Macular sensitivity changes for detection of chloroquine toxicity in asymptomatic patient

Purpose To describe the efficacy of microperimetry (MP-1) in detecting early retinal toxicity as a result of chronic use of chloroquine and in monitoring the changes in macular sensitivity in an asymptomatic patient with best-corrected visual acuity of 20/20 bilaterally. Methods A 60-year-old woman presented for routine ocular examination with a medical history of severe rheumatoid arthritis, for which she had been receiving 3 mg chloroquine (CQ) per kilogram for the past 17 years. The patient was asymptomatic with best-corrected visual acuity of 20/20 bilaterally. Results Microperimeter showed loss of sensitivity in the macular region with a dense scotoma within the central 12 degrees (2.80 ± 4.7 dB right eye and 2.84 ± 4.7 dB left eye). CQ treatment was discontinued and substituted by Plaquenil. Conclusions Chloroquine retinal toxicity can be recognized in a subclincal form by the presence of early changes in macular sensitivity, detected by MP-1.