The European Medicines Agency’s (EMA) safety committee announced on Friday that popular weight loss and diabetes medications from Novo Nordisk — Wegovy and Ozempic — may, in very rare cases, cause serious eye conditions that can lead to vision loss, Reuters reported.

Previous studies involving patients with type 2 diabetes had linked Ozempic to a condition called non-arteritic anterior ischemic optic neuropathy (NAION). However, this is the first time a regulatory authority has officially confirmed the side effect. According to the EMA, up to 1 in 10,000 people taking semaglutide — the active ingredient in Wegovy, Ozempic, and another Novo diabetes drug, Rybelsus — may be affected by this condition.

The EMA, which launched a review in December, has requested that the Danish drugmaker update the product information for all semaglutide-containing medications to include NAION as a “very rare” side effect. Inflammation is the second most common cause of blindness due to optic nerve damage, following glaucoma.

Novo Nordisk stated that it would cooperate with the EMA to update labeling but noted that clinical trials and post-market studies have not demonstrated a reasonable likelihood that the drugs cause this condition.

Wegovy and Eli Lilly’s Zepbound are currently the two leading weight-loss drugs dominating a market expected to reach \$150 billion within the next decade.

The EMA reported that several large-scale studies involving type 2 diabetes patients indicated that the use of Novo Nordisk drugs could double the risk of developing NAION.

A major study involving nearly 350,000 diabetes patients, published earlier this year, found that the risk of developing NAION more than doubled with long-term semaglutide use compared to patients taking medications from other drug classes.