Prevalence of amblyopia with anisometropia or strabismus among schoolchildren in the Sultanate of Oman

Abstract

Purpose: The purpose of this study was to investigate the prevalence of common eye disorders in a nationwide school survey conducted in the Sultanate of Oman. The results presented here are those involving amblyopia induced by strabismus or anisometropia.

Methods: A random selection of primary schools provided a sample that included 49 schools with 6541 children in Grades 1 and 6. Examinations of the eyes of 96%, of these children were conducted doing visual acuity screening to 0.5. All 6292 children had an external eye examination. All children failing the visual acuity test had a complete eye examination.

Results: Amblyopia was found in 0.92%, strabismic amblyopia in 0.48%, anisometropic amblyopia in 0.44% and strabismus with or without amblyopia was seen in 0.9%. There was statistically significantly (p<0.05) more amblyopia in 11-12 year olds (Grade 6) when compared with the 6-7 year olds (Grade 1). This difference was only found among the strabismic children.

Conclusion: When compared to Europe or North America the prevalence of strabismic amblyopia is lower, whereas anisometropic amblyopia occurs with approximately the same frequency. The increase of strabismic amblyopia in the older children indicates a development of amblyopia after the age of 6 to 7 years in an untreated population.