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I. Z. Fejes, P. Kocsis, G. Pokorny, M. Janáky; Early Detection of Chloroquine Retinal Toxicity With Electrophysiological Methods. Invest. Ophthalmol. Vis. Sci. 2008;49(13):882. doi: https://doi.org/.
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Though known to cause irreversible "bull’s eye" retinopathy, chloroquine is frequently used to treat autoimmune diseases. We tested the efficiency of electrophysiological methods in the detection of early-stage retinopathy.
38 patients (74 eyes) treated with chloroquine (mean dose: 455±70.6 (SEM) g) were examined via visual evoked potentials (VEPs), pattern electroretinography (PERG) and multifocal electroretinography (mfERG). Three patients treated with a dose of 221.25±8.93 g were followed up for 29.5±1.19 months because of non-characteristic fundus alterations. Nineteen healthy volunteers with good vision served as controls. All examinations were performed according to the International Society for Clinical Electrophysiology of Vision guidelines with a RETI-Port 32 System (Roland Consult Gmbh, Wiesbaden, Germany).
There was no significant difference between the patient and the control P100 implicit times of the VEPs. PERG, however, revealed a significantly delayed P50 implicit time for the patients (p<0.001). The N35/P50 and P50/N95 amplitudes were similarly significantly smaller for the patients than for the controls (p<0.001). The patients mfERGs demonstrated a significantly lower amplitude in Rings 1-4 (86.3 vs 71.7 nV/deg2, p=0.005; 44.9 vs 35.7 nV/deg2, p<0.001; 27.6 vs 24.17 nV/deg2, p=0.019; 17.4 vs 16.6 nV/deg2; p<0.001, respectively).Follow-up Pearson tests indicated that the duration of chloroquine treatment correlated significantly with the P50 implicit time (r=0.38, p=0.033), the PERG P50/N95 component amplitude (r=-0.47, p=0.01), and the mfERG response amplitudes of in Rings 2 (r=-0.4, p=0.036) and 3 (r=-0.41, p=0.029).
Electrophysiological methods may detect retinotoxicity before the characteristic ophthalmoscopic signs appear. PERG also seems to reveal drug-induced damage. The altered PERGs suggest that prolonged chloroquine treatment can affect both the outer and inner retinal layers.
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