Changes in cornea structure after corneal collagen crosslinking in keratoconus

Abstract

Introduction. The article considers an objective assessment of the state of morphofunctional status of cornea in keratoconus after a corneal collagen crosslinking procedure.Aim. To assess changes in cornea structure after corneal collagen crosslinking in keratoconus. Materials and methods. The study included 24 patients: 30 eyes with KC stage I–III aged 17 to 42 years. The patients were examined before and after the  corneal collagen crosslinking procedure. The postoperative follow-up period was 12  months. The patients underwent anterior segment OCT (AS-OCT) imaging to assess the demarcation line depth. The cornea and cornea nerve fibers were assessed layer-by-layer using сonfocal laser scanning microscopy, followed by the  analysis of  resulting confocal images through the author’s analysis algorithm.Results and discussion. The epithelialization of the cornea completed on day 3–5 after the procedure. According to OCT findings, the depth of the demarcation line averaged to 260 µm in the center and 140 µm in the periphery. The pronounced edema of the outer stroma was observed during the first-week follow-up, and a decrease in the density and apoptosis of keratocytes was noted during the first month. Over a 3–12-month postoperative follow-up period, the transient lacunar edema regressed and the density of keratocytes was restored to the baseline level. During the first three months, a pronounced disruption of the direction and structure of the cornea nerve fibres is seen.Conclusion. The crosslinking procedure results in changes in the cornea structure, one of which is appearance of the demarcation line in the stroma, which indicates the depth of penetration of the photochemical corneal collagen crosslinking process. The laser corneal confocal microscopy allows to objectively assess the depth of this effect, while the values obtained in the same follow-up periods are comparable with the findings of OCT imaging.