Newswise — A new study suggests patients taking semaglutide — the active ingredient in Ozempic and Wegovy — may be at higher risk of developing an eye condition that can cause blindness. Non-arteritic anterior ischemic optic neuropathy or NAION, happens when blood flow to the optic nerve is blocked, causing sudden, painless loss of vision in one eye.

Here’s what the American Academy of Ophthalmology and the North American Neuro- Ophthalmology Society want you to know about this study published July 3 in JAMA Ophthalmology:

  • This is not the type of study that can show the treatment caused NAION. But the careful analysis conducted by the Harvard neuro-ophthalmology research team did identify a potential link between semaglutide treatment and NAION. This intriguing finding should inspire more research that will help clarify if semaglutide does cause NAION.
  • Semaglutide was rigorously studied in several randomized, controlled trials worldwide. The U.S. FDA approved semaglutide for medical use in 2017. Many millions of people take this medicine throughout the world. This is the first study to report an association between semaglutide and NAION.
  • The subjects in this study were either overweight or obese or had type 2 diabetes. People who have diabetes are already at risk of NAION. Other risk factors for NAION include heart disease, history of heart attack, high blood pressure, and sleep apnea.
  • All the patients included in the study were seen at the same large eye hospital, which treats most of the region’s NAION patients, making it hard to determine if this association is true of all people taking semaglutide. A postmarketing surveillance study – a type of study that monitors the safety and effectiveness of a product after it has been released to patients – could be helpful in determining if there is a connection between semaglutide and NAION.

Implications for Patients

  • At this time, we do not recommend that people stop taking semaglutide.
  • If you take semaglutide and have a sudden loss of vision, stop taking the drug and see a doctor immediately.
  • Is it safe for people who previously had NAION? The study offers no information about people who previously had NAION who then developed it again following a prescription for semaglutide.  
  • Should people also be concerned about other diabetes drugs, such as tirzepatide (Zepbound or Mounjaro)? Semaglutide is the only drug investigated in this study.
  • Patients should talk with their primary care physician to determine if semaglutide is right for them.

NAION Symptoms

  • The people in the study developed NAION symptoms following their first prescription of semaglutide. NAION symptoms include:
    • Blurred vision
    • Color distortion
    • Loss of peripheral vision
    • A dark or gray spot in the vision that doesn't move
    • Loss of contrast or light sensitivity 
  • NAION usually happens without any warning. Vision loss can range from mild to severe. Most people don’t feel pain, but it can occur in up to 10 percent of patients. If there is pain, it may be an indication of another cause of vision loss. There is no cure for NAION.

Other Vision Changes Linked to Semaglutide

  • While the link to NAION is new, the medical community has been aware of other vision changes with semaglutide for some time. Previous studies have shown that semaglutide can cause blurred vision, worsening of diabetic retinopathy and macular complications. However, this appears to be a temporary side effect that goes away after three or four months.
  • How can semaglutide cause temporary vision changes? When the body experiences a change in sugar level, it can affect the shape of the eye’s lens. This change is what causes blurry vision.
  • Could a similar phenomenon be at play in this study? Could the ability of semaglutide to rapidly reduce glucose levels and blood pressure cause NAION and not the drug itself? It’s unknown. Only further research can answer that question.

Journal Link: JAMA Ophthalmology