Hundreds of consumers have taken legal action against the manufacturers of GLP-1 receptor agonists, claiming that the medications may increase the risk of a rare form of vision loss known as NAION (nonarteritic anterior ischemic optic neuropathy). This condition occurs when blood flow to the optic nerve decreases suddenly, resulting in sudden vision loss. According to the American Academy of Ophthalmology and the National Eye Institute, NAION is the most common cause of acute optic nerve injury in adults over 50 and is often described as an ‘eye stroke.’
Dr. Douglas Lazzaro, an ophthalmologist at NYU Langone Health, mentioned to Fox News Digital that NAION can cause significant vision loss, stating, ‘The problem with NAION is there’s no treatment.’ He emphasized the severity of the condition, noting its potential for profound impacts on vision.
The companies involved in these lawsuits, Novo Nordisk (producers of Ozempic and Wegovy) and Eli Lilly (producers of Mounjaro and Zepbound), have denied the allegations. Novo Nordisk labeled the lawsuits as without merit, referencing research funded by the company that showed no increased risk of NAION with its drugs. Eli Lilly stated that they continue to monitor safety data and current research does not confirm a causal relationship between GLP-1 medications and the development of NAION.
Research Insights
Current research has primarily focused on semaglutide rather than tirzepatide. A 2025 data analysis by JAMA Ophthalmology involving 37 million adults revealed a modest increase in NAION risk among people using semaglutide compared to those taking SGLT2 inhibitors, another diabetes medication class. Meanwhile, a 2024 study from Harvard Medical School noted that individuals with type 2 diabetes prescribed semaglutide had about a fourfold increase in relative risk for developing NAION, though the absolute risk remained low.
The authors of these studies stressed that the research was observational and could not definitively connect the medication to NAION. More evidence is needed to establish a causal link.
The FDA is reviewing evidence regarding potential associations between semaglutide and NAION but has not determined that semaglutide causes the condition or issued safety warnings. However, the European Medicines Agency recommended listing NAION as a ‘very rare’ adverse reaction to semaglutide on product information in Europe due to evidence of a possible link.
Understanding NAION
NAION typically results in sudden, painless vision loss in one eye. Other possible symptoms, according to the American Academy of Ophthalmology, include blurred vision, dim vision, loss of peripheral vision, or decreased color vision. Symptoms often develop in the morning after waking up.
Risk factors for NAION include age, diabetes, high blood pressure, high cholesterol, obstructive sleep apnea, and smoking. For patients taking GLP-1 medications, their diabetes or obesity may contribute to vision issues. Observational studies have noted that diabetes itself is a recognized risk factor for NAION, making it a challenge to distinguish the impacts of the disease from those of the medication.
The condition of NAION is rare with two to ten cases per 100,000 individuals annually, depending on the population studied. Vision loss from NAION is often permanent, and while some may regain partial vision over time, there is no proven treatment that can reverse the optic nerve damage. Despite this, experts agree that patients should consult their healthcare provider before discontinuing any GLP-1 medication. For many dealing with diabetes or obesity, the evident benefits of these medications can outweigh potential vision risks.
Dr. Lazzaro advised caution with prescribing semaglutide to patients who have a ‘disk at risk.’ He has stated, ‘If I had a patient with what I would see on exam is a disk at risk… I would tell that patient probably to not go on a semaglutide.’
He further expressed his view that there may be a slight increased risk of NAION from using semaglutides but overall believes that the health benefits of these medications may surpass associated risks. He would likely recommend them unless a patient has a high-risk optic nerve condition.
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