Search

The corneal shape of 196 eyes was determined by photokeratoscopy and subsequent fitting of a conicoid equation to four individual corneal meridians. This conicoid was found in almost all instances to be ellipsoidal, with the asphericity not varying between meridians. The corneal radius of curvature did vary as expected between meridians. The radii of curvature of these corneal meridians also varied with the age of the subjects, resulting in reduced corneal astigmatism, while the asphericity of each meridian did not vary substantially with age.

Monocular diplopia, reported by a subject following near work, was shown to be caused by changes in the corneal topography. Prior slit lamp biomicroscopy had revealed no corneal abnormality. The degree of corneal distortion and ray tracing calculations confirmed the presence and position of the resultant diplopia.

Contact lens wear generally induces changes of corneal curvature as measured with the keratometer. Previous studies have considered only one dimension of the curvature change or the fir of the lens. This paper introduces a graphical system in which a co-ordinate system is used to express two dimensions of the lens to cornea fitting relationship. A vector from the initial mode of fit point gives a two dimensional expression of curvature change. There are suggestions on statistical analyses of data plotted on this graphical system.