The Epidemiology Of Refractive Errors And Visual Impairment In School-age Children In Yongchuan District Of Chongqing

ObjectiveTo understand refractive errors, visual impairment and eye diseases in children in Yongchuan District of Chongqing, so as to provide the basis for the prevention and treatment of eye diseases and visual impairment in children.MethodsA random sampling strategy in geographically defined clusters was used based on population to identify children aged 6-15 years in Yongchuan, a socio-economically representative area in Western China. We carried a door-to-door survey and actual eye examinations, including visual acuity measurements, stereoscopic vision examination, cover-uncover test and eyeball movements, anterior segment examination with a slit lamp, cycloplegic retinoscopy with 1% cyclopentolate , and fundus examinations.ResultsA total of 3469 children living in 2552 households were selected, eye examinations were conducted in 3079 children finally. The distributions of refractive status were positively-skewed for 6-8-year-olds, and negatively-skewed for 9-12 and 13-15-year-olds. The prevalence of hyperopia (≥+2.00 D spherical equivalent [SE]), myopia (≤-0.50 D SE), and astigmatism (≥1.00 diopter of cylinder [DC]) were 3.25%, 13.71%, and 3.73%, respectively. As children's ages increased, the prevalence rate of hyperopia decreased (P<0.001) and that of myopia increased significantly (P<0.001). Children in academically challenging schools had a higher risk of myopia (P<0.001) and astigmatism (≥1.00DC, P =0.04) than those in regular schools.The prevalences of eye diseases were as follows: refractive errors 20.69% (637/3079), conjunctivitis 11.76%(362/3079), amblyopia 1.88% (58/3079), color vision defects 0.52% (16/3079), keratitis 0.36% (11/3079), strabismus 0.29% (9/3079), cataract 0.23% (7/3079), myopia disease 0.19% (6/3079), ocular truma 0.13% (4/3079), corneal opacity 0.03% (1/3079), corneal staphyloma 0.03% (1/3079), optic neuropathy 0.03% (1/3079), macular diseases 0.03% (1/3079)and myelinated nerve fibers 0.03% (1/3079). The prevalence of presenting visual impairment (visual acuity≤20/40 in the better eye) was 7.70%(237/3079).In eyes with visual impairment, uncorrected refractive error was the cause in 86.08 %(204/237), amblyopia in 9.70%(23/237), myopia disease in 1.27%(3/237), congenital cataract in 0.42%(1/237), and unexplained causes in 2.11%(5/237).Conclusion1. The distribution of refractive status changes gradually from positively-skewed to negatively-skewed distributions as age increases, with 9-year-old being the critical age for the changes. Environmental factors and study intensity influence the occurrence and development of myopia.2. The prevalence of refractive errors is the highest among eye diseases in children. At present, uncorrected refractive error is recognized as a significant cause of visual impairment in school-age children in underdeveloped regions.