Decreased peri-parafoveal RPE, EZ and ELM intensity: A novel predictive biomarker for hydroxychloroquine retinal toxicity

Purpose To evaluate the reflectivities of the retinal pigment epithelium (RPE), ellipsoid zone (EZ), and external limiting membrane (ELM) in the central fovea, perifoveal, and parafoveal regions with Optical Coherence Tomography (OCT) and the change in choroid vascular index (CVI) in patients using hydroxychloroquine (HCQ). Methods Sixty-one patients underwent HCQ treatment; age and sex-matched 44 control group subjects were included in the study. The RPE, EZ, and ELM reflectivities were measured with the ImageJ program at 5 points, and CVI was calculated. Results RPE, EZ, and ELM reflectivities in the central fovea were higher in the HCQ group than in the control group ( p