Non‑arteritic anterior ischaemic optic neuropathy (NAION) is a sudden, painless loss of vision caused by interrupted blood flow to the front part of the optic nerve without evidence of giant cell arteritis. It typically affects middle‑aged or older adults.
Risk Factors and Features
NAION is associated with crowded optic discs, sleep apnoea, diabetes, hypertension, and nocturnal hypotension.
- Patients wake with unilateral visual loss and an altitudinal visual field defect.
- The optic disc appears swollen and pale or hyperaemic.
- Pain is usually absent, differentiating it from optic neuritis.
- The fellow eye has a risk of similar events over time.
Management
There is no universally proven treatment to reverse NAION, so care focuses on excluding arteritic causes, addressing vascular risk factors, and supporting vision.
- Urgent ESR/CRP and systemic assessment are essential to rule out giant cell arteritis.
- Blood pressure, diabetes, lipids, and sleep apnoea should be optimised.
- Some visual improvement can occur spontaneously over months, but many are left with residual defects.
- Patients should be counselled about risk to the fellow eye and need for systemic health monitoring.
