Objectives: 1. To ascertain the causes of severe visual impairment and blindness in children in schools for the blind in South Africa. 2. To determine the major avoidable causes. 3. To determine causation by ethnic group.
Design: A cross-sectional survey, undertaken at 15 of the 16 schools for the blind in South Africa, during May-September 1996, using standard WHO methodology.
Subjects: Children less than 16 years of age on May 1996.
Results: Of 1,615 eligible children, 1,311 were examined. According to WHO categories of visual impairment, using the corrected visual acuity in the better eye, 30.4% of children were blind (< 3/60, BL), 12.6% had severe visual impairment (< 6/60-3/60, SVI), 42.3% were visually impaired (< 6/18-6/60), and 12.0% had no impairment (6/18 or better). The anatomical sites of SVI/BL in 564 children were: retina 38.5%; optic nerve 15.2%; cornea/phthisis bulbi 11.0% and glaucoma 6.7%. Aetiological categories of SVI/BL were: hereditary diseases 33.0%; intra-uterine factors 0.9%; perinatal conditions 13.1%; acquired conditions of childhood 11.5%. In 41.5% the underlying cause could not be determined. In 38.8% of children with SVI/BL the cause was avoidable, i.e. preventable or treatable. The main causes varied between ethnic groups, the major difference being the higher proportion of retinopathy of prematurity in white and Indian children.
Conclusions: The study suggests that 38.8% of causes of SVI or blindness in children in schools for the blind in South Africa are avoidable, and that specific control measures need to be targeted at different ethnic groups.