Monitoring Central Electroretroretinal Function in Patients on Long-Term Hydroxychloroquine Therapy

Abstract

Purpose:: Chloroquine and Plaquenil (hydroxychloroquine) are medications whose primary clinical indications are collagen vascular diseases including systemic lupus erythematosus and rheumatoid arthritis. Multifocal electroretinography (mERG) has been developed for clinical monitoring of central electroretinal function in patients with inherited and acquired maculopathy. We have investigated mERG correlates in patients on long-term Chloroquine and Plaquenil therapy to determine the potential clinical utility of mERG in detecting early changes in retinal function.

Methods:: 140 eyes of 70 consecutive patients (61 females, 9 males) on long-term treatment (duration 3 to 15 years (mean = 8.1 years) using Chloroquine or Plaquenil (8 on Chloroquine , 62 on Plaquenil) had serial multifocal ERG recordings performed over a period of 2 to 6 years while on treatment. Multifocal ERGS were recorded with DTL fiber electrodes through dilated pupils. The 61 hexagon stimulus subtended 45 degrees centered on the fovea. Timing and response amplitude of the foveal, parafoveal, and paracental rings was measured.

Results:: Forty-eight (69%) of patients showed no significant changes in mERG during 2 to 6 years of monitored treatment. Sixteen (23%) of patients did show significant changes in mERG during 2 to 4 years of monitored treatment. Five (7%) of patients did show significant changes in mERG after 4 years of monitored treatment. In those affected patients there was generally good correlation with changes in clinical findings such as 10-2 perimetry and color vision. Interestingly, in several patents taken off Plaquenil there was subsequent improvement in mERG noted within 12 months.

Conclusions:: Multifocal ERG is an objective, non-invasive method to accurately assess central electroretinal function in patients on long-term Chloroquine and Plaquenil therapy. It has demonstrated clinical utility in early detection of changes in electroretinal function in patients on potentially retinotoxic compounds.

Keywords: electroretinography: clinical • drug toxicity/drug effects • macula/fovea