For millions taking GLP-1 medicines, the expected story is about shrinking waistlines, lower blood sugar and better health goals. Now, an unexpected twist has put popular drugs including Ozempic, Wegovy and Zepbound under scrutiny, with dozens of Americans suing their makers over alleged sudden vision loss.
The lawsuits centre on a rare eye condition called nonarteritic anterior ischemic optic neuropathy, or NAION, but there is an important catch. Researchers have not established that GLP-1 medicines cause the condition, and larger studies have produced mixed findings.
Lawsuits Put Vision Loss in Spotlight
Dozens of personal injury lawsuits have been filed against manufacturers including Novo Nordisk and Eli Lilly. Plaintiffs claim they were not properly warned about the potential risk of NAION and say they experienced sudden vision loss while taking GLP-1 medicines.
Novo Nordisk, which makes Ozempic and Wegovy, has rejected the claims and said it considers the lawsuits without merit. Eli Lilly, which makes Zepbound and Mounjaro, said it actively monitors safety information and continues to review data involving possible eye-related issues.
NAION Can Cause Sudden Vision Loss
NAION affects the optic nerve when its blood supply is disrupted. Ophthalmology and neurology specialist Dr John Chen told ABC News that it can cause an acute, painless loss of vision, which is usually permanent and currently has no specific treatment.
The condition is rare, however, and GLP-1 use is not the only factor being considered. Diabetes itself can increase the risk, while other factors include overnight low blood pressure and having a very small optic nerve cup.
US Has No Specific NAION Warning
Here is where the story takes its biggest turn. The US Food and Drug Administration currently does not require manufacturers to list NAION as a specific risk on these medicines, although vision problems are already included among possible side effects and the agency is reviewing the potential safety signal.
That differs from the approach taken elsewhere. The European Medicines Agency (EMA) concluded that NAION is a very rare side effect of semaglutide medicines, including Ozempic and Wegovy, and recommended updating their product information to include the condition.
The Science Still Has Important Questions
The concern first gained attention after researchers at a Boston health system published findings in 2024 suggesting a possible increased risk among people with type 2 diabetes prescribed with semaglutide. Since then, larger studies have produced mixed results, and no study has proven that GLP-1 medicines cause NAION.
The American Academy of Ophthalmology and North American Neuro-Ophthalmology Society have also said some research suggests a small possible increased risk, while other studies have found no correlation. Their joint statement said the overall magnitude of the potential risk remains low.
The Risk Remains Very Rare
The EMA estimates that NAION could affect up to one in 10,000 people taking semaglutide, based on its review of available evidence. Its assessment also found an approximately two-fold relative increase in NAION risk among adults with type 2 diabetes taking semaglutide, corresponding to about one additional case per 10,000 person-years of treatment.
That distinction matters because a possible association is not the same as proof that the medicine caused someone's condition. For now, doctors cited by ABC News say the evidence remains inconclusive, while the medicines continue to have established benefits for conditions including diabetes and severe obesity.
Doctors Urge Patients Not To Panic
Doctors advise people taking GLP-1 medicines to discuss concerns and potential side effects with their own healthcare professionals rather than stopping treatment on their own. For people taking semaglutide without symptoms, Dr Raj Maturi said patients should continue taking it as instructed while discussing questions with their primary care physician.
Sudden, painless vision loss should be treated as a medical concern and assessed promptly by an eye specialist. So while the phrase 'didn't see that coming' may have appeared as a social-media reaction to the unexpected story, the medical reality is more complicated: lawsuits are piling up, regulators are watching, and researchers are still working out exactly what, if anything, GLP-1 medicines have to do with this rare condition.
