Epithelial thickness up to 26 years after radial keratotomy: three-dimensional display with Artemis very high-frequency digital ultrasound.

PURPOSE: To characterize the epithelial thickness profile in a population of eyes after radial keratotomy for myopia.

METHODS: The epithelial thickness profile was measured in vivo by Artemis very high-frequency digital ultrasound arc-scanning (ArcScan Inc) across the central 10-mm diameter of the cornea on 14 eyes after radial keratotomy for myopia. Maps of the mean and standard deviation of epithelial thickness were plotted and compared to the epithelial thickness of a previously published population of normal untreated eyes.

RESULTS: Ultrasound scanning using the Artemis was performed a mean 16.7±5.8 years (range: 1.6 to 26.3 years) after radial keratotomy. The mean epithelial thickness profile showed the epithelium to be thicker centrally and thinner paracentrally, which was different from the population of normal eyes. The mean thickest epithelial thickness was 78.8±6.0 μm (range: 64.8 to 89.6 μm) and the mean thinnest epithelial thickness was 43.7±4.3 μm (range: 36.1 to 49.3 μm), which were statistically significantly different from the epithelial thickness at these locations in the population of normal eyes.

CONCLUSIONS: Three-dimensional thickness mapping of the epithelial thickness profile demonstrated epithelial changes that compensated in part for the central corneal flattening induced by the radial keratotomy incisions. The fact that epithelial changes were consistent across eyes from approximately 2 to 26 years after radial keratotomy suggests that epithelial changes are a permanent response to corneal curvature changes.