Recent studies have shown that about one in eight people have taken a glucagon-like peptide-1 agonist, better known as GLP-1 drugs, according to Medical News Today.

Initially used to treat type 2 diabetes, these drugs have gained popularity in recent years for weight loss.

Currently, the most common types of GLP-1 drugs are semaglutide — sold under the brand names Ozempic for type 2 diabetes and Wegovy for weight loss — and tirzepatide, sold under the brand names Mounjaro for type 2 diabetes and Zepbound for weight loss.

Like any medication, GLP-1 drugs have potential side effects and complications. One potential complication was first reported in July 2024, when a study found that people using semaglutide were at a four times higher risk of developing non-arterial anterior ischemic optic neuropathy (NAION). This was followed by a study published in January 2025, which found that people taking semaglutide or tirzepatide may be at an increased risk of potential vision loss.

Now, a new study published recently in the journal JAMA Ophthalmology has reported that older adults with diabetes who take any type of GLP-1 medication may be at an increased risk of developing neovascular age-related macular degeneration (nAMD).

Focus on semaglutide

For this study, researchers analyzed health records from 2020 to 2023 of over 139,000 Ontario residents with an average age of 66 who had been diagnosed with diabetes.

Participants who took GLP-1 medications did so for more than six months.

"Our study includes all GLP-1 receptor agonists that were prescribed during the study period in Ontario, Canada; we did not exclude any specific type of these medications,"

Rajeev H. Muni, associate professor and vice chair of clinical research in the Department of Ophthalmology and Visual Sciences at the University of Toronto, Canada, and lead researcher in this study, explained to Medical News Today. "However, semaglutide accounted for the majority of use in our cohort, comprising 97.5% of all GLP-1 prescriptions."

"Lixisenatide accounted for the remaining 2.5%, with almost all lixisenatide prescriptions being in combination with insulin glargine," Muni continued. "Tirzepatide was not included because it was not yet approved in Canada at the time of the study."

"In addition, although Wegovy was approved at the end of 2021, our study focused on patients with diabetes from 2020 to 2023," he added. "Therefore, it is very likely that semaglutide included in our analysis was prescribed as Ozempic, which is indicated for blood sugar control in type 2 diabetes."

Older people taking GLP-1 are at twice the risk

In the analysis, the researchers found that participants with diabetes taking GLP-1 drugs were at twice the risk of developing nAMD, a type of AMD in which deformed blood vessels grow under the retina, leading to fluid leakage into the macula of the eye.

There is currently no treatment for nAMD, and it is a condition that can lead to blindness.

"We found that among patients with diabetes aged 66 years and older, the incidence of nAMD was approximately 1 in 1,000 among those who have never taken GLP-1 receptor agonists, compared to about 2 in 1,000 among those who have been exposed to these drugs for at least six months," said Muni. "Although the absolute risk remains low, this represents a relative doubling of the risk."

"While our findings should not cause alarm, they do warrant increased clinical vigilance," he continued. "These drugs have well-established benefits for the cardiovascular, renal, and metabolic systems. However, patients who may be at higher risk of nAMD, such as older people, should be aware of the possibility of new visual symptoms. If new vision changes occur while taking these drugs, patients should immediately inform their doctor and be referred to an ophthalmologist for further evaluation."

Higher risk of eye disease in people who use GLP-1 for longer periods

In addition, Muni and his team observed that the highest risk of nAMD was associated with participants who had been taking GLP-1 drugs for the longest period of time.

"In our analysis, we observed a clear dose-response relationship, with the risk of nAMD increasing with longer exposure to GLP-1 receptor agonists," explained Mooney. "This finding is clinically significant because it suggests that the risk may accumulate over time."

"Given that many people use these drugs chronically, whether for blood sugar control or weight loss, the long-term ocular safety of GLP-1 RAs warrants further study," he continued. "Although observational data alone cannot prove a causal relationship, observing such a graded association suggests that prolonged exposure may play a role in increasing risk; however, this needs to be confirmed in future studies."

Study limitations

MNT also spoke with Dr. Demetrios Vavvas, director of retina at Massachusetts Eye and Ear, to discuss this study.

Dr. Vavvas commented that the strength of the study lies in the large scale of real-world data, the robust statistical techniques used, and the evidence it found for a dose-response relationship.

"The risk of developing nAMD appears to increase with the duration of a patient's exposure to the drug," he added. "This type of pattern makes the potential association more compelling than a single, static finding and provides a significant signal that warrants serious follow-up."

However, Vavvas pointed out that the study has some limitations: "The most significant limitation is that this study can only show an association, not prove that the drug causes this eye disease. This is because critical risk factors such as smoking, obesity (BMI), and sun exposure were not accounted for in the data. Since GLP-1 RAs are often prescribed to patients with obesity, this single unmeasured factor could be the real driver of the observed risk."

"Second, the results may be influenced by observation bias," Vavvas emphasized. "Patients who start taking a new powerful drug such as GLP-1 RA are likely to be monitored more closely by their doctors. This increased medical attention may lead to a higher likelihood of detecting and treating their eye problems, which was measured in the study, creating the impression of an increased risk."

"Third, the actual events were very few—less than 0.2%—so despite the statistical adjustment, the results may not be accurate," he said. "Finally, since the majority of GLP-1 RAs in this study were semaglutide, this may not apply to all GLP-1 RAs, and furthermore, since the analysis excludes over 26,000 patients who cannot be matched, the results may not be valid for the full spectrum of patients taking these drugs in the real world, especially those with more complex health profiles."

Eye health monitoring is important when taking GLP-1 drugs

MNT spoke with David I. Geffen, director of optometric and refractive services at Gordon Schanzlin New Vision in La Jolla, California, about this study.

Geffen commented that because GLP-1 drugs are prescribed to a huge number of patients — and because it has been observed that not all patients are symptom-free and side effect-free — doctors need to be very careful to ensure that their patients’ eye health is not compromised by the use of these drugs.

"It's important to make sure we know that our patients are taking these drugs," he explained. "This study shows that with the approval of new drugs, we need to be careful because there may be long-term side effects that we didn't know about."

"Diabetes is very common in our practice, and many of our patients take GPL-1," Geffen continued. "We need to be vigilant when examining patients with diabetes. If these drugs are being used, this is even more important. One study is not enough to make too many assumptions when deciding whether to use these drugs. GLP-1 drugs have shown many benefits for most patients." "It is important to continue studies in other countries to see if this is also observed in other populations," he added.

"It is important to know more about the demographic characteristics of the affected populations. Knowing the condition of the retina in patients before starting treatment with these drugs would be helpful in determining safety profiles." |BGNES