The key informant strategy to determine the prevalence and causes of functional low vision among children in South India

Purpose: To report the prevalence and causes of functional low vision (FLV) in school-age children in Coimbatore District, Tamil Nadu, India and to report our experience using the key informant (KI) method in this setting.

Methods: Children suspected of having low vision were identified by KIs or Aravind Eye Hospital personnel in Coimbatore District. All identified children underwent a cycloplegic refraction and full eye exam. A primary cause of decreased vision was determined for each child. The prevalence of FLV was calculated for children 6–14 years old. Spectacles and low vision devices were provided free of charge.

Results: 345 children aged 6–14 years were referred and 231 had FLV. The positive-predictive value of KI referrals was 64.5%. The prevalence of FLV was 0.071% (7.1 per 10,000; 95% CI 0.062–0.080%) and ranged from 0.026% to 0.141% across the district’s blocks. Older children (age 11–14 years; OR 1.41; 95% CI 1.09–1.82) and males (OR 1.52; 95% CI 1.16–1.98) had greater odds of being diagnosed with FLV. The most common causes of FLV were retinal disorders (30.0%) and amblyopia (25.5%). Low vision devices were provided to 169 children who had a mean near and distance visual acuity improvement of 0.31 and 0.63 logMAR, respectively (p < 0.001).

Conclusions: This study reports a moderate prevalence of FLV and demonstrates the ability of KIs to identify school-age children with FLV in South India. The provision of basic low vision services can improve visual outcomes in this population.