The study explored the interocular differences in biometry to determine the potential role of other factors in refractive development.
In 362 subjects Childhood Errors of Refraction study were studied.257 subjects had an interocular difference of <0.50 D (ISO group) and 29% a difference of ≥0.50 D (ANISO group). 6.9% had anisometropia ≥1.00 D and 2.5% had anisometropia ≥1.50 D. The two groups, ISO and ANISO, showed different refractive distributions (p=0.001) with the ISO group showing a nearly Gaussian distribution and the ANISO group showing positive skew, a hyperopic shift and a bi-Gaussian distribution. A marker of emmetropization is the poor correlation between refraction and corneal curvature seen in older children. There was no significant correlation between refraction and corneal curvature of each eye in the ISO group (r=0.09, p=0.19), but these parameters were significantly correlated in the ANISO group (r=0.28, p=0.004).
In young children, small degrees of anisometropia (≥0.5 D) are associated with impaired emmetropization. This suggests that anisometropia is a marker for poorly regulated eye growth, indicating that, in addition to environmental and genetic influences on eye growth, stochastic processes contribute to refractive outcomes.