Natural history of corneal topography after excimer laser photorefractive keratectomy.

Abstract

To investigate the natural history of corneal topography after excimer laser photorefractive keratectomy (PRK). A prospective, single center clinical study. A total of 40 eyes of 34 patients with myopia were studied. Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed. Preoperative, 1 week, and 1, 2, and 3 months postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite "average" topography maps. Corneal topography was generally not homogeneous at 1 week after PRK. By 3 months, there had been considerable smoothing of corneal contour. A general "central island" effect early in the postoperative period flattened over time. When right and left eyes were evaluated independently, a tendency toward a keyhole-semicircular pattern was seen on average; the maximum flattening was nasal and the least flattening was inferotemporal for both right and left eyes. A tendency, on average, toward central island and keyhole-semicircular patterns is seen early in the postoperative course after PRK. Central islands tend to evolve into the keyhole-semicircular pattern, and the corneal topography in general after PRK tends to smooth considerably with time.