Ocular biometry and its relationship to incident myopia and hyperopia in children

Abstract

AbstractPurpose Establish relationship of changes in ocular biometry in children with the development of refractionMethods Sydney Myopia Study participants aged 6 and 12 years were re‐examined 5‐6 years later. Axial length (AL), anterior chamber depth (ACD) and corneal radius (CR) were measured using the IOLMaster (Carl Zeiss, Germany). Spherical equivalent refraction (SER) in dioptres (D) was calculated from cycloplegic autorefraction (cyclopentolate 1%; Canon RK‐F1) and myopia was defined SER ≤‐0.50D. All measures were made at baseline and follow‐up using the same methodology.Results Longitudinal data was available 860 children at follow‐up, mean age 12.8 years and 1150 aged 17.2 years. There was significant change (p<0.0001) in SER from baseline to follow‐up for both cohorts and for all biometric measures, other than ACD in the older cohort (p=0.854). Marginal flattening of CR (0.05, 0.02mm, in younger and older cohorts respectively) was not clinically significant. Change in SER was significantly correlated in both the younger and older cohorts with AL and AL/CR (p <0.0001) with AL/CR the biometric parameter most strongly correlated with SER at both baseline and follow‐up in both cohorts (younger r = ‐0.63, 0.77, older r= ‐0.81, ‐0.86 respectively). In the younger cohort an AL/CR ratio ≤2.75 was associated with a baseline refraction of ≥+2D in all cases and 87.5% of these remained significantly hyperopic at age 12.Conclusion Baseline AL/CR was the best biometric measure for predicting 5 year incidence myopia in both cohorts. In principle AL/CR also has the potential to resolve the ambiguity of visual acuity measures for the detection of hyperopia in younger children using a non‐invasive technique.