You have probably heard about the nausea and stomach troubles that come with the new weight loss shots. For most people, those pass within weeks. But researchers are now paying attention to something much rarer, and far more serious.
A large US study has linked GLP-1 drugs to a small increased risk of sudden vision loss. The group includes semaglutide, sold as Ozempic and Wegovy by Novo Nordisk, and tirzepatide, sold as Mounjaro and Zepbound by Eli Lilly.
The analysis in Annals of Internal Medicine, led by researchers at Rutgers University, followed US adults aged 18 to 65 with type 2 diabetes. It compared people who started a GLP-1 drug with those placed on other diabetes medicines.
The condition they tracked is called ischemic optic neuropathy. It happens when blood flow to the optic nerve is suddenly cut off, and the result can be blurring, dimming or loss of part of the field of view in one eye. The vision loss is often permanent.
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How big the risk actually is
Lead researcher Chintan Dave of Rutgers put the increase at roughly three to four extra cases per 10,000 patients on a GLP-1 drug over 18 months. That is about one additional case for every 2,500 users.
For context, this type of optic nerve damage is rare in general. The American Academy of Ophthalmology puts the annual rate at roughly 2 to 10 cases per 100,000 adults over 50.
Men and adults aged 50 to 65 made up most of the cases in the Rutgers data. The authors stressed that the finding does not prove the drugs directly damage the optic nerve. Other health conditions in these patients could help explain the pattern.
What symptoms to watch for
More than four in five cases of ischemic optic neuropathy are of the non-arteritic anterior type. It usually hits one eye only, with no pain, and often shows up on waking.
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Warning signs include a sudden blur, a dimming of what you see, or a dark patch missing from your field of view in one eye. About one in three patients regain some vision, usually in the first six months. Full recovery is uncommon.
There is no reliable treatment once the damage is done. Anyone with those symptoms should see an eye doctor urgently.
What it adds to earlier findings
The Rutgers team is not the first to raise the question. In 2024, researchers at Mass Eye and Ear and Harvard Medical School published a smaller analysis in JAMA Ophthalmology.
That earlier study reviewed records from a single Boston eye hospital. It reported about a fourfold higher relative risk of this type of vision loss in semaglutide users with type 2 diabetes, and roughly sevenfold among those prescribed the drug for overweight or obesity.
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The new Rutgers work is far larger and nationwide, which puts the much smaller absolute figure on firmer ground.
The authors note the benefits of GLP-1 drugs for diabetes, obesity and heart and kidney health remain well established. Anyone on these medicines should call an eye doctor without delay if vision changes suddenly in one eye.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.