Optic Atrophy

Optic atrophy is the term used to describe the loss of a proportion of optic disc nerve fibres. It is an important sign of advanced optic nerve disease. It is said to be primary if it occurs without any preceding optic nerve head oedema and secondary if it is preceded by oedema. It may also be described according to the underlying aetiology (i.e. whether this relates to primary disease of the retina or whether the problem originates at the level of the optic nerve).

This depends to a certain extent on the causative condition (see below) but optic disc atrophy in isolation would result in the following symptoms and signs.

Symptoms

There will be a loss of vision which may be central or peripheral depending on the underlying condition. There may also be a degree of colour vision impairment.

Signs

The disc is pale - comparison with the fellow eye may help elicit this sign. There is usually a reduction of the small blood vessels crossing its surface and in the case of secondary atrophy, the disc margin may be poorly delineated (this is due to gliosis rather than oedema). Where the atrophy is glaucomatous in origin, disc cupping may also be present.

It is diagnosed on fundoscopy and further investigation may then be required to assess its function (such as formal visual field testing and colour testing). Depending on the associated findings and suspected underlying cause, further investigations may be carried out for example, to assess for the presence of a tumour (full neurological examination, imaging), to identify genetic abnormalities or blood tests in the case of suspected toxic neuropathies.

More common causes
Primary optic nerve disease:

• Chronic glaucoma
• Retrobulbar neuritis
• Traumatic optic neuropathy (may be secondary)
• Compressive lesions (e.g. aneurysms, Paget's disease, tumours) - may be secondary

• Central retinal artery / vein occlusion

• Ischaemic optic neuropathy
• Chronic papilloedema
• Chronic optic neuritis

• Hereditary optic neuropathies (e.g. Leber's optic neuropathy)
• Toxic retinopathies (e.g. isoniazid, toluene from glue sniffing)
• Tobacco retinopathy
• Alcohol / nutritional retinopathy (e.g. vitamin B₁₂ deficiency)
• Retinal degeneration e.g. retinitis pigmentosa
• Retinal storage diseases (e.g. Tay-Sachs)
• Radiation neuropathy
• Syphilis

This depends on the associated disease.

Visual loss, the degree and nature of which will depend on the severity and type of underlying disease.

Optic atrophy is irreversible and treatment - where available - will be aimed at limiting its progression. The optic atrophy related to optic neuritis may, in some cases, be limited somewhat by the judicious use of steroids. Such patients should be under joint neurological and ophthalmologist care.

Certain conditions such as glaucoma and optic disc atrophy secondary to toxic, alcohol, tobacco and nutritional retinopathies can be limited by optimal management of the underlying problem.