A population-based study on the prevalence and causes of childhood blindness and visual impairment in North India

Purpose: This was a population-based study to determine the prevalence and causes of visual impairment in children less than 16 years in Urban North India. Methods: This cross-sectional study was conducted in 40 clusters of urban Delhi. 20,955 children aged less than 16 years underwent visual acuity screening using age-appropriate visual acuity charts. Unaided visual acuity of enumerated children aged over 2 years was assessed by using Lea symbols chart in 3-5 years age group and logMAR tumbling E charts for the 6-15 years age group. For children aged 0-2 years, fixation and following to torch light was assessed. All the children with unaided visual acuity of <6/12 in any eye in age group 3-15 years and inability to follow the light in age <3 years were referred for detailed ophthalmic examination. Results: Amongst 20,955 children examined for visual acuity a total of 789 children were referred to the central clinic for detailed ophthalmic examination. Of these referred children, a total of 124 had presenting visual acuity <6/18 in the better eye. The prevalence of visual impairment (VI) was 5.92 per thousand (95% CI: 4.96-7.05). The prevalence of moderate to severe visual impairment was maximum in the age group of 11 to 15 years. The main cause of avoidable VI in these children was a refractive error (75.7%). The prevalence of blindness was 0.42 per thousand. Conclusion: Optic nerve abnormalities were the most important cause of blindness in children. Refractive error is the most important cause of visual impairment amongst children and needs to be addressed.