The European Medicines Agency warned that semaglutide is associated with a rare risk of non-arteritic anterior ischemic optic neuropathy (NAION). The agency recommended updating product information for the medicines to include this condition as a very rare side effect.

Following a review of available data from June 2 to June 5, 2025, the Pharmacovigilance Risk Assessment Committee (PRAC) concluded that NAION is a side effect of semaglutide medicines. The committee determined the frequency is very rare, affecting up to 1 in 10,000 people taking the medication.

Semaglutide is a GLP-1 receptor agonist marketed under the brand names Ozempic and Wegovy. These GLP-1 receptor agonists are used for the treatment of type 2 diabetes and weight loss. The European Medicines Agency is the highest regulatory authority on medicines in the European Union.

NAION is caused by a reduction in blood flow to the optic nerve head and can lead to vision loss. Symptoms include sudden painless vision loss in one eye, a dim or dark area in part of the visual field, and swelling of the optic nerve.

Researchers have not yet established that GLP-1 medications directly cause NAION. People with diabetes are at higher risk of developing NAION regardless of medication use.

"People with diabetes are known to be at higher risk of developing NAION regardless of medication use, so more research is necessary to confirm what role semaglutide medications have in this occurrence, if at all," ophthalmologist Raj Maturi said.

Optometrist Teri Geist emphasized the need for vigilance without alarm. "Most people taking GLP-1 medications will never experience a serious eye complication," she said.

Geist advised patients to maintain regular eye care rather than discontinuing treatment based on these findings alone. "These findings don’t mean patients should stop taking their medication, but they do reinforce the importance of a baseline comprehensive eye exam and regular follow-up care so doctors of optometry can identify changes early and adjust monitoring based on each patient’s eye health and risk factors," she said.

Some people may notice temporary blurry or fluctuating vision after starting a GLP-1 medication. This temporary blurry vision associated with GLP-1 drugs is often caused by rapid changes in blood sugar affecting the shape of the eye’s lens.

"When the body experiences a drastic change in sugar level, it can affect the shape of the eye’s lens," Maturi said. "These changes can temporarily affect the eye’s refractive error and cause osmotic changes in the natural lens, making vision seem blurry or inconsistent until the body adjusts."

Geist noted that vision typically improves as the body adapts to the medication. "As blood sugar stabilizes, vision often stabilizes as well," she said. However, she cautioned that not every visual change is benign.

"Not every episode of blurry vision is harmless," Geist said. "While temporary refractive changes are common, blurred vision can also be an early sign of a more serious eye condition, particularly in people with diabetes or preexisting retinal disease." She added, "That’s why patients shouldn’t ignore new visual symptoms."

Starting a GLP-1 medication can trigger a temporary worsening of diabetic retinopathy symptoms, usually within the first 12 months. Ophthalmologist Dagny Zhu stated that this effect is generally short-lived. "This (worsening) is temporary, usually occurring within the first 12 months, and the overall long-term effect of GLP-1 on diabetic retinopathy is beneficial," Zhu said. "If anything, some studies have shown a protective effect." Studies have shown potential relationships between GLP-1 drugs and ophthalmic conditions including neovascular age-related macular degeneration and diabetic retinopathy.

Dehydration from gastrointestinal side effects of GLP-1 drugs may worsen dry eye symptoms. There is no evidence suggesting that GLP-1 use causes dry eye, she said. "Dehydration may worsen dry eye symptoms or make existing dry eye more noticeable." She advised patients to report specific symptoms to their providers. "Patients experiencing dryness, burning, irritation, fluctuating vision or excessive tearing should let their optometrist know," she said.

In 2024, the FDA added a warning about pulmonary aspiration during general anesthesia or deep sedation to most GLP-1 drugs. The FDA warning on pulmonary aspiration followed rare postmarketing reports of the condition in patients undergoing surgery. The American Society of Anesthesiologists initially called for stopping GLP-1 drugs before surgery but now states most patients can continue taking them until the day of surgery.

Why It Matters

The European Medicines Agency's identification of a rare link between semaglutide and non-arteritic anterior ischemic optic neuropathy requires updated product information for medications used in diabetes treatment and weight loss. Although researchers have not established direct causation and people with diabetes face higher baseline risks, the potential for vision loss affects up to 1 in 10,000 users. This development adds to existing data connecting GLP-1 drugs to various ophthalmic conditions, including diabetic retinopathy and macular degeneration.