Role of the corneal epithelium in refractive changes following laser in situ keratomileusis for high myopia

PURPOSE: Epithelial hyperplasia is one of the factors that plays a role in myopic regression after photorefractive keratectomy (PRK). We evaluated the role of the epithelium following excimer laser in situ keratomileusis (LASIK) performed on highly myopic eyes. METHODS: Fifty eyes of 32 patients (18 females and 14 males; mean age, 31.7 +/- 6.5 years) were treated with LASIK for myopia with an attempted correction ranging between -8.50 and -12.25 D (mean, -10.48 +/- 1.43 D). No sutures were placed. The thickness of the central epithelium was evaluated either with a 50-MHz ultrasonic pachymeter or an ultrasound biomicroscope, Postoperatively, topical corticosteroid drops were administered for at least 1 month. RESULTS: Follow-up was at least 12 months. Epithelium measurements were thicker compared to preoperative measurements from the first week postoperatively (mean, +1.9 mu m, +2.77%; P<.05), Epithelial thickness peaked at the third month after LASIK (mean, +6.5 mu m, +9.5%; P<.05) and remained stable through 12 months, A negative correlation between epithelium thickness and manifest refraction from the first month postoperatively to the end of follow-up was present, CONCLUSION: The epithelium seemed to have a role in the regression of refractive effect after LASIK to correct high myopia.