Official ESCRS | European Society of Cataract & Refractive Surgeons
Copenhagen 2016 Registration Programme Exhibitor Information Virtual Exhibition Satellite Meetings Glaucoma Day 2016 Hotel Star Alliance

10 - 14 Sept. 2016, Bella Center, Copenhagen, Denmark

This Meeting has been awarded 27 CME credits


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Optical aberrations in phototherapeutic keratectomy vs manual epithelial debridement for corneal collagen cross-linking in keratoconus

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Session Details

Session Title: Cross-Linking

Session Date/Time: Sunday 11/09/2016 | 08:00-09:30

Paper Time: 09:04

Venue: Auditorium A

First Author: : H.Nithianandan CANADA

Co Author(s): :    Y. Yang   P. Arjmand   G. Mintsioulis   S. Ziai   K. Baig        

Abstract Details


To evaluate and compare the changes in optical aberrations following corneal collagen cross-linking (CXL) using two different techniques for epithelial removal: phototherapeutic keratectomy (PTK) vs. manual epithelial debridement.


University of Ottawa Eye Institute, Ottawa, Canada


This retrospective study included keratoconic eyes undergoing CXL using either PTK or manual brush at the University of Ottawa Eye Institute between 2010 and 2015. Higher order aberrations (HOAs) were measured using the Pentacam® Scheimpflug camera system at baseline, 3, 6 and 12 months post-operatively. The wavefront error was fitted with Zernicke Polynomial up to the 8th order to calculate root-mean-square (RMS) data, with the pupil diameter set to 6.5 mm. Total anterior corneal HOAs, and second to fourth order aberrations were compared pre-operatively and at 12 months post-operatively.


309 eyes were included with 71 eyes in the PTK group and 238 eyes in the manual debridement group. The mean preoperative total anterior corneal HOA was 1.17 ± 0.78 μm (SD) for the manual group and 1.12 ± 0.50 μm for the PTK group (p>0.05). At 12 months follow up, both groups showed significant improvements in total corneal aberrations, total corneal HOA, and coma compared to baseline (p<0.05). Compared to the manual group, the PTK group demonstrated greater reduction in total corneal aberrations, total corneal HOAs, coma, fourth order astigmatism and spherical aberrations (p<0.05).


Optical aberrations significantly improved after CXL at 12 months postoperatively with either PTK or manual epithelial debridement. However, compared to manual epithelial debridement, the PTK group had greater magnitudes of improvement in total corneal aberrations, corneal HOAs, coma, fourth order astigmatism and spherical aberration.

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