Purpose
The early detection of drug induced HCQ toxicity is paramount in preventing permanent blindness. The recent AAO guidelines describe several tests, including multifocal electroretinogram (mfERG), central automated perimetry (eg Humphrey 10-2 fields (HVF), or macular optical coherence tomography (OCT) as screening tools for HCQ induced toxicity. The purpose of this study was to determine the extent to which the different tests agree in their identification of those patients with toxicity due to HCQ.
Methods
Retrospective review of records and diagnostic studies of HCQ patients undergoing surveillance for drug-related retinal toxicity. Exclusion criteria included patients with glaucoma, retinal dystrophy, or diabetic retinopathy.
Results
Sixty-nine patients with prior or current use of HCQ use were evaluated. Of the 19 patients who had at least mfERG and HVF studies, 9 cases (all with < 6 years (yrs) of exposure) did not show abnormalities on HVF and mfERG testing. Four patients had abnormal HVF and mfERG studies after > 10 years of exposure with presumed toxicity. Six individuals demonstrated disparities between their mfERG and HVF test results. (see table below)
Conclusions
These cases with disparate findings between mfERG and HVF testing for HCQ-related toxicity raise the possibility that a single testing modality may not be sufficient for screening of drug-related retinal toxicity. These unique cases also suggest that HCQ-toxicity may involve a more complex mechanism of action, not simply affecting the RPE, but might include retinal and optic nerve dysfunction.
Keywords: 503 drug toxicity/drug effects •
758 visual fields •
509 electroretinography: clinical