GLP-1 Drugs Could Double Risk of Severe Eye Disease in Older Adults With Diabetes

GLP-1 drugs may increase the risk of a severe form of macular degeneration in older adults with diabetes, according to a recent study published in JAMA Ophthalmology.

A growing collection of research has raised concerns that these popular obesity and diabetes medications could affect eye health. The new study found that GLP-1 drugs appear to double the risk for developing neovascular age-related macular degeneration (nAMD), a condition that causes vision loss. However, the overall risk remains low.

What Did the Study Find?

The retrospective study analyzed health records of nearly 140,000 people in Ontario, Canada, between 2020 and 2023. All participants were 65 or older and had a diabetes diagnosis. Researchers matched each person who used a GLP-1 drug for at least six months with two non-users who had similar health and demographic profiles.

More than 97% of participants took semaglutide, while the rest took lixisenatide, an older GLP-1 medication. The researchers didn’t track exactly which medication participants took, but they noted that Ozempic was the only semaglutide product approved for treating diabetes in Canada at the time of the study.  

In the group that took a GLP-1 drug, one in 500 developed nAMD, compared to about one in 1,000 in the non-user group.

“This is an interesting study by an excellent group of researchers. They used a large data set from Canada to answer this question, but it’s still too early to say if there is a causative relationship between GLP-1 medications and nAMD,” Sunir Garg, MD, spokesperson for the American Academy of Ophthalmology and professor of ophthalmology at Wills Eye Hospital, said in an email.

Garg, who was not involved in the study, noted that while the study shows a significant link, the overall risk of developing nAMD remains low, even among GLP-1 users.  

What Is nAMD?

Neovascular age-related macular degeneration (nAMD), also called “wet AMD,” is an eye condition in which vision gradually worsens, particularly in older adults. It occurs when abnormal blood vessels grow into the retina. These vessels can leak blood and other fluids under the retina, leading to scarring and central vision impairment.

Future research will need to include larger study populations and investigations into the biological processes that might be driving nAMD in GLP-1 drug users, said co-author Reut Shor, MD, of the Department of Ophthalmology and Vision Sciences at the University of Toronto.

This study only included people with diabetes. Shor said in an email that it will be interesting to examine whether GLP-1 drugs have similar effects on vision in people who don’t have diabetes, such as those who take the medication for obesity.

Why Might GLP-1 Drug Use Increase nAMD Risk?

Diabetes is associated with a greater risk for several eye conditions, including diabetic retinopathy and diabetic macular edema. Some common diabetes medications have been linked to a lower risk of developing nAMD.

“We know that if [the GLP-1] medicines help patients control their blood sugars, there will be significant health benefits to them, both in terms of cardiovascular health as well as potentially a reduction in ocular complications and vision loss,” Garg said.

That’s not what this study found, however. Shor said some research suggests that GLP-1 drugs may contribute to eye problems due to the “sudden and sharp” drop in blood glucose after a person starts the drug.

If that were the case with nAMD, the risk of the disease should decline once blood sugar levels stabilize over time. “However, in our study, we observed that the risk actually increased with prolonged exposure,” Shor said. “GLP-1 receptor agonists appear to have several different adverse effects on the eye, and it seems that the net effect may be harmful in the context of neovascular AMD.”

One possible explanation, Shor said, is that GLP-1 receptors are found in certain retinal cells. Mice studies suggest that activating these receptors may cut off oxygen supply to the retina, promoting the abnormal blood vessel growth that leads to nAMD.

More research must be conducted to understand the true mechanisms of action.

Should You Stop Taking GLP-1 Drugs?

Other studies have linked GLP-1 drug use to non-arteritic ischemic optic neuropathy (NAION) and worsening diabetic retinopathy.

“We need better data to understand which patients are potentially at increased risk. As with any treatment, while there may be some undesirable side effects, we have to weigh them against the many patients who may benefit greatly from these medications,” Garg said.

Young people who use GLP-1 drugs are at lower risk of developing age-related eye conditions like nAMD. Older patients, Garg said, should be aware of the warning signs of macular degeneration.

Early symptoms of wet AMD include blurriness or waviness in central vision. To test for symptoms, older adults can cover one eye and look at objects with fine details, like a newspaper or a neighbor’s house, or objects with straight lines, like window blinds and tiles. If you start noticing distortion, it could be worth talking to an ophthalmologist.

All people with diabetes should have an eye exam at least once a year. Those visits provide an opportunity to discuss concerns about vision health and medications.

“GLP-1 receptor agonists provide significant benefits for cardiovascular, metabolic, and kidney outcomes, and those benefits remain very important,” Shor said. “However, patients, especially those at higher risk for AMD, should be monitored carefully, and clinicians should remain vigilant for any new visual symptoms in these patients.”