US FDA Flags Rare Vision-Loss Risk for GLP-1 Drugs, Indian Doctors Advise Caution Without Panic

The US Food and Drug Administration (FDA) has asked makers of all GLP-1 receptor agonist medicines to include a warning on their product labels regarding a potential link to a rare but serious eye condition that can lead to permanent vision loss. Indian endocrinologists have responded by stating that the risk appears extremely small, while emphasizing the importance of routine eye examinations and prompt medical attention if symptoms arise.

In a drug safety communication issued on November 9, the FDA stated that these medications may be associated with non-arteritic anterior ischaemic optic neuropathy (NAION). This condition occurs when blood flow to the optic nerve decreases, causing sudden and painless loss of vision in one eye, which can sometimes result in permanent damage. Manufacturers are now required to update the “Warnings and Precautions” section of their product information.

The affected class includes widely prescribed drugs such as semaglutide (marketed as Ozempic, Wegovy, and Rybelsus), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity), and tirzepatide (Mounjaro, Zepbound). These treatments are primarily utilized for type 2 diabetes and obesity, with certain versions also approved to mitigate heart and kidney risks.

The regulatory review by the FDA incorporated clinical trials, animal studies, post-marketing reports, and observational studies. A meta-analysis comprising 126 trials and 134,253 participants identified 15 probable cases of NAION, split between 10 GLP-1 users and five individuals receiving a placebo. The estimated incidence was calculated at 6.4 cases per 100,000 person-years among GLP-1 users, compared to 3.8 cases for those on comparison treatments. The FDA noted that the evidence points to a possible association rather than establishing direct causation.

Leading Indian endocrinologists have shared their perspectives based on clinical practice. Dr SK Wangnoo, a Senior Consultant Endocrinologist, reported encountering a single patient who developed sudden blurring of vision while on a GLP-1 medication. The patient experienced a complete recovery within a month of discontinuing the drug and later resumed the treatment successfully with precautions. Dr Wangnoo noted that it remains unclear whether the eye changes stem directly from the drug or from rapid fluctuations in blood sugar levels.

Dr Ambrish Mithal stated that he has not encountered cases of NAION in his practice, cautioning that not every episode of blurred vision should be classified as the condition. He noted that the incidence rate of 6.4 cases per 100,000 patient-years is only marginally higher than the estimated four cases seen in the general population. Dr Mithal recommended conducting detailed eye examinations prior to prescribing these drugs and avoiding them for patients at higher risk.

Dr Anoop Misra noted that among several thousand patients treated with GLP-1 medicines in his practice, he encountered only one suspected case of NAION. He highlighted that European regulators have similarly classified NAION as a very rare side effect affecting up to one in 10,000 people. He emphasized that the significant benefits of these medicines for diabetes, obesity, and organ protection must be weighed against this minor potential risk.

The FDA has advised patients to seek immediate medical attention if they encounter sudden, painless vision loss, blurred vision, or blind spots, and doctors have been instructed to refer suspected cases promptly to eye specialists. Experts have cautioned patients against discontinuing their prescribed medications without consulting their medical practitioner.

"Regulatory updates regarding widely used pharmaceutical products require careful, data-driven evaluation by healthcare providers and enterprises alike. While safety communications from bodies like the US FDA necessitate compliance and heightened vigilance from drug manufacturers, medical professionals highlight that the statistical risk remains low. For businesses and stakeholders operating in the healthcare and life sciences sector, transparent communication and patient safety must remain central priorities when balancing therapeutic benefits against newly identified, rare side effects." — Dr. Shishir Gupta, Founder & CEO, StartupLanes