People with diabetes taking GLP-1 drugs face a low but elevated risk of developing serious eye conditions, according to two new studies that add to growing concerns about ocular safety in patients using these popular medications.
Doubled Risk of Advanced Macular Degeneration
A large observational study published in JAMA Ophthalmology found that people with diabetes taking GLP-1 drugs had more than twice the risk of developing neovascular age-related macular degeneration (nAMD) compared to similar patients not taking the medications. The research analyzed health records from nearly 140,000 patients in Canada, with participants matched for socioeconomic status and multiple medical conditions.
After one year, 0.2% of people taking GLP-1 drugs developed nAMD compared to 0.1% of those who didn't take the medications. The study participants averaged 66 years old, an age group particularly vulnerable to AMD, which is a leading cause of irreversible blindness in older adults.
"Seeing such a clear signal in our study was striking," said co-author Reut Shor of the University of Toronto. "The absolute risk remains low, but the advanced form of AMD is a condition with serious implications for vision and quality of life. So a doubling of risk is clinically meaningful, particularly for vulnerable populations like older adults who may already be at elevated baseline risk."
Case Reports Document Vision-Threatening Events
A separate study published in JAMA Ophthalmology documented nine patients in their 50s and 60s who developed sight-threatening conditions after taking GLP-1 medications including semaglutide (Wegovy/Ozempic) and tirzepatide (Mounjaro/Zepbound).
Seven of the nine patients developed nonarteritic anterior ischemic optic neuropathy (NAION), a condition where blood vessels fail to supply adequate blood to the optic nerve, potentially causing sudden and permanent partial vision loss. One patient developed a maculopathy (blind spot), while another experienced papillitis, an inflammation of the optic nerve head.
The investigation began when lead author Dr. Bradley Katz of the John A. Moran Eye Center at University of Utah Health noticed a patient who experienced sudden, painless vision loss in one eye after starting semaglutide. When the patient resumed the medication after a brief halt, vision loss occurred in the other eye.
Potential Mechanisms Under Investigation
Researchers are exploring several potential mechanisms for the increased eye disease risk. GLP-1 drugs may trigger abnormal blood vessel growth in the retina through rapidly declining blood glucose levels. Additionally, GLP-1 receptors exist in the retina, and these medications increase levels of molecules that can lead to harmful blood vessel formation.
"So are these drugs increasing the risk for an episode of visual loss?" asked study co-author Dr. Norah Lincoff, a neuro-ophthalmologist at the University at Buffalo. "The message to the patient is that we are still investigating if these drugs put them at higher risk of ischemic optic nerve damage."
Clinical Implications and Monitoring Recommendations
The findings raise important questions about monitoring patients on GLP-1 therapy, though experts emphasize the results should not cause alarm or prompt abrupt prescribing changes. Brian VanderBeek of the Scheie Eye Institute at the University of Pennsylvania noted that if the findings are confirmed, as many as 1 in 1,000 GLP-1 users might develop nAMD.
"GLP-1 RAs have had a tremendous role in the care of patients with diabetes and now those needing additional help with weight management," VanderBeek wrote in a companion editorial. "While certainly not outweighing the good these medications offer, prescribing physicians need to keep in mind the real and serious ocular adverse events that may occur."
Researchers recommend that patients on GLP-1 drugs should promptly report visual symptoms including blurred or distorted vision, straight lines appearing wavy, or new blind spots. These symptoms could indicate early signs of AMD and should trigger immediate referral to an ophthalmologist.
"If a patient on one of these medications calls you and says that there is blurring or vision loss, have them see their ophthalmologist as soon as possible. Don't wait," Lincoff advised. "Maybe it's a fluctuation in glucose or it could be something more serious."
Future Research Directions
The studies highlight the need for additional research to establish causality and determine optimal monitoring strategies. Future investigations should include animal model studies, human tissue research to determine mechanisms, and large prospective clinical studies in diverse populations, including people without diabetes who use GLP-1s for weight loss.
Whether discontinuing GLP-1 therapy upon developing visual symptoms would reduce AMD risk remains an open question for future research. For now, patients already taking GLP-1 medications shouldn't panic, as vision problems remain very rare, but awareness and appropriate monitoring are essential.
