Features and risk factors for new (secondary) permanent visual involvement in giant cell arteritis.

New permanent visual loss (PVL) in treated patients with giant cell arteritis (GCA) is a rare but worrisome occurrence. In this study, we aimed to describe the frequency and main features of new PVL occurring after the beginning of glucocorticoid therapy in patients with newly diagnosed GCA. We included in an inception cohort all consecutive patients newly diagnosed with GCA in the internal medicine department of a tertiary-care hospital between 1976 and May 2020. The study population comprised all the patients without bilateral PVL before treatment who were followed for at least one year. Only well-documented visual events that set after the initiation of glucocorticoid treatment were regarded as new PVL. Eleven out of 502 patients (2.2%) experienced a new PVL including 6 occurrences during the initial therapeutic phase and 5 during the tapering phase. Patients with new PVL during treatment had higher mean age, more often displayed temporal artery abnormalities on physical examination, and had higher mean platelet counts at GCA onset. There was a strong excess risk of contralateral recurrence during treatment in patients with unilateral loss at GCA onset compared with patients with uncomplicated GCA (10.5% vs 1.1%, OR=10.26, p<0.001). New PVL in treated GCA is a rare, but significant occurrence. Older patients and patients who already had unilateral PVL at diagnosis have higher risk of new ischaemic visual loss during treatment compared to the other patients. Close clinical, laboratory, and eye monitoring of these high-risk patients is of paramount importance.