Refractive errors and ocular biometry components in thalassemia major patients.

Abstract

The aim of this study is to determine and compare biometric and refractive characteristics of thalassemia major patients and normal individuals. In this cross-sectional study, 54 thalassemia major patients were selected randomly as case group, and 54 age- and sex-matched healthy subjects were regarded as control group. Refractive errors, corneal curvature and ocular components were measured by autokeratorefractometery and A-scan ultrasonography, respectively. Mean spherical equivalent was -0.0093±0.86D in thalassemia patients and -0.22±1.33D in the normal group. The prevalence of myopia, Hyperopia, and emmetropia among thalassemia patients was 16.7, 19.4, and 63.9%, respectively. While in the control group, 26.9% were myopic, 25% were hyperopic, and 48.1% were emmetropic. The prevalence of astigmatism in case group was 22.2%, which was not significantly different from that in control group, (27.8%, p=0.346). Mean axial length in thalassemia patients was 22.89±0.70 which was significantly lower than that in normal group (23.37±0.91, p=0.000). The flattest meridian of the cornea (R1) was significantly steeper in thalassemia patients (7.77±0.24) in comparison to normal individuals (7.85±0.28). Although thalassemic patients had significantly smaller axial length and vitreous chamber depth in comparison to normal group, which could be due to their abnormal physical growth, there was no significant difference between the mean of spherical equivalent among two groups. This can be due to their steeper corneal curvature that overcomes the refractive disadvantage of their shorter axial length.