Abstract
OBJECTIVE: This study determined the prevalence and aetiology of unilateral visual impairment (VI) and blindness and its associated factors in school children. METHODS: We conducted a multistage, cross-sectional study in primary and secondary schools of Saki-East Local Government Area of Oyo State, Nigeria. Unilateral VI was defined as presenting visual acuity (PVA) worse than +0.3 LogMAR (6/12) and unilateral blindness as PVA worse than +1.3 LogMAR (3/60) in the worse eye. Detailed ocular examinations were performed for students with unilateral VI, and Logistic regression analysis was performed to explore associations with independent variables. RESULTS: The mean age of participants was 11 ± 3.2 years. Thirty-six (0.98%) of 3671 children had unilateral VI, and fifteen children had unilateral blindness (0.41%), giving a combined prevalence of 1.39 ± 0.5%. History of ocular trauma was reported by 14 (27.5%) participants with unilateral VI and blindness. In addition, those with a history of ocular trauma were 6.5 times more likely to be blind or have a severe VI (95% CI 1.5-2.8) than those without a history of ocular trauma. Uncorrected refractive error was the major cause of unilateral VI in 26 (51%) participants, while traumatic cataract was the main cause of unilateral blindness seen in 5 (9.8%) participants, none of whom had a previous eye examination. CONCLUSION: Fourteen per thousand school children had unilateral VI in this study; the major causes were refractive error and cataract, which are treatable. Ocular trauma was a significant risk factor for unilateral VI and blindness.