[A CT study of the relation between ocular axial biometry and refraction].

Ocular biometry in 255 eyes (131 subjects) with CT scan revealed that the length of the antero-posterior 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 length of the horizontal transverse axis was correspondingly 24.61 +/- 0.53 mm, 24.91 +/- 0.37 mm 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 the varying axial lengths. The authors propose the parameter of the ocular diametrical ratio which is the 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 the ratio in the vicinity of 1. The authors point out that the refractive state is determined by the ocular diametrical ratio.