Written by Sophie Vergnaud, MD | Reviewed by Alyssa Billingsley, PharmD
Updated on July 8, 2024
Key takeaways:
New research has shown a link between taking semaglutide (Ozempic, Wegovy) and a rare kind of eye stroke called non-arteritic anterior ischemic optic neuropathy (NAION) — especially in the first year of taking the medication.
Semaglutide has also been linked to short-term changes in vision, especially in people with diabetic eye disease.
Much more research is needed to better understand the short- and long-term health effects of powerful medications like semaglutide.
Possible risks should be weighed against possible benefits for your unique health situation. The best way to do this is with an honest conversation with your healthcare team.
Table of contents
Eye stroke
Diabetic eye disease
Blurred vision
What to do
Bottom line
References
shironosov/iStock via Getty Images Plus
A new study looked into whether there’s a link between taking semaglutide (Ozempic, Wegovy) and the risk of developing a rare type of eye stroke that can cause blindness in one eye.
Semaglutide is part of a class of medications that was originally approved to treat Type 2 diabetes. It’s also approved as a treatment for weight loss, under the name Wegovy.
Semaglutide works by mimicking a hormone that’s released naturally after eating. This hormone is what makes you feel full and stop eating. It also tells the body to make more insulin, which helps lower blood glucose levels.
But there’s very little data about the safety of using this medication long term. And there’s a lot we still don’t know about the possible risks.
Read on to learn what we do know about how semaglutide affects your eye health and vision.
Semaglutide and NAION
In a new study published in JAMA Ophthalmology, researchers explored a possible link between semaglutide and a rare kind of eye stroke called non-arteritic anterior ischemic optic neuropathy (NAION).
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NAION isn’t a common issue. Out of 100,000 people, up to 10 people are affected by it each year. But it’s very serious: It can cause permanent blindness in one eye. This vision loss is painless. It comes on suddenly and typically gets worse over a few days before stabilizing. And there are no treatments that can improve or reverse it. Diagnosing it is difficult, and understanding why it happens is still a mystery. Experts think it happens as a result of reduced blood flow to the optic nerve.
The researchers behind this new study noticed a cluster of new cases of NAION in summer 2023. They also noticed that all three people affected were taking semaglutide.
To understand if this was more than a coincidence, they decided to look back at all the patients seen in their eye clinic over the previous 6 years. This coincided with a period of time during which semaglutide first came on the market and then surged in popularity.
The researchers used detailed patient records to compare four groups of people:
People with diabetes taking semaglutide
People with diabetes taking another diabetes medication (not semaglutide)
People without diabetes taking semaglutide for weight loss
People without diabetes taking another weight-loss medication (not semaglutide)
They carefully matched the groups based on factors like age, sex, and other health conditions.
And, when they looked at the results, they found a link between someone starting to take semaglutide and the development of NAION.
But this link is just that — a link. It doesn’t mean that taking semaglutide caused the cases of NAION. In fact, showing that the two are linked is only the first step. Proving that the medication causes the condition is much more challenging.
It’s possible that NAION may not be caused by semaglutide at all. Instead, it could be a result of the rapid cardiovascular and metabolic changes that happen when a person starts taking semaglutide.
According to Nishika Reddy, MD, another possibility is that semaglutide is just the common thread linking these cases together. After all, you’re more likely to get NAION if you have high blood pressure, obstructive sleep apnea, or diabetes. And these conditions are more common in people who take semaglutide.
Much more research is needed to understand the exact relationship.
Semaglutide and diabetic retinopathy
There are other surprising links between semaglutide and eye health. For instance, there’s some evidence that semaglutide can worsen diabetic eye disease (diabetic retinopathy).
Diabetic retinopathy happens when high blood glucose levels damage the blood vessels in the light-sensitive tissue at the back of the eye (the retina). It’s a major cause of vision loss in people with diabetes.
So, it’s surprising that semaglutide — a medication that improves blood glucose levels — would worsen diabetic retinopathy. But some research suggests semaglutide might temporarily worsen diabetic retinopathy in people who already have a severe form of it.
The link between semaglutide and worsening diabetic retinopathy may be due to the rapid improvement in blood glucose levels that comes with starting the medication. Keeping blood glucose levels “in range” is important for long-term health in people with diabetes. But in the short term, these rapid improvements can sometimes make diabetic retinopathy worse before it gets better. This phenomenon has been observed with other diabetes treatments too.
Recent research — and looking ahead
More recent research was reassuring. The research, from the American Academy of Ophthalmology in 2023, looked at detailed patient records between 2013 and 2021. It found that the eye disease did worsen in a small number of people with no pre-existing diabetic retinopathy or with early-stage disease while taking semaglutide.
However, nearly 60% of people with advanced disease actually experienced improvement in their diabetic eye disease while taking the medication.
The researchers called for more forward-looking research to better understand the impact of medications like semaglutide on diabetic eye disease. A 5-year study called FOCUS is underway and is due to be completed in 2027.
In the meantime, if you take or are considering taking semaglutide for diabetes, and you’re worried about your eye health, speak with your primary care provider or eye care specialist. They can help you understand some of the short- and long-term implications of taking this medication.
Does semaglutide cause blurred vision?
It’s possible that starting semaglutide can cause blurred vision. This is related to blood glucose levels dropping rapidly. When your blood glucose levels change, this can affect the shape of the eye’s lens. This can cause blurry vision, and it often happens as a
symptom of dangerously low blood glucose levels (hypoglycemia).
Older adults may be more likely to experience blurred vision when starting semaglutide. That’s because the eye’s lens becomes less flexible with age. For some people, it may take longer for vision to stabilize after starting semaglutide. But this side effect should go away within a few months of starting semaglutide (or changing the dose).
What to do if you’re taking semaglutide and worried about your vision?
It can feel scary to add another risk to your health — especially if you’re already living with the health risks of diabetes and other cardiovascular and metabolic conditions.
And the truth is, we don’t know everything about the short- and long-term impacts of medications like semaglutide. What we better understand are some of the long-term health risks of living with diabetes, cardiovascular disease, and excess weight.
So, like many things in life (and healthcare), it’s a question of balancing risks and benefits. And deciding if the benefits are worth the risks — or not — is entirely unique to you and your situation.
In the case of NAION, some people may be less able than others to take on the risk. Examples of these cases are if you already have vision loss, or if you already have an eye condition that affects your optic nerve, like glaucoma.
As Dr. Reddy explains, there are certain conditions that affect the structure of the eye and create crowding at the back of the eye, where the optic nerve connects. This location is called the optic disc. And, says Dr. Reddy, conditions that put your “disc at risk” can increase your risk of NAION.
If you’re not sure how healthy your optic disc is, schedule a routine eye exam with your eye doctor. It’s a good idea to do this once a year anyway.
Getting help
It’s important to speak with your medical care team if you’re worried about your eye health. This may be your primary care provider, your diabetes or weight specialist, or your eye doctor.
Let them know what medications you’re taking, and tell them about your medical history (if they don’t already know it). Be honest about your fears. And have your eyes checked regularly. Your eye doctor can monitor for any changes in your vision and suggest treatments if needed.
The bottom line
Semaglutide (Ozempic, Wegovy) is an important and potentially life-changing medication for people managing Type 2 diabetes and weight loss. It’s very effective at lowering blood glucose levels, reducing body weight, and improving many related health conditions.
Given the popularity of semaglutide, and the huge numbers of people taking this medication, the risk of developing blindness as a result of taking the medication currently seems very low. But much more research is needed to fully understand the effect of semaglutide on eye health.
As more people take this medication, researchers and healthcare professionals will understand more about new and emerging risks and side effects — and how to protect users from them.
References
American Academy of Ophthalmology. (2023). Popular weight loss drug does not appear to worsen diabetic eye disease in most patients, new study suggests.
DCCT Research Group. (1987). Diabetes control and complications trial (DCCT): Results of feasibility study. Diabetes Care.
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