Hundreds of consumers are suing the makers of popular GLP-1 weight-loss and diabetes drugs, alleging the medications caused a rare form of sudden vision loss known as nonarteritic anterior ischemic optic neuropathy, or NAION. The lawsuits target Novo Nordisk, which makes Ozempic and Wegovy, and Eli Lilly, which makes Mounjaro and Zepbound, according to a report in The Wall Street Journal.
NAION occurs when blood flow to the optic nerve is suddenly reduced, leading to abrupt and often permanent vision loss. The American Academy of Ophthalmology and the National Eye Institute describe it as an «eye stroke» and note it is the most common cause of acute optic nerve injury in adults over 50. Symptoms typically appear upon waking and may include blurred or dim vision, loss of peripheral vision, or decreased color vision in one eye.
«The problem with NAION is there's no treatment,» Dr. Douglas Lazzaro, an ophthalmologist at NYU Langone Health, told Fox News Digital. «So it can cause some very profound vision loss.»
Both companies have disputed the allegations. Novo Nordisk called the lawsuits meritless and pointed to company-funded research that found no increased risk of NAION with its drugs. Eli Lilly said it continues to monitor safety data and maintained that current studies do not prove GLP-1 medications cause the condition.
Most published research has focused on semaglutide, the active ingredient in Ozempic and Wegovy, rather than tirzepatide, used in Mounjaro and Zepbound. A 2025 analysis of 37 million adults published in JAMA Ophthalmology found that people using semaglutide had a modest increase in NAION risk compared with those taking SGLT2 inhibitors, another class of diabetes medication. A 2024 Harvard Medical School study in the same journal found that patients with type 2 diabetes prescribed semaglutide had roughly a fourfold higher relative risk of developing NAION, though the absolute risk remained very low.
Both studies were observational and could not prove that the medication caused NAION. The authors emphasized that more evidence is needed. The FDA has said it is reviewing available evidence on a possible association between semaglutide and NAION but has not concluded that the drug causes the condition and has not issued a safety warning. The European Medicines Agency, by contrast, concluded there is sufficient evidence of a possible association to recommend adding NAION as a «very rare» adverse reaction to semaglutide product information in Europe.
Lazzaro agreed that the statistical picture is difficult to assess. «Whether or not that's statistically significant is hard to assess, because there were so many variables in this and it's hard to exactly match patients,» he said. «But when they removed all of what they felt were confounding variables… how obese were the patients, male versus female, age, hypertension, level of obesity… they did find that there was a higher risk of NAION.»
NAION is rare, with roughly two to 10 cases per 100,000 people each year, depending on the population studied. Its biggest risk factors include age, diabetes, high blood pressure, high cholesterol, obstructive sleep apnea, and smoking. Because many people taking GLP-1 drugs have diabetes or obesity, some of these underlying conditions could contribute to vision problems, making it difficult for observational studies to separate the effects of the disease from those of the medication.
Vision loss from NAION is often permanent. While some patients may regain partial vision over time, there is no proven treatment to reverse the optic nerve damage. Experts emphasize that patients should not stop taking a prescribed GLP-1 medication without first speaking with their healthcare provider. For many people with diabetes or obesity, the medications' proven benefits may outweigh any potential vision risk.
Lazzaro said one important factor is what doctors call a «disc at risk,» referring to certain characteristics of the optic disc. «If I had a patient who had what I would see on exam is a disk at risk, a very compact optic nerve where everything's crowded, I would tell that patient probably to not go on a semaglutide,» he advised. «My overall take on the matter is there's probably a slightly increased risk of NAION when using the semaglutides, but I think the health benefits outweigh the risks. And unless I have a patient with a disk at risk, I would probably tell them to go on them if they're going to be a lot healthier from an overall standpoint.»