LASEK Induces Less Corneal Wound Healing and Better Transmittance Than PRK in the Iber Braun Hens Corneal Model

Abstract

Abstract: : Purpose: To compare corneal wound healing and transmittance after laser subepithelial keratomileusis (LASEK) and photorefractive keratectomy (PRK) in the Iber Braun hens corneal model. Methods: LASEK surgery (–6 D, optical zone 6.0 mm, 67 µm) was performed on Iber Braun hens (2,5 kg) corneal model. Iber Braun hens corneal epithelium was exposed to 20% ethanol in BBS for 40 seconds using as the reservoir a 7.5 mm trephine. The epithelium was detached by the technique "in the bag" and then treated with an excimer laser (Summit apex plus). The epithelial flap was repositioned. Morphologic changes were evaluated by optic (H–E) and electronic microscopy examination. Proliferation and apoptosis were studied at 24 and 72 hours. The transmittance and scattering measurements were done with a scatter meter constructed in the Optic’s Department (University of Valladolid) at 15 and 30 days. Results: LASEK corneas showed TUNEL positive cells in the basal layer of the epithelial flap. In the stroma, there are less keratocyte apoptosis in LASEK than PRK corneas at 24 hours, and both of them decreased at 72 hours but remained higher after PRK than LASEK. Keratocyte proliferation rate at 72 hours were higher in the two superior thirds of the corneas in the PRK than the LASEK model. LASEK corneas had less scattering and better transmittance than PRK corneas at 15 and 30 days. Conclusions: LASEK induces less stromal scarring compared to PRK in the Iber Braun hens corneal model. LASEK corneas have better transmittance than PRK corneas. Iber Braun hens offer a very good model of LASEK corneal refractive surgery.

Keywords: cornea: basic science • wound healing • refractive surgery