Rutgers University researchers report that adults with type 2 diabetes who took a GLP-1 drug had about three to four additional cases of ischemic optic neuropathy, a cause of sudden vision loss, for every 10,000 patients treated over 18 months. The finding, published in Annals of Internal Medicine, is an association. The researchers say it does not establish that the medicines damage the optic nerve.
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The drugs studied were semaglutide, sold as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound. Ischemic optic neuropathy occurs when blood flow to the optic nerve is reduced, and it usually costs part of the vision in one eye rather than causing total blindness. More than 80% of cases are the non-arteritic anterior form, in which the front of the nerve gets too little blood, according to the release.
What the Rutgers team measured
Chintan Dave, an associate professor at the Rutgers Ernest Mario School of Pharmacy, is the lead author, working with Kamika Reynolds, Kimberly O’Malley and Jason Roy. According to the Rutgers release carried by ScienceDaily, the team examined a large database of U.S. adults aged 18 to 65 with type 2 diabetes who had recently started diabetes medication, including GLP-1 receptor agonists. Reporting from Powers Health adds that the study was funded by the National Institutes of Health and compared GLP-1 users with patients taking SGLT2 inhibitors or DPP4 inhibitors, two other classes of diabetes drugs.
Technology Networks quotes Dave on the size of the effect: “The increase in risk was small – approximately three to four additional cases per 10,000 patients treated with GLP-1s over 18 months.” The sources read for this article do not give the number of patients, the name of the database or a relative-risk figure, so the 3-to-4-per-10,000 absolute increase is the only quantified result available here.Put in plainer terms, an extra three to four cases per 10,000 patients is roughly one additional case for every 2,500 to 3,300 people treated for 18 months. That is a difference measured against the other patients in the study, not a statement that three or four in 10,000 users lost vision in total. The release does not report how many cases occurred in either group, so the baseline rate that the extra cases sit on top of is not available from the sources read.
Who had the cases, and how rare they were
The release says cases were more common in men and in adults aged 50 to 65. Dave told News12 New Jersey that most of the study participants who developed ischemic optic neuropathy were either men or women aged 50 to 65. The outcome is uncommon, which is why the absolute increase is so small: three to four extra cases in 10,000 treated patients works out to well under a tenth of one percent over 18 months.
Dave said the condition matters despite its rarity. “Although ischemic optic neuropathy was rare, it is clinically important because it can involve sudden vision loss,” he said, according to the release. The release adds that vision loss from the condition is often permanent, that about a third of patients recover some vision, usually within the first six months, and that some impairment typically remains. Symptoms can include sudden blurriness, dimming or missing areas in the field of view.
The limits of an association
The researchers are explicit that the study shows an association, not causation. Differences in the underlying health of patients could partly explain the higher risk, and everyone in the study had type 2 diabetes, a condition that carries its own risks to the eyes and blood vessels. The release says more research is needed to determine whether the medications themselves contribute to the condition, and the authors stress that the absolute risk remains low.
The comparison group matters to how the result should be read. Powers Health reports that GLP-1 users were compared with patients taking SGLT2 inhibitors or DPP4 inhibitors, so the extra cases are measured against other people being treated for type 2 diabetes rather than against the general population. The release adds that differences in patients’ underlying health conditions could partly explain the higher risk, and the researchers state that the findings do not establish that GLP-1 drugs directly damage the optic nerve. How much of the gap reflects the drugs and how much reflects the patients who receive them is the question the authors say requires additional research, and the sources read do not say how the groups were matched or adjusted.
They also argue for continued safety monitoring given how widely the drugs are prescribed, including to people without diabetes, a group the study did not include. Dave said early recognition of symptoms and prompt evaluation by an eye specialist may be especially important for patients at higher risk. The full paper is indexed as DOI 10.7326/ANNALS-25-00860, and the reports read for this article do not describe its methods beyond the outline given here.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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