Lawsuits Pursue Manufacturers of Weight-Loss Drugs After Reports of Rare Vision Loss

Manufacturers of GLP-1 drugs are facing a wave of lawsuits filed by hundreds of consumers, alleging that these drugs may be linked to an increased risk of a rare type of vision loss known as "nonarteritic anterior ischemic optic neuropathy."

According to the Wall Street Journal, plaintiffs claim GLP-1 drugs caused them to develop the condition, which occurs when blood flow to the optic nerve suddenly decreases, leading to a sudden loss of vision.

Nonarteritic anterior ischemic optic neuropathy is one of the most common causes of acute optic nerve injury in adults over 50, and the American Academy of Ophthalmology and the National Eye Institute describe it as similar to an "eye stroke."

Dr. Douglas Lazaro, an ophthalmologist at New York Langone Health, said the danger of the condition lies in the lack of any proven treatment, explaining that "the problem with nonarteritic anterior ischemic optic neuropathy is that there is no treatment for it. So it can cause very severe vision loss."

The drugs in question include widely used products for weight loss and diabetes treatment, among them Novo Nordisk’s Ozempic and Wegovy, and Eli Lilly’s Mounjaro and Zepbound.

Both companies denied a proven causal link between their drugs and the condition, according to the Wall Street Journal.

Novo Nordisk said the lawsuits are "without merit," pointing to company-funded research that did not find an increased risk of nonarteritic anterior ischemic optic neuropathy among users of its drugs.

Eli Lilly said it continues to monitor safety data and emphasized that currently available studies do not prove that GLP-1 drugs cause this condition.

What is nonarteritic anterior ischemic optic neuropathy?

The condition typically causes a sudden, painless loss of vision in one eye. Symptoms can appear as blurriness or dimming of vision, loss of part of the peripheral visual field, or reduced ability to distinguish colors.

Symptoms often appear upon waking in the morning. Major risk factors include older age, diabetes, high blood pressure, high cholesterol, obstructive sleep apnea and smoking.

Data indicate that many users of GLP-1 drugs — particularly those with diabetes or obesity — have these risk factors, which makes determining a relationship between the drugs and the condition more complicated. Diabetes itself is a known risk factor for nonarteritic anterior ischemic optic neuropathy, making it difficult for observational studies to separate the effect of the disease from that of the medication.

Vision loss from this condition is often permanent, although some patients may regain part of their sight over time, and there is currently no proven treatment that can reverse the damage to the optic nerve.

Amid debate over a possible link between GLP-1 drugs and the condition, experts emphasize that patients should not stop prescribed medications on their own and must consult their doctor before making any changes in treatment, especially since these drugs are widely used to treat diabetes and obesity and have proven health benefits for those conditions.