Ocular dominance, laterality, and refraction in Singaporean children

To explore the effect of dominance and laterality on refractive error and axial length.

Ocular dominance was assessed with the hole-in-the-card test in 543 children during their 2006 follow-up visits for the Singapore Cohort study Of the Risk factors for Myopia (SCORM). Data were compared to cycloplegic refractions and axial lengths measured by ultrasound.

The spherical equivalent refraction was essentially the same between the right and left eyes, although there was a small but statistically significant longer axial length in the right eyes. Right and left ocular dominance was noted in 58% and 30% of the subjects, respectively, with 12% having no eye preference. There was no significant difference in spherical equivalent refraction (2.56 +/- 2.46 D [mean +/- SD] vs. -2.45 +/- 2.52 D, P = 0.22) or axial length (24.36 +/- 1.19 mm vs. 24.32 +/- 1.18 mm, P = 0.05) between dominant and nondominant eyes. In subjects with anisometropia >or=0.5 D, dominant eyes were more myopic in 52%. Dominant eyes, however, had less astigmatic power (-0.88 +/- 0.80 D versus -1.00 +/- 0.92 D; P < 0.001).

Ocular laterality and dominance have no significant effect on spherical equivalent. All axial length and astigmatic differences were small and clinically insignificant. The study findings suggest that in Singaporean children, bias is not present in those investigations that restrict analyses to right or left eyes. Although there is no apparent association between refraction and ocular dominance in young Singaporean children, more research is needed to resolve the disparate results in existing reports.