Science Day held in the NAION MDL

Judge Karen S. Marston held a "Science Day" on June 2, 2026, in MDL 3163, the federal multidistrict litigation over claims that GLP-1 drugs caused non-arteritic anterior ischemic optic neuropathy (NAION), a form of sudden and usually permanent vision loss ^[1][3]. At a Science Day, both sides present the underlying science in a non-adversarial setting so the judge can get up to speed ^[3]. Nothing is decided, no evidence is ruled admissible or inadmissible, and no case is won or lost.

MDL 3163 was created by the Judicial Panel on Multidistrict Litigation on December 15, 2025, and sits in the Eastern District of Pennsylvania before Judge Marston, who also oversees MDL 3094, the much larger litigation over gastrointestinal injuries ^[1][3]. The NAION MDL names Novo Nordisk and Eli Lilly as defendants, with Ozempic, Wegovy, Saxenda and Trulicity identified as drugs at issue in the JPML materials ^[1]; one litigation tracker also lists Mounjaro and Zepbound among included products ^[3].

The numbers behind the docket

The NAION MDL is small but growing fast. It started with 21 actions in December 2025 and reached 86 pending cases on the May 1, 2026 JPML report, 110 on the June 1, 2026 report, and 216 by September 1, 2026 ^[1][3]. For comparison, MDL 3094, the GI-injury litigation, had 3,763 cases pending as of June 1, 2026 ^[1].

The scientific dispute the judge heard has two sides. Plaintiffs lean on a July 2024 study from Massachusetts Eye and Ear published in JAMA Ophthalmology, which followed 16,827 patients and reported a 4.28-times higher NAION risk in patients with type 2 diabetes prescribed semaglutide (8.9% versus 1.8% cumulative incidence) and 7.64 times higher in patients prescribed it for weight loss (6.7% versus 0.8%) ^[2][3]. Later studies found smaller effects: a February 2025 analysis of 37.1 million patients reported a modest incidence rate ratio of 1.32, and a Danish-Norwegian study of more than 424,000 people found a 2.19-times higher rate compared with SGLT2 inhibitors ^[3].

Defense arguments center on confounding. NAION's known risk factors include diabetes, high blood pressure, sleep apnea, a "disc at risk" optic nerve anatomy, and age over 50 — conditions common among GLP-1 users ^[3]. NAION affects roughly 21,000 Americans a year, usually strikes one eye with sudden painless vision loss often noticed on waking, and involves the second eye in 15% to 25% of cases within five years ^[3]. Proposed biological mechanisms, including rapid metabolic changes affecting optic nerve blood flow, remain under investigation ^[3].

Regulators have split. In June 2025, the European Medicines Agency's safety committee concluded NAION is a "very rare" side effect of semaglutide and recommended adding it to European labels, with advice to stop the medicine if NAION is confirmed ^[3]. As of September 2026, the FDA had not added a NAION warning to U.S. labels for Ozempic, Wegovy or Rybelsus, and the agency was reportedly still evaluating the evidence ^[3]. That gap is central to the plaintiffs' failure-to-warn theory ^[3].

Why it matters for patients

A Science Day is a signal about timing, not about truth. It typically precedes decisions on case-management and bellwether schedules, so it marks the point where the NAION litigation starts moving from organization to substance ^[3]. It does not establish that GLP-1 drugs cause NAION, and it does not change any drug label.

For people taking or considering semaglutide, the practical situation is unchanged as of the most recent source check: U.S. prescribing information for Ozempic, Wegovy and Rybelsus carries no NAION warning, while European labels do ^[3]. The studies themselves disagree on how large any risk is — from 1.32 times to more than 7 times — and none of the sources here establish causation ^[3]. Whether the FDA will act, and when, is not yet known.

What happens next

No bellwether trial date has been set in either GLP-1 MDL as of public orders reviewed on June 17, 2026, and no global settlement was located ^[1]. In the NAION MDL, later public orders include Case Management Orders No. 9 and No. 10 and an April 30, 2026 amended scheduling order ^[1]. In the GI MDL, the court set a Rule 702 expert hearing window for September 10–18, 2026, with status conferences on October 13, November 17 and December 15, 2026 ^[1].