Optic neuropathies
- Lesion
The optic nerve can be starved of blood, swollen by raised brain pressure, inflamed or poisoned; each pattern points to a different cause.
What it is
The optic nerve is a tract of the CNS, wrapped in meninges and myelinated by oligodendrocytes. It has a limited set of responses: swelling of the disc, then atrophy with a pale disc. Anterior ischemic optic neuropathy is an infarct of the nerve head, arteritic (giant cell arteritis) or non-arteritic. Papilledema is disc swelling from raised intracranial pressure. Optic neuritis is inflammatory demyelination, often the first sign of multiple sclerosis or neuromyelitis optica. Glaucoma causes cupping. Hereditary (Leber) and toxic-nutritional optic neuropathies affect the central fibres.
Step by step
- Raised CSF pressure is transmitted along the optic nerve sheath.
- Pressure at the lamina cribrosa slows axoplasmic flow.
- Axons swell at the disc and veins congest.
- The disc becomes elevated with blurred margins and hemorrhages.
- Prolonged swelling ends in optic atrophy and field loss.
Optic neuropathies compared
| Disorder | Mechanism | Disc | Typical patient |
|---|---|---|---|
| Arteritic AION | Inflamed short posterior ciliary arteries | Pale, swollen | Over 50, with headache and jaw claudication |
| Non-arteritic AION | Hypoperfusion of a crowded disc | Swollen, sector | Older adult with vascular risk |
| Papilledema | Raised intracranial pressure blocks axonal flow | Bilateral swelling | Tumour, venous thrombosis, idiopathic intracranial hypertension |
| Optic neuritis | Inflammatory demyelination | Normal (retrobulbar) or swollen | Young adult woman, MS or NMO |
| Glaucoma | Pressure-related axon loss | Enlarged cup | Older adult, often silent |
| Leber hereditary optic neuropathy | Mitochondrial complex I mutations | Swollen then pale | Young man, maternal inheritance |
| Toxic or nutritional | Mitochondrial poisoning, deficiency | Pale temporal disc | Methanol, ethambutol, B12 deficiency |
Clinical notes
- Optic atrophy of any cause shows as a pale disc with loss of nerve fibre layer.
- In an older adult with sudden visual loss and headache, giant cell arteritis is treated before the biopsy result.
Test yourself
Think of the answer, then tap the question to see it.
What is papilledema?
Swelling of the optic disc caused by raised intracranial pressure, usually on both sides.
Which systemic disease causes arteritic anterior ischemic optic neuropathy?
Giant cell arteritis.
How is Leber hereditary optic neuropathy inherited?
Through mitochondrial DNA, from the mother; it mostly affects young men.
Elsewhere in DurgiPedia
- The swollen optic disc: papilloedema or not
- Giant cell arteritis and the eye: treat before the biopsy
- Ethambutol and the optic nerve
- The optic disc: cup, rim and colour
- The visual pathway, pupillary reflexes and eye movements
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Optic neuritis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Leber hereditary optic neuropathy: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.