NEW APPROACHES TO CROSSLINKING IN COMBINATION WITH REFRACTIVE KERATOMODELING IN CORNEAL ECTASIA

Abstract

Objective: To consider new approaches to crosslinking in combination with refractive keratomodeling in corneal ectasia of various etiologies.Methods: The work is based on clinical observations of the immediate and remote results of prophylactic and therapeutic corneal crosslinking with argon-fluorine excimer laser radiation (over 700 operations) over periods from 1 month to 13 years. Particular emphasis was placed on the formation of a Bowman-like membrane structure on the ablation surface and local exposure with a personalized gradient refractive profile of the total dose of radiation to achieve a greater keratomodeling effect. Rapid transition without additional calibrations to energy densities below the ablation threshold was carried out on the Russian excimer laser “Microscan Visum-500”.Results: Experimental and clinical studies have shown that excimer laser radiation on argon-fluorine can be used for corneal crosslinking, with energy densities in the pulse being below the ablation threshold. The advantage of excimer laser crosslinking was scanning with a narrow beam, which disrupts the oxygenation of the corneal stroma to a lesser extent and allows for the implementation of personalized local refractive keratomodeling based on keratotopography or aberrometry data. In this case, the induced secondary radiation covers all four peaks of maximum absorption by riboflavin. The use of subablative energy densities during irradiation of the cornea in the personalized PRK mode made it possible to locally affect the ectasia zone and enhance the refractive effect due to the gradient distribution of the total radiation dose.Conclusion: Radiation from an argon-fluorine excimer laser opens up new possibilities for refractive ablative and non-ablative refractive keratomodeling of the cornea in combination with laser-induced crosslinking in keratoconus and secondary keratoectasias of various etiologies.