The FDA is warning users of GLP-1 drugs of the potential for increased risk of a serious eye condition that can lead to sudden blindness. The condition is caused by a decrease in blood flow to the front part of the optic nerve, however the underlying cause is still unknown. Several manufacturers have said there is no proof of cause-and-effect tying the vision risks to weight loss and diabetes medication. The FDA says the new warning comes after researchers evaluated a slew of data including clinical trials and animal studies. The condition is permanent with no treatment. The warning covers all GLP-1s, including Novo Nordisk’s Ozempic and Wegovy and Eli Lilly’s Mounjaro and Zepbound, as well as several older GLP-1 diabetes medications.