Prevalence of Strabismus and Amblyopia in Singapore Chinese Children: The Strabismus, Amblyopia and Refractive Error in Singaporean Children (STARS) Study

Abstract

Purpose: : To determine the prevalence of strabismus and amblyopia in Singapore Chinese children aged 6 to 72 months.

Methods: : A population based survey was undertaken in the South-Western region of Singapore. Disproportionate random sampling by 6 month age groups was performed. Children underwent an Orthoptic assessment and cycloplegic (3 drops of cyclopentolate at 5 minute intervals) refraction using a table-mounted autorefractor in children older than 24 months, or a hand-held autorefractor in children aged 24 months or older, or streak retinoscopy if autorefraction failed. LogMAR Visual acuity was tested in children aged 30 months or older. If amblyopia was suspected (two line difference in visual acuity), visual acuity was re-tested.

Results: : 3009 children were recruited (participation rate = 72.3%), of which 3004 were analysed. The prevalence of strabismus in children (6 to 72 months) was 0.84% (95% Confidence Interval, CI: 0.80%-1.19%). Prevalence increased from 0.56% to 0.96% between ages 6 to 36 months and 37 to 72 months, but this was not significant (p=0.23) and there were no gender difference (p=0.54). Exotropia (20/24, 83.3%) was the most common strabismus, followed by Esotropia (3/24, 12.5%). The prevalence of amblyopia in children aged between 30 to 72 months was 1.87% (95% CI 1.81-1.94). There were no significant age and gender differences (p = 0.17). Amblyopia was attributed to refractive error alone in 72%, combined refraction/strabismus in 23%, and strabismus alone in 5%. Refractive causes of amblyopia included astigmatism (59%), high hyperopia (20%), and myopia (14%).

Conclusions: : The prevalence of Strabismus and Amblyopia in preschool Singaporean Chinese children was low. Exotropia was the most common strabismus and astigmatism was the main determinant of amblyopia.

Keywords: amblyopia • strabismus • astigmatism