The results of this obesity medication are literally eye-popping.
A new review of adverse effects reports to the FDA between the years 2017 and 2024 reveals that Ozempic and Wegovy have both been linked to dozens of cases of ischemic optic neuropathy (ION), or sudden vision loss caused by restricted blood flow to the optic nerve.
And one version has a significantly higher risk.
Wegovy, which was approved by the FDA in 2021, was nearly five times as likely to cause ION compared to similar drugs, including Ozempic, which was approved in 2017. It was also three times more likely to be reported by men than women.
While the FDA had technically logged more reports of ION related to Ozempic, the proportion of reports linked to Wegovy was significantly higher given that it’s been on the market for almost half as long.
Now commonly known as a GLP-1 receptor agonist, semaglutide — marketed as Wegovy, Ozempic and Rybelsus — is prescribed to treat a range of conditions including obesity and diabetes, and is increasingly used to lower the risk of cardiovascular disease.
Though prescribed for similar things, semaglutide is different from the dual GLP-1/GIP agonist tirzepatide (marketed as Mounjaro and Zepbound). These researchers found no notable connection between tirzepatide and ION.
The study’s author, University of Toronto Department of Ophthalmology’s Dr. Edward Margolin, tells The Post that patients taking GLP-1s shouldn’t necessarily expect severe complications from these drugs.
That said, he still has his concerns.
“Weight loss is a very individual thing and should be done thoughtfully under the guidance of [a] physician. Losing weight rapidly and losing a lot of weight is hard on a body,” he says.
While the exact clinical link between GLP-1s and ION is not yet clear, it’s thought that the higher doses of Wegovy and Ozempic, particularly when administered through injection, could be the culprit.
To demonstrate this, the researchers also considered Rybelsus, another form of semaglutide sold as a once-daily tablet to treat type 2 diabetes that wasn’t linked to any instances of ION. Tablets are more slowly absorbed than injectables, with fewer spikes, which might explain the difference.
Though rare in the general population, especially for those under 50, ION can have varying degrees of severity. Sometimes called an “eye stroke,” it can lead to permanent vision loss if blood flow isn’t promptly restored.
Unfortunately for patients taking GLP-1s, Margolin says there’s nothing proactive they can do to protect themselves from an ION. And the FDA data didn’t include information about co-existing conditions or disease severity, either, so there’s not currently an understanding of what might make someone more likely to experience a semaglutide-related ION beyond dosage and sex.
But that doesn’t mean an individual should avoid GLP-1s altogether if the drugs are best for their overall health, as determined with the help of their doctor.
“These medications are still super important for many patients,” Margolin assures. But “they should be thoughtful when starting them, re: dose and rapidity of weight loss.”
This isn’t the first time these drugs have been linked to eye problems, including blindness.
A study published in JAMA Ophthalmology in 2025 found that after one year, GLP-1 users were more than twice as likely to develop neovascular age-related macular degeneration than those who were not taking the drugs.
Age-related macular degeneration gradually damages the part of your eye’s retina responsible for sharp, central vision. People with the condition find it increasingly difficult to see things directly in front of them, while their peripheral vision remains largely unaffected.
But Dr. Talia Kaden, director of the Northwell Health retina fellowship, said she thinks there’s actually relatively low risk.
“That ‘two times’ number is really powerful, but when you look at the raw data, I don’t think it’s quite as strong a punch. I don’t think that number should be a reason for people not to be on these drugs. I do think, though, it is worth continuing to look into,” she told The Post.
