Frosted Branch Angiitis in the Setting of Active COVID-19 Infection and Underlying Mixed Connective Tissue Disease.

Frosted branch angiitis (FBA) is an uncommon form of retinal vasculitis and is typically associated with vision loss. We report a unique case of FBA that manifested in the setting of an active COVID-19 infection in a patient with Mixed Connective Tissue Disease (MCTD). A 34-year-old female with a history of MCTD, including overlapping findings of dermatomyositis, systemic lupus erythematosus, and rheumatoid arthritis, on immunosuppressive medications, presented for left-sided vision loss. She was also found to have an active COVID-19 infection with symptoms including sore throat and dry cough. The patient's visual acuity was counting fingers in her affected eye with a fundus exam revealing diffuse retinal hemorrhages, retinal whitening, cystoid macular edema, and perivascular sheathing of tertiary arterioles and venules, characteristic of FBA. Labs showed mildly elevated inflammatory markers. She exhibited no other signs or symptoms concerning systemic rheumatologic flare. There was no evidence of COVID-19 on viral PCR testing of intraocular fluid but given her positive nasopharyngeal PCR, COVID-induced retinal vasculitis with FBA remained high on the differential. The patient's retinal vasculitis later improved with heightened immunosuppressive therapy including high-dose intravenous corticosteroids. Clinicians should be aware of the possibility of COVID-related FBA, particularly in patients with an underlying predisposition to autoimmune inflammation. Our experience with this patient highlights the utility of high-dose systemic immunosuppressive therapy in treating such inflammatory occlusive retinal vasculitis. Further studies are needed to characterize retinal manifestations of COVID-19 in the setting of autoimmune disease.