Unilateral visual impairment and blindness in school children – prevalence and aetiology in Saki-East LGA of Oyo State, Nigeria

This study determined the prevalence and aetiology of unilateral visual impairment (VI) and blindness and its associated factors in school children.

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.

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.

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.