A new method of the eye refraction correction under non‐ablative laser radiation

Abstract

AbstractPurpose The aim is to present a new approach of cornea reshaping using termomechanical effect of pulse repetitive laser radiation both on sclera and cornea.Methods Experiments were performed in vitro with eyes of pigs, rabbits, cadavers, and in‐vivo with rabbit eyes using an Erbuim glass fiber laser of 1.56 microns in wavelength. Thermomechaniucal properties of sclera and cornea during laser heating were studied with an indenter test and using thermo mechanical analyzer. The alterations in eye refraction was measured with various optical techniques including coherent tomography, confocal microscopy and shlieren visualization. Histological technique was used to study possible alterations in tissues structure.Results The results have shown different thermomechanical properties of cornea and sclera allowing to change eye refraction under nondestructive laser irradiation. Denaturation thresholds for stromal collagen of the cornea were measured for various laser wavelengths. Optimal laser settings were established allowing obtain vision correction without visible damage and denaturation of the eye tissues. The maximal change of eye refraction obtained was of 6 diopters. The stability of rabbit eye refraction was established during at least 6 months. Hystological analysis did not revile substantial alterations in cornea structure.Conclusion The advantages of the new approach are provided by the following factors (1) noninvasive and potentially reversible nature of exposure on the cornea and sclera, (2) minimal exposure on the central zone of the cornea, (3) availability of a feed back control system that prevents denaturation and damage of the cornea, (4) possibility of a repeated procedure.