Eye health & medication safety
NAION and semaglutide (Ozempic / Wegovy)
NAION (Non-Arteritic Anterior Ischemic Optic Neuropathy) is a condition in which blood flow to the front part of the optic nerve is compromised, causing sudden, painless vision loss in one eye. The vision loss is often irreversible, and there is no proven effective therapy to reverse it.
Risk factors for NAION
Known risk factors
Hypertension and diabetes
"Disc at risk" anatomy
Present in ~95% of NAION cases
A small, crowded optic disc with cup-to-disc ratio ≤0.2
Found in ~10–20% of the general population
An anatomic variant — not a disease
Predisposes to NAION but alone is not sufficient to cause it
Evidence of association with semaglutide
WHO safety alert — June 2025
The WHO issued a safety alert noting a potential increased risk of NAION with semaglutide-containing medications (Ozempic, Rybelsus, Wegovy).
A large retrospective cohort study of 3,344,205 patients with diabetes found a higher hazard of NAION in semaglutide users at 2, 3, and 4 years compared to non-users. Some studies reported a 3–4 fold increased relative risk; others showed no increased association. No studies suggest causation.
Magnitude of risk
Baseline annual risk
0.2–1.0
per 10,000 (no semaglutide)
Estimated risk on semaglutide
0.4–3.0
per 10,000 per year
Absolute increase
0.2–2.0
extra cases per 10,000 users per year
To put this in context
Laparoscopic appendicectomy
2–5 in 10,000
mortality risk (non-perforated)
Cardiac ablation (AF)
3–5 in 10,000
mortality risk
Elective hip replacement
2–5 in 10,000
mortality risk (age 50–60)
Elective knee replacement
2–4 in 10,000
mortality risk (age 50–60)
The absolute increase in NAION risk from semaglutide is comparable to or lower than the mortality risk of many routine elective procedures.
Clinical recommendations
⚠️
If you experience sudden or rapidly worsening vision while using semaglutide, seek immediate evaluation by an ophthalmologist or neuro-ophthalmologist. Regulatory guidelines recommend discontinuing semaglutide if NAION is confirmed.
OCT screening before starting Ozempic / Wegovy / Mounjaro
Optical coherence tomography (OCT) can identify whether you have a "disc at risk" anatomy. If OCT confirms normal anatomy, your risk of NAION becomes virtually the same as someone not taking semaglutide.
We recommend seeing an optometrist for OCT prior to starting treatment
No screening guideline currently mandates this, but it allows informed risk counselling
A comprehensive eye examination including OCT typically costs $80–$150
Most optometrists offer this service
Optometrists in Melbourne CBD offering OCT imaging
Eyes on Optometrists
Shop 2, 185–191 Queen St, Melbourne 3000
Mon–Fri: 9:00am – 5:00pm
OCT imaging available
Collins St Optometrists
Level 9, 267 Collins St, Melbourne 3000
Mon–Fri: 9:00am – 6:00pm
OCT imaging available
Other optometrists in Melbourne may also offer this service. This list is not exhaustive.