When starting any new medication, it’s important to familiarize yourself with potential side effects. Fortunately, so much research has come out about diabetes and weight-loss drugs like Ozempic and Wegovy that we know constipation, bloating, heartburn, and gastrointestinal discomfort aren't out of the ordinary. However, now that semaglutide injections are becoming more mainstream, lesser-known complications of the drugs are coming to light. In fact, a new study says GLP-1 medications could cause patients to permanently lose their vision.
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Research identifies vision loss as a potentially dangerous side effect of GLP-1 medications.
Concerns regarding vision loss in connection with GLP-1 drugs have been circulating in the medical field for quite some time.
A previous study published in 2024 found that people using semaglutide are four times more likely to develop a rare but scary eye condition called nonarteritic anterior ischemic optic neuropathy, or NAION for short. But in January 2025, a new study published in the journal JAMA Ophthalmology took this discovery one step further.
The study’s research team, led by ophthalmologist Bradley Katz, PhD, says both semaglutide (sold under brand names like Ozempic and Wegovy) and tirzepatide (sold under brand names like Mounjaro and Zepbound) can lead to NAION, as well as an additional two blinding-eye conditions.
“Between 2-3% of the U.S. population received a prescription for one of these medications in 2023,” Katz told MedicalNewsToday. “Because so many people are using these medications it’s critical to monitor any ill effects on the eye or other parts of the body.”
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Here's how weight-loss drugs can affect vision.
Of the nine patients (ages 37 to 77) assessed in the study, seven were diagnosed with NAION following the use of weight-loss drugs. Both active ingredients, semaglutide and tirzepatide, were represented in the study.
“One [participant] developed a stroke in the retina—this is the part of your eye that absorbs light and turns it into an electrical signal for your brain,” explained Katz, adding that NAOIN can have serious consequences: “This stroke also causes irreversible loss of vision in one eye.”
In addition to NAOIN, some patients developed papillitis (inflammation of the optic nerve) and paracentral acute middle maculopathy (impacting your eyes’ blood vessels).
According to Katz, a disruption in eye vision can be caused by a number of variables. But in terms of GLP-1 medications, fluctuating blood sugar levels are likely to blame.
“These drugs are very effective at reducing blood sugar and when one rapidly reduces blood sugar it can cause swelling in the optic nerve,” he told the health outlet. “It can also temporarily worsen diabetic eye changes. How it causes swelling is thought to be due an osmotic shift. When there’s more ‘stuff’ in your blood—in this case sugar—and you suddenly reduce the amount of stuff in the blood, it causes rapid shifts in fluid between blood vessels and cells in the eye.”
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The takeaway:
The study warns that semaglutide and tirzepatide can potentially cause “irreversible loss of vision.” But does that mean you shouldn’t use Ozempic or Zepbound? Not necessarily. Researchers say these eye conditions are rare; however, patients experiencing any abnormal or drastic changes in vision should notify their doctor immediately before irreversible damage is caused.
“What we are recommending is that if you experience a change in your vision while using one of these drugs, you should consult the prescribing doctor and see an ophthalmologist,” said Katz.
He continued, “We are also recommending that if patients are starting these drugs or increasing the dose of these drugs, they should do so slowly to reduce the risk of dropping their blood sugar and causing an osmotic shift.”
