Quantitative Changes in Perimacular Retinal Thickness by Optical Coherence Tomography in Patients on Long-Term Hydroxychloroquine Therapy

Spectral domain-optical coherence tomography (SD-OCT) can show qualitative changes prior to visual field loss in patients on long-term hydroxychloroquine (HCQ) therapy. Loss of the inner-/outer-segment line, thinning of the outer nuclear layer and downward displacement of inner retinal layers involving the perifoveal retina are signs of toxicity, but may be difficult to identify conclusively. A simpler quantitative marker of incipient HCQ retinopathy would be of value in assessment of patients on HCQ as a disease modifying agent in rheumatological disease.