The Diagnostic Utility of Multifocal Electroretinography in Detecting Chloroquine and Hydroxychloroquine Retinal Toxicity.

•Multifocal electroretinography (mfERG) is highly sensitive for detecting hydroxychloroquine retinal toxicity.•Ring 2 P1 amplitude is the most sensitive mfERG parameter to detect hydroxychloroquine retinal toxicity.•Ring 2 P1 amplitude is inversely related to cumulative and daily doses of hydroxychloroquine.•Parafoveal mfERG depression is more sensitive than the recommended screening tests.