Microperimetric sensitivity in patients on hydroxychloroquine (Plaquenil) therapy

The purpose of this study was to measure macular sensitivity using microperimetry in patients on Plaquenil therapy without evidence of retinopathy as assessed by recommended screening standards.

Sixteen patients from a clinical practice treated with 200 or 400 mg/day of Plaquenil for more than 5 years, without visual complaints (visual acuity 20/25 or better), and without a history of diabetes or macular disease were included. Participants underwent a complete ophthalmic examination with spectral-domain optical coherence tomography (SD-OCT), 10-2 Humphrey visual field (HVF), fundus autofluoresecene (FAF), multifocal electroretinography (mfERG), and microperimetry that covered the central 12° of the visual field. Ten age-similar, visually normal subjects served as controls.

The average age of the study cohort was of 54.5 years, with an average daily Plaquenil dose of 4.00 mg/kg/day (range, 1.77-6.67 mg/kg/day) and an average cumulative dose of 1485 g (range, 256-3650 g). All patients had normal ocular exams, and no evidence of retinopathy based on 10-2 HVF, FAF, mfERG, and SD-OCT. The mean retinal sensitivity by microperimetry was 15.0 dB (OD) and 14.6 dB (OS). The overall mean microperimetry sensitivity of the patients (14.7±1.9 dB) was significantly lower (P<0.001) than that of the controls (16.5±2.1 dB).

Patients on Plaquenil without clinical evidence of retinal toxicity can have reduced retinal sensitivity, as assessed by microperimetry. The mean sensitivity difference between the patients and controls suggests that microperimetry can provide important information regarding visual function in patients on Plaquenil therapy.