I am taking semaglutide to help with weight loss, and I have been very successful with it. I have been able to lower my blood pressure, and my cholesterol is coming down too. I am feeling great! So I was really disappointed when I read about a recent study that semaglutide can cause blindness. Should I be worried?
—Concerned but feeling good
I am thrilled to hear that you are feeling good and improving your health with semaglutide. You are also not alone. Several of my patients have asked about reports like this one about this study from JAMA Ophthalmology.
The study was designed to look for an association between taking semaglutide — marketed as Ozempic for Type 2 diabetes and Wegovy for weight loss — and a very specific type of vision loss called nonarteritic anterior ischemic optic neuropathy (NAION). The authors found that there was an increased incidence of NAION among the patients prescribed semaglutide compared to patients with Type 2 diabetes or obesity not prescribed semaglutide.
What does this mean for patients taking semaglutide? I would argue not much.
The study shows an association, not a causal relationship, between semaglutide and NAION. This type of vision loss is quite rare, affecting just 2 to 10 per 100,000 people. Even with the four- to seven-fold increase in the incidence of the disease, it would still be rare. Additionally, the study was based on records from a neuro-ophthalmic referral center that specializes in NAION. As a result, their patient population, from which they drew their study subjects, may not be representative of the general population.
The authors do not propose a biochemical mechanism by which semaglutide and NAION might be connected, nor do they know for sure that the patients included in the study who were prescribed semaglutide actually took the medication. They also point out that they cannot show a correlation between the dose of semaglutide prescribed and the incidence of NAION or that stopping semaglutide was associated with an improvement in NAION, both of which would be needed to suggest causation.
In my clinical experience prescribing semaglutide to thousands of patients in the past 6.5 years, I have never had a patient diagnosed with NAION. In fact, it is so rare that as a doctor who is not an ophthalmologist, I had never heard of NAION until this study was published.
Consider too that there would be a downside to stopping semaglutide. In addition to effectively lowering blood sugar and assisting with weight loss, semaglutide has been shown to reduce the risk of cardiovascular disease in people with and without Type 2 diabetes. In patients with prediabetes, semaglutide reduces the risk of progression from prediabetes to diabetes.
The takeaway: Taking semaglutide may be associated with NAION, a rare cause of vision loss; however, for many people, the health benefits of taking semaglutide will outweigh the very small risk of NAION.
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