As weight loss drugs like Ozempic and Wegovy continue to surge in popularity across the U.S., medical researchers are increasingly looking into ways the medications are potentially affecting other systems in the body. Even the eyes.
In July, a research team from Harvard published a paper in JAMA Ophthalmology suggesting there may be a link between semaglutide use in patients with diabetes and increased risk for non-arteritic anterior ischemic optic neuropathy (NAION), which happens when blood flow to the optic nerve is blocked and causes sudden irreversible blindness in the eye.
While data on the association is still limited and experts don’t believe these findings should be reason for concern for most patients, neuro-ophthalmologist Mary Labowsky, MD, assistant professor of ophthalmology at the University of Colorado School of Medicine, says it can be helpful to discuss with an eye doctor to assess the risk of developing NAION.
This research could also contribute to a broader understanding of the condition.
“NAION is the most common optic neuropathy besides glaucoma, and causes irreversible vision loss,” Labowsky explains. “Nevertheless, it is still exceedingly rare, and only occurs in about two per 100,000 individuals over the age of 50 per year. It is very difficult to prove causation in such a rare disease. We know that risk factors for NAION include high blood pressure, diabetes, obesity, sleep apnea, age, and certain anatomic features of the optic nerve itself. But we need more research on what exactly causes the limited blood flow to the optic nerve. We only have theories about why this happens.”
“We want to continue working to understand the underlying mechanisms of NAION and the culmination of risk factors that contribute to it,” she continues. “This research on GLP-1 agonists highlights the gaps in our knowledge regarding NAION and the importance of additional investigations to understand this disease better.”
The knowns and unknowns
The drug semaglutide was approved by the U.S. Food and Drug Administration in 2017 to help diabetes patients control blood sugar and treat obesity. The medication, an injection, aids the body in releasing the GLP-1 hormone, which makes the body feel full while eating, and create more insulin. This helps reduces blood sugar.
Semaglutides have been rigorously studied in various randomized controlled trials.
“An important thing to understand with this study specifically is that researchers saw an association and that doesn’t necessarily mean causation,” Labowsky says.
Patients who have diabetes are also at a higher risk of developing NAION, whether they are using these weight loss medications or not, and the study focused solely on patients with type 2 diabetes taking the weight loss drug.
“There are confounding factors,” Labowsky says. “Patients who may be on Ozempic certainly may just be at higher risk for NAION due to their underlying medical diagnoses. That being said, the researchers did take confounding variables into account and still found that there is a significantly greater risk of developing NAION compared with patients who did not take the drug. However, there could still be other confounding reasons for which a patient may be put on these medications by their doctors over other patients with a similar medical background.”
In the study of 710 patients, there were 17 cases of NAION in patients who were prescribed semalgutide compared to six cases in patients who were not prescribed the drug.
Future research needs
There are still a lot of questions surrounding the perpetuating event of NAION, its risk factors, and what exactly causes the sudden irreversible blindness. Current theories suggest that an imbalance of pressure in the eye could be the reason.
Additional research, especially large, randomized control studies, could be beneficial to patients, doctors, and researchers who study NAION, including Labowsky.
For now, Labowsky says present research shouldn’t stop diabetes patients from taking Ozempic, Wegovy, or another semaglutide if they’ve discussed it with their doctor.
“Certainly, if you’ve already had NAION or a history of blindness, you’ll want to consider the risks and be cognizant of the symptoms of NAION, which is painless vision loss,” she says.
