OXYGEN BOOSTED TRANSEPITHELIAL CORNEAL COLLAGEN CROSS-LINKING : ULTRASTRUCTURAL RESULTS

Published 2022 - 26th ESCRS Winter Meeting

Reference: P202 | Type: Abstracts | DOI: 10.82333/7xa5-n048

Authors: David Touboul* ¹ , Pierre Legout ¹ , Valentine Saunier ¹

¹Ophthalmology,CHU Bordeaux,Bordeaux,France

Purpose

Corneal collagen cross-linking (CXL) treatment is an oxygen-dependent reaction. A new technique of transepithelial CXL using specially designed oxygen delivery goggles has been proposed to provide a high oxygen environment into the cornea.

Setting

Bordeaux Hospital and University, national reference center for keratoconus, Bordeaux, France

Methods

Patients with progressive KC were involved and transepithelial, pulsed, accelerated CXL in an oxygen-rich atmosphere was performed (Oxygen boosted CXL from Avedro - USA). We registered postoperatively the OCT demarcation line depth using an anterior segment optical coherence tomography (AS-OCT) and a swept-source OCT-topography (SS-OCT) in between 3 and 6 months. Corneal innervation and keratocyte activation were subjectively evaluated with confocal microscopy. As well, endothelial cells count was assessed at each visit using a non-contact specular microscopy.

Results

Ten eyes of 10 patients were enrolled. The mean patient age was 23,8 (16-31). The mean preoperative Kmax was 47,4 ± 2,9 D and the mean corneal thickness at the thinnest point was 467 μm ± 44. At 3 months, a posterior demarcation line was visible in 9 eyes (90%) with a mean depth of 414 μm ± 80,91 with AS-OCT and 397 μm ± 148 with SS-OCT (85,7 % of mean corneal full thickness). We also observed, more anteriorly, a hyperreflective band reaching the depth of 213 μm ± 42 with AS-OCT. Compared to baseline, the corneal sub-basal nerve density had significantly decreased and superficially keratocytes apoptosis was observed at 3 months postoperatively. Indeed, there were no statistically significant differences between the mean endothelial cell counts before and 6 months after CXL. No intraoperative, neither postoperative complication were observed.

Conclusion

Previous work suggests that the supplementary oxygen strategy might increase the aerobic type II reaction, enabling a potentially deeper and more effective CXL. The posterior demarcation line depth we found in our study, despite the absence of epithelial debridement, does confirm this hypothesis. We can assume that the hyperreflective anterior band we visualized was a change in corneal refractive index. Occurring in the strongest corneal part with closer collagen fibers and decreased in water content, we hypothesized the healing process could be amplified in that area. The posterior demarcation line remains probably the posterior limit of CXL biological interaction. Transepithelial oxygen boosted CXL could provide a deep corneal photo reticulation, avoiding the drawbacks of epithelium removal. Further complementary studies are necessary to confirm the long-term safety and efficacy.