Rates of epithelial ingrowth after LASIK for different excimer laser systems

PURPOSE: To investigae the incidence of epithelial ingrowth after laser in situ keratomilensis (LASIK) using the VISX 20/20B and VISX Star S3 laser systems. METHODS: A chart review of patients who had undergone LASIK between April 1999 and December 2001 was perfomed Patients having known risk factors for epithelial ingrowth were excided from the study. Both eyes of patients who were operated with both laser systems were inctuded in a paired analysis. The first operated eyes of the remaining patients were induded in an unpaired analysis. The cutcomes studied were epithelial ingrowth (a region of epithelia growth under the flap that was contiguous with the flap edge and extended at least 0.7 mm in the redial direction and epithelial ingrowth requiring treatment (extending into the pupillary zone, causing reduced vision, causing hightime glare, or inducing any melting of the flap edge). RESULTS: In the paired study, 11 (61, 1%) of 18 eyes treated with the VISX 20/2008 had epithelial ingrowth and 7 (38.9%) eyes required treatment. None of the eyes treated with the VISX Star S3 had epithelial ingrowth. In the unpaired study, 39 (37.1%) of 105 eyes treated with the VISX 20/20B were epited to have epithelial ingrowth and 14 (13.3%) eyes required treatment. None of the eyes treated with the VISX Star S3 had epithelial ingrowth. The incldence of epithelial ligrowth was significantly different for the VISX 20/20B and the VISX Star S3 in both analyses (paired: P<.001, McNemar's test; unpaired; P<.001. Fisher's exact test). CONCLUSIONS: The laser system used in LASIK is a risk factor for the development of eptithlial ingrowth.