The condition, known as ischemic optic neuropathy, occurs when blood flow to the optic nerve is reduced. Because the optic nerve carries visual information from the eye to the brain, damage to it can lead to significant vision problems.

Study Links GLP-1 Drugs to Rare Vision Loss

The study, published in Annals of Internal Medicine, analyzed information from a large database of US adults ages 18 to 65 with Type 2 diabetes. Researchers focused on patients who had recently started taking medications to manage their condition, including a class of drugs known as glucagon-like peptide-1 receptor agonists, or GLP-1s.

These medications include semaglutide (sold as Ozempic and Wegovy) and tirzepatide (sold as Mounjaro and Zepbound). In addition to helping control blood sugar and manage weight, GLP-1 medications can reduce the risks of certain cardiovascular and kidney problems. However, scientists are still investigating their potential side effects as their use becomes increasingly widespread.

The researchers found that GLP-1 use was associated with a modest increase in the likelihood of ischemic optic neuropathy. Although the condition was uncommon, its potential consequences make the finding important.

"Although ischemic optic neuropathy was rare, it is clinically important because it can involve sudden vision loss," said Chintan Dave, a core faculty member of the Center for Pharmacoepidemiology and Treatment Science at Rutgers Institute for Health, Health Care Policy and Aging Research. "The increase in risk was small -- approximately three to four additional cases per 10,000 patients treated with GLP-1s over 18 months, but clinicians and patients should be aware of this potential association."

While the absolute risk remains low, researchers say the growing popularity of GLP-1 medications makes continued safety monitoring especially important. These drugs are now widely prescribed to people both with and without Type 2 diabetes.

Who May Be Most at Risk?

The study also identified patterns among patients who developed the eye condition. Cases were more common among men and adults in the older portion of the study population.

"Most patients in our study who had ischemic optic neuropathy were either men or men and women aged 50 to 65," said Dave, an associate professor at the Ernest Mario School of Pharmacy and the lead author of the study. "Because ischemic optic neuropathy can present with sudden vision loss, which may be permanent, early recognition of symptoms and prompt ophthalmologic evaluation may be especially important for patients at higher baseline risk."

More than 80% of ischemic optic neuropathy cases are estimated to involve the non-arteritic anterior form of the condition. This occurs when blood supply to the front portion of the optic nerve becomes insufficient, potentially damaging the nerve and interfering with vision.

The resulting vision loss is often permanent. According to Dave, approximately one-third of affected patients experience some recovery, usually during the first six months. Even when improvement occurs, some degree of visual impairment typically remains.

Rather than causing complete blindness, the condition usually affects part of the vision in one eye. Patients may notice sudden blurriness, dimming, or missing areas in their field of view.

Do Weight Loss Drugs Actually Cause Vision Loss?

Despite the association, the researchers caution that their findings do not establish that GLP-1 medications directly cause optic nerve damage.

Other factors, including differences in patients' underlying health conditions, could help explain the increased risk observed in the study. Additional research will be necessary to determine whether the medications themselves contribute to the condition.

For now, the findings highlight the importance of recognizing sudden vision changes and seeking prompt medical evaluation, particularly among people who may already be at greater risk.

The research team also included Kamika Reynolds and Kimberly O'Malley of the Institute for Health, along with Jason Roy of the Rutgers School of Public Health.