Simultaneous combined wavefront-guided transepithelial photorefractive keratectomy and corneal collagen cross-linking for stage II-III keratoconus

Session Details

Session Title: Photoablation, Cross-Linking and Intracorneal Ring Segment

Session Date/Time: Monday 07/09/2015 | 08:00-10:30

Paper Time: 08:06

Venue: Room 16

First Author: : B.Allan UK

Co Author(s): :    D. Gore                    

Abstract Details

Purpose:

Simultaneous transepithelial photorefractive keratectomy (TransPRK) and corneal collagen cross-linking (CXL) aims to reverse visual loss attributable to irregular astigmatism in early stage keratoconus without compromise to stabilization of disease progression. Here we present interim 3 month visual results from the TransPRK/CXL trial (NCT02208089) using a commercially available tissue saving wavefront guided algorithm for TransPRK which exclusively targets dominant higher order aberrations (irregular astigmatism).

Setting:

The Refractive Surgery Service, Moorfields Eye Hospital, London

Methods:

Patients with progressive stage II-III keratoconus, LogMAR corrected distance vision acuity (CDVA) <0.00 (<6/6) and no ocular copathology were included. Aberrometry guided TransPRK (≥8mm diameter) was performed using the Schwind Amaris 750S excimer laser platform (Schwind Eye-tech Solutions, Kleinostheim, Germany). Mitomycin C was not used. Tissue ablation depth was minimised by treating dominant higher order aberrations only with no compensatory additional tissue removal to control for induced changes in sphere and cylinder. An accelerated CXL protocol was used: 10 minute soak (Vibex Rapid), 4 minutes (1.5sec pulsed) UV exposure (30mW/cm2) using an Avedro KXL UV source (Avedro, Waltham MA).

Results:

To date, 26 eyes of 26 patients have been treated (recruitment target 50 patients, study launch August 2014). 3-month outcomes are available for 11 eyes. Mean (SD) stromal ablation depth at the cone apex was 32µm (±9µm). Mean (SD) CDVA improved from 0.31 (±0.25) pre-operatively to 0.12 (±0.18) 3 months post treatment (p=0.012 t test). One eye lost CDVA (0.14 logMAR units) in association with anterior stromal haze. Coma was the dominant aberration preoperatively. Significant reductions in coma and corneal asymmetry were evident in topographic comparison maps.

Conclusions:

Wavefront guided transPRK in combination with accelerated CXL reduces irregular astigmatism and results in significant early gains of CDVA in patients with stage II-III keratoconus. Long-term follow-up and comparison of results with historical control eyes treated with the same accelerated CXL protocol and no TransPRK will further quantify these visual gains and help to identify any negative effect of combined treatment on corneal shape stability.

Financial Interest:

NONE