Date Published: April 18, 2019
Publisher: Public Library of Science
Author(s): Min Hu, Yuan Zhou, Shanshan Huang, Nathan Congdon, Ling Jin, Xiuqin Wang, Ruth Hogg, Hong Zhang, Yongkang Cun, Luhua Yang, Xianshun Li, Chaoguang Liang, Ahmed Awadein.
To measure myopia, glasses wear and free glasses acceptance among minority and Han children in China.
Visual acuity testing and questionnaires assessing ethnicity, study time, and parental and teacher factors were administered to a population-based sample of 9–12 year old minority and Han children in Yunnan and Guangdong, and their teachers and parents. Refraction was performed on children with uncorrected visual acuity (VA) < = 6/12 in either eye, and acceptance of free glasses assessed. Baseline myopia (uncorrected visual acuity < = 6/12 in > = 1 eye and spherical equivalent refractive power < = -0.5D in both eyes); baseline glasses wear; free glasses acceptance. Among 10,037 children (mean age 10.6 years, 52.3% boys), 800 (8.0%) were myopic, 4.04% among Yunnan Minority children (OR 0.47, 95%CI 0.33, 0.67, P<0.001), 6.48% in Yunnan Han (OR 0.65, 95%CI 0.45, 0.93, P = 0.019), 9.87% in Guangdong Han (Reference). Differences remained significant after adjusting for study time and parental glasses wear. Difference in baseline glasses ownership (Yunnan Minority 4.95%, Yunnan Han 6.15%, Guangdong Han 15.3%) was not significant after adjustment for VA. Yunnan minority children (71.0%) were more likely than Yunnan Han (59.6%) or Guangdong Han (36.8%) to accept free glasses. The difference was significant after adjustment only compared to Guangdong Han (OR 3.34, 95% CI 1.62, 6.90, P = 0.001). Myopia is more common among Han children and in wealthier Guangdong. Baseline differences in glasses wear could be explained by student, teacher and parental factors. Yunnan Minority children were more likely to accept free glasses.
Refractive error (RE) is a common eye disorder and the leading cause of visual impairment and blindness in children worldwide.  Myopia is the most common RE among school-aged children, and tends to increase with age and additional schooling.  China has among the highest prevalence of childhood myopia in the world. [3–9] Among the 13 million children with visual impairment due to uncorrected refractive error, nearly half live in China. 
This study was approved by the Institutional Review Boards at Stanford University (Palo Alto, USA), the Zhongshan Ophthalmic Center (Guangzhou, China) and Yunnan Red Cross Hospital (Kunming, China). Permission was received from local boards of education in each region and the principals of all schools, and written informed consent was provided by at least one parent on behalf of all children. The principles of the Declaration of Helsinki were followed throughout.
Among 10,234 students in the selected classes that completed baseline questionnaires and vision screening, 165 (1.61%) minority children from Guangdong and 32 (0.31%) children with missing ethnicity data were excluded from analysis, leaving 10,037 children (98.1%): 6293 Guangdong Han (62.7%; mean age 10.6 years, 53.6% males), 1142 Yunnan Han (11.4%, mean age 10.5 years, 52.5% males) and 2602 Yunnan minority (25.9%, mean age 10.6 years, 49.1% males). Among these, 9087 (90.5%) passed vision screening, 950 (9.46%) failed screening and 800 (7.97%) were myopic (uncorrected visual acuity < = 6/12 in at least one eye and SE < = -0.5 D in both eyes). These included 621 Guangdong Han (77.6%), 74 Yunnan Han (9.25%) and 105 Yunnan minority (13.1%) children. The prevalence of myopia was 9.87% among Guangdong Han children, 6.48% among Yunnan Han and 4.04% among Yunnan Minority. (Table 1). The importance of the current study lies in the fact that very little population-based information exists about prevalence and especially treatment of refractive error among ethnic minority children in China. The majority of Chinese people (92%) are from the Han group, but nearly 8% or 110 million Chinese are from 55 diverse minority ethnic groups.  Many minority groups live in sparsely populated, relatively impoverished areas, resulting in differences which are socioeconomic as well as cultural. [21, 22] Genetic differences between minority and Han groups have also been identified. [23, 24] Source: http://doi.org/10.1371/journal.pone.0215660