A Computed Tomographic Study of the Relation Between Ocular Axial Biometry and Refraction

Summary

Ocular biometry in 255 eyes (131 subjects) with computed tomographic (CT) scan revealed that the length of the anteroposterior axis was 23.63 ± 0.92 mm in hyperopia, 24.62 ± 0.38 mm in emmetropia, and 26.68 ± 0.75 mm in myopia, and the respective lengths of the horizontal transverse axis were 24.61 ± 0.53, 24.91 ± 0.37, and 25.12 ± 0.73 mm. There were significant differences among groups of different refractions, and the axial length increased with the severity of myopia. It was evident that refractive errors were chiefly caused by varying axial lengths. We propose the parameter of the ocular diametrical ratio of the anteroposterior axis to the horizontal transverse axis, and accordingly hyperopia has a ratio under 1, myopia a ratio over 1, and an emmetropic eye is apparently spherical with a ratio in the vicinity of 1. The refractive state is determined by the ocular diametrical ratio.