(The Hill) — Those who take Ozempic or Wegovy may have an increased risk of developing a rare form of blindness, though future research is needed to make a final determination, researchers in a new study said.

Published Wednesday in the medical journal JAMA Ophthalmology, the study analyzed more than 16,800 people in the Boston area over the past six years, none of whom initially had the eye condition, called nonarteritic anterior ischemic optic neuropathy (NAION).

NAOIN occurs when there is a loss of blood flow to the optic nerve that typically causes vision loss in one way. Visual loss usually does not get significantly better or worse once it occurs.

Researchers looked specifically at a subgroup of about 1,700 patients who were overweight or obese or had diabetes, and compared the frequency of NAION in those who were prescribed semaglutide, the ingredient in Ozempic and Wegovy, to those who were not.

Ozempic and Wegovy are both typically used for those with Type 2 diabetes or for weight management.

Out of the 194 patients with Type 2 diabetes who took semaglutide, 17 eventually developed NAION over the course of the 36 months researchers observed, per the study. This rate of diagnosis was more than four times higher than those who were not prescribed semaglutide.

Of those with obesity who took semaglutide, 20 people developed NAION — eight times more than those who did not take semaglutide drugs.

Researchers noted the study suggests an association between semaglutide and NAION, but since it was an observation study based on data already existent, future research is needed to determine if semaglutide causes the eye condition.

Novo Nordisk, the maker of the only semaglutide medications in the U.S., noted the study is a single, observational study that cannot determine a causal relationship between NAION and semaglutide.

“Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from use of our medicines very seriously,” a spokesperson for Novo Nordisk wrote to The Hill.

NAION “is not an adverse drug reaction for the marketed formulations of semaglutide … as per the approved labels,” the spokesperson added.