Enhancing Patient Comfort in Epi-Off Crosslinking: The Potential of High-O2 Chambers

PURPOSE: To evaluate the impact of high oxygen concentration using a novel oxygen chamber on epi-off corneal cross-linking (CXL) efficacy and patients' perceived pain during the procedure. SETTING: Farabi Eye Hospital, Tehran, Iran. DESIGN: Interventional randomized clinical trial. METHODS: Forty-eight eyes with progressive keratoconus were enrolled. The high-oxygen group (24 eyes) underwent accelerated epi-off CXL (9 mW/cm2 UV-A, 5.4 J/cm2 for 10 minutes) in a controlled high-oxygen environment (∼60%) using a novel oxygen chamber, while the control group (24 eyes) underwent the same protocol under ambient air oxygen (∼21%). Visual acuity, manifest refraction, and keratometry values were measured at baseline, 1 month, and 12 months post-CXL. Demarcation line depth and endothelial cell density were recorded at 1 month postoperatively. Pain was assessed intraoperatively using the Wong-Baker FACES scale (WBF). RESULTS: The high-oxygen group demonstrated significantly deeper demarcation line depth (307 ± 14 µm vs 279 ± 23 µm, p<0.001) and greater reductions in keratometry values (K1 and K2) at 12 months (p=0.04 and p=0.02, respectively). Compared to baseline, significant improvements in K1 (p=0.02), K2 (p=0.02), and Kmax (p<0.01) were observed in the high-oxygen group, whereas only K1 showed a significant improvement in the ambient oxygen group (p=0.02). Endothelial cell count remained stable in both groups. Patient reported intraoperative pain scores were significantly lower in the high-oxygen group (Wong-Baker FACES scale (2.4 ± 0.9 vs 3.4 ± 0.7, p=0.003). CONCLUSION: Use of the oxygen chamber to create a high-oxygen environment during accelerated epi-off CXL was associated with deeper stromal demarcation and improved keratometric outcomes, while also reducing intraoperative pain. This approach may improve clinical outcomes and patient experience during CXL.