Distribution of Ocular Biometric Parameters in a Population–Based Study of Australian Children

Abstract

Abstract: : Purpose: To study the distribution of spherical equivalent refraction and ocular biometric parameters in a young Australian population. Methods: Non–contact methods were used to examine ocular dimensions (Zeiss IOLMaster) and cycloplegic refraction (Canon RK–F1) in a stratified random cluster sample of Year 1 Sydney school–students, mean age 6 years (n=1765). Five repeated measures of axial length and anterior chamber depth, and 3 measures of greatest and least corneal radius of curvature (CR1, CR2) were taken from each eye. Right and left eye findings were strongly correlated. Refraction was measured as spherical equivalent. Results: Mean spherical equivalent refraction in right eyes was +1.26D (standard error of the mean, SEM 0.03). The distribution was peaked (kurtosis 14.4) and slightly skewed to the right (skewness 1.7). Axial length, anterior chamber depth and corneal radii of curvature were normally distributed. The mean axial length in right eyes was 22.61mm (SEM 0.02, range 19.64mm to 25.35mm). The mean anterior chamber depth was 3.34mm (SEM 0.01, range 2.14mm to 4.06mm). Mean CR1 was 7.85mm (SEM 0.01) and mean CR2 was 7.71mm (SEM 0.01). The distribution of axial length/mean corneal radius ratio was peaked (leptokurtic) with mean 2.906. Mean axial length was longer, anterior chambers were deeper and corneas flatter in boys. Conclusions: A peaked (leptokurtic) distribution of spherical equivalent refraction was present in this predominantly hyperopic 6–year old population. The study also found that axial length and other ocular biometric measures were normally distributed with statistically significant gender differences found in measurements.

Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • refraction • emmetropization