Scientists remain puzzled as to why some individuals taking popular weight loss and diabetes medications such as Ozempic and Wegovy develop complications with their eyesight, highlighting that we still have a lot to learn about this relatively new class of drugs.
Physicians at the University of Utah's John A. Moran Eye Center are the latest researchers to identify the medications as the one commonality shared by patients suffering newly developed vision issues. In their study, nine patients had succumbed to potentially blinding conditions, as a result of damage to the optic nerve, while taking common GLP-1 agonist drugs such as semaglutide and tirzepatide.
We first highlighted this possible link back in July 2024, when researchers found that the class of drugs increased users' risk of developing non-arteritic anterior ischemic optic neuropathy (NAION) – which is, essentially, eye stroke – by a factor of seven. NAION is, however, rare and causation was not established.
In December, two more studies out of Denmark – the home of the GLP-1 pioneers Novo Nordisk – also found that NAION risk was up to four times greater for those taking these medications to manage either diabetes or obesity. Like the earlier research, while the prevalence of eye stroke was much higher in those on these drugs, it couldn't be scientifically proven that they were the trigger.
In the latest study, the nine patients presented with broader vision impairments, with all three conditions – NOION, papillitis and praracentral acute middle maculopathy – affecting the optic nerve, responsible for transmitting visual information to the brain.
The large team of researchers hypothesized that, based on what we know so far, rapid blood-sugar changes that these drugs drive could be behind the eyesight issues. This would rule out earlier suggestions that it could be caused by GLP-1 toxicity.
“This review was not conducted in any way that we can say these drugs caused the complications,” said lead author Bradley Katz, a professor at The University of Utah's Department of Ophthalmology & Visual Sciences. “Further studies are needed to test our hypothesis. However, this is an important issue for ophthalmologists as we monitor the usage of these drugs and how to best be in communication with our patients about them.”
One of the issues is the newness of the class of drugs; it's an emerging field of research, but early signs have showed that they may have many other positive health impacts, from kidney and heart benefits to greatly reducing the risk of cancer. Semaglutide (Ozempic, Wegovy and Rybelsus) and tirzepatide (Mounjaro and Zepbound) have been nothing short of revolutionary for millions of people around the world, with the surge in the last two years due to their reclassification as an effective weight-loss treatment. While around 12% of US adults have reportedly tried a GLP-1 drug, it's estimated that nine million people around the world – and 44% in the US – will be regularly taking one of these medications primarily for weight management by 2029.
There have also been studies that have found links with suicidal ideation and surgery complications.
However, much of these findings have emerged in the last few years. And while an ongoing five-year study is currently underway to examine the affect of semaglutude on eye disease in type 2 diabetes patients, it's still preliminary.
“Because of the association of semaglutide with a temporary worsening of diabetic retinopathy, the increased incidence of diabetic macular edema, and the concern that rapid correction of hyperglycemia could induce papillitis, physicians prescribing this medication to their patients with type 2 diabetes should consider a drug regimen that more gradually lowers HbA1C level,” the authors noted in latest study.
Appearing on the Journal of American Medical Association (JAMA) Network's podcast, Katz explained how his patient had experienced rapid vision loss in one eye, just one day after starting on medication, while the other eight cases developed sight issues more slowly. This in itself has left scientists scratching their heads.
"My patient experienced vision loss the next day," he said. "So it was just one day after starting the drug. And then the other cases that I collected were anywhere from three months to 16 months on treatment before ischemic optic neuropathy manifested.
"In my patient, it was sequential, first one eye and then the other. In two of the other cases that were referred to me, even though the optic neuropathy was only in one eye, they presented with bilateral disc swelling, which is very atypical for ischemic optic neuropathy, and then the other four cases presented with typical unilateral swelling."
The one thing that all cases did have in common, he explained, was "a small cup to disk ratio," which is seen in patients at greater risk of developing vision complications.
Katz, however, cautions that this new study is by no means conclusive and people should not stop taking their medication – but that they and their physicians should be aware that there is a potential link here.
"The American Academy of Ophthalmology published a press release shortly after the JAMA Ophthalmology report last summer showing this increased incidence of ischemic optic neuropathy, because that spooked a lot of patients, and it spooked a lot of doctors," he said on the podcast. "And I think the recommendation from their standpoint, from the Academy standpoint, is that we need to look into this further. We need to know what the denominator is."
Overall, Katz emphasized, a lot more research is needed into finding out the possible mechanisms involved in linking vision loss to GLP-1 use, in order to identify at-risk patients and to mitigate any potential eyesight damage.
"The recommendation in our manuscript is just that you shouldn't not take these drugs," he added. "They're very effective. But we would recommend that physicians prescribing these drugs just take some extra care to go onto them slowly, and try to drop the blood sugar in patients more slowly, and that might reduce the incidence of this ocular complication."
The researchers added that, out of an abundance of caution rather than to spark panic, anyone who experiences sudden loss of vision should stop taking the medication and see a doctor immediately.
You can hear the full podcast episode in the link below.
The research was published in the the Journal of the American Medical Association's Ophthalmology.
Source: The University of Utah
