Refractive error and visual impairment in primary school children in Onitsha, Anambra State, Nigeria

Background:  Vision problems have been shown to adversely affect a child’s achievement in school. Aim:  To determine the prevalence of refractive error and visual impairment in primary school children in Onitsha, Anambra State, Nigeria. Setting:  The study was conducted in a primary school in Onitsha, Anambra State, Nigeria. Methods:  A stratified random cluster sampling method was used to select primary school children aged between 5 and 15 years from grades 1 to 6 in primary schools in Onitsha North and South. A total of 1020 children in 102 clusters were enumerated and 998 (97.8%) were examined. The examination included visual acuity measurements, ocular motilities, retinoscopy and auto-refraction under cycloplegia, and examination of the anterior segment, media and fundae. Results:  The prevalence of uncorrected, presenting and best corrected visual acuity of 20/40 or worse in the better eye was 9.7%, 7.7% and 1.3%, respectively. Refractive error accounted for 86.6% of all causes of visual impairment. Myopia was the most prevalent refractive error (46.4%), followed by astigmatism (36.1%) and hyperopia (17.5%). Refractive error and visual impairment were significantly more prevalent in females than in males ( p  = 0.04). Refractive error was highest among children aged between 11 and 13 years, while visual impairment was greatest among children aged between 5 and 7 years. Conclusion:  The prevalence of refractive error and visual impairment among primary school children in Onitsha was relatively high, highlighting the need for services and strategies to address these conditions in that area.