Early morpho-functional changes in patients treated with hydroxychloroquine: a prospective cohort study

Purpose We aimed to find earlier morphological and functional alterations in the retinas of patients treated with hydroxychloroquine (HCQ). This was a prospective cohort study. Methods We examined 33 patients (mean age, 57.14 [SD, 11.02] years) who were affected by various types of rheumatic diseases. The mean treatment period was 124.7 [SD, 99.4] months, and the mean total drug intake was 5.41 [SD, 3.34] g daily at baseline. The control group consisted of 28 subjects with a mean age of 61.25 [SD, 2.16 years]. The set of tests encompassed best-corrected visual acuity (BCVA), a multifocal electroretinogram (mfERG), spectral-domain optical coherence tomography (SD-OCT), fundus auto fluorescence (FAF), the 10-2 automated visual field (VF) test (10-2 VF), and frequency-doubling technology (FDT). Results The mfERG P1 wave density amplitudes decreased in all the rings, from 31.10 to 28.02 (p = 0.008) in the first ring, and from 18.29 to 16.55 [p < 0.001], from 12.050 to 10.91 [p = 0.002], from 9.53 to 8.69 [p = 0.003], and from 8.25 to 7.48 [p = 0.001] nanovolts/degree2 in rings 2, 3, 4, and 5, respectively. A significant reduction was found also in the N1 wave in the second ring. The SD-OCT retinal thickness measurement revealed significant thinning in five sectors, including the outer and inner nasal sectors, the outer and inner temporal sectors, and the inner superior sector. The 10-2 VF mean deviation paradoxically improved, while minimal FAF alterations in the retinal pigment epithelium were found in eight eyes. Conclusions mfERGs and SD-OCT were altered in our patients before significant retinal changes occurred.