Rapid onset hydroxychloroquine toxicity

Hydroxychloroquine (HCQ) can cause irreversible damage to the retina, especially when taken over longer periods. The American Academy of Ophthalmology recommends a regimen for dosing, screening and monitoring of patients treated with HCQ. We present an unusual case of a rapid development of severe HCQ-associated-retinopathy already after 2 years after commencing HCQ treatment.Observational case report. Clinical examination, optical coherence tomography (OCT), fundus autofluorescence imaging (FAF), perimetry, full-field & multifocal electroretinography (ERG) were performed. Ancillary tests included neoplastic and paraneoplastic work-up, vitamin levels and whole exome sequencing, in order to rule out other potential causes of a panretinal degeneration.We report on a 58-year-old woman with rheumatoid arthritis, treated initially with 200mg HCQ daily for 1 year (daily dose 3.6mg/kg), then 400mg daily for 1 year (daily dose 7.2mg/kg), and a cumulative dose of 216 g. Her medical history was otherwise unremarkable. No family history for inherited retinal conditions. She was referred due to a rapid and sudden progressive and severe concentric visual field constriction, two years after commencing HCQ treatment.This case of a rapid-onset, severe panretinal degeneration shortly after start of HCQ treatment suggests underlying mechanisms and risk factors for HCQ toxicity in addition to those previously reported, and a potential need for supplementary screening tests to prevent HCQ toxicity. AAO dosing guidelines of 5 MG/KG should be strictly adhered to in patients receiving HCQ therapy.