Résumé
Objective: to assess early quantitative and qualitative microstructural changes induced by corneal collagen Cross-Linking surgery in patients with progressive keratoconus using in vivo confocal microscopy (IVCM).Design: prospective, non-comparative, interventional case series.Methods: sixteen eyes from eleven patients with progressive keratoconus were included between March 2022 and May 2023 at the Ophthalmology Department of the University Hospital Gui de Chauliac in Montpellier. All patients underwent accelerated corneal collagen Cross-Linking surgery. Examinations were conducted preoperatively, at 1 week, 1 month, and 3 months postoperatively. Each visit included slit-lamp examination and in vivo confocal microscopy of the cornea (Heidelberg Retina Tomograph III). Anterior segment optical coherence tomography (OCT) (RTVue XR 100 Avanti,OPTOVUE) was performed at 1 month postoperatively to determine the depth of the demarcation line. Corneal topography examination (Pentacam, OCULUS) at 3 months postoperatively enabled the correlation studies between keratometric, pachymetric, and confocal microscopy data.Results: on IVCM, a rapid decline of keratocyte densities was observed in the anterior and middle stroma until 1 month postoperatively (p< 0.01), followed by an increase of these densities between the 1st and 3rd postoperative (p< 0.01). No significant differences were detected for cell densities in the posterior stroma and endothelium at each visit (respectively, p= 0.58 and p= 0.72). We highlighted an immediate loss of sub-basal nerve plexus (SBP) and its regeneration occurred between the 1st and 3rd postoperative months. Corneal topography revealed a significant decrease in maximum keratometry of 0.92 ± 1.41 D (p= 0.04), a non-significant decrease in central 3mm keratometry of 0.3 ± 0.65 D (p= 0.12), and pachymetry at the 3-month postoperative evaluation of 3.77 ± 8.71 µm (p= 0.15).Correlation analyses using the Wilcoxon signed-rank test did not reveal any significant correlations between the extent of keratocyte loss and pachymetry, average keratometry, or maximum keratometry. Similarly, no correlations were demonstrated between the depth of the demarcation line and pre/postoperative pachymetric differences.Conclusion: early postoperative Cross-Linking induces a significant depletion of keratocytes in the anterior and mid-stroma and a significant loss of the sub-basal corneal plexus. The activation of keratocytes into fibroblasts enables an accelerated turnover of corneal collagen. However, no correlation is found between the extent of the procedure's effect measured by IVCM and the topographic parameters at 3 months postoperatively.