A comparison of structural and functional changes in patients screened for hydroxychloroquine retinopathy

The aims of this retrospective study were to compare the results of recommended screening tests for hydroxychloroquine-related retinal toxicity and analyze disparities between the structural and functional findings. Thirty-four patients (31 women and 3 men) were included in the study. All were evaluated with standard automated perimetry using the 10-2 and/or 24-2 visual field program (Zeiss, Meditec), multifocal electroretinography (mfERG), spectral-domain optical coherence tomography (SD-OCT), and short-wavelength fundus autofluorescent imaging (SW-FAF). The results for the right eye from each patient were analyzed. Visual fields were classified as normal or abnormal based on pattern deviation plots, and mfERGs based on a comparison of R-5 ring ratios to values from 20 controls. The SW-FAF images were examined for areas/rings of abnormal hypo- and/or hyperautofluorescence, and the SD-OCT line scans were classified as abnormal based on visual inspection and thickness measurements of the outer segment plus retinal pigment epithelial layer and total receptor layers compared to mean thicknesses from 35 controls. Fifteen patients had abnormal results on at least one test; however, only two patients had abnormal results on all four tests. Excluding SW-FAF, seven of the 15 had abnormal visual fields, mfERG ring ratios, and SD-OCTs. The remaining eight had either abnormal mfERGs and/or visual fields and normal SD-OCTs. We found no evidence of abnormal SD-OCTs in the presence of normal mfERG and visual field results. The findings suggest that functional deficits precede structural changes seen on SD-OCT in these patients.