Visual Acuity and the Causes of Visual Loss in a Population–based Sample of 6–year–old Australian Children

Abstract

Abstract: : PURPOSE: To describe the distribution of visual acuity and the causes of visual loss in a representative sample of 6–year old Australian children. DESIGN: Population–based cross–sectional study. PARTICIPANTS: 1738 children (1292, aged 6 and 446, aged 7 years) examined during 2003–4. Methods: Logarithm of the minimum angle of resolution (logMAR) visual acuity was measured in both eyes before and after pinhole correction, and with spectacles if worn. Cycloplegia was induced with cyclopentolate and a detailed dilated fundus examination performed. MAIN OUTCOME MEASURES: Visual impairment was defined as: any (visual acuity <20/40; <40 letters) or severe (visual acuity ≤20/200; 0–5 letters), for both better and worse eyes. Results: The mean visual acuity of this sample was 20/25 (49.3 letters). Uncorrected visual impairment was found in the better eye of 23 children (1.3%) and in the worse eye of 71 children (4.1%). The prevalence was higher in girls than boys and among children of lower socioeconomic status. Refractive error was the most frequent cause, accounting for 69.0%, followed by amblyopia (22.5%). Astigmatism was the principal refractive error causing visual impairment and was frequently uncorrected. Presenting visual impairment (using current glasses if worn) was found in the better and worse eyes of 15 children (0.9%) and 54 children (2.8%), respectively. This was mainly due to under– or un–corrected refractive error. Conclusions: This study has documented a relatively low prevalence of visual impairment in a population of Australian children. Uncorrected astigmatism and amblyopia were the most frequent causes.

Keywords: visual acuity • amblyopia • astigmatism