Prevalence of Anisometropia and its Association with Amblyopia Among Pupils in Primary Schools in Katsina State

Anisometropia, a condition characterized by a significant difference in refractive power between the two eyes, is one of the most important risk factors for anisometropic amblyopia in children. Despite this clinical significance, population-based studies on anisometropia prevalence and its association with amblyopia in Nigerian primary school children are scarce in the North West zone. This study estimates the prevalence of anisometropia and examines its association with amblyopia among primary school pupils in Katsina State. A cross-sectional analytical design will be employed, with 1,000 pupils aged 5 to 12 years selected through multistage cluster sampling from 20 schools across five local government areas. Visual acuity will be measured using the HOTV chart for younger children and the Snellen chart for older ones. Cycloplegic autorefraction will be performed to determine anisometropia, defined as an interocular difference of 1.00 dioptre or more in any meridian. Amblyopia will be diagnosed using standard visual acuity criteria with habitual and best-corrected correction. Logistic regression will identify the magnitude of anisometropia associated with amblyopia risk. Findings will be submitted to the Katsina State Ministry of Education to support statewide school vision screening programs. This research advances the epidemiology of anisometropia and amblyopia in the North West zone and provides critical evidence for early intervention policies. Keywords: anisometropia, amblyopia, primary school children, Katsina State, refractive error