New stages of technology development of transepithelial PRK and its optimization on the basis of photoprotection
Purpose: In recent years there increased the interest to the surface transepithelial photorefractive ablation in connection with a smaller weakening of the biomechanical properties of the cornea after the operation, the possibility of correction of myopia of a high degree of thin corneal and significant reduction of pain symptoms when you apply a new generation of contact lenses. Consideration of the main stages in the development of technology in transepithelial PRK and new approaches to its optimization on the basis of photoprotection. Methods: To justify the photoprotection clinical observation results trans-epithelial PRK and data about the peculiarities of interaction of excimer laser radiation with a wavelength of 193 nm and corneal tissue are used. Local tolerability of photoprotectiye drugs and their influence on the development of subepithelial fibroplasias was studied on 48 eyes of 24 patients with myopia. Photoprotection of glasses with the usual sun, polarization and photochromic glasses was assessed on 52 eyes of 26 patients with high myopia after transepithelial PRK. A control group comprised 50 eyes of 25 patients with high myopia after transepithelial PRK without the use of UV photoprotection with glasses. Results: Transepithelial ablation has a number of advantages before PRK with preliminary mechanical scarification of epithelium the technology and makes an average of 1.5 times to reduce the time of onset of epithelialization of the ablation zone, considerably reduce postoperative corneal syndrome and development of fibroplasias. It was demonstrated that in the pathogenesis of fibroplasias plays an important role plays the transformation of part of excimer laser radiation with a wavelength of 193 nm radiation with more longer wavelength in the diapason of 310-330 nm, which penetrates into the layers of the cornea, adjacent to the ablation zone. This fact implies a need of photoprotection. Application of photoprotective drugs at the preparatory stage, during the transepithelial PRK and UV photoprotection with glasses in the postoperative period, allows you to exclude the development of irreversible forms of subepithelial fibroplasias completely. The photoprotective drugs did not caused the development of local toxic allergic reactions in none of the 48 eyes. Conclusion: Technology of transepithelial PRK with photoprotection expands the arsenal of new methods of photore-fractive surgery of the cornea.