Short answer: Two eye issues are on record. US labels warn that diabetic retinopathy can get worse, mainly in people who already have it: in a 2-year Ozempic trial, complications occurred in 3.0% versus 1.8% on placebo. Separately, Europe's regulator concluded in 2025 that NAION, a sudden loss of vision from reduced blood flow to the optic nerve, is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people. The US labels read for this page do not list NAION.
Diabetic retinopathy is damage to the blood vessels at the back of the eye caused by diabetes. All four US labels carry a warning about it, and all four leaflets say to tell your healthcare provider if you have changes in vision during treatment.
The numbers come from a 2-year trial of Ozempic 0.5 mg and 1 mg in people with type 2 diabetes and high heart risk. Diabetic retinopathy complications occurred in 3.0% on Ozempic and 1.8% on placebo. The gap was larger in people who already had retinopathy (8.2% versus 5.2%) than in those without a known history (0.7% versus 0.4%).
In the Wegovy trial of adults with type 2 diabetes and overweight, diabetic retinopathy was reported in 4% on Wegovy 2.4 mg and 2.7% on placebo. The Mounjaro and Zepbound labels give no trial rate but carry the same warning.
The labels give one explanation: rapid improvement in blood sugar control has been linked to a temporary worsening of diabetic retinopathy. They say the long-term effect has not been studied and that people with a history of diabetic retinopathy should be monitored for progression. The Wegovy and Zepbound warnings apply to people with type 2 diabetes.
Non-arteritic anterior ischemic optic neuropathy (NAION) is an eye condition in which reduced blood flow damages the optic nerve, and it may cause loss of vision. In June 2025, the European Medicines Agency's safety committee (PRAC) finished a review of semaglutide medicines (Ozempic, Rybelsus and Wegovy) and concluded that NAION is a very rare side effect, meaning it may affect up to 1 in 10,000 people taking semaglutide.
PRAC said several large population studies suggest semaglutide is linked to about a two-fold higher risk of NAION in adults with type 2 diabetes compared with people not taking it, which works out to about one extra case per 10,000 person-years of treatment (one person-year is one person taking it for a year). Clinical trial data also pointed to a slightly higher risk than placebo.
EMA recommended adding NAION to the European product information. Its advice: people who have a sudden loss of vision or rapidly worsening eyesight during treatment should contact their doctor without delay, and if NAION is confirmed, semaglutide should be stopped.
The US labels for Ozempic, Wegovy, Mounjaro and Zepbound read for this page (versions dated June to August 2026) do not mention NAION or optic neuropathy. The EMA review covered semaglutide only; it did not reach a conclusion about tirzepatide (Mounjaro, Zepbound).
Whatever the label says, sudden vision loss is not something to wait on. The general leaflet advice applies to all four: tell your provider about any change in vision during treatment.
If you have diabetes, the date of your last eye exam and any retinopathy finding are worth having on record when starting one of these medicines, since the labels single out people with a history of it. For any vision change, note which eye, whether it came on suddenly or gradually, and the date relative to your doses. Dose Track keeps side-effect notes and lab results next to your doses.
Read more on Dose Track: Ozempic side effects · Wegovy side effects · Rybelsus side effects · Mounjaro side effects · HbA1c (glossary)