Correlations Between Visual Acuity (VA), Humphrey Visual Fields (HVF), And Multifocal Electroretinogram (mfERG) In Patients With Retinal Toxicity Secondary To Hydroxychloroquine (Plaquenil) Therapy (PT)

Abstract

Purpose: : To study correlations between visual functions and retinal electrophysiologicalresponses in patients with retinal toxicity secondary to PT and evaluate the reversibility of the retinal function loss after discontinuation of plaquenil.

Methods: : Study included retrospective analysis of test results of 50 patients diagnosedwith plaquenil-induced retinal toxicity. Visual acuity varied from 20/20 to20/2000. Duration of the PT varied from 6 weeks to 32 years. Time after thediscontinuation of PT varied from 1 to 30 months. VA losses, mfERG amplitude depression, and HVF defects (10-2 threshold test) were analyzed quantitatively and analysis of correlations between these parameters was performed.

Results: : MfERG amplitude loss was observed in 100% of patients. There was no statistically significant difference between central and paracentral losses of retinal activity: 35% of patients showed classical pattern of annular perifovealmfERG amplitude depression, 25% had central mfERG amplitude depression, 20% had central depression combined with sectoral depression, and 20% had general mfERG depression. Moderate correlation was found between VA loss and mfERG amplitude depression (r=0.46). With VA 20/20, perifoveal depression of the mfERG amplitudes ranged from 5 to 35%. Defects of HVF were present in 50% of the examined eyes. Moderate correlation was found between HVF loss and mfERG loss (r=0.56 for the foveal responses, and r=0.40 for the parafoveal responses). After discontinuation of plaquenil, VA improved to 20/20 in 25% of patients (whose HVF were not or mildly affected), although their mfERG amplitudes remained depressed by 25-30%. In 10% of patients, retinal functions continued to decrease. Irreversible losses of VA and mfERG were observed in patients whose mfERG amplitudes were depressed by ≥50%. All observations were not dose-dependent, nor did they correlate with the duration of the PT.

Conclusions: : Our findings suggest that the mfERG is the most sensitive tool for early diagnostic and especially prognostic evaluation of patients with retinal toxicity secondary to PT. Annual mfERG is recommended to prevent irreversible vision loss.

Keywords: retina • drug toxicity/drug effects • electrophysiology: clinical