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Are popular semaglutide drugs linked to a rare and aggressive eye condition? Image credit: Serg Myshkovsky/Getty Images.
  • A new study finds an association between semaglutide and a rare eye condition.
  • The condition, called nonarteritic anterior ischemic optic neuropathy, can cause blindness.
  • The authors note that this finding is preliminary, and more research is needed.

A new study, which appeared in JAMA Ophthalmology earlier this week, identified a potential link between the diabetes and weight loss drug, semaglutide and a rare eye disease that causes blindness.

The condition, called nonarteritic anterior ischemic optic neuropathy (NAION), affects around 2.3 people per 100,000 people in the United States.

The new study finds that people with diabetes who were prescribed semaglutide — which is marketed as Ozempic and Wegovy, among other names — were more than four times more likely to develop NAION compared with people with diabetes on other medications.

Similarly, those who were prescribed the drug to treat overweight or obesity were over seven times more likely to receive a NAION diagnosis than people taking other weight loss drugs.

Despite being relatively rare, NAION is a significant cause of blindness in the U.S. It causes a painless, permanent loss of vision, which often occurs when waking from sleep.

Medical News Today spoke with Joel Kopelman, MD an oculofacial plastic surgeon and board-certified ophthalmologist.

He explained that: “This vision loss can range from mild to severe. The condition can progress quickly, with most of the vision loss occurring within days to weeks of the onset of symptoms.”

Kopleman, who was not involved in the recent study, also told us that NAION has “an estimated incidence of 2-10 per 100,000 people annually in the United States. The prevalence is similar globally,” he explained, “although exact figures can vary based on regional health demographics and reporting practices.”

Most commonly, it affects middle-aged or older white people. Generally, it only affects one eye at a time. However, for around 43% of people, their other eye becomes affected within the following 3 years.

MNT contacted Dr. Arun Gulani, an eye surgeon at the Gulani Vision Institute, who explained that “there is no established treatment protocol for NAION, which is considered irreversible.”

However, Gulani, who was also not involved in the study, told us that “Experimental treatments are being evaluated nationally and worldwide.”

The lead author of the recent study was Joseph Rizzo, MD, director of the Neuro-Ophthalmology Service at Mass Eye and Ear in Boston, MA. He first decided to investigate the link between semaglutide and NAION based on an observation.

He and colleagues noted that three patients in their practice were diagnosed with NAION in just 1 week. This is unusual for such a rare condition. Rizzo and colleagues also noted that all three patients were taking semaglutide.

To investigate, they analyzed retrospective data from 16,827 Mass Eye and Ear patients. They divided the individuals into two groups based on the reason for taking the medication — type 2 diabetes or obesity.

In these two groups, some received semaglutide, while others took unrelated drugs to treat their condition. This division is important because people with diabetes are at an increased risk of NAION, so by analyzing them separately, they could account for this.

In the diabetes group, 8.9% of those taking semaglutide received a NAION diagnosis, compared with 1.8% of those taking other medications for diabetes.

Similarly, in the group with obesity, 6.7% of those taking semaglutide developed NAION, compared with only 0.8% of those taking other medications.

This means that people with diabetes taking semaglutide were more than four times more likely to receive a NAION diagnosis. Those who taking semaglutide to treat obesity were more than seven times more likely to receive a diagnosis.

“While the exact mechanism linking semaglutide to NAION is not fully understood,” Kopelman told MNT, “there are a few theories.”

He explained that semaglutide “may influence vascular health and blood flow, potentially contributing to ischemic events in predisposed individuals.”

An ischemic event is when an organ or tissue does not receive adequate blood, and therefore oxygen. NAION is caused by ischemia specifically in the optic nerve.

“Patients with diabetes are already at higher risk for vascular complications,” he continued, “and any additional factors that could affect blood flow to the optic nerve might increase the risk of NAION.”

Another theory involves the mechanism by which semaglutide works. Semaglutide is a GLP-1 agonist, which means it works at a receptor called GLP-1.

The authors of the study note that GLP-1 receptors are present on the optic nerve. Activating them may influence blood supply to the optic nerve, increasing NAION risk.

Scientists will need to carry out much more work to explore the connections between semaglutide and NAION. Then, if confirmed, more work will be necessary to unravel the mechanisms involved.

We asked Kopelman if there are any ways to reduce the risk of developing NAION. “Reducing the risk of NAION involves managing underlying health conditions that contribute to its development,” he told us.

He outlined the following key preventive measures:

  • control blood pressure and diabetes — maintaining optimal control of blood pressure and blood glucose levels is crucial
  • regular eye examinations — regular check-ups with an ophthalmologist can help monitor and manage risk factors
  • healthy lifestyle — adopting a healthy lifestyle, including a balanced diet, regular exercise, and avoiding smoking, can improve overall vascular health.

The study does have limitations. As the authors explain, because their institution specialises in eye conditions, they are more likely to see higher numbers of NAION cases. This means that their findings “may not be fully generalizable to other settings.”

They also note that their records only show whether a medication was dispensed to a patient and not whether they took it as prescribed. Finally, because NAION is rare, their analysis only contained a small number of cases. This can make the statistics harder to interpret.

However, caveats considered, the authors write, “If true, our data anticipate increasing numbers of NAION cases related to this class of drugs.”

They believe that their research is the first to find a link between NAION risk and semaglutide.

“Our findings should be viewed as being significant but tentative, as future studies are needed to examine these questions in a much larger and more diverse population,” Rizzo explained in a press release.

He advised that:

“This is information we did not have before and it should be included in discussions between patients and their doctors, especially if patients have other known optic nerve problems like glaucoma or if there is preexisting significant visual loss from other causes.”