Epithelium-off corneal cross-linking versus transepithelial diluted alcohol and iontophoresis-assisted corneal cross-linking in keratoconus patients with thin corneas

Aims:To evaluate the efficacy and safety of transepithelial diluted alcohol and iontophoresis-assisted corneal cross-linking (DAI-CXL) and compare 24-month visual and topographic outcomes with accelerated CXL using hypo-osmolar riboflavin (A-CXL) in keratoconus patients with thin corneas (below 400 μm with epithelium).Methods:This retrospective study included keratoconus patients who underwent DAI-CXL or A-CXL. Uncorrected and corrected distance visual acuity (UDVA and CDVA) and data obtained from corneal topography were analyzed at baseline and 12 and 24 months of follow-up. Corneal demarcation line depth (DLD) at 1 month and corneal endothelial cell density (ECD) at 24 months were also evaluated.Results:The study included 25 eyes of 25 keratoconus patients (mean age: 25.48±6.69 years, male: 52%). DAI-CXL and A-CXL groups consisted of 13 and 12 patients, respectively. In both groups, median UDVA improved significantly at 24 months (p<0.05) whereas CDVA was similar despite a trend towards improvement. Median K-max decreased by 2.77 [interquartile range (IQR): 2.67] D and 2.24 (IQR: 4.38) D in DAI-CXL group (p=0.033) and A-CXL group (p=0.060), respectively. Corneal HOAs showed a significant improvement in only the DAI-CXL group (p=0.004). Average DLD was 237±67 μm in DAI-CXL and 242±57 μm in A-CXL (p=0.346). No significant changes in ECD were observed in both groups. Median follow-up changes in UDVA, CDVA, K-max, HOAs, and ECD were similar in the groups.Conclusions:We observed similar efficacy of transepithelial DAI-CXL to A-CXL in slowing down the progression of keratoconus in thin corneas without notable effects during a 24-month follow-up period.