[Multifocal electroretinography in follow-up of patients treated with hydroxychloroquine]

Ophthalmologic follow-up of hydroxychloroquine-treated patients is of major importance because of the risk for potentially irreversible retinal toxicity. The use of the multifocal electroretinogram for the follow-up of such patients has already been reported. We studied the capacity of the multifocal electroretinogram to detect early signs of retinal toxicity.

This study consisted of multifocal electroretinogram analysis of 28 patients treated with hydroxychloroquine for a period of 6-72 months. All patients selected had a normal clinical and paraclinical ophthalmological evaluation. A multifocal electroretinogram according to the international recommendations was obtained. We analyzed the amplitude and the implicit time for kernel 1 responses by quadrant and by ring.

For both eyes, in both ring and quadrant analyses, the average implicit times of patients receiving hydroxychloroquine were significantly elevated (p<0.01). On the other hand, the amplitudes were not significantly attenuated. In a total of 28 patients, seven (25%) presented a significant prolongation of the implicit time and significant amplitude attenuation was found in only one patient.

Implicit time prolongation in hydroxychloroquine-treated patients has already been reported. However, dissociation between amplitude and implicit time changes has, to our knowledge, never been previously described. This observation is important given that numerous studies focus exclusively on amplitude.

The multifocal electroretinogram of patients receiving hydroxychloroquine can present lengthened kernel 1 implicit time, despite otherwise normal ophthalmological evaluation. Further studies are necessary to evaluate the prognostic value of mfERG responses in the early detection of patients presenting a retinotoxicity risk.