Shi-Ming Li1, Shifei Wei1, David A Atchison2, Meng-Tian Kang1, Luoru Liu3, He Li3, Siyuan Li4, Zhou Yang5, Yipeng Wang3, Fengju Zhang1, Ningli Wang1. 1. Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China. 2. Centre for Vision and Eye Research, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia. 3. Anyang Eye Hospital, Henan Province, China. 4. Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, China. 5. Department of Ophthalmology, Children's Hospital Attached to The Capital Institute of Pediatrics, Beijing, China.
Abstract
Purpose: To determine the annual incidences and rates of progression of myopia and high myopia in Chinese schoolchildren from grade 1 to grade 6 and explore the possible cause-specific risk factors for myopia. Methods: From 11 randomly selected primary schools in Anyang city, central China, 2835 grade 1 students were examined with annual follow ups for 5 years. Students were invited to undergo a comprehensive examination, including cycloplegic autorefraction, ocular biometry, and standardized questionnaires. Results: The mean spherical equivalent refraction decreased substantially from +0.94 ± 1.03 diopter (D) in grade 1 to -1.37 ± 2.08 D in grade 6, with rapid annual myopic shifts, especially for students in grades 3 through 6 (-0.51 to -0.59 D). The prevalence of myopia increased substantially, with the yearly incidence of myopia increasing from 7.8% in grade 1 and 2 to 25.3% in grades 5 and 6, and the incidence of high myopia increased from 0.1% to 1.0%. The 5-year incidence of myopia was lowest among children who has a baseline spherical equivalent refraction of greater than +2.00 D (4.4%), and increased to nearly 92.0% among children whose baseline spherical equivalent refraction was 0.00 to -0.50 D. The incidence of myopia was higher in children who had less hyperopic baseline refraction, two myopic parents, longer axial length, deeper anterior chamber, higher axial length-corneal radius of curvature ratio, and thinner lenses. Conclusions: Both the annual incidence and progression rates of myopia and high myopia were high in Chinese schoolchildren, especially after grade 3. Hyperopic refraction of children should be monitored before primary school as hyperopia reserve to prevent the onset of myopia and high myopia.
Purpose: To determine the annual incidences and rates of progression of myopia and high myopia in Chinese schoolchildren from grade 1 to grade 6 and explore the possible cause-specific risk factors for myopia. Methods: From 11 randomly selected primary schools in Anyang city, central China, 2835 grade 1 students were examined with annual follow ups for 5 years. Students were invited to undergo a comprehensive examination, including cycloplegic autorefraction, ocular biometry, and standardized questionnaires. Results: The mean spherical equivalent refraction decreased substantially from +0.94 ± 1.03 diopter (D) in grade 1 to -1.37 ± 2.08 D in grade 6, with rapid annual myopic shifts, especially for students in grades 3 through 6 (-0.51 to -0.59 D). The prevalence of myopia increased substantially, with the yearly incidence of myopia increasing from 7.8% in grade 1 and 2 to 25.3% in grades 5 and 6, and the incidence of high myopia increased from 0.1% to 1.0%. The 5-year incidence of myopia was lowest among children who has a baseline spherical equivalent refraction of greater than +2.00 D (4.4%), and increased to nearly 92.0% among children whose baseline spherical equivalent refraction was 0.00 to -0.50 D. The incidence of myopia was higher in children who had less hyperopic baseline refraction, two myopic parents, longer axial length, deeper anterior chamber, higher axial length-corneal radius of curvature ratio, and thinner lenses. Conclusions: Both the annual incidence and progression rates of myopia and high myopia were high in Chinese schoolchildren, especially after grade 3. Hyperopic refraction of children should be monitored before primary school as hyperopia reserve to prevent the onset of myopia and high myopia.
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