectacle ownership (odds ratio = 5.73; 95% CI, 3.81-8.62; P < .001), but parental education and family wealth were not.

Conclusions and Revelance: Among urban migrant children, there was a high prevalence of need for spectacles and a very low rate of spectacle ownership. Spectacle distribution programs are needed specifically targeting migrant children.

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Journal Articles

Safety of Spectacles for Children's Vision: A Cluster-Randomized Controlled Trial

Xiaochen Ma, Nathan Congdon, Hongmei Yi, Xiaopeng Pang, Yaojiang Shi, Scott Rozelle
American Journal of Ophthalmology, 2015 August 25, 2015
Purpose: To study safety of children's glasses in rural China, where fear that glasses harm vision is an important barrier for families and policy makers. Design: Exploratory analysis from a cluster-randomized, investigator-masked, controlled trial. Methods: Among primary schools (n = 252) in western China, children were randomized by school to 1 of 3 interventions: free glasses provided in class, vouchers for free glasses at a local facility, or glasses prescriptions only (Control group). The main outcome of this analysis is uncorrected visual acuity after 8 months, adjusted for baseline acuity. Results: Among 19 934 children randomly selected for screening, 5852 myopic (spherical equivalent refractive error ≤−0.5 diopters) eyes of 3001 children (14.7%, mean age 10.5 years) had VA ≤6/12 without glasses correctable to >6/12 with glasses, and were eligible. Among these, 1903 (32.5%), 1798 (30.7%), and 2151 (36.8%) were randomized to Control, Voucher, and Free Glasses, respectively. Intention-to-treat analyses were performed on all 1831 (96.2%), 1699 (94.5%), and 2007 (93.3%) eyes of children with follow-up in Control, Voucher, and Free Glasses groups. Final visual acuity for eyes of children in the treatment groups (Free Glasses and Voucher) was significantly better than for Control children, adjusting only for baseline visual acuity (difference of 0.023 logMAR units [0.23 vision chart lines, 95% CI: 0.03, 0.43]) or for other baseline factors as well (0.025 logMAR units [0.25 lines, 95% CI 0.04, 0.45]). Conclusion: We found no evidence that spectacles promote decline in uncorrected vision with aging among children.
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Journal Articles

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

Zhongqiang Zhou, Xiaochen Ma, Hongmei Yi, Xiaopeng Pang, Yaojiang Shi, Qianyun Chen, Mirjam E. Meltzer, Carlos Price-Sanchez, Mingguang He, Scott Rozelle, Ian Morgan, Nathan Congdon
Ophthalmology, 2015 February 5, 2015

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.

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Journal Articles

Poor Vision Among China’s Rural Primary School Students: Prevalence, Correlates and Consequences

Hongmei Yi, Linxiu Zhang, Xiaochen Ma, Nathan Congdon, Yaojiang Shi, Xiaopeng Pang, Junxia Zeng, Lei Wang, Matthew Boswell, Scott Rozelle
2015 January 1, 2015

Using a survey of 19,977 children in two provinces, this paper explores the prevalence, correlates and potential consequences of poor vision among children in China's vast but understudied rural areas. We find that 24% of sample students suffer from reduced uncorrected visual acuity in either eye and 16% in both eyes. Poor vision is significantly correlated with individual, parental and family characteristics, with modest magnitudes for all correlates but home province and grade level. The results also suggest a possible adverse impact of poor vision on academic performance and mental health, particularly among students with severe poor vision.

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Journal Articles

An Investigation of Vision Problems and the Vision Care System in Rural China

Yunli Bai, Hongmei Yi, Linxiu Zhang, Yaojiang Shi, Xiaochen Ma, Nathan Congdon, Zhongqiang Zhou, Matthew Boswell, Scott Rozelle
Southeast Asian Journal of Tropical Medicine and Public Health, 2014 November 1, 2014

This paper examines the prevalence of vision problems and accessibility to and quality of vision care in rural China. We obtained data from 4 sources: 1) the National Rural Vision Care Survey; 2) the Private Optometrists Survey; 3) the County Hospital Eye Care Survey; and 4) the Rural School Vision Care Survey. The data from each of the surveys were collected by the authors during 2012. Thirty-three percent of the rural population surveyed self-reported vision problems. Twenty-two percent of subjects surveryed had ever had a vision exam.

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Journal Articles

Effect of providing free glasses on children's educational outcomes in China: The "Seeing is Learning" cluster-randomized controlled trial

Xiaochen Ma, Zhongqiang Zhou, Hongmei Yi, Xiaopeng Pang, Yaojiang Shi, Qianyun Chen, Mirjam E. Meltzer, Saskia le Cessie, Mingguang He, Scott Rozelle, Yizhi Liu, Nathan Congdon
British Medical Journal, 2014 October 14, 2014

Objective: To study for the first time using a clinical trial the effect of free glasses on academic performance in rural Chinese children, among whom uncorrected myopia is the leading cause of visual impairment.

Participants: Among 19,934 children in grades 4 and 5 randomly selected for visual acuity screening, 3177 (15.9%, mean age 10.5 years) had visual acuity < 6/12 in either eye without glasses correctable to > 6/12 with glasses, and were eligible for allocation. Among these, 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: free glasses provided in class, vouchers for free glasses at a local facility or glasses prescriptions only (Control group).

Results: Among 3177 eligible children, 1036 (32.6%), 988 (31.1%) and 1153 (36.3%) were randomized to Control, Voucher and Free Glasses respectively. All eligible children would benefit from glasses, but only 15% had them at baseline. Intention-to-treat analyses were performed on all 1002 (96.8%), 946 (95.9%) and 1104 (95.8%) children completing final testing in Control, Voucher and Free Glasses groups. Effect on test score was 0.11 SD (95% Confidence Interval [CI] 0.01 to 0.21, p = 0.03) comparing the Free Glasses and Control groups. Adjusted effect of providing free glasses (0.10 SD, 95% CI 0.01 to 0.20; p = 0.04) was greater than parental education (0.03, 95% CI -0.03 to 0.10) or family wealth (0.002, 95% CI -0.07 to 0.07). Closeout glasses wear was 41% (observed), 68% (self-reported) in the Free Glasses group.

Conclusions: Providing free glasses improves children's performance on mathematics testing to a statistically significant degree, despite imperfect compliance. Myopia is common and rarely corrected in this setting.

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Journal Articles

Accuracy of Rural Refractionists in Western China

Zhongqiang Zhou, Junxia Zeng, Xiaochen Ma, Xiaopeng Pang, Hongmei Yi, Qianyu Chen, Mirjam Meltzer, Mingguang He, Scott Rozelle, Nathan Congdon
Investigative Ophthalmology & Visual Science , 2013 March 4, 2013
PURPOSE. We assessed the prevalence and predictors of inaccurate refractive error among rural refractionists in western China. METHODS. A subset of primary school children with visual acuity (VA) ≤6/12 in ≥ 1 eye, undergoing subjective refinement by local refractionists after cycloplegic autorefraction in an ongoing population-based study, received repeat refraction by university optometrists for quality control. RESULTS. Among 502 children (mean age 10.5 years, 53.2% girls), independent predictors of poor (inaccurate by ≥1.0 diopter [D]) refraction by 21 rural practitioners (66.7% with high school or lower education) included hyperopia (odds ratio [OR], 4.2; 95% confidence interval [CI ], 2.4–7.3, P 6/12 by the rural refractionist (OR 1⁄4 4.7; 95% CI, 3.1–7.3; P 1⁄4 6/12 by the university optometrist in 110 (54.7%). We estimate vision could be so improved in 9.1% of all children refracted by these rural refractionists. A reason for inaccuracy in this setting is the erroneous tendency of rural refractionists to adjust instrument values for accommodation, even under cycloplegia. CONCLUSIONS. Rural refractionists in western China have little formal training and frequently
fail to optimize VA among children, even when autorefractors are used. Training is needed emphasizing better use of automated refraction, particularly in children with astigmatism and hyperopia. Keywords: China, rural, refractionist, refraction, optometrist, accuracy
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