The Effect of Corneal Collagen Crosslinking on Corneal Tissue Regeneration and Fibrosis. An Experimental Study

The most modern and effective method of treating degenerative corneal diseases is corneal crosslinking (CXL). This technique involves three steps: epithelial removal, stromal saturation with riboflavin, and UV irradiation at a wavelength of 370 nm. This exposure increases corneal rigidity. Consequently, assessing the impact of this technique on the regeneration and fibrosis processes in corneal tissues is of significant interest.

Aim: to study the effect of CXL on rat corneas by assessing TGF-β1 and FGF-1 expression in relation to corneal structural characteristics.

Materials and Methods. Experiments were conducted in two groups: Control (intact), Group 2 Experimental, in which a corneal crosslinking technique was performed. This technique involved deepithelialization of a 3-mm-diameter area of the cornea, instillation of DEXTRALINK solution (0.1 % riboflavin mononucleotide and 20 % dextran), and UVA irradiation of the cornea using the “UFalink” device (exposure parameters: 3 mW/cm² for 10 minutes at a wavelength of 370 nm). On days 14 and 30, the eyeballs were enucleated and examined using morphological, immunohistochemical (TGF-β1 and FGF-1), and electron microscopy. For statistical analysis, the Mann-Whitney U-test was used to calculate TGF-β1⁺ and FGF-1⁺ keratocytes.

Results. Mild pathological changes associated with keratocyte destruction in the stroma were detected in the experimental group on day 14. By day 30, however, no such changes were observed in the corneal stromal lamellae. The ultrastructural organization of the cornea, including the lamellae and cellular composition, appeared normal. The expression of TGF-β1and FGF-1-positive keratocytes decreased 14 days after exposure to UV radiation and Dextralink solution, but returned to normal levels after 30 days, matching those of an intact cornea.

Conclusions. Corneal crosslinking with DEXTRALINK solution does not lead to the overproduction of TGF-β1 and FGF-1 in keratocytes. On day 14, preservation of the collagen structure of the cornea and the outer and inner epithelial layers was observed, along with signs of destruction and loss of keratocytes. Subsequently, on day 30, keratocytes with signs of increased functional activity were identified.

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