Efectos producidos por diferentes tipos de láser en córnea de cobayos: identificación de un láser capaz de provocar lesiones superficiales sin dejar cicatrices

Abstract

To evaluate the effects of four different types of lasers with different power and exposure time conditions in the cornea of normal guinea pigs. To determine which laser and conditions only damage the epithelium and superficial stroma and to study the kinetics of wound healing.Methods: Damage was induced in the cornea of guinea pigs using different powers and exposure times of 4 types of Laser: Argon, CO2, Diode and ND-Yag and such injuries were evaluated by biomicroscopy (BM) and optical microscopy. Corneas from other normal animals were exposed to Argon laser (350 mW, 0.3 seconds, 50 μm of diameter) and the induced alterations were studied at different times using BM, Optical Coherence Tomography (OCT) and Transmission Electron Microscopy (TEM).Results: Only Argon laser at 350 mW, 0.3 seconds, 50 μm of diameter produced epithelium and superficial stroma lesions. Some leukomas were observed by BM, and they disappeared by day 15. Corneal thickness measured by OCT decreased in the eyes treated with Argon laser, during the first week. By TEM, different ultra structural alterations in corneal epithelium and stroma were observed during the early days, which disappeared by day 15.Conclusions: It was possible to develop reproducibly corneal epithelium and anterior stroma injuries using Argon laser at 350 mW, 0.3seconds, 50 μm of diameter. In vivo and in vitro studies showed that injured corneas with these laser conditions did not leave irreversible microscopic or ultrastructural alterations.