Ozempic and Wegovy (semaglutide) may add a very small risk of a rare eye condition called NAION, which can cause sudden vision loss in one eye. It’s rare, a link hasn’t been proven to be cause and effect, and for most people the benefits are much greater than the risk. Don’t stop your medicine because of a headline. If the vision in one eye suddenly turns blurry or dim, see an eye doctor that same day.
What NAION is
NAION (non-arteritic anterior ischemic optic neuropathy) is essentially a stroke of the optic nerve: the nerve at the back of the eye loses its blood supply. It usually affects one eye, and the vision loss is often permanent.
How rare it is
About 2 to 10 people in every 100,000 get NAION each year, whether or not they take these medicines. The European Medicines Agency reviewed the evidence in 2025 and classed NAION as a very rare side effect of semaglutide, affecting up to 1 in 10,000 people. Large studies in adults with type 2 diabetes suggest the risk roughly doubles, which works out to about one extra case for every 10,000 years of treatment. US eye specialists (the American Academy of Ophthalmology and the North American Neuro-Ophthalmology Society) describe a possible small increase in risk that hasn’t been shown to be cause and effect.
Why the headlines overstate it
NAION is more common in people with diabetes, heart disease, high blood pressure and sleep apnea, the same people often prescribed these medicines. That makes cause and effect hard to separate, a problem called confounding. The study behind the “blindness doubled” claims came from one specialty eye hospital, which can’t answer a question about the whole population. Larger studies that accounted for these health risks found no clear overall increase, while allowing that a rare risk may exist.
You may also have seen lawsuits in the news. A lawsuit is a claim, not proof.
What to do
- Don’t stop your medicine because of a news story. For someone with hard-to-control diabetes, stopping carries its own real risk. Talk it through with your doctor.
- If you have diabetes, heart disease, high blood pressure or sleep apnea, mention it. It’s part of choosing the right plan.
- Know the warning sign: sudden blurring, dimming or loss of vision in one eye means an eye doctor the same day, and calling your prescriber. The European and US guidance is to stop semaglutide if NAION is confirmed.
Sources
- European Medicines Agency, 2025: NAION is a very rare side effect of semaglutide
- American Academy of Ophthalmology and North American Neuro-Ophthalmology Society: consensus statements on semaglutide and NAION
- Wegovy prescribing information
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