An analysis of three meridional keratometric measurement of the anterior corneal surface.

Analysis of measurements taken in three meridians of a toroidal optical surface can produce a spherocylindrical result without having to locate the principal meridians. This technique is assessed for the anterior corneal surface using keratometry. Good agreement is found with measurements taken in the principal meridians making this a suitable method for the assessment of the eye's optical surfaces by Purkinje image measurement.