Abstract
Purpose: :
Patients taking hydroxychloroquine (Plaquenil) for the treatment of rheumatoid arthritis, systemic lupus erythematosus, or related diseases are at risk for developing retinal toxicity. Three patterns of function loss from Plaquenil-related retinal toxicity have been identified using the multifocal electroretinogram (mfERG): central amplitude depression, paracentral amplitude depression, and full-field loss (Lyons and Severns, AJO 2007;143:801-809). Patients with full-field loss, the second most common pattern of function loss, typically have different symptoms than the other two groups. The purpose of this study is to investigate the mechanism of this function loss.
Methods: :
MfERGs were recorded in 90 patients routinely referred for Plaquenil monitoring, and in 62 patients suspected of having Plaquenil retinal toxicity. Ganzfeld ERGs were recorded in patients with severely depressed mfERG amplitudes throughout the tested area.
Results: :
8 out of 45 affected eyes were identified with full-field mfERG loss. Ganzfeld ERGs of these patients showed either extreme depression of the b-wave (negative ERG), or loss of both a- and b-waves. Six (75%) of these patients had nyctalopia and peripheral field loss; at least 2 reported sudden onset and rapid progression of their symptoms. One patient with a negative ERG was later shown to have lymphoma, indicating paraneoplastic neurological syndrome (PNS). Repeat testing on 2 patients showed no ERG recovery after discontinuing Plaquenil.
Conclusions: :
Approximately 18% (8 of 45) of patients diagnosed with Plaquenil toxicity had profoundly reduced full-field mfERGs and depressed ganzfeld ERGs. The pattern of functional loss and the symptoms of nyctalopia and peripheral field constriction in these patients is suggestive of autoimmune retinopathy, not Plaquenil toxicity. In particular, the negative ERG in 3 of the 8 patients implicates anti-rod ON-bipolar cell antibodies. Global cone abnormalities in the mfERG also have been reported in association with antienolase antibodies (Weleber et al., AJO 2005; 139:780-794). We will obtain blood samples to test for retinal antibodies and to try to identify the specific antigens affected. We recommend that patients with severely depressed mfERGs have Ganzfeld ERGs recorded to identify this condition. Other etiologies of vision loss in patients taking Plaquenil should be considered in cases where the mfERG is very reduced.
Keywords: autoimmune disease • electroretinography: clinical • retina