The prevalence and causes of visual impairment in special schools and blind schools in Shanxi Province, China: a cross-sectional study

Abstract

Abstract This study aimed to determine the prevalence and causes of low vision and blindness among students in special education schools (serving children with disabilities, including intellectual disabilities) and blind schools (for students with blindness or visual impairment) in Shanxi Province, China. A cross-sectional investigation was conducted across nine special education schools and two blind schools in Shanxi Province from March to September 2018. Participants underwent comprehensive ophthalmic examinations, including visual acuity (VA) assessment using Lea Symbols or Cardiff Cards, refraction testing, and anterior/posterior segment evaluations. Non-cycloplegic refraction was performed initially, with cycloplegic refraction administered when VA was subnormal for age. Visual impairment was classified according to World Health Organization (WHO) criteria. Demographic and general health data were also collected. The study included 441 children from special schools (mean age: 12.3 ± 3.5 years) and 56 children from blind schools or blind classes within special schools (mean age: 13.0 ± 3.2 years). Among special school students, 44 (10.0%) had visual impairment (mild: 9.1%; moderate: 0.9%), primarily attributable to uncorrected refractive errors (90.7%); 10 cases (2.3%) remained undetermined due to poor compliance. In blind schools/classes, 30 children (53.6%) were classified as blind, 22 (39.3%) as visually impaired (moderate: 28.6%; severe: 8.9%), and 4 (7.1%) as undetermined. Notably, 44.6% of visual impairment cases were avoidable, with nystagmus (25.0%), amblyopia (19.6%), and cataract (8.9%) identified as leading causes. These findings underscore the significant burden of uncorrected refractive errors in special schools and the high prevalence of nystagmus in blind schools. The substantial proportion of avoidable visual impairment highlights the critical need for early screening and targeted interventions to improve visual function for children with disabilities.