Igor Komilovskiy
Pirogov National Medical-Surgical Center, Russia
Title: Photorefractive Ablation Of The Cornea With Cross-linking Effect
Biography
Biography: Igor Komilovskiy
Abstract
Purpose: To evaluate the effect of a cross-linking under photorefractive ablation of the cornea saturated with riboflavin
Methods: Several studies on corneal collagen cross-linking (CXL) and secondary radiation induced by excimer laser ablation were reviewed. TransPRK, LASIK and FemtoLASIK were performed on 402 eyes with myopia and myopic astigmatism. Photorefractive ablation was performed after corneal stroma saturation with 0.25% isotonic riboflavin. Follow-up varied from 1 month to 4 years. The effects of CXL were assessed by spectral-domain OCT and corneal densitometry
Results: CXL induced by photorefractive ablation with riboflavin is realized through the series of consecutive reactions of riboflavin activation. Activation of riboflavin with the secondary radiation induced by corneal ablation is considered as a trigger. Broad spectrum of the secondary radiation covers all four peaks of maximum riboflavin absorption at 223, 268, 374, and 445 nm. Cross-linking effect amplifies due to the secondary interaction of riboflavin with peroxyl radicals of the oxidative stress and aseptic inflammation in the stroma in response to photorefractive keratectomy. Corneal densitometry and anterior segment OCT demonstrate that CXL increases optical density of the residual stroma and enhances the absorption of external UV photons. This improves or compensates impaired mechanical and photo protective functions of the ablated cornea. Thin membrane-like Structure on the ablation surface as well as higher optical density of the corneal stroma adjacent to the ablation zone are revealed after TransPRK with riboflavin. In addition to the higher optical density of the corneal stroma, demarcation line of various intensity (which resolves later) is revealed after LASIK and FemtoLASIK.
Conclusions: The effect of crosslinking in photorefractive ablation with riboflavin was realized through the formation of a membrane-like structure on the ablation surface and was accompanied by an increase in the optical density in the layers of the stroma adjacent to the ablation zone
Key words: cross-linking, secondary excimer laser radiation, photorefractive ablation, riboflavin.