Stability of Optical Power of Cornea after Photorefractive Keratectomy

Overview

Changes in the values of optical power of cornea in patients after photorefractivekeratectomy (PRK) obtained by Fourier analysis of videotopographic picture ofcornea were investigated. The authors compared changes of cornea surface(optical power) in patients with preoperation myopia up to 6 and more than 6diopters. Moreover, the changes of absolute values of corneal optical power werecompared with the development of refraction of the optical system as a whole. Inpatients with a lower degree of myopia the cornea optical power became stableup to 6 months after the operation. The cornea surface in patients with highermyopia was still changing one year after the operation.The changes of optical power of cornea in patients with a higher myopia weremore marked, but the differences were not statistically significant (except for theperiod after cornea ablation). There was not any significant difference betweenthe changes of objective refraction and the changes of cornea optical power. Themain cause of fluctuating postoperative refraction is apparently the change ofcornea surface associated with healing of cornea.

Key words:
optical power of cornea, stability of cornea surface, healing of corneaand photorefractive keratectomy