Early Epithelial Remodeling After Standard and Iontophoresis-Assisted Corneal Cross-linking as Evaluated by Spectral-Domain Optical Coherence Tomography.

Purpose: To evaluate and compare epithelial remodeling after standard corneal cross-linking (S-CXL) and iontophoresis-assisted CXL (I-CXL) in eyes with keratoconus by anterior segment optical coherence tomography (AS-OCT).

Methods: In this prospective, observational study, AS-OCT and corneal topography were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry was performed and epithelial and stromal thicknesses (central and 16 points on the 6-mm central zone) and the maximum simulated keratometry value (Kmax) were measured.

Results: Two groups of 30 patients (60 eyes total) with progressive keratoconus underwent S-CXL or I-CXL. Before surgery, both groups of patients presented with an irregular epithelial thickness profile. At 6 months postoperatively, localized corneal epithelial thinning was observed in the superior (P = .026), inferior (P = .034), inferonasal (P = .024), and nasal (P = .035) areas at 3 mm and in the superior (P = .039), nasal (P = .043), and inferior (P = .01) areas at 6 mm in the SCXL group. Localized corneal epithelial thinning was observed at 3 (P = .04) and 6 (P = .01) mm in the inferior area in the I-CXL group. No significant stromal changes were observed for either group. Kmax was stable in both groups at 6 months.

Conclusions: Significant epithelial remodeling occurs after S-CXL, resulting in a thinner, more regular thickness profile than after I-CXL. Epithelial thickness profile measurements after I-CXL could be used as an adjunctive follow-up tool for monitoring the efficacy of CXL in progressive keratoconus. [J Refract Surg. 2018;34(8):551-558.].