Microperimetry in hydroxychloroquine macular toxicity

Objective: The aim was to evaluate the value of microperimetry (MP) in the early detection of toxic maculopathy caused by HCQ treatment in patients with normal fundoscopy, as well as normal structural optical coherence tomography (OCT). Materials and methods: Microperimetry was performed in 13 patients under hydroxychloroquine treatment, who did not present fundoscopic or structural OCT alterations compatible with maculopathy. We used Nidek MP3s equipment (Nidek, Gamagori, Japan) with a 13-point pattern centered in fovea, in mesopic mode and in scotopic mode. Results: The mean retinal sensitivity (MRS) in the study group was 27.25 +/ - 2.80 dB (95% CI 26.09 to 28.41 dB) while in the group of healthy volunteers 29.34 +/ - 2.18 dB (95% CI 28.67 to 30.1 dB). In scotopic mode, the mean sensitivity was 13.38 +/ - 1.43 dB (95% CI 12.79 to 13.97 dB) for HCQ users and 14.40 +/ - 2.1 dB (95% CI 13.76 to 15.04 dB) in the non-user group. Central retinal sensitivity (CRS) was also lower in patients using HCQ 26.52 +/ -4.0 dB (95% CI 24.8 to 28.15 dB) vs. 29.06 +/ - 2.5 dB (95% CI 28.33 to 29.87 dB) in the control group in mesopic mode. The trend was repeated in scotopic CRS (10.85 +/ -1.84 dB vs. 12.16 +/ - 2.61 dB respectively). Discussion: Our results showed that MP, especially in its mesopic mode, is a useful method to detect retinal toxicity caused by HCQ consumption in patients without funduscopic alteration and with normal macular OCT. Conclusions: In mesopic mode, MRS was significantly lower in patients with long-term hydroxychloroquine treatment compared to those who did not use it, even in cases in which no fundoscopic or structural OCT alteration was detected. Abbreviations: HCQ = hydroxychloroquine, MP = microperimetry, OCT = optical coherence tomography, BCVA = best corrected visual acuity, CRS = central retinal sensitivity, RS = retinal sensitivity, GEE = generalized estimating equations, MRS = mean retinal sensitivity, MfERG = multifocal electroretinogram, AMD = age-related macular degeneration