Top health experts have issued fresh warnings over potential vision-threatening side effects from GLP-1 weight-loss drugs such as Ozempic, Wegovy, and Mounjaro. Studies suggest these medications may trigger conditions that reduce blood flow or cause inflammation in the eye, potentially leading to permanent vision loss.
First linked to a rare condition known as non-arteritic anterior ischemic optic neuropathy (NAION) in 2024, the drugs have been associated with irreversible damage to the optic nerve. NAION causes sudden and sometimes permanent blindness.
Research last year documented nine cases in the United States of patients experiencing severe vision loss after taking semaglutide or tirzepatide, the active ingredients in Ozempic and Mounjaro. Seven of the patients were diagnosed with NAION.
In one case, a woman who received a single dose of semaglutide for diabetes woke up blind in her left eye. After pausing treatment for two months, she resumed the medication, only to lose sight in her right eye within two weeks. Another patient taking semaglutide for a year noticed a “painless shadow” over her left eye, later found to be retinal blood vessel damage. A male patient on tirzepatide suffered retinal bleeding after a year on the drug.
Experts say the mechanism behind these complications is not fully understood. Rapid blood sugar reduction caused by GLP-1 drugs may damage ocular blood vessels, though the side effect remains rare, affecting roughly one in 10,000 patients.
Dr David Sinclair, a Harvard genetics professor, highlighted ongoing research into potential treatments for drug-induced blindness at the World Governments Summit in Dubai. Describing the condition as an “eye stroke,” Sinclair said his team has successfully restored vision in animal models by rejuvenating damaged cells to their stem-cell state.
“This regeneration method could repair damaged optic nerves,” Sinclair said. “Eventually, we aim to treat all tissues, potentially achieving a whole-body reset in six weeks.”
The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has updated product information to highlight the risk of NAION in patients using semaglutide. Officials advise anyone experiencing sudden changes in vision to seek immediate medical attention.
While the risk remains extremely small, Dr Alison Cave, MHRA chief safety officer, emphasised the importance of awareness among patients and healthcare professionals. NAION is more likely to affect individuals with diabetes, high blood pressure, or sleep apnea.
Most patients with NAION see improvement within days or weeks after discontinuing the drug, though some cases have resulted in lasting damage. Health authorities urge patients to remain vigilant for early signs of vision changes while taking GLP-1 medications.
