Researchers believe the first step toward formulating a reliable and reproducible screening protocol for hydroxychloroquine retinopathy is to evaluate the sensitivity and specificity of each screening test. Recognizing the condition at an early stage is important because it can progress even after the drug is stopped, and the risk of visual loss is directly related to the severity of retinopathy at the time of detection.

A recent study reviewed microperimetry efficacy on 197 patients with history of hydroxychloroquine use for more than five years. The retrospective review found that 22 patients had hydroxychloroquine retinopathy. In this cohort, the average age was 54 and 96% were women. Regarding hydroxychloroquine use, the average daily dose was 5.7mg/kg with a cumulative dose of 2,041g and duration of 15 years.

Researchers found that microperimetry has a sensitivity of 73%, a lower value than other tests, but a specificity of 93%, which is on par with them. The team believes that the primary utility of the visual test seems to be in its negative predictive value (96%), which can permit confident exclusion of the condition when the test is normal, in corroboration with other clinical characteristics and testing.

The study concludes that microperimetry may be a useful ancillary test to exclude retinopathy, especially in high-risk patients or those with conflicting results on different modalities.

Iftikhar M, Kaur R, Nefalar A, et al. Microperimetry as a screening test for hydroxychloroquine retinopathy. Retina. September 17, 2018. [Epub ahead of print].