Purpose: To evaluate macular function using multifocal electroretinography (mfERG) in a cohort of asymptomatic patients taking hydroxychloroquine and a patient with maculopathy secondary to hydroxychloroquine treatment.
Methods: mfERG recordings were obtained for both eyes of 11 patients taking hydroxychloroquine without clinical signs of toxicity and 1 patient with toxic maculopathy. Initially, the classic m-sequence paradigm for the first-order kernel (103 hexagons; 2.7 candela x seconds/m2 peak luminance) was recorded. After that, another special stimulation mode was applied, which emphasized second-order adaptational effects (modulated multifocal flashes with interleaved global flashes, MF0F0 paradigm).
Results: The patient with toxic maculopathy and one patient without toxicity had multiple areas of decreased retinal responses bilaterally (classic m-sequence). The patient with toxicity and another three patients without toxicity presented with multiple areas of decreased retinal function in both eyes with the second-order component of the MF0F0 paradigm. Repeated recordings of 1 patient 8 months after the initial recording demonstrated evidence for reproducibility of the second-order adaptive effects.
Conclusion: Clinically asymptomatic patients receiving hydroxychloroquine treatment can have substantial local decreases in their retinal function, as reflected by the changes in mfERG recordings, possibly indicating a preclinical stage of drug-related toxicity.