You may have seen news about a rare eye condition, non-arteritic anterior ischaemic optic neuropathy (NAION), linked to GLP-1 medicines such as Wegovy, Ozempic and Mounjaro. The US warning doesn’t change our advice in the UK. Here’s what the risk really means, what to do if you take these medicines, and which eye symptoms need help the same day.
The US Food and Drug Administration (FDA) now requires GLP-1 medicines sold in the United States to carry a warning about a rare eye condition called NAION. This is aimed at patients and prescribers in the US, and it does not change the College of Optometrists’ advice for people in the UK.
In the UK, the medicines regulator (the MHRA) updated its safety information for semaglutide in 2025, the FDA’s analysis suggests a slightly higher incidence of NAION than the EMA review found. Even so, this remains a rare condition, and the absolute risk to any individual is very low.
Daniel Hardiman-McCartney MBE FCOptom, Lead Clinical Adviser at the College of Optometrists says “NAION is a rare but serious condition, and it is right that patients and prescribers are told about it. The FDA’s analysis points to a slightly higher incidence than the earlier European review, but the absolute risk remains very low. Our advice to people taking these medicines in the UK has not changed: don’t stop your medication because of a headline, tell your optometrist what you are taking, and if you notice sudden loss of vision in one eye, get it checked the same day.”
What the condition is: non-arteritic anterior ischaemic optic neuropathy (NAION), often called an “eye stroke”. It happens when the blood supply to the optic nerve suddenly drops. It is painless, usually affects one eye, and people often notice it on waking.
Very rare. The European Medicines Agency estimates it affects up to around 1 in 10,000 people taking semaglutide (Wegovy, Ozempic, Rybelsus). Some studies suggest the relative risk may be higher, but the absolute risk remains very low.
A study presented at the American Academy of Ophthalmology annual meeting in October 2026 found that, among people who developed NAION in both eyes, the second eye tended to be affected sooner in GLP-1 users. The researchers stress this shows an association, not proof of cause, and that the GLP-1 users in the study had higher blood sugar levels, which is itself a risk factor.
Sudden loss of vision in one eye, a patch missing from your vision, colours suddenly looking washed out, or sudden blur you can’t explain. Go to eye casualty or A&E the same day, and let your prescribing clinician know.
