Prevalence of vision impairment and refractive error in school children in Ba Ria - Vung Tau province, Vietnam

Background: To assess the prevalence of vision impairment and refractive error in school children 12-15 years of age in Ba Ria - Vung Tau province, Vietnam.

Design: Prospective, cross-sectional study.

Participants: 2238 secondary school children.

Methods: Subjects were selected based on stratified multistage cluster sampling of 13 secondary schools from urban, rural and semi-urban areas. The examination included visual acuity measurements, ocular motility evaluation, cycloplegic autorefraction, and examination of the external eye, anterior segment, media and fundus.

Main outcome measures: Visual acuity and principal cause of vision impairment.

Results: The prevalence of uncorrected and presenting visual acuity ≤6/12 in the better eye were 19.4% (95% confidence interval, 12.5-26.3) and 12.2% (95% confidence interval, 8.8-15.6), respectively. Refractive error was the cause of vision impairment in 92.7%, amblyopia in 2.2%, cataract in 0.7%, retinal disorders in 0.4%, other causes in 1.5% and unexplained causes in the remaining 2.6%. The prevalence of vision impairment due to myopia in either eye (-0.50 diopter or greater) was 20.4% (95% confidence interval, 12.8-28.0), hyperopia (≥2.00 D) was 0.4% (95% confidence interval, 0.0-0.7) and emmetropia with astigmatism (≥0.75 D) was 0.7% (95% confidence interval, 0.2-1.2). Vision impairment due to myopia was associated with higher school grade and increased time spent reading and working on a computer.

Conclusions: Uncorrected refractive error, particularly myopia, among secondary school children in Vietnam is a major public health problem. School-based eye health initiative such as refractive error screening is warranted to reduce vision impairment.