PRELIMINARY RESULTS OF A RANDOMIZED CONTROLLED TRIAL COMPARING TRANSEPITHELIAL CORNEAL CROSS-LINKING WITH IONTOPHORESIS AND STANDARD CROSS-LINKING IN PATIENTS WITH PROGRESSIVE KERATOCONUS

Abstract

Purpose : To report the clinical outcomes 3 months after transepithelial corneal cross-linking (CL) using iontophoresis (T-ionto CL) in comparison with standard corneal cross-linking in eyes with progressive keratoconus.

Methods : Transepithelial CL using iontophoresis was performed using hypotonic ethylenediaminetetraacetic acid and trometamol enriched dextran-free 0.1% riboflavin solution and UV-A irradiation with 10 mW/cm² UV-A device for 9 minutes. Standard CL was performed according to the “Dresden protocol” using 20% dextran enriched 0.1% riboflavin solution and UV-A irradiation with 3 mW/cm² UV-A device for 30 minutes. The primary outcome measure was the maximum simulated keratometry value (K_max). Other outcome measures were best spectacle corrected visual acuity (BSCVA; logMAR units), manifest refraction, central corneal thickness (CCT; using AS-OCT) and endothelial cell density (ECD; no-contact specular microscopy). Follow-up visits were scheduled at 3 and 7 days, 1- and 3-months.

Results : Thirty-four eyes with progressive keratoconus were recruited in the study and randomized in two groups: T-ionto CL (22 eyes) and standard CL (12 eyes). At 3 months, K_max decreased from 54.7±4.0 D to 54.2±3.9 D (P=0.11) and from 54.7±4.2 D to 54.3±4.7 D (P=0.33) in the study and in control group respectively. At 3 months, BSCVA improved from 0.12±0.20 LogMAR to 0.04±0.10 LogMAR (P=0.01) after T-ionto CL; no change in BSCVA was found after standard CL (from 0.03±0.09 LogMAR to 0.06±0.09 LogMAR; P=0.26). The manifest spherical equivalent refraction changed averagely by +0.57 D (P=0.02) and +0.22 D (P=0.26) in the T-ionto CL and standard CL groups respectively at 3 months. CCT ranged from 484±37 µm to 486±28 µm (P=0.72) and from 494±34 µm to 484±38 µm (P=0.15) in the study and control group respectively from preoperatively to 3 months. ECD count did not change during 3 months, except for a drop at day 3 in the control group, due to posterior stromal edema in 60% of cases. There was 1 eye in the control group with peripheral corneal infiltrates that did not affect the 3 months visual acuity.

Conclusions : The 3-months results are demonstrating that T-ionto CL is safe with comparable efficacy to conventional treatment for halting keratoconus progression in the short term period.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.