Optic Neuritis

Causes

• multiple sclerosis: the commonest associated disease
• diabetes
• syphilis

Features

• unilateral decrease in visual acuity over hours or days
• poor discrimination of colours, 'red desaturation'
• pain worse on eye movement
• relative afferent pupillary defect
• central scotoma

Investigation

• MRI of the brain and orbits with gadolinium contrast is diagnostic in most cases

Management

• high-dose steroids
• recovery usually takes 4-6 weeks

Prognosis

• MRI: if > 3 white-matter lesions, 5-year risk of developing multiple sclerosis is c. 50%