Randomized Clinical Trial Comparing Customized Corneal Crosslinking: Epi-on in High Oxygen and Epi-off in Room Air for Keratoconus

Abstract

Purpose: To compare clinical outcomes of customized transepithelial (epi-on) corneal crosslinking (CXL) in high oxygen and customized CXL with epithelial removal (epi-off) in room air for keratoconus (KC). Setting: Umeå University Hospital, Umeå, Sweden. Design: Prospective, randomized, single-masked, intra-individually comparing study Methods: Thirty-two participants with bilateral progressive KC were treated with bilateral customized topography-guided CXL, 30 mW/cm2; 7.2-15 J/cm2 and were randomized to epi-on in one eye (32 eyes) and epi-off in the fellow eye (32 eyes). Uncorrected (UDVA) and best corrected visual acuities (BCVA), maximal keratometry (Kmax), subjective ocular discomfort, low-contrast visual acuities (LCVA) at 10% and 2.5% contrast, ocular and anterior corneal wavefront aberrations, manifest refractive spherical equivalent (MRSE), endothelial cell count (ECC) and adverse events were assessed through 24 months. Results: Both treatments showed improvements at 24 months in UDVA; -0.16 ± 0.24 (p < 0.001) and -0.13 ± 0.20 logMAR (p = 0.006), respectively, BCVA; -0.10 ± 0.11 (p < 0.001) and -0.10 ± 0.12 (p = 0.001), Kmax; -1.74 ± 1.31 (p < 0.001) and -1.72 ± 1.36 D (p < 0.001). LCVA 10% improved for both protocols (p < 0.001), but LCVA 2.5% improved for epi-on CXL only (p = 0.001). ECC was unaltered and no adverse events occurred. The epi-on eyes had significantly less discomfort symptoms during the whole first week posttreatment (p < 0.05). Conclusions: High-oxygen customized epi-on CXL is a viable alternative to room air customized epi-off CXL, with faster improvements in BCVA and LCVA and less early ocular discomfort.