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Revisiting corneal collagen crossliniking ( CXL ) safety: Evaluation of the effect of ultraviolet‐A ( UVA ) radiation on the retina with multifocal electroretinogram (mf‐ ERG ) and optical coherence tomography ( OCT )
Author(s) -
Lazaridis A.,
Tsamassiotis S.,
Besgen V.,
Sekundo W.,
Wenner Y.,
Droutsas K.
Publication year - 2017
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2017.02383
Subject(s) - ophthalmology , medicine , keratoconus , erg , ectasia , optical coherence tomography , retina , densitometry , phakic intraocular lens , visual acuity , retinal , cornea , refractive error , surgery , optics , physics
Purpose The evaluation of the effect of UVA radiation on the photoreceptors after CXL. 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. Uncorrected ( UDVA ) and corrected distance visual acuity ( CDVA ), corneal densitometry 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 significant differences compared to preoperative values (P>.05). Corneal densitometry increased to statistically significant level at 2 (P<.001) and 6 weeks (P<.001), 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. Although a temporary dysfunction of the photoreceptors the first postoperative weeks cannot be excluded, the increase of 6‐weeks‐P1 amplitudes at preoperative (physiologic) values confirms the safety standards of the duration and intensity of UVA radiation as proposed by the Dresden protocol.