Weight loss medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are commonly used to manage diabetes and obesity. While they are effective for weight loss, they have been linked to side effects including nausea, diarrhoea, stomach paralysis and kidney issues.
Now, new research is raising concerns about potential eye-related side effects, with some calling the issue ‘Ozempic blindness’.
A study published in JAMA Ophthalmology examined nine patients who developed severe vision problems, including sudden blindness, while taking semaglutide or tirzepatide. Of these cases:
- Seven developed non-arteritic ischaemic anterior optic neuropathy (NAION) – a condition where reduced blood flow to the optic nerve leads to sudden and often permanent vision loss.
- One developed bilateral papillitis, which causes optic nerve swelling and can result in vision impairment or blindness.
- One was diagnosed with paracentral acute middle maculopathy, a retinal issue that may cause vision loss.
Some participants also experienced gradual vision loss, optic disc swelling and vision impairment in just one eye.
While these findings are concerning, researchers warn that it is too early to confirm a direct link between these medications and blindness. More studies are needed to understand whether this is a rare complication or a potential risk factor for certain patients.
Is there a link between weight loss drugs and blindness?
First, let’s cover the basics. Semaglutide belongs to a class of medications called GLP-1 receptor agonists, which mimic a natural protein in the body known as glucagon-like peptide 1 (GLP-1). These drugs help regulate blood sugar, slow digestion and reduce appetite, explains bariatric surgeon Dr Mir Ali.
Tirzepatide is in a different class, targeting both GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors. While it functions similarly to semaglutide, it also affects an additional pathway that may enhance its effects on blood sugar regulation and appetite suppression, says Dr Ali.
This isn’t the first study to explore a possible link between GLP-1 medications and vision issues.
A study published in JAMA Ophthalmology in July found that semaglutide users with diabetes were more than four times more likely to develop NAION (non-arteritic ischaemic anterior optic neuropathy), a condition that causes sudden vision loss due to reduced blood flow to the optic nerve.
People who were overweight or had obesity were seven times more likely to develop NAION while taking semaglutide. Cases remained low overall but the data suggests a possible increased risk for certain individuals.
The latest study expands on these findings, suggesting that tirzepatide may also be linked to similar vision complications.
One theory suggests that vision complications may not be caused by the drugs themselves but by how quickly they lower blood sugar.
“In some cases, it is hypothesised that rapid correction of hyperglycaemia induced by these drugs, rather than a toxic effect of the drugs, could be associated with the ophthalmic complications reported,” the study’s authors wrote.
Simply put, when blood sugar levels drop too quickly, it may impact eye health. This isn’t a new concern, says endocrinologist, Dr Christoph Buettner.
Sudden changes in blood pressure have been linked to retinopathy (a leading cause of preventable blindness). Papillitis (optic nerve inflammation) has also been connected to rapid metabolic shifts.
“Both drugs are very powerful in helping patients lose weight and rapidly normalise blood sugar levels,” says Dr Buettner. However, he also notes that improving diabetes and managing weight are more likely to enhance eye health—not worsen it.
While there are still many unknowns,surgical neuro-ophthalmologist Dr Howard Krauss, says this issue is “worthy of further investigation.”
How common is vision loss with GLP-1s?
There are no definitive statistics on how often semaglutide or tirzepatide may lead to vision loss, but doctors emphasise that this is extremely rare.
“These complications are so rare that it’s difficult to determine the exact cause,” says Dr Ali.
Dr Buettner agrees, adding that he has never encountered this issue in a patient. “These are very rare complications,” he says. It is also unclear whether obesity or diabetes increases the risk, meaning there are still many unknowns.
What to do if you have vision changes on these medications
If you notice changes in your vision while taking semaglutide or tirzepatide, Dr Buettner advises that you stop taking the medication and contact your doctor immediately.
If you’re considering starting one of these medications, discuss the pace of your weight loss and blood sugar management with your doctor.
Rapid blood sugar changes may increase the risk of eye complications. Regular check-ups can help your doctor monitor weight loss progress and vision health. Your doctor may also adjust your dose to slow weight loss if needed.
“These medications can be adjusted by reducing the dose if blood sugar or weight loss is happening too quickly,” says Dr Buettner.
While serious eye complications remain uncommon, if you notice vision changes, contact your doctor immediately.
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