Academic Appointments

  • Social Science Research Scholar, Center on Food Security and Environment at FSI

All Publications

  • Safety of eyeglasses wear for visual acuity among middle school students in northwestern rural China: a cluster-randomised controlled trial BMJ OPEN OPHTHALMOLOGY Ma, Y., Zhang, X., Li, H., Ma, X., Friesen, D., Rozelle, S., Pang, X., Zhou, M., Congdon, N. 2020; 5 (1)
  • Impact of spectacles wear on uncorrected visual acuity among urban migrant primary school children in China: a cluster-randomised clinical trial. The British journal of ophthalmology Zhang, X., Zhou, M., Ma, X., Yi, H., Zhang, H., Wang, X., Jin, L., Naidoo, K., Minto, H., Zou, H., Rozelle, S., Congdon, N., Ma, Y. 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 10.9years, 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<0.001), respectively. Uncorrected final VA for eyes of treatment children was significantly better than control children, adjusting only for baseline VA (difference of 0.039 LogMAR units, 95% CI: 0.008, 0.070, equivalent to 0.39 lines, p=0.014) or baseline VA and other baseline factors (0.040 LogMAR units, 95% CI 0.007 to 0.074, equivalent to 0.40 lines, p=0.020).CONCLUSION: We found no evidence that spectacles wear worsens children's uncorrected VA among urban migrant Chinese school children.

    View details for DOI 10.1136/bjophthalmol-2020-316213

    View details for PubMedID 32727732

  • Depressive Symptoms and the Link with Academic Performance among Rural Taiwanese Children. International journal of environmental research and public health Gao, Y., Hu, D., Peng, E., Abbey, C., Ma, Y., Wu, C., Chang, C., Hung, W., Rozelle, S. 2020; 17 (8)


    Previous studies reflect a high prevalence of depressive symptoms among Taiwanese adolescents (ages 13-18), but there is an absence of literature related to the risk of depression of children in Taiwan (ages 6-12), particularly among potentially vulnerable subgroups. To provide insight into the distribution of depressive symptoms among children in rural Taiwan and measure the correlation between academic performance, we conducted a survey of 1655 randomly selected fourth and fifth-grade students at 92 sample schools in four relatively low-income counties or municipalities. Using the Center for Epidemiological Studies-Depression Scale (CES-D) we assessed the prevalence of depressive symptoms in this sample, in addition to collecting other data, such as performance on a standardized math test as well as information on a number of individual and household characteristics. We demonstrate that the share of children with clinically significant symptoms is high: 38% of the students were at risk of general depression (depression score ≥ 16) and 8% of the students were at risk of major depression (depression score > 28). The results of the multivariate regression and heterogeneous analysis suggest that poor academic performance is closely associated with a high prevalence of depressive symptoms. Among low-performing students, certain groups were disproportionately affected, including girls and students whose parents have migrated away for work. Results also suggest that, overall, students who had a parent who was an immigrant from another country were at greater risk of depression. These findings highlight the need for greater resource allocation toward mental health services for elementary school students in rural Taiwan, particularly for at-risk groups.

    View details for DOI 10.3390/ijerph17082778

    View details for PubMedID 32316516

  • The Landscape of Early Childhood Development in Rural China ASIA-PACIFIC JOURNAL-JAPAN FOCUS Dill, S., Ma, Y., Sun, A., Rozelle, S. 2019; 17 (16)
  • Teachers' influence on purchase and wear of children's glasses in rural China: The PRICE study CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY Wang, X., Ma, Y., Hu, M., Jin, L., Xiao, B., Ni, M., Yi, H., Ma, X., Wang, C., Varga, B., Huang, Y., Rozelle, S., Congdon, N. 2019; 47 (2): 179–86


    Uncorrected refractive error causes 90% of poor vision among Chinese children.Little is known about teachers' influence on children's glasses wear.Cohort study.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.Teachers and children underwent VA testing and completed questionnaires about spectacles use and attitudes towards children's vision.Children's acceptance of free glasses, spectacle purchase and wear.A total of 882 children (mean age 10.6 years, 45.5% boys) and 276 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 < 0.05); supporting children's classroom glasses wear (increased glasses wear, univariate model: RR 2.20, 95% CI 1.23, 3.95, P < 0.01); and advising children to obtain glasses (increased free glasses acceptance, multivariate model: RR 2.74, 95% CI 1.29, 5.84, P < 0.01; increased wear, univariate model: RR 2.93, 95% CI 1.45, 5.90, P < 0.01), but not teacher's ownership/wear of glasses.Though teachers had limited knowledge about children's vision, they influenced children's glasses acceptance.

    View details for PubMedID 30117241

  • Impact of a Local Vision Care Center on Glasses Ownership and Wearing Behavior in Northwestern Rural China: A Cluster-Randomized Controlled Trial. International journal of environmental research and public health Ma, Y., Gao, Y., Wang, Y., Li, H., Ma, L., Jing, J., Shi, Y., Guan, H., Congdon, N. 2018; 15 (12)


    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.

    View details for PubMedID 30544793

  • Impact of a Local Vision Care Center on Glasses Ownership and Wearing Behavior in Northwestern Rural China: A Cluster-Randomized Controlled Trial INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH Ma, Y., Gao, Y., Wang, Y., Li, H., Ma, L., Jing, J., Shi, Y., Guan, H., Congdon, N. 2018; 15 (12)
  • Effect of a Local Vision Care Center on Eyeglasses Use and School Performance in Rural China A Cluster Randomized Clinical Trial JAMA OPHTHALMOLOGY Ma, Y., Congdon, N., Shi, Y., Hogg, R., Medina, A., Boswell, M., Rozelle, S., Iyer, M. 2018; 136 (7): 731–37


    Visual impairment is common among children in rural China, but fewer than one-third of children with poor vision own and wear eyeglasses.To study the effect of hospital-based vision centers on academic performance, ownership of eyeglasses, and eyeglasses-wearing behavior in rural Chinese children.Cluster randomized, investigator-masked, clinical trial from September 2014 through June 2015. A vision center capable of providing refractive services was established in the Hospital of Yongshou County, a nationally designated poor county in rural Shaanxi Province, western China. All 31 rural primary schools in Yongshou County participated; participants were all children in grades 4 through 6 (aged approximately 10-12 years) with uncorrected visual acuity of Snellen 6/12 or worse in either eye (2613 children). Data analysis was conducted March through May 2016, and data were analyzed by the intention-to-treat principle.After teacher-led vision screening early in the school year (September-October 2014), schools were randomly assigned to either early referral (December 2014-February 2015) to the vision center for refraction and free eyeglasses if needed or late referral (March-June 2015) for the identical intervention.The primary outcome was score on a study-administered mathematics test (June 2015) adjusted for baseline score. Secondary outcomes were self-reported eyeglasses ownership and wear at final examination (June 2015).All 2613 children evaluated were of Han Chinese race/ethnicity, and 1209 (46.3%) were female. Twelve hundred children (45.9%) met the vision criteria. Among these, 543 (45.3%) were randomized to early screening and 657 (54.7%) to late screening; 433 (79.7%) of the early screening group and 516 (78.5%) of the late screening group completed the study. Of eligible children, 120 (27.7%) owned eyeglasses at baseline. The adjusted effect on test scores comparing early and late groups was 0.25 SD (95% CI, 0.01-0.48; 1-sided P = .04), with the point estimate equivalent to half a semester of additional learning. At the end of the study, 347 of the 433 participants in the early group (80%) reported owning eyeglasses and 326 (75%) reported wearing eyeglasses; among the 516 participants in the late group, 371 (61%) reported owning and 286 (55%) reported wearing eyeglasses.In this study, early provision of free eyeglasses was seen to improve children's academic performance and wearing of spectacles. These findings suggest that a county hospital-based vision center may be an effective way to improve children's educational opportunities in rural Identifier: ISRCTN03252665.

    View details for PubMedID 29801081

  • 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 PLOS ONE Wang, X., Congdon, N., Ma, Y., Hu, M., Zhou, Y., Liao, W., Jin, L., Xiao, B., Wu, X., Ni, M., Yi, H., Huang, Y., Varga, B., Zhang, H., Cun, Y., Li, X., Yang, L., Liang, C., Huang, W., Rozelle, S., Ma, X. 2017; 12 (11): e0187808


    Offering free glasses can be important to increase children's wear. We sought to assess whether "Upgrade glasses" could avoid reduced glasses sales when offering free glasses to children in China.In this cluster-randomized, controlled trial, children with uncorrected visual acuity (VA)< = 6/12 in either eye correctable to >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.Among 10,234 children screened, 882 (8.62%, mean age 10.6 years, 45.5% boys) were eligible and 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.Upgrade glasses can prevent reductions in glasses purchase when free spectacles are provided, providing important program Identifier: NCT02231606. Registered on 31 August 2014.

    View details for PubMedID 29161286

  • Cluster-randomized controlled trial of the effects of free glasses on glasses purchase in China: the PRICE (Potentiating Rural Investment in Children's Eyecare) study Congdon, N. G., Wang, X., Ma, Y., Liao, W., Xiao, B., Ni, M., Huang, Y., Yi, H., Ma, X., Rozelle, S. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2016
  • Teachers' influence on glasses purchase and wear in China: the PRICE (Potentiating Rural Investment in Children's Eyecare) study Wang, X., Ma, Y., Zhou, Y., Jin, L., Xiao, B., Ni, M., Yi, H., Ma, X., Rozelle, S., Congdon, N. G. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2016
  • Inequities in the allocation of medical resources in China's Township Health Centers CHINA AGRICULTURAL ECONOMIC REVIEW Ma, Y., Zhang, L., Boswell, M. 2016; 8 (4): 637-646
  • Dropping Out of Rural China's Secondary Schools: A Mixed-methods Analysis CHINA QUARTERLY Shi, Y., Zhang, L., Ma, Y., Yi, H., Liu, C., Johnson, N., Chu, J., Loyalka, P., Rozelle, S. 2015; 224: 1048-1069
  • Exploring the dropout rates and causes of dropout in upper-secondary technical and vocational education and training (TVET) schools in China INTERNATIONAL JOURNAL OF EDUCATIONAL DEVELOPMENT Yi, H., Zhang, L., Yao, Y., Wang, A., Ma, Y., Shi, Y., Chu, J., Loyalka, P., Rozelle, S. 2015; 42: 115-123