Among U.S. adults with type 2 diabetes who started a GLP-1 medicine, researchers at Rutgers University estimate that 3 to 4 additional people per 10,000 treated developed a sudden, often permanent form of vision loss over 18 months. The condition is ischemic optic neuropathy, a loss of blood flow to the optic nerve. The absolute risk is small, but the drugs involved, including Ozempic and Wegovy, are among the most widely prescribed in the country.
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Chintan Dave, the Rutgers associate professor who led the work, described the increase in risk as small while saying clinicians and patients “should be aware of this potential association.” The finding is an association drawn from health records, not proof that the drugs damage the optic nerve, and the researchers say so directly.
Inside the Rutgers analysis of optic-nerve damage
Rutgers described the work in a university news release, and the paper appeared in Annals of Internal Medicine, authored by Dave, Kamika Reynolds and Kimberly O’Malley of the Rutgers Institute for Health, Health Care Policy and Aging Research, and Jason Roy of the Rutgers School of Public Health. The team drew on a large U.S. database of adults aged 18 to 65 with type 2 diabetes who had recently started diabetes medication, including GLP-1 receptor agonists. The drugs examined were semaglutide, sold as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound.
According to the summary republished by ScienceDaily, GLP-1 use was tied to “approximately three to four additional cases per 10,000 patients treated with GLP-1s over 18 months.” That is the 3 to 4 per 10,000 figure, and it is an excess over what would otherwise be expected, not the total number of cases. The summary does not name the database or describe the comparison group in detail, so the exact baseline against which the excess was measured cannot be reconstructed from the public text alone. What it does make clear is the scope: adults from 18 to 65, a diabetes population, and a follow-up of 18 months rather than a lifetime.
Non-arteritic anterior ischemic optic neuropathy
More than four in five cases of ischemic optic neuropathy are estimated to be the non-arteritic anterior form, usually shortened to NAION. It typically strikes one eye, producing blurring, dimming or a missing patch of the visual field rather than total blindness, and the loss is often sudden. About one-third of affected patients recover some vision, usually within the first six months, though some impairment generally remains.
In the Rutgers data the cases were more common in men and in the older end of the study population, mostly people aged 50 to 65. Dave said early recognition of symptoms and prompt ophthalmologic evaluation may be especially important for people at higher baseline risk, a point that matters because the damage can be hard to reverse once it sets in.
How European regulators handled the signal
The Rutgers estimate arrives after regulators had already flagged the problem for semaglutide. In June 2025 the European Medicines Agency’s safety committee, known as PRAC, concluded that NAION is a very rare side effect of semaglutide medicines, meaning it may affect up to 1 in 10,000 people taking them. The agency noted that studies in adults with type 2 diabetes found about a twofold higher risk, equal to roughly one extra case per 10,000 person-years of treatment.
The two numbers are not directly interchangeable. The European figure is expressed per person-year of treatment and applies to semaglutide alone, while the Rutgers figure covers an 18-month window and pools GLP-1 drugs including tirzepatide. Both point the same direction: a real but uncommon excess of optic-nerve events. EMA’s advice to patients was to contact a doctor right away after sudden vision loss or eyesight that worsens quickly, and to stop semaglutide if NAION is confirmed.
Limits on what the study can say
The Rutgers authors cautioned that differences in patients’ underlying health may explain some or all of the association. Patients who are prescribed these newer drugs may differ from comparison patients in ways a health-records database cannot fully capture. The researchers called for more work to establish whether the medications contribute to the condition.
They also stressed continued safety monitoring because the drugs are prescribed so widely, including to people who do not have diabetes, a group the study did not examine. For patients already on one of these medicines, the practical message in the research is narrow: sudden changes in vision in one eye warrant a prompt eye examination rather than a wait-and-see approach.
What remains unsettled is the mechanism. None of the material reviewed here shows how a GLP-1 drug would reduce blood flow to the optic nerve, and the absolute numbers, a handful of cases per 10,000 patients over 18 months, are small enough that individual patients and their doctors will weigh them against the reason the drug was prescribed in the first place. Dave’s own framing was that the risk is low in absolute terms but worth tracking as prescriptions keep growing.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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