Transepithelial Corneal Collagen Cross-Linking in Keratoconus

To evaluate the clinical effects of transepithelial corneal cross-linking (CXL) on keratoconic eyes pre-treated with substances enhancing epithelial permeability.Prospective, consecutive, single-masked, paired-eye study on 51 patients. The eye with more severe keratoconus was treated; the fellow eye served as the control. Gentamicin, benzalkonium chloride, and ethylenediaminetetraacetic acid were instilled for 3 hours, then oxybuprocaine for 30 minutes. Riboflavin 0.1% in 20% dextran T500 and oxybuprocaine were instilled for 30 minutes. Finally, ultraviolet A irradiation to the central 7.5 mm of the cornea was applied for 30 minutes, while riboflavin was instilled every 5 minutes.Mean corrected distance visual acuity improved by 0.036 logMAR after CXL and worsened by 0.039 logMAR in the control eyes (P<.05). Safety index was 1.05 after CXL and 0.96 in the control group. Mean spherical equivalent refraction decreased by 0.35 D (less myopic) after CXL and increased by 0.83 diopters (D) in the control eyes (P<.05). Mean apex curvature on tangential videokeratography increased by 0.51 D after CXL and by 1.61 D in the control eyes (P=.16). Mean average simulated keratometry decreased by 0.10 D after CXL and increased by 0.88 D in the control eyes (P<.05). Mean index of surface variance increased (worsened) by 0.9 after CXL and 5.3 in the control eyes (P<.05). Mean endothelial cell density was unchanged.A limited but favorable effect of transepithelial CXL was noted on keratoconic eyes, without complications. The effect appears to be less pronounced than described in the literature after CXL with de-epithelialization.