---
title: "What is non-arteritic anterior ischemic optic neuropathy (NAION)?"
description: "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. ##…"
url: "https://bluefinvision.com/knowledge-base/topics/conditions-diseases/what-is-non-arteritic-anterior-ischemic-optic-neuropathy-naion/"
updated: "2025-12-15"
category: "Conditions & Diseases"
---

# What is non-arteritic anterior ischemic optic neuropathy (NAION)?

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.