New insights in pathogenic mechanism of hydroxychloroquine retinal toxicity through optical coherence tomography angiography analysis

Introduction There is only a unique report with a small sample size studying hydroxychloroquine (HCQ) retinal toxicity with swept-source (SS) optical coherence tomography angiography (OCTA). The aim of this study was to quantify OCTA quantitative parameters in patients who underwent HCQ therapy. Methods We conducted a retrospective study. The study included 43 eyes of 22 patients taking HCQ for more than 5 years (high-risk group), 57 eyes of 29 patients taking HCQ for 5 years or less (low-risk group) and 25 eyes of 50 age-matched healthy controls. OCTA quantitative parameters (vessel density (VD) and foveal avascular zone (FAZ) area in superficial capillary plexus (SCP), middle capillary plexus (MCP), deep capillary plexus (DCP), total capillary plexus (TCP), and choriocapillaris (CC)) were recorded. Results In the low-risk group, VD in the SCP and MCP was increased compared to control group ( p value <.05). In the high-risk group, VD in the SCP, MCP and TCP was increased ( p value <.05). The subgroup analysis revealed an increased VD at SCP in systemic lupus erythematosus (SLE) high-risk patients, an increased VD at TCP and CC in rheumatoid arthritis (RA) high-risk subjects, and a decreased VD at CC level in the high-risk group patients with Sjögren's syndrome (SS) and connective tissue disease (CTD) ( p value <.05). Furthermore, we demonstrated a significant enlargement of FAZ area at MCP level in the high-risk group patients with SS and CTD ( p value <.05). Conclusion We demonstrated an increase of VD in patients who underwent HCQ treatment, so we suggest that HCQ retinal toxicity is not vascular mediated.