The incidence, monitoring coverage and clinical characteristics of hydroxychloroquine retinopathy in the United Kingdom

Background: Retinal monitoring is recommended for hydroxychloroquine users to detect pre-symptomatic retinopathy and preserve visual function. However, the incidence of hydroxychloroquine retinopathy and monitoring coverage in the U.K. are incompletely characterised. Moreover, the visual benefits of monitoring for retinopathy – recommended for over 70,000 long-term hydroxychloroquine users in the U.K. - remain unproven. Methods: A national, prospective observational study was undertaken with the British Ophthalmological Surveillance Unit (BOSU). Newly diagnosed cases of hydroxychloroquine retinopathy in the U.K. were reported and data captured using a standardised questionnaire over 3.5 years (July 2018–Dec 2021). The frequency of retinopathy and coverage of monitoring amongst long-term users was estimated. Visual function was compared between asymptomatic individuals detected on monitoring and those presenting with visual symptoms. The clinical characteristics, dosing and management of reported cases were captured. Results: The annualised number of incident cases of hydroxychloroquine retinopathy was 29–57, with an annualised frequency of 0.04–0.08% amongst long-term users (~1 in 1247–2625). The coverage of monitoring was approximately 2.6–5.5%. Visual acuity (0.1 vs. 0.22 logMAR; p = 0.007) and visual field mean deviation (−3.73 dB vs. −8.69 dB; p = 0.017) were better preserved in asymptomatic individuals compared to those presenting with visual symptoms. Conclusion: These data support the efficacy of monitoring in the preservation of visual function in patients with hydroxychloroquine retinopathy at diagnosis. The overall population coverage of monitoring was low, consistent with the high proportion of symptomatic patients at diagnosis. This study presents a method for evaluating the yield of monitoring for hydroxychloroquine retinopathy in the U.K.