Incidence of and Factors Associated With Myopia and High Myopia in Chinese Children, Based on Refraction Without Cycloplegia

Abstract

IMPORTANCE Myopia has reached epidemic levels among children in regions of East and Southeast Asia. High myopia is associated with myopic macular degeneration, glaucoma, and retinal detachment.OBJECTIVE To determine the incidence of myopia and high myopia based on refraction without cycloplegia among children in primary and junior high schools in China. DESIGN, SETTING, AND PARTICIPANTSThis observational cohort study was completed in Guangzhou, China. It consisted of a cohort from 19 primary schools, who were followed up from 2010 to 2015, and a cohort from 22 junior high schools, who were followed up from 2010 to 2012. All schools were randomly chosen at rates proportional to the number of schools in each of the city's 11 districts. Students with or without myopia in grade 1 (primary school) or grade 7 (junior high school) were eligible for inclusion. Data analysis occurred from February 2017 to October 2017. MAIN OUTCOMES AND MEASURESMyopia was defined as a spherical equivalent refraction (SER) of −0.50 diopters (D) or less, as measured by subjective refraction without cycloplegia; high myopia was defined as a SER of −6.0 D or less. Annual incidences were defined as the proportion of participants each year found to have myopia or high myopia who did not previously have the condition. Height, weight, axial length (AL), corneal radius of curvature (CRC), and AL/CRC ratio were examined to assess if these measures were associated with future myopia or high myopia.RESULTS A total of 4741 students with or without myopia in either grade 1 for the primary school cohort (mean [SD] age 7.2 [0.4] years; 932 of 1975 [47.2%] female) or grade 7 for the junior high school cohort (mean [SD] age 13.2 [0.5] years; 1254 of 2670 [47.0%] female) were included. Baseline mean (SD) SER was 0.31 (0.86) D among 1975 students in grade 1 vs −1.60 (2.00) D among 2670 students in grade 7. Baseline prevalence of myopia was 12.0% in grade 1 students (n = 237 of 1969) and 67.4% in grade 7 students (n = 1795 of 2663). The incidence of myopia was 20% to 30% each year throughout both cohorts. The incidence of high myopia was initially less than 1% in the primary school cohort (grade 1: n = 2 of 1825; 0.1% [95% CI, 0.0%-0.3%]), but incidence exceeded 2% in the junior high school cohort (in grade 9: n = 48 of 2044; 2.3% [95% CI, 1.0%-3.7%]). CONCLUSIONS AND RELEVANCEThe incidence of myopia among Chinese students based on refraction without cycloplegia is among the highest of any cultural or ethnic group. If confirmed with cycloplegic refraction, interventions to prevent myopia onset in Chinese populations should be initiated in primary schools.

Growth curves of myopia-related parameters to clinically monitor the refractive development in Chinese schoolchildren

“…This paper showed what has been commented on the epidemic levels of myopia reached in areas of the Asian continent [24,25]. The results showed prevalence's of myopia above 12.00% at the age of 6 years, with a continuous progression from the age of 7 years, reaching prevalence levels close to 55.00% in both genders.…”

Genome-Wide Association of Genetic Variants With Refraction, Axial Length, and Corneal Curvature: A Longitudinal Study of Chinese Schoolchildren

“…Myopia (nearsightedness) is a common eye disorder that is reaching epidemic proportions worldwide (Williams et al, 2015;Wang et al, 2018;Tideman et al, 2019). The global prevalence of myopia is increasing and expected to increase from one in four persons in 2000 to nearly half of the global population by 2050 (Holden et al, 2016).…”

Effect of Corneal Refractive Surgery on Accommodative and Binocular Dysfunctions Among Civilian Pilots in Southwest China

“…Each item had ve possible answers with an associated value -always (4), frequently (3), occasional (2), seldom (1), and never (0). A total score of 20 and above is a concern and further evaluation is needed.…”

“…Authors' information 1 Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China. 2 Department of Ophthalmology, Chengdu Civil Aviation Medical Center, Chengdu, Sichuan Province, China.…”

“…The high prevalence of myopia in China [1,2] has been a long-standing problem for the Civil Aviation Administration of China (CAAC), as the need to maintain stringent aeromedical visual standards must be balanced with the con icting requirement of meeting aircrew recruitment demands. To increase the recruitment pool of potential civilian pilots, the CAAC ultimately approved corneal refractive surgery (CRS) for civilian pilots in 2006 [3].…”