Effects of hydroxychloroquine on retinal structure and function: A comparative study in a Sri Lankan setting

Objective: To evaluate the impact of long-term Hydroxychloroquine (HCQ) therapy on visual performance and retinal structure in patients with Rheumatoid Arthritis (RA) in a Sri Lankan cohort.Methodology: This prospective cross-sectional study included 300 participants (150 RA patients on HCQ therapy for over six months and 150 control participants). Visual function assessments included visual acuity (VA), color vision, contrast sensitivity, and foveal sensitivity, along with Optical Coherence Tomography (OCT) measurements to evaluate macular and retinal nerve fiber layer (RNFL) thickness. Group comparisons were conducted using independent samples t-tests, with statistical significance set at p<0.05.Results: RA patients on HCQ therapy demonstrated significantly reduced VA, color discrimination, contrast sensitivity, and foveal sensitivity compared to controls (p < 0.05). OCT measurements revealed thinning of central foveal and parafoveal regions, correlating positively with HCQ therapy duration. Specifically, central foveal thickness was lower in HCQ patients by an average of 11.1μm compared to controls (p=0.03). Ganglion cell layer (GCL) and RNFL thickness remained largely unaffected by HCQ duration.Conclusion: Long-term HCQ therapy is associated with noticeable declines in visual function and retinal structure changes in RA patients. Regular ophthalmic screening is recommended for early detection and prevention of HCQ-induced retinal toxicity.