- The most commonly used types of GLP-1 receptor agonists are semaglutide and tirzepatide, which are used to treat type 2 diabetes and aid weight loss.
- Past studies have linked GLP-1 medications to a risk of potentially blinding eye diseases.
- A new study reports that older adults with diabetes taking any type of GLP-1 medication may be at a heightened risk for developing neovascular age-related macular degeneration (nAMD).
Recent tracking polls report that about one in eight people have taken a glucagon-like peptide-1 receptor agonist, more commonly known as GLP-1 medications.
Originally used to help treat type 2 diabetes, these medications have gained in popularity over the last few 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
Just like any medication, GLP-1 drugs have possible side effects and complications. One potential complication was first reported in July 2024 when a study found people using semaglutide were at a
Now, a new study recently published in the journal
For this study, researchers analyzed health records from 2020 to 2023 of more than 139,000 Ontario residents with an average age of 66 and diagnosis of diabetes. Participants who used GLP-1 medications did so for more than six months.
“Our study included any 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, MD MSc FRCSC, associate professor and vice chair of Clinical Research in the Department of Ophthalmology and Vision Sciences at the University of Toronto in Canada, and principal investigator of this study explained to Medical News Today. “However, semaglutide represented the vast majority of use in our cohort, accounting for 97.5% of all GLP-1 prescriptions.”
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“Furthermore, while Wegovy was approved in late 2021, our study focused on patients with diabetes from 2020 to 2023,” he added. “Therefore, it is very likely that the semaglutide included in our analysis was prescribed as Ozempic, which is indicated for blood sugar control in type 2 diabetes.”
Upon analysis, researchers found that participants with diabetes taking a GLP-1 medication had a two-fold higher risk of developing nAMD — a type of AMD where malformed blood vessels grow underneath the retina, causing fluids to leak into the macula of the eye.
There is currently no cure for nAMD and it is a condition that can potentially cause blindness.
“We found that among patients with diabetes aged 66 and older, the incidence of nAMD was approximately 1 in 1,000 in those who had never used GLP-1 receptor agonists, compared to about 2 in 1,000 among those who had been exposed to these medications for at least six months,” Muni said. “While the absolute risk remains low, this represents a relative doubling in risk.”
“While our findings should not prompt alarm, they do warrant increased clinical awareness,” he continued. “These medications have well-established benefits for cardiovascular,
Additionally, Muni and his team observed that the highest nAMD risk was associated with participants who had used GLP-1 medications for the longest amount of time.
“We observed a clear dose-response relationship in our analysis, with the risk of nAMD increasing as the duration of GLP-1 receptor agonist exposure increased,” Muni explained. “This finding is clinically meaningful because it suggests that the risk may accumulate over time.”
“Given that many individuals use these medications chronically, whether for blood sugar control or for weight loss, the long-term ocular safety of GLP-1 RAs requires further investigation,” he continued. “While observational data can’t prove causation on its own, seeing a graded relationship like this suggests that prolonged exposure could play a role in increasing risk; however, this needs to be validated in future studies.”
MNT also talked to Demetrios Vavvas, MD, PhD, director of the retina service at Mass Eye and Ear in Massachusetts, about this research.
Vavvas commented that the study’s strength is on its massive scale of real-world data, the robust statistical technique used, and the evidence it found of a “dose-response” relationship.
“The risk of developing nAMD appeared to increase the longer a patient was exposed to the medication,” he continued. “This type of pattern makes a potential link more compelling than a single, static finding and provides a significant signal that warrants serious follow-up investigation.”
However, Vavvas did point 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 condition. This is because critical risk factors like 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 true driver of the observed risk.”
— Demetrios Vavvas, MD, PhD
“Second, the results may be influenced by surveillance bias,” Vavvas continued. “Patients starting a powerful new medication like a GLP-1 RA are likely to be monitored more closely by their doctors. This increased medical attention could lead to a higher likelihood of their eye problems being detected and treated, which is what the study measured, creating the appearance of increased risk.”
“Thirdly, the actual events were very small — less than 0.2% so despite statistical adjustment results may not be accurate,” he added. “Lastly as the majority of GLP-1 RAs in this study were semaglutide, this may not apply to all GLP-1 RAs and additionally, because the analysis excluded over 26,000 patients who could not be matched, the results may not apply to the full spectrum of patients taking these drugs in the real world, particularly those with more complex Health profiles.”
MNT spoke with David I. Geffen, OD, FAAO, director of optometric and refractive services at the Gordon Schanzlin New Vision in La Jolla, CA, about this study.
Geffen commented that as GLP-1 medications are being prescribed to a huge number of patients — and as it’s been observed that not all patients are symptom free and not side effect free — doctors must be very careful to make sure their patients’ eye health is not compromised utilizing these medications.
“It is important to make sure that we know our patients are taking these medications,” he explained. “This study shows that as new medications are approved we need to be careful as long term side-effects may be seen that we were not aware of.”
“Diabetes is very common in our practices and many of our patients are put on the GPL-1s,” Geffen continued. “We need (to) be vigilant in examining patients with diabetes. If using these meds, it is even more important. One study is not enough to make too many assumptions however in deciding to use these meds. The GLP-1 medications have shown many benefits for most patients.”
“It is important to carry on further studies in other countries to see if this is seen in other populations,” he added. “It would be important to know more of the demographics of the afflicted populations. Knowing the status of the retina in the individuals before being put on the medications would be helpful in determining safety profiles.”
