Revisiting corneal collagen cross-linking safety: evaluation of the effect of ultraviolet-A (UVA) radiation on the retina with multifocal electroretinogram (mf-ERG) and ocular coherence tomography (OCT)

Session Details

Session Title: Cross-Linking

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

Paper Time: 08:52

Venue: Auditorium A

First Author: : A.Lazaridis GREECE

Co Author(s): :    S. Tsamassiotis   V. Besgen   W. Sekundo   Y. Wenner   M. Petrak   K. Droutsas     

Abstract Details

Purpose:

The evaluation of the effect of UVA radiation on the photoreceptors after corneal collagen crossliniking (CXL)

Setting:

Department of Ophthalmology, Philipps University of Marburg, Germany

Methods:

Seventeen eyes of 17 patients with keratoconus (n=15), pellucid marginal degeneration (n=1) and post-LASIK ectasia (n=1), underwent CXL (Dresden protocol). The patients were examined preoperatively, at 2 and 6 weeks postoperatively with mf-ERG and OCT. The P1 amplitude of the photoreceptor response was documented in 4 concentric rings, with ring 1 (R1) representing the foveal response and rings 2–4 (R2-R4) corresponding to the successive annuli of stimulation. Data of biomicroscopy, uncorrected (UDVA) and corrected distance visual acuity (CDVA), corneal topography, Scheimpflug tomography and densitometry, biometry, endothelial cell density and central retinal thickness were also recorded.

Results:

The preoperative mean values of P1 amplitudes for the 4 rings were R1=109.96±28.96 nV/deg2, R2=49.8±14.46, R3=29.85±8.9 and R4=19.33±6.3. At 2 weeks after CXL these values were R1=77.54±24.47, R2=36.55±12.53, R3=21.53±7.71 and R4=15.3±6.13, showing a statistically significant reduction for all rings (P<.05). At 6 weeks postoperatively P1 amplitudes were R1=99.8±31.23, R2=40.67±16.39, R3=24.98±7.13 and R4=16.35±4.84, showing for each ring no statistically significant differences (P>.05) compared to preoperative values. Corneal densitometry increased to statistically significant level at 2 (P=.000) and 6 weeks (P=.000), demonstrating a weak negative correlation with the postoperative P1 amplitudes. UDVA and fovea thickness showed no significant changes at 2 and 6 weeks.

Conclusions:

This is to our knowledge the first study assessing the photoreceptor response after CXL with the Dresden protocol. The amplitude reduction of the photoreceptor responses observed 2 weeks after CXL correlated weakly to postoperative haze. At 6 weeks after surgery the P1 amplitudes returned to preoperative (physiologic) values. Although a temporary dysfunction of the photoreceptors the first postoperative weeks cannot be excluded, the increase of 6-weeks-P1 amplitudes at preoperative levels confirm the safety standards of the duration and intensity of UVA radiation as proposed by the protocol of Dresden.

Financial Disclosure:

NONE