Popular GLP-1 medicines including Ozempic, Wegovy and Mounjaro are facing lawsuits in the US over allegations that they may be linked to a rare eye condition called non-arteritic anterior ischaemic optic neuropathy (NAION), which can cause sudden and potentially permanent vision loss.
NAION occurs when blood flow to the optic nerve is disrupted. Vision loss is typically sudden and painless and can be permanent. Diabetes itself is also a known risk factor for the condition, making it difficult to establish whether a reported case is caused by the medicine or underlying health conditions.
Research into a possible connection with GLP-1 medicines has produced mixed findings. A 2024 study raised concerns about semaglutide and NAION, but subsequent research has not established that GLP-1 medicines cause the condition. The US FDA has also been evaluating the potential safety signal.
European regulators have reached a more specific conclusion for semaglutide. The European Medicines Agency classified NAION as a very rare side effect, estimating that it may affect up to one in 10,000 people taking semaglutide. It recommended updating product information to reflect the risk.
The current evidence does not establish the same level of risk for every GLP-1 medicine. Anyone taking these medicines who experiences sudden or rapidly worsening vision should seek urgent medical assessment rather than stopping treatment without medical advice.
