US regulators require GLP-1 makers to warn of rare optic nerve condition

The US Food and Drug Administration has ordered makers of popular GLP-1 medicines to add warnings about NAION, a rare eye condition that can cause sudden, potentially permanent vision loss. The decision follows a review that found an increased risk of rare cases among people taking the drugs, though it has not established that the medicines cause the condition.

NAION occurs when blood flow to the optic nerve is blocked, and there is no known treatment to reverse resulting vision loss. The European Medicines Agency has estimated that up to 1 in 10,000 people taking semaglutide may be affected; one study of 17,000 patients found a fourfold higher diagnosis rate among users, but its authors called the findings tentative. Eye specialists say the added risk appears small and advise patients not to stop treatment without consulting a doctor, while seeking prompt care for sudden, painless vision loss in one eye.