GLP-1 vision loss lawsuits get their own federal court group

The U.S. Judicial Panel on Multidistrict Litigation has created a second federal consolidation for lawsuits alleging that GLP-1 medications caused non-arteritic anterior ischemic optic neuropathy, or NAION, a form of sudden vision loss. The new proceeding, MDL No. 3163, was created December 15, 2025, and assigned to U.S. District Judge Karen S. Marston in the Eastern District of Pennsylvania ^[1][2][3].

The Panel declined requests to fold the vision cases into the existing GLP-1 gastrointestinal injury MDL, No. 3094, also before Judge Marston. It concluded that NAION is a distinct injury that calls for different expert witnesses and different causation evidence than the stomach and bowel claims. The vision MDL lists ophthalmology and neuro-ophthalmology as its expert areas, while the older case relies on gastroenterology ^[1][2].

Both proceedings name Novo Nordisk, the maker of Ozempic, Wegovy and Rybelsus, and Eli Lilly, the maker of Mounjaro and Zepbound. Tirzepatide, the active ingredient in Mounjaro and Zepbound, is a dual GIP/GLP-1 receptor agonist rather than a pure GLP-1 drug ^[2][4].

Case filings have grown quickly. MDL 3163 held 216 pending cases as of September 1, 2026, according to Judicial Panel statistics ^[3], after starting with roughly 21 filings in December 2025 ^[2]. One litigation tracker put the opening count nearer 30 and reported more than 130 cases by early July 2026 ^[4]. The gastrointestinal MDL held 4,022 pending cases as of the same September 2026 report, for a combined total of 4,238 federal GLP-1 lawsuits ^[3][5]. Claims in the vision MDL include failure to warn, design defect and breach of warranty ^[1].

The central factual dispute is whether the drugs can cause NAION. A Harvard-affiliated study of 16,827 patients published in JAMA Ophthalmology in July 2024 found a 4.28 times higher risk among patients with type 2 diabetes (8.9 percent versus 1.8 percent cumulative incidence) and a 7.64 times higher risk among patients treated for weight loss (6.7 percent versus 0.8 percent) ^[2][5]. A Veterans Affairs study of 588,168 patients published in JAMA Network Open in 2026 found a 35 percent higher risk, with 39 NAION cases per 10,000 GLP-1 users versus 29 per 10,000 users of SGLT2 diabetes drugs ^[5]. Earlier registry research from Denmark and Norway covering more than 424,000 patients reported a 2.19 times higher risk against SGLT2 inhibitors, and a separate analysis of 37.1 million patients found a modest elevation ^[2]. These are observational studies, which can show an association but do not by themselves prove that the drugs cause the injury. Defendants have pointed to pre-existing conditions common in this patient group, including diabetes, high blood pressure and sleep apnea, as possible explanations ^[2].

Regulators have acted differently across countries. The European Medicines Agency concluded in June 2025 that NAION is a "very rare" side effect of semaglutide and recommended adding it to European labels ^[2][4]. Australia's regulator added NAION warnings to the product information for Ozempic, Wegovy, Mounjaro, Saxenda and Trulicity in July 2026 ^[5]. U.S. labels for Ozempic, Wegovy and Rybelsus still contained no NAION warning as of September 2026, a gap plaintiffs call central to their failure-to-warn claims ^[2][4].

"This Order recognizes that vision loss is a fundamentally different injury that demands focused attention," said Cameron Stephenson of the law firm Levin Papantonio, a member of the plaintiffs' executive committee in the gastrointestinal MDL ^[1].

Why it matters for patients

NAION happens when blood flow to the optic nerve is reduced. It is typically sudden and painless, often noticed upon waking, and usually affects one eye first; the second eye is affected in 15 to 25 percent of cases over five years. There is no proven treatment that restores lost vision, and the condition affects roughly 21,000 Americans a year from all causes ^[1][2].

Because the U.S. labels do not mention NAION, patients on these drugs in the United States are not receiving the same written information as patients in Europe or Australia ^[2][4][5]. The lawsuits do not change what the drugs are approved for, and they do not establish that the drugs caused any individual's vision loss. Judge Marston has ordered the litigation to address two threshold questions first: whether GLP-1 drugs are capable of causing NAION, and whether federal law preempts the failure-to-warn claims ^[5]. The outcome of that phase will shape whether the remaining cases proceed.

Court records do not show any change to prescribing instructions in the United States, and no national screening program for eye exams on GLP-1 drugs has been reported ^[2][4].

What happens next

Judge Marston held a Science Day on June 2, 2026, where both sides presented non-adversarial scientific evidence on the GLP-1 and NAION link ^[2][5]. Under her case management order, plaintiffs' proposed fact sheet was due September 25, 2026, and a master complaint by October 28, 2026. Fact discovery against Lilly is due December 18, 2026, and against Novo Nordisk on February 26, 2027. Plaintiffs' general causation experts are due March 26, 2027, defense reports April 23, 2027, and expert depositions must finish by June 4, 2027. Expert challenges and summary judgment motions are due July 2, 2027, with oppositions August 13 and replies August 31, 2027 ^[5].

Bellwether trials in the vision MDL are likely years away, and no global settlement has been reported in either federal proceeding ^[2][4].