Morphological And Immunohistochemical Changes In The Cornea After Different Uv-Crosslinking Protocols.

Purpose: to assess the dependence of oxidative and morphological changes in the cornea on the basis of immunohistochemical methods, confocal microscopy and optocoherence tomography after corneal crosslinking (CXL).

The shown pathomorphological changes in the cornea can form the basis for choosing the optimal protocol for varying degrees of risk of disease progression in patients with keratoconus.

Methods: the study was performed in 33 patients (33 eyes) with stage I-III keratoconus (classification according to Amsler-Krumeich) who were hospitalized at the Ufa Research Institute of Eye Diseases, incl. men - 21 (63.6%), women - 12 (36.4%). The standard UV crosslinking group (S-CXL) consisted of 20 patients (20 eyes), and the accelerated (A-CXL) group consisted of 13 patients (13 eyes). The average age of the patients is 28.7 ± 5.6 years. The local level of superoxide dismutase (SOD) and total antioxidant status (TAS) and their correlation with the density of keratocytes and the depth of the demarcation line (DL) in the corneal stroma were determined. 

Patients with keratoconus have a statistically significant low baseline OSA level of 1.68 ± 0.21 mmol / L with a significant decrease after S-CXL - on the 3rd day - to 0.81 ± 0.12 mmol / L, on the 7th day - 0.98 ± 0.11 mmol / l. 14th - 1.19 ± 0.15 mmol / L and 30th - 1.31 ± 0.19 mmol / L, respectively. After A-CXL, this indicator turned out to be slightly higher: 3rd - 1.03 ± 0.14 mmol / L, 7th - 1.15 ± 0.15 mmol / L, 14th - 1.47 ± 0.21 mmol / L, and 30th - 1.80 ± 0.24 mmol / l.

CXL in human keratoconus can cause significant morphological changes in the cornea in the form of increased oxidative stress and keratocyte death. The severity of oxidative stress after S-CXL in comparison with A-CXL deserves special attention due to the increased penetration ability of UV radiation and the involvement of a larger volume of corneal tissue.