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

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Session Details

Session Title: Cornea
Session Date/Time: Sunday 28/02/2016 | 08:30-11:00
Paper Time: 09:18
Venue: MC2 Room
First Author: : A.Lazaridis GERMANY
Co Author(s): :    S. Tsamassiotis   V. Besgen   M. Schroeder   W. Sekundo   Y. Wenner   K. Droutsas

Abstract Details


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


Department of Ophthalmology, Philipps University of Marburg, Germany


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 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 (UCVA) and best corrected visual acuity (BCVA), corneal topography, Scheimpflug tomography and densitometry, biometry, endothelial cell density and central retinal thickness were also recorded.


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 to P1 amplitudes. UCVA and fovea thickness showed no significant changes at 2 and 6 weeks.


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.

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