Abstract
Purpose: :
To assess the prevalence of refractive error in a preschool population in Australia and determine whether iris colour and its relationship to cycloplegia affect its measurement.
Methods: :
The Sydney Paediatric Eye Disease Study randomly selected a postcode from each of the Australian Bureau of Statistics inner, middle and outer geographical regions of Sydney. Households in the postcode were enumerated to determine eligible children aged 6 months to 6 years, who were then invited to participate in the study. Participating families provided written, informed consent for their child/children to participate. Comprehensive eye examinations were performed on each child, including cycloplegic refraction, following 2 drops of cyclopentolate 1.0%, 5 mins apart (0.5% for children aged ≤12 months), using auto-refraction (Canon RK-F1 or Retinomax) or by retinoscopy. They were classified by spherical equivalent (SE) of the right eye. Iris colour was graded by reference photographs. Data from only the outer suburban site is presented.
Results: :
Of the 1098 children who participated at this site (76% response rate), mild hyperopia (≥+0.5 to +2.0D) was the most prevalent refractive state (70.1%) and myopia (≤-0.5D) was found in only 2.4% of the population. Mean SE and myopia prevalence for children aged 6 to <12 months was +1.54D (SD 1.17), 2.0%; 12 to <24 months +0.99 (SD 1.18), 4.3%; 24 to <36 months +1.17D (SD 1.07), 1.7%; age 36 months or older +1.35D (SD 1.22), 1.8%. Mean SE in the 6 to <12 month group was not significantly different from that in the oldest age group (p=0.5349). The distribution of refractive error in children with European Caucasian ethnicity was more hyperopic than that in children with East Asian (p<0.0001) or South Asian origin (p=0.2724). In European Caucasian children, iris colour ranging from blue to dark brown was associated with a trend towards less hyperopic refraction but only for ages >30 to 48 months.
Conclusions: :
Myopia was very uncommon at all ages in this population of Australian preschool children, in contrast to recent US reports using similar protocols. The prevalence of myopia in the 6 to <12 month age group was not higher than other age groups and iris colour did not appear to influence refraction measures. Children of Asian ethnicity were however, significantly less hyperopic than their European Caucasian counterparts.
Keywords: refractive error development • myopia • refraction