A federal judicial panel on Monday ordered that a growing number of lawsuits accusing Novo Nordisk and Eli Lilly of causing vision loss be centralized before a single judge in Pennsylvania, marking a significant new phase in litigation over the widely used weight-loss and diabetes drugs.

The U.S. Judicial Panel on Multidistrict Litigation (JPML) ruled that the cases should proceed as a separate multidistrict litigation (MDL) in federal court in Philadelphia, rather than being folded into an existing MDL involving gastrointestinal side effects linked to the same class of medications. The new proceedings will also be overseen by U.S. District Judge Karen Marston, who is already presiding over the gastroparesis-related litigation.

Although the injuries alleged in the two sets of cases differ, the panel said there would be enough overlap for efficiency if both MDLs were handled by the same judge, while still proceeding separately due to distinct medical and scientific issues.

Allegations of Vision Loss

The lawsuits allege that the drugs—including Novo Nordisk’s Ozempic, Wegovy, and Saxenda, and Eli Lilly’s Trulicity—can trigger non-arteritic anterior ischemic optic neuropathy (NAION), a condition caused by reduced or blocked blood flow to the optic nerve. NAION can result in sudden and often permanent vision loss, and in some cases, blindness.

There are currently about 30 optic neuropathy lawsuits pending in federal court, along with more than 40 similar cases in state courts, according to court records. The claims began appearing more frequently after a July 2024 study raised concerns about a possible association between the drugs and NAION.

Novo Nordisk and Eli Lilly did not immediately respond to requests for comment following the panel’s decision. In previous court filings, both companies have denied liability, arguing that no definitive causal link has been established between their drugs and the alleged injuries.

Separate From Gastroparesis Litigation

The companies had urged the JPML to add the vision-loss cases to the existing MDL over gastroparesis, a condition involving paralysis of the gastrointestinal tract. That MDL, also overseen by Judge Marston, currently includes nearly 3,000 lawsuits.

Plaintiffs, however, argued that optic neuropathy involves different medical questions, scientific evidence, and expert testimony. The panel agreed, concluding that the vision-loss cases warranted their own MDL.

Attorneys for the plaintiffs welcomed the decision, saying they look forward to working with Judge Marston as the litigation moves forward.

Drugs Widely Used in the US

The medications at the center of the lawsuits belong to a class known as GLP-1 receptor agonists, injectable drugs that mimic a hormone regulating blood sugar, slowing digestion and increasing feelings of fullness. Originally developed to treat diabetes, several versions are now also prescribed for weight loss.

The drugs are among the most widely used medications in the United States. A study by the Centers for Disease Control and Prevention (CDC) published in August found that more than one in four adults with diabetes had used a GLP-1 drug.

Scientific Evidence Still Emerging

While a small number of patients taking GLP-1 drugs have reported vision problems, a direct causal link has not been conclusively established, according to recent research.

A retrospective study published online on January 30 in JAMA Ophthalmology examined nine patients who experienced vision problems while using semaglutide (Ozempic and Wegovy) or tirzepatide (Mounjaro and Zepbound). The study found that seven patients had NAION-like symptoms, while others experienced conditions such as optic nerve inflammation or vision loss related to retinal blood flow.

The study was prompted after senior author Dr. Bradley J. Katz of the University of Utah Health observed a patient who developed sudden, painless vision loss after starting semaglutide, and then experienced similar loss in the other eye after resuming the drug. Katz sought feedback from colleagues nationwide, leading to the identification of similar cases.

Researchers emphasized that such incidents remain rare, but expressed concern due to the rapidly growing use of the drugs. A 2024 study found that 12 percent of the US population has taken a GLP-1 medication at some point, and about 6 percent are currently using one.

Caution Urged, Not Alarm

Experts involved in the research stressed that patients should not stop taking the medications without consulting their doctors, noting that the drugs provide well-documented benefits for diabetes and weight management.

However, they advised patients experiencing blurred vision or vision loss while on GLP-1 drugs to seek immediate medical attention. The authors also called for a post-marketing safety survey, in coordination with the American Academy of Ophthalmology, to better assess potential ocular risks.

As the new MDL moves forward, Judge Marston will oversee pretrial proceedings, including discovery and expert testimony, in a case that could have major implications for drug safety oversight and one of the most lucrative pharmaceutical markets in recent years. (ILKHA)