Several people diagnosed with a rare eye condition that can cause sudden and alarming vision loss say they believe the problem may be linked to weight-loss medications. Their accounts come as medical experts urge patients to consider eye examinations before starting these drugs.

The concerns follow a recent safety alert from the UK’s medicines regulator, which received reports connecting the drug Semaglutide—sold under the brand names Ozempic, Wegovy and Rybelsus—to a rare condition known as NAION (Non-Arteritic Anterior Ischemic Optic Neuropathy).

Often described as an “eye stroke,” NAION can cause sudden, painless loss of vision, usually affecting one eye but sometimes both. The condition is believed to result from reduced blood flow to the optic nerve. Known risk factors include sleep apnoea, high blood pressure and type 2 diabetes.

New research published in the British Journal of Ophthalmology suggests that the weight-loss injection Wegovy may carry a higher risk of sudden vision loss than other Semaglutide medications. Wegovy is approved by the NHS for weight management at higher doses, while Ozempic and Rybelsus are primarily used to treat type 2 diabetes.

Peter Osler, 68, from Harrogate, says he developed NAION in both eyes after being prescribed Ozempic for diabetes. He lost his peripheral vision and describes his sight as similar to “looking through binoculars.” After his diagnosis, he had to stop working and give up driving.

“The common thread with NAION is that people often wake up with it,” he said. “But I wasn’t asleep when it happened. I’ve never had high blood pressure, so in my mind Ozempic is the only possible cause.”

Although Peter has diabetes, he says his condition had always been well controlled and he had never shown signs of diabetic eye disease. He now worries about the widespread use of Semaglutide for weight loss.

“My experience has been frightening and life-changing,” he said. “You lose your independence, your mobility, and you suddenly depend on others.”

Research also suggests the odds of developing NAION may be nearly five times higher for people taking Wegovy compared with Ozempic, and more than three times higher in men than in women.

Another patient, identified only as “Miles” from Hertfordshire, told ITV News he developed NAION in one eye after using Ozempic and later Wegovy. He chose to remain anonymous because he fears the stigma surrounding vision loss could affect his career.

“Now that I understand the implications, I regret taking the medication,” he said. “It helps many people, but people should be aware of the risks.”

Miles said he now lives with the constant fear of another NAION episode that could further damage his sight. Doctors later discovered he has a “crowded optic nerve,” sometimes called a “disc at risk,” which can increase vulnerability to the condition.

In the United States, Todd Engel from Maryland says his life changed completely after suffering two NAION events that left him fully blind. He had been taking Ozempic to manage diabetes.

“This isn’t just a side effect,” Engel said. “It’s a catastrophic, life-changing injury. I’ll never see my wife, my children or my grandchildren again.”

Engel is one of more than 20 people in the U.S. pursuing legal action against the drug’s manufacturer, Novo Nordisk.

Medical authorities stress that NAION linked to Semaglutide remains extremely rare. European regulators estimate the condition may affect up to one in 10,000 patients taking the medication. However, experts say awareness and informed decision-making are essential.

Dr. Sui Wong, a neuro-ophthalmologist at Moorfields Eye Hospital, says patients should discuss potential risks with their doctors before starting treatment.

“Even if the risk is small, for the person affected it can be devastating,” she said. “Having an informed conversation and possibly an eye check beforehand could help people make better decisions.”

Novo Nordisk said patient safety remains its top priority and noted that product information for Ozempic, Wegovy and Rybelsus has already been updated to include NAION as a very rare potential side effect. The company maintains that current evidence does not establish a direct causal link between Semaglutide and the condition.

Patients experiencing sudden vision changes while taking these medications are advised to seek immediate medical attention.