A Prospective Study of Anterior Segment Ocular Parameters in Anisometropia

The aim of this study was to investigate the differences in anterior segment ocular parameters in anisometropia >1 D.

This study included 202 eyes of 101 subjects ranging from 10 to 40 years of age with anisometropia of 1 D or more. The subjects were divided into groups according to anisomyopia, anisoastigmatism, and anisohypermetropia. After providing informed consent, each patient underwent a detailed ophthalmological examination including cycloplegic refraction, best-corrected visual acuity, cover test, axial length (AL) measurement using A-scan ultrasound biometer, keratometry, anterior chamber depth, and central corneal thickness measurement. For each participant, the eye with greater refractive error was compared to the fellow eye via paired t-tests. Correlations between parameters were studied using the Pearson correlation coefficient.

The average age of subjects was 21.7 ± 9.3 years. Of 101 subjects, 31 had anisomyopia; 42 had anisohypermetropia; and 28 had anisoastigmatism. A predisposition toward greater myopia in right eyes was noted in anisomyopia (24 of 31 subjects, 77%). The inter-ocular acuity difference was significant in all three groups (p < 0.01). As the degree of anisometropia increased, there was significant positive correlation in the difference in AL in myopes (r = 0.863, p < 0.01) and hypermetropes (r = 0.669, p < 0.01) and the difference in corneal curvature in anisoastigmatism (r = 0.564, p = 0.002) and hypermetropes (r = 0.376, p = 0.014). A significant positive correlation was also present between the anterior chamber depth difference and refractive difference in hypermetropes (r = 0.359, p = 0.020).

This study showed that anisomyopia is correlated only with anterior chamber differences. Anisohypermetropia is correlated with AL differences as well as corneal curvature difference and anterior chamber depth difference. The amount of anisoastigmatism correlates only with corneal curvature difference.