Popular weight loss, diabetes drugs linked to blindness

People who take Ozempic or Wegovy may have a higher risk of developing a rare form of blindness called naion, a new study suggests. Still, doctors say it shouldn’t deter patients from using the medicines to treat diabetes or obesity. The condition is relatively rare — up to 10 out of 100,000 people in the general population may experience it — but the doctors noted three cases in one week, and each of those patients was taking semaglutide (antidiabetic) medications.

In a study, published Wednesday3 July in the medical journal JAMA Ophthalmology, cannot prove that semaglutide medications cause naion. And, the small number of patients, an average of about 100 cases were identified each year, from one specialized medical centre may not apply to a broader population.

Novo Nordisk, the manufacturer of the only semaglutide medications in the US, emphasized that the data in the new study is not sufficient to establish a causal association between the use of semaglutide medications and naion. “Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from the use of our medicines very seriously,” notes the manufacturer. Semaglutide prescriptions have soared in the US, which could raise the number of people at risk for a potential side effect. And naion is the second-leading cause of optic nerve blindness after glaucoma. But, even with an increased risk, the condition remains relatively uncommon.

“The use of these drugs has exploded throughout industrialized countries and they have provided very significant benefits in many ways, but future discussions between a patient and their physician should include naion as a potential risk”, lead researcher Dr Joseph Rizzo, director of the neuro-ophthalmology at Mass Eye and Ear and a professor at the Harvard Medical School, said in a news release. “Our findings should be viewed as being significant but tentative, as future studies are needed to examine these questions in a much larger and more diverse population.”

Experts agree that the potential risk of naion should not deter the use of semaglutide medications to treat diabetes or obesity. “In the ever-changing landscape of systemic therapies, being vigilant for potential new disease associations is a duty we all share on behalf of patients,” Susan Mollan, an ophthalmologist with the University Hospitals Birmingham in the UK wrote in a related commentary.

The ways that semaglutides interact with the eyes are not entirely understood. And, the exact cause of naion is not known either. The condition causes damage to the optic nerve, but there is often no warning before vision loss.

Changes in blood sugar levels can affect the shape of the lens of the eye and may affect vision, said Dr Disha Narang, an endocrinologist and director of obesity medicine at Endeavor Health in Chicago. She was not involved in the new study. And, the use of semaglutides, which prompt the body to create more insulin to reduce blood sugar, has been previously linked to temporary vision changes — new or worsening cases of diabetic retinopathy.