What You Need to Know About GLP-1 Medications and Your Vision

GLP-1 medications work by mimicking a natural hormone that stimulates insulin production, lowers blood sugar levels, slows digestion, and signals fullness to the brain. While their impact on body weight and blood glucose control is well established, healthcare providers have long monitored how rapid changes in blood sugar affect ocular structures.

For patients with pre-existing diabetic eye disease, rapid drops in blood glucose—though beneficial long-term—can sometimes cause temporary changes in retinal blood vessels or short-term shifts in vision clarity. Beyond blood sugar fluctuations, researchers and drug regulatory bodies worldwide are now closely examining how these medications directly interact with vascular tissue supplying the optic nerve.

NAION occurs when the blood supply to the head of the optic nerve is suddenly reduced or blocked.

Because the optic nerve acts as the data cable transmitting visual signals from your eye to your brain, a loss of blood flow essentially causes a stroke of the optic nerve itself.

Key Characteristics of NAION:

• It typically causes sudden, painless, loss or blurring of vision in one eye, which patients often notice immediately upon waking.
• It frequently affects central vision or the lower half of your field of vision (creating a shadow or blind spot).
• Unlike some other eye conditions, there is currently no medical or surgical treatment proven to restore lost visual acuity following NAION. This makes prompt clinical evaluation vital if you experience these symptoms.

There are a number of other risk factors for NAION:

• type 2 diabetes,
• high blood pressure and
• obstructive sleep apnoea
• plus increasing age

can also increase your risk of developing NAION.

Following international reviews by health authorities including the European Medicines Agency (EMA) and the World Health Organisation (WHO), the TGA updated the official product information for GLP-1 medications to include formal warnings regarding reported cases of NAION.

Crucial Information:

• NAION is extremely rare. The overwhelming majority of people taking Ozempic, Wegovy, or Mounjaro will never develop this condition.
• Do not stop taking your medication. If you are currently prescribed a GLP-1, do not cease treatment on your own. Abruptly stopping your medication can lead to dangerous spikes in blood sugar or other health complications. Any decisions regarding your prescription should always be made in consultation with your prescribing GP or specialist.
• According to the Database of Adverse Event Notifications, 36 cases of optic ischaemic neuropathy with GLP-1s have been identified, including 23 for semaglutide, 10 for tirzepatide and three for liraglutide.

If you are currently taking or planning to start a GLP-1, you should monitor your sight for any sudden changes.

Contact an optometrist immediately if you notice:

• Sudden loss or dimming of vision in one or both eyes - even if partial
• Shadows or missing areas in your central or peripheral (side) vision
• Sudden, unexplained blurring or graying of vision that does not clear with blinking

Emergency Care:
Any sudden change in vision should be treated as a medical emergency. Do not wait several days to see if your vision recovers on its own.

Whether you are starting a new medication or have been managing diabetes for years, working closely with your optometrist is your best defence against sight-threatening conditions.

• Always let us know about all prescription medications you take. Updating your health profile at every visit allows us to tailor our examinations to your specific risks.
• During a comprehensive eye examination, we evaluate the anatomical structure of your optic nerve head (checking for structural predispositions like a "disc at risk") and monitor for signs of diabetic retinopathy using high-definition imaging.
• If you experience sudden vision loss, our optometrists can perform an immediate clinical assessment and coordinate rapid emergency referrals.