Effect of ametropia on peripheral refraction.

Peripheral refraction was measured in 62 eyes along the horizontal meridian from 60 degrees nasally to 60 degrees temporally, using a Topcon refractometer. The amount of astigmatism was found to increase progressively, although less than predicted theoretically, toward the periphery in 91% of the eyes. Dividing the sample into myopes, hyperopes, and near-emmetropes showed that the type of astigmatism differed significantly with each group of eyes and that this factor played a most important role.