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).

There is also a rare autosomal dominant condition, optic atrophy 1 (also known as juvenile optic atrophy or Kjer-type optic atrophy) characterised by an insidious onset of visual impairment in early childhood with moderate-to-severe loss of visual acuity, temporal optic disc pallor, colour vision deficits and centrocecal scotoma of variable density.¹

Presentation

This depends to a certain extent on the causative condition. However, 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, particularly in Kjer-type optic atrophy where blue-yellow dyschromatopsia is noted.¹

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 will also be present.

Investigations

It is diagnosed on fundoscopy and may be confirmed with optical coherence tomography (a quick and painless imaging technique that can be performed in the outpatient clinic). Further investigation may then be required to assess its function, such as formal visual field testing and colour testing. For a detailed account of assessing optic disc function, see separate article Examination of the Eye.

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.

Associated diseases^2,3

More common causes

Primary optic nerve disease:

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

• Central retinal artery occlusion or central retinal vein occlusion.

• Ischaemic optic neuropathy.
• Chronic papilloedema.
• Chronic optic neuritis.

Less common causes

• 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 disease).
• Radiation neuropathy.
• Syphilis.

Management

This depends on the associated disease.

Complications

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

Prognosis

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 ophthalmological care.

Prevention

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.

Document references

1. Optic Atrophy 1; OPA1, Online Mendelian Inheritance in Man (OMIM)
2. Kanski J. Clinical Ophthalmology, A Systematic Approach, 5th ed. Butterworth Heinemann (2003)
3. Kunimoto DY, Kanitkar KD, Makar MS; The Wills Eye Manual (4th ed.) 2004. Lippincott, Williams and Wilkins