Another study has been published suggesting that patients taking semaglutide—the active ingredient in Novo Nordisk's blockbuster drug Ozempic—may face a higher risk of developing a rare eye condition that can lead to blindness. 

"The glucagon-like peptide 1 receptor agonist (GLP-1RA) semaglutide has quickly become a key treatment for managing type 2 diabetes and obesity. Recent findings have raised concern about a potential association between semaglutide use and non-arteritic anterior ischemic optic neuropathy (NAION)," according to a new Danish–Norwegian study, backing up similar results from a Harvard University study published in July. 

Non-arteritic anterior ischemic optic neuropathy, or NAION, occurs when blood flow to the optic nerve is blocked, causing sudden vision loss. 

Bloomberg first reported the results on Friday afternoon. The findings were initially published on Wednesday on medRxiv, an online platform for sharing research.

The results indicate that a type 2 diabetes patient taking Ozempic for two decades would have a .3% to .5% chance of developing NAION. 

"The vision loss is usually irreversible and there is no treatment. Given the serious nature of this potential adverse effect of semaglutide, we leveraged the nationwide Danish and Norwegian health registries to further investigate this association," according to authors from the University of Southern Denmark, Norwegian Institute of Public Health, and the University of Copenhagen.

The authors emphasized: "Given the well-established effects of semaglutide in managing both diabetes and obesity, it is crucial to weigh the potential risk of NAION against the substantial therapeutic benefits of semaglutide. While the association observed for the use of semaglutide in type 2 diabetes represents a two-fold or higher relative risk increase..." 

The Nordic study comes months after Harvard-affiliated Massachusetts Eye and Ear found the rising risk of Ozempic patients developing NAION. 

In Copenhagen, Novo shares slid as much as 5.4%. Since peaking in June at 1,000 Krone, shares have entered a bear market (-26%). 

Using Goldman's index of companies with high exposure to GLP-1s, the Trump dump pressured the index lower from nearly 40% gains on the year in late summer to hovering around 14% on Friday, while companies at risk from GLP-1s have steadily gained on the year, 13%.

In addition to the risk of vision loss, Ozempic and Wegovy users can also develop "Ozempic Face" after rapid body fat loss.