GLP-1 Drugs Linked to Faster Vision Loss in the Second Eye, New Study Finds

GLP-1 Drugs Linked to Faster Vision Loss in the Second Eye, New Study Finds

Among patients who suffered a rare optic nerve stroke in both eyes, those taking GLP-1 drugs saw the second eye affected sooner. They caution that causation hasn't been established, only an association.<_o3a_p>

NEW ORLEANS - For patients who lose vision in one eye to a sudden stroke of the optic nerve, there is a lingering fear that the other eye will eventually follow. A new study suggests that for people taking GLP-1 drugs, the popular class of medications used for diabetes and weight loss, that second blow may come sooner.<_o3a_p>

The research presented at the 130th annual meeting of the American Academy of Ophthalmology, found that among patients who developed the condition in both eyes, GLP-1 users were substantially more likely to have the second eye affected within six months of the first.<_o3a_p>

The condition, non-arteritic anterior ischemic optic neuropathy or NAION, happens when the optic nerve does not get enough blood flow, causing sudden, painless loss of vision in one eye. It typically strikes one eye. But it can affect the fellow eye.<_o3a_p>

"Approximately 15% of patients will develop NAION in the fellow eye within five years after a diagnosis in the first eye," said Ashley Tin, the study's co-author and medical student at the Carle Illinois College of Medicine. "Rapid, sequential involvement of the second eye is typically less common."<_o3a_p>

The study began with a clinical hunch. One of Ms. Tin's co-authors, ophthalmologist Matthew D. Kay, MD, noticed a cluster of patients arriving in a short span of time with NAION in both eyes, one after the other in quick succession and occasionally at the same time. All were taking GLP-1 agonists.<_o3a_p>

"The apparent increase in rapidly sequential presentations seemed unusual and prompted us to investigate whether this pattern could also be seen in a large national database," Ms. Tin said.<_o3a_p>

To find out, the researchers turned to Epic Cosmos, a large repository of health records, and looked at second-eye NAION events recorded from 2015 to 2025. They compared about 1,440 GLP-1 users with roughly 20,700 people who were not taking the drugs, tracking how long after the first event the second eye was affected, from one month to five years.<_o3a_p>

The difference was striking. Among GLP-1 users, 56.8 percent of second-eye events occurred within six months, compared with 40.6 percent among those not taking the medication. In the researchers' statistical model, the shift toward early rather than late events was about 1.98 times as strong in the GLP-1 group. The pattern held both before and after the drugs came into widespread use.<_o3a_p>

"We were not particularly surprised by the findings because the large-database analysis was consistent with the clinical observation that prompted the study," Ms. Tin said. "That said, seeing the clinical impression reproduced across a very large dataset was striking and underscored the need to investigate the association further."<_o3a_p>

The study comes as use of GLP-1 drugs has soared, and as doctors and researchers started investigating whether the medications bear any relationship to NAION.<_o3a_p>

But the researchers were careful to note what their work does not show. GLP-1 users in the study had higher average hemoglobin A1C levels, a measure of long-term blood sugar, by 1.0 to 1.4 percentage points. That raises the possibility that more severe diabetes, rather than the drugs themselves, accounts for some or all of the difference. And because the data were aggregated rather than drawn from individual patient records, the study cannot establish cause and effect.<_o3a_p>

For ophthalmologists, Ms. Tin said, the message is one of vigilance rather than alarm. "GLP-1 use should be an important part of the medication history in patients presenting with NAION, particularly when counseling patients after a first-eye event," she said, adding that treatment decisions "should continue to consider the substantial systemic benefits of these medications."<_o3a_p>

Her message to patients is equally clear. Do not stop taking the drugs because of this study.<_o3a_p>

"These drugs have important benefits for diabetes, obesity and cardiovascular health, and our study identifies an association rather than proving that the medications cause NAION," Ms. Tin said. Anyone who experiences sudden, painless vision loss or a new area of missing vision, she added, should seek prompt evaluation by an eye doctor and raise any concerns with the physician who prescribed the medication.<_o3a_p>

The American Academy of Ophthalmology and the North American Neuro-Ophthalmology Society last month issued a statement, providing additional information and advice to both ophthalmologists and the public.<_o3a_p>

The next step, the researchers said, is to untangle whether the drugs themselves or the underlying health of the people who take them is driving the pattern. That will require studies with detailed patient-level data that can account for diabetes severity and other vascular conditions, and that can examine which specific drug a patient took, at what dose, for how long, and when treatment began relative to each eye's event. Ultimately, Ms. Tin said, prospective studies will be needed to determine whether the relationship is causal.<_o3a_p>

About the American Academy of Ophthalmology<_o3a_p>

The American Academy of Ophthalmology is the world's largest association of eye physicians and surgeons. A global community of 32,000 medical doctors, we protect sight and empower lives by setting the standards for ophthalmic education and advocating for our patients and the public. We innovate and support research to advance our profession and to ensure the delivery of the highest-quality eye care. Our EyeSmart® program provides the public with the most trusted information about eye health. For more information, visit aao.org.<_o3a_p>

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