Vision and NAION

What NAION is

Non-arteritic anterior ischemic optic neuropathy (NAION) happens when blood flow to the front of the optic nerve drops, usually causing sudden, painless vision loss in one eye, which may be permanent. It is rare.^[1]

What the studies found

The first study, from one eye centre in Boston, found NAION more often in people prescribed semaglutide: hazard ratios of 4.28 in people with diabetes and 7.64 in people with overweight or obesity. The numbers of cases were small (17 and 20), so those figures are imprecise.^[2] A larger nationwide study from Denmark and Norway found a pooled hazard ratio of 2.81, which worked out to about 1.4 extra cases per 10,000 person-years.^[3]

What regulators say

In June 2025, the European Medicines Agency's safety committee concluded NAION is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people, with roughly a doubled risk in people with type 2 diabetes. It was added to the EU product information, with advice to contact a doctor about sudden vision loss and to stop semaglutide if NAION is confirmed.^[1] As of the mid-2026 US labels we read, NAION is not listed in the Wegovy or Ozempic prescribing information.^[4][5]

A different eye issue in diabetes

Separately, the labels warn about diabetic retinopathy complications in people with type 2 diabetes. In a two-year Ozempic trial, these occurred in 3.0% versus 1.8% on placebo, and the increase was larger in people who already had retinopathy (8.2% versus 5.2%).^[5] Rapid improvement in blood sugar is known to temporarily worsen retinopathy, which may explain part of this.^[5]

What to do

• Sudden loss of vision, a dark area or blurring in one eye: same-day eye or emergency care
• If you have diabetic retinopathy: the labels advise monitoring; ask about eye checks^[4][5]

The short version

Questions to bring to your prescriber

Print these or screenshot them. They are conversation starters, not a checklist of things to do.

• Do I have risk factors for NAION, and does that change anything for me?
• If I have diabetes, how often should my eyes be checked while on this medicine?
• What should I do if I notice a vision change on a weekend?

Sources

Every number on this page traces to one of these. "Primary read" means the full paper or label was read; "abstract only" means only the abstract was available; "secondary" means the figure was taken from a named review.

1. European Medicines Agency, PRAC. PRAC concludes eye condition NAION is a very rare side effect of semaglutide medicines, 6 June 2025. primary read · regulator review
2. Hathaway JT et al. Risk of nonarteritic anterior ischemic optic neuropathy in patients prescribed semaglutide. JAMA Ophthalmol 2024. abstract only · single-centre cohort
3. Danish and Norwegian nationwide cohort study of semaglutide and NAION, 2025. abstract only · cohort
4. Novo Nordisk / FDA. Wegovy (semaglutide) injection and tablets, prescribing information, revised 06/2026. label
5. Novo Nordisk / FDA. Ozempic (semaglutide) prescribing information, revised 05/2026. label

Related explainers

All 35 questions