Hundreds of thousands of Australians taking popular diabetes and weight-loss drugs have been warned to watch for changes to their vision after a rare but serious side effect was identified.

An estimated 500,000 Australians are using medicines such as Ozempic, Wegovy and Mounjaro, with some researchers predicting one in 10 Australians could be taking the treatments by 2030.

The Therapeutic Goods Administration has issued a warning that GLP-1-based drugs could be linked to 36 rare cases of an eye rare disorder called non-arteritic anterior ischaemic optic neuropathy (NAION), which can cause permanent vision loss.

Optometry Australia has alerted eye health professionals, urging patients who notice vision changes while taking the drugs to stop use and seek urgent medical attention.