Central and peripheral corneal thickness in keratoconus and normal patient groups.

Central and peripheral (superior, inferior, nasal, and temporal) corneal thickness was measured in patients with and without keratoconus using ultrasonic pachometry. In 28 normal eyes (14 patients) mean central corneal thickness (CCT) was 0.56 +/- 0.02 mm and the mean difference in thickness between the mean peripheral corneal thickness (PCT) and CCT was 0.24 mm. In 28 keratoconic eyes (14 patients) CCT was 0.52 +/- 0.04 mm, and PCT-CCT was 0.29 mm. For keratoconic right eyes, CCT and PCT-CCT were significantly different from normals (p = 0.01). Additional studies within the normal patient group showed no diurnal or day-to-day variations in CCT; they also confirmed the repeatability of the measurements.