A new study published in JAMA Ophthalmology has revealed a concerning association between popular diabetes and weight-loss medications Ozempic and Wegovy and a rare eye condition that can cause permanent blindness. Researchers at Harvard Medical School found that patients prescribed semaglutide, the active ingredient in both drugs, faced significantly elevated risks of developing non-arteritic anterior ischemic optic neuropathy (NAION).
Study Findings Reveal Elevated Risk
The research, led by Joseph Rizzo, professor of ophthalmology at Harvard Medical School, analyzed data from more than 16,000 patients treated at Mass Eye and Ear over a six-year period. The study compared patients who received semaglutide prescriptions with those taking other diabetes or weight-loss medications.
Among patients with type 2 diabetes, those prescribed semaglutide were more than four times more likely to develop NAION. The data showed 17 NAION events occurred in semaglutide patients compared to six in those taking other diabetes drugs. Over three years, 8.9% of people on semaglutide developed NAION compared to 1.8% on alternative medications.
The risk was even more pronounced in overweight or obese patients, who were more than seven times as likely to develop the condition. In this group, 20 NAION events occurred in semaglutide patients compared to three in those on other weight-loss drugs, with 6.7% developing NAION over three years versus 0.8% on other treatments.
Understanding NAION
NAION represents the second-leading cause of optic nerve blindness, though it remains relatively uncommon, affecting approximately 10 out of 100,000 people in the general population. The condition occurs due to insufficient blood flow to the optic nerve, typically resulting in sudden, painless vision loss in one eye that patients often notice upon waking.
"The visual loss caused by NAION was painless and could progress over many days before stabilising," Rizzo explained. Currently, no effective treatments exist for NAION, and vision often does not improve following diagnosis.
Research Origins and Methodology
The investigation was prompted by an unusual cluster of cases in Rizzo's practice last summer, when three patients taking semaglutide were diagnosed with NAION-related vision loss within a single week. This observation led researchers to examine potential connections between the medication and the eye condition.
The study examined 16,827 patients, including 710 with type 2 diabetes (194 prescribed semaglutide) and 979 who were overweight or obese (361 prescribed semaglutide). The research team tracked NAION diagnoses across both groups over the study period.
Clinical Implications and Expert Perspectives
Rizzo emphasized the significance of the findings while acknowledging their preliminary nature: "The use of these drugs has exploded throughout industrialised countries and they have provided very significant benefits in many ways, but future discussions between a patient and their physician should include NAION as a potential risk."
He stressed that "the increased risk relates to a disorder that is relatively uncommon" and noted that the findings "should be viewed as being significant but tentative, as future studies are needed to examine these questions in a much larger and more diverse population."
Graham McGeown, honorary professor of physiology at Queen's University Belfast, provided additional context: "This research does suggest an association between semaglutide treatment and one form of sight-threatening optic neuropathy, but this would ideally be tested in larger studies."
Study Limitations and Future Research
The researchers acknowledged several limitations to their study, including the relatively small number of NAION cases observed over the six-year period and the fact that Mass Eye and Ear sees an unusually high number of patients with rare eye diseases, which may not represent the general population.
Rizzo recommended that the information "should be included in discussions between patients and their doctors, especially if patients have other known optic nerve problems like glaucoma or if there is pre-existing significant visual loss from other causes."
Manufacturer Response
Novo Nordisk, which manufactures both Ozempic and Wegovy, responded to the study findings through a spokesperson: "Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from use of our medicines very seriously."
The company noted that "NAION is not listed as a known adverse drug reaction in the Summary of Product Characteristics for the marketed formulations of semaglutide (Ozempic and Rybelsus for type 2 diabetes and Wegovy for weight management) as per the approved labels."
The research adds to the growing body of knowledge about semaglutide's effects as its use continues to expand globally for both diabetes management and weight loss applications.
