Recently weight loss medications have boomed in popularity, helping people and celebrities alike lose pounds fast. New research suggests a link between popular diabetes and weight loss medications Ozempic and Wegovy and an uncommon eye condition that can cause blindness.
The study, published in JAMA Ophthalmology found that patients with type 2 diabetes and obesity who take these drugs, which contain semaglutide appear to be at greater risk of nonarteritic anterior ischemic optic neuropathy (NAION) compared to those prescribed other drugs.
What is NAION?
NAION (nonarteritic anterior ischemic optic neuropathy) is a rare blinding disease that causes sudden blindness in one eye, often after waking. It is caused by a lack of blood flow (ischemia) to the optic nerve, which connects the eye to the brain. The optic nerve is a bundle of over one million nerve fibres that transmit visual signals.
NAION is a rare condition that affects 2-10 people out of every 100,000. It is also the second most common cause of optic nerve blindness, with no effective cure.
The cause or pathogenesis of NAION is still not well understood, although it is generally believed to be associated with vasculopathic risk factors including diabetes, hypertension, and high cholesterol.
The Link Between Semaglutide and NAION
Joseph Rizzo, director of the Neuro-Ophthalmology Service at Massachusetts Eye and Ear hospital in Boston, Massachusetts, US, who is also the study’s corresponding author, decided to investigate the link between semaglutide and NAION based on an observation. He and colleagues noted that three patients in their practice were diagnosed with NAION in just 1 week. This is unusual for such a rare condition. They also noted that all three patients were taking semaglutide.
To investigate, they analyzed retrospective data from 16,827 Mass Eye and Ear patients over one year. They divided the individuals into two groups based on the reason for taking the medication — type 2 diabetes or obesity. In these two groups, some received semaglutide, while others took unrelated drugs to treat their condition. This division is important because people with diabetes are at an increased risk of NAION, so by analyzing them separately, they could account for this.
Among patients with type 2 diabetes, the average age was 59 years old and more than half were female. The age of patients in the overweight or obese group skewed younger, an average of 47 years old, and 72% were female.
In the diabetes group, 8.9% of those taking semaglutide received a NAION diagnosis, compared with 1.8% of those taking other medications for diabetes. Similarly, in the group with obesity, 6.7% of those taking semaglutide developed NAION, compared with only 0.8% of those taking other medications.
This means that people with diabetes taking semaglutide were more than four times more likely to receive a NAION diagnosis. Those who taking semaglutide to treat obesity were more than seven times more likely to receive a diagnosis.
The researchers did, however, point out that being male may increase the risk of NAION in type 2 diabetes patients. Furthermore, overweight or obese people taking semaglutide who also have hyperlipidemia (high levels of lipids in the blood such as cholesterol and triglycerides) may be at a higher risk of developing NAION.
The researchers also stated that patients with diabetic retinopathy — a complication of diabetes that causes damage to the blood vessels of the retina, the light-sensitive part of the eye — who received semaglutide may have an increased risk of worsening retinopathy. They also likely had a faster rate of progression in the development of new vessels on the inner surface of the retina, which can endanger vision.
The researchers said that the findings should be viewed as being significant but tentative, as future studies are needed to examine these questions in a much larger and more diverse population. They also suggest that future discussions between a patient and their physician should include NAION as a potential risk, especially if patients have other known optic nerve problems like glaucoma or if there is preexisting significant visual loss from other causes.
Growing Use of These Drugs
The use of these drugs has exploded throughout industrialised countries and they have provided very significant benefits in many ways. Ozempic was approved to treat type 2 diabetes by the United States Food and Drug Administration (FDA) in 2017. It helps lower blood sugar levels by encouraging the body to produce more insulin. In high doses, these drugs reduce appetite and signal fullness before eating by targeting the brain.
In 2021, the FDA approved Wegovy injection for chronic weight management in adults who are obese or overweight and have at least one weight-related condition, such as high blood pressure, type 2 diabetes, or elevated cholesterol.
The findings are compelling, but experts caution that they are preliminary and observational. The findings do not demonstrate a causal link between the drug and NAION. Nonetheless, with the massive popularity of semaglutide, it is important for both doctors and patients to be aware of the potential risk.
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