[Variability of chloroquine and hydroxychloroquine retinopathy among various ethnicities]

Current screening recommendations for chloroquine (CQ) and hydroxychloroquine (HCQ) retinopathy are based on central 10°C static perimetry and a high-resolution SD-OCT with a special attention to the inferior part of the macula where the toxicity usually starts by ellipsoid zone disruption. However, Melles and Marmor, have recently shown a great variability in the topography of the initial toxicity observed among various ethnicities, which is important to keep in mind so as not to miss early toxicity in certain subgroups of patients.

Review of the literature.

Ethnic differences have been shown regarding the topography of the initial retinal toxicity of CQ and HCQ, particularly between Caucasian and Asian subjects. In Caucasians, the first signs of toxicity are more often localized in the inferior para-foveal area associated with a decrease in retinal sensitivity in the upper 10°C visual field. However, in Asian subjects, the first signs of toxicity appear more pericentral (still inferior) with an extramacular pattern that could be missed by the usual 10°C visual field screening.

The pathophysiology of these ethnic differences is unknown and may be due to distinct genetic predisposition to CQ and HCQ toxicity. Screening strategies should be adjusted to the ethnicity and performed in Asian subjects with larger visual fields (30°C), along with SD-OCT, looking for ellipsoid disruption≥8°C from the fovea. The recognition of this pericentral topography and an adjusted screening protocol should avoid late diagnosis in Asians treated with CQ and HCQ.