A case-control study of biometry in healthy and cataractous Eritrean eyes.

The keratometry and axial length readings of healthy eyes (405 subjects) and cataractous eyes (63 subjects) from a sample of Tigrinians living in the Eritrean capital of Asmara were obtained. All subjects were at least 40 years of age. The mean keratometry reading for healthy eyes was 43.37 diopters (SD +/- 1.61), while that for cataractous eyes was 43.57 diopters (SD +/- 1.79). These values were not significantly different. Similarly, there was no significant difference in the mean ocular axial length for the two groups (healthy eyes; 23.03 mm, SD +/- 1.24: cataractous eyes; 23.34 mm, SD +/- 1.54). There was no correlation between age and the biometry readings of healthy eyes. Data from this study has been used to calculate a standard intraocular lens power for use by Eritrea's Blindness Prevention Programme during cataract surgery on this population (22 diopters at A constant 118.3). With this intraocular lens, 48% of patients will be within +/- 1D of emmetropia when left without spectacle correction; 73% will need a spectacle correction within +/- 2D to produce emmetropia.