The aim of this study is to measure retinal vessel density and thickness of the macula by optical coherence tomography angiography in patients with rheumatoid arthritis taking hydroxychloroquine.
The study included 40 patients with rheumatoid arthritis taking hydroxychloroquine and 20 age-, gender-, and axial length-matched control subjects. Patients were divided into two groups according to the duration of hydroxychloroquine use. Twenty four of the patients were taking hydroxychloroquine for more than 5 years (Group 1), and the rest of 16 were taking hydroxychloroquine for less than 5 years (Group 2). A total of 20 age- and gender-matched volunteers with similar axial length were selected as Group 3. All of the patients underwent optical coherence tomography angiography, and 3 mm × 3 mm scanning mode was chosen for analyzing vascular density and morphological characteristics on the choriocapillaris layer. In addition, Humphrey visual field 10-2 was evaluated in each subject.
The temporal deep vascular density was measured as 48.13% ± 8.5% in Group 1, 54.42% ± 10.3% in Group 2, and 60.35% ± 13.1% in Group 3. Deep temporal and deep hemi-inferior vascular density was significantly lower in Group 1 in comparison with Group 3 (p = 0.041 and p = 0.046, respectively). Visual field testing was normal in all patients.
The optical coherence tomography angiography findings showed that the parafoveal deep temporal and deep hemi-inferior vascular plexus density was reduced in patients taking hydroxychloroquine for more than 5 years despite having normal perimetry. This observation, which can be obtained only through optical coherence tomography angiography, may be relevant to the early findings of hydroxychloroquine toxicity.