Abstract
Abstract: :
Purpose: To investigate the role of exogenous keratinocyte growth factor (KGF) on wound healing following corneal laser refractive procedures (PRK & LASIK). Methods: In a prospective randomised placebo controlled trial 24 New Zealand white female rabbits were divided into three groups. Group 1 (n=8) underwent photorefractive keratectomy of - 6 dioptres using Chiron Technolas 217 Z laser. Group 2 (n=8) underwent laser insitu keratomileusis with a flap depth of 140 microns and - 6.0 D correction and group 3 (n=8) underwent LASIK with a 180 micron flap and - 6.0 D correction (Amadeus microkeratome, Allergan). The rabbits within group 1,2 & 3 were randomised into the study and placebo controlled subgroups. Exogenous KGF (Repifermin, Human genome, Rockville, M.D.) at a dose of 20 µg/ml was administered to the study group topically four times a day for 72 hrs following surgery. Epithelial healing was followed by serial digital imaging, corneal haze by objective measurement of back scatter and the stromal response by histopathology at 5 weeks following surgery. Results: In group 1, the re-epithelialisation following PRK was 2.13 mm2/day in the KGF treated eyes as compared to 6.99 mm2/day in the control eyes (p = 0.034). There was no significant difference in the gray scale measurement of back scatter in the KGF (mean=154 +/- 45.95) and control eyes (mean=141+/- 38.45) following PRK (p = 0.42). The histology revealed significantly less epithelial cell layers (3-4) in the KGF eyes as compared to 6-7 layers in the control eyes (p = 0.01). The anterior stromal vacuolation extended to a mean of 105 um +/- 20 S.D. in the KGF eyes following PRK when compared to the control eyes (89.6 +/- 16 um S.D., p = 0.02). There was no difference in keratocyte recruitment between the KGF and control eyes following PRK (p=0.77). In groups 2 & 3 there was no significant difference in back scatter, epithelial layers, keratocyte recruitment and stromal vacuolation between the KGF and control eyes following LASIK. Conclusions: Topical KGF at a concentration of 20 µg/ml delays re-epithelialisation following PRK. It has no effect on wound healing in LASIK eyes with an intact epithelial barrier. Further dose response studies are essential to establish the optimal dose of KGF and to evaluate its epithelial proliferative effects following corneal laser refractive procedures.
Keywords: cornea: epithelium • growth factors/growth factor receptors • refractive surgery