Two-year outcomes of a randomized controlled trial of transepithelial corneal crosslinking with iontophoresis for keratoconus.

Abstract

PURPOSE\nTo evaluate the 2-year clinical outcomes of corneal crosslinking (CXL) using transepithelial iontophoresis CXL (T-ionto CXL) in comparison with standard CXL for the treatment of progressive keratoconus.\n\n\nSETTING\nSingle-site study.\n\n\nDESIGN\nRandomized controlled clinical trial with identifier code NCT02117999.\n\n\nMETHODS\nThe eyes of the participants were randomized to have either T-ionto CXL and/or standard CXL. Assessments of uncorrected (UDVA) and corrected (CDVA) distance visual acuities (logarithm of the minimum angle of resolution [logMAR]), manifest refraction spherical equivalent, maximum simulated keratometry (K) (diopters [D]), corneal higher-order aberrations (HOAs), central corneal thickness (CCT), and endothelial cell density (ECD) were performed at 3\xa0days, 7\xa0days, and 1, 3, 6, 12, and 24\xa0months postoperatively.\n\n\nRESULTS\nThe study comprised 34 eyes (25 patients). There were 22 eyes in the T-ionto CXL group and 12 eyes in the standard CXL group. Two years after T-ionto CXL and standard CXL, the mean maximum K flattened by -1.05\xa0±\xa01.20 D (P\xa0=\xa0.07) (20 eyes) and -1.51\xa0±\xa0.89 D (P\xa0<\xa0.001) (11 eyes), respectively. Two study cases (10%) and no control showed maximum K steepening of more than 1.0 D at 24\xa0months postoperatively. The mean change in CDVA was -0.08\xa0±\xa00.15 logMAR (P\xa0=\xa0.04) and -0.02\xa0±\xa00.06 logMAR (P\xa0=\xa0.34) after T-ionto CXL and standard CXL, respectively. A significant average decrease in the myopic defocus (+0.81 D; P\xa0<\xa0.05) was found in both groups. No significant differences in the outcome measures between treatments were found at 24\xa0months. The corneal HOAs, CCT, and ECD values did not change significantly in any group at 2\xa0years postoperatively.\n\n\nCONCLUSIONS\nClinically significant topographic, visual, and refractive improvements were found 2\xa0years after T-ionto CXL; standard CXL showed more significant corneal apex flattening than the transepithelial iontophoresis protocol.