Measurement of posterior corneal surface toricity.

We describe a method in which posterior corneal surface toricity can be determined by photographing catoptric (Purkinje) images in three fixed meridians simultaneously using infrared light sources. Keratometry, the comparison of anterior and posterior corneal catoptric (Purkinje) images and pachometric results, are applied to three meridional analysis equations, allowing the posterior corneal surface to be described in spherocylindrical form. The technique is evaluated on five subjects with anterior corneal radii varying from 7.11 to 8.52 mm.