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Optic Neuritis

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Overview

Optic neuritis is the inflammation of the optic nerve leading to blurred vision and pain in moving the eye. It may be the first presenting symptom of multiple sclerosis (MS). In most cases, it is self-limiting.

Epidemiology

  • Peak age of onset between 20-50 years
  • Females are affected more than males

Causes

Risk Factors

  • Female sex
  • White ethnicity
  • 30-50 years of age
  • Personal or family history of autoimmune disease
  • Personal history of infectious disease

Presentation

Patients usually have a painful eye with visual impairment with an onset of a couple of hours or days which peaks at 1-2 weeks. Symptoms may be:

  • Pain that is worse with eye movement:
    • This may be peri-orbital or retro-orbital
  • Reduced visual acuity:
    • Patients often describe their vision as if they’re looking through fog
    • There may be a scotoma
  • Colour desaturation:
    • Colours are not as bright as before, usually seen in the form of red desaturation
  • Relative afferent pupillary defect:
    • The lesion is in the optic nerve, so the afferent pathway of the pupillary reflex is impaired
  • Optic disc swelling
  • Phosphenes:
    • The same bright lights are seen when one closes their eyes and presses on the eyelids

Investigations

  • MRI of the optic nerves, brain and spinal cord with gadolinium contrast:
    • There may be swelling/white matter lesions of the optic nerve
    • There might be white matter lesions disseminated in time and space in patients with multiple sclerosis
  • FBC:
    • There may be derangements in white cell counts suggesting infection
  • ESR:
    • Very high in giant cell arteritis
  • CRP:
    • High in infection/inflammation
  • Syphilis testing:
    • If suspected
  • Serum ACE:
    • Elevated in sarcoidosis
  • Autoantibodies for other autoimmune diseases e.g. anti-nuclear antibodies for SLE
  • CSF analysis
    • May show oligoclonal bands and high IgG in multiple sclerosis

Management

  • 1st-line: high-dose corticosteroids e.g. IV methylprednisolone
  • Management of the underlying condition

Monitoring

  • There is close follow-up by ophthalmology or neurology to assess recovery, which usually takes 4-6 weeks.
  • Patients with suspected multiple sclerosis have repeat MRI scanning every 6 months
  • If patients have established multiple sclerosis or other autoimmune diseases, they are followed up as normal in their respective clinics 

Patient Advice

  • Patients are advised to reduce smoking as this can help reduce the risk of inducing a pro-inflammatory state
  • Patients should be safety-netted on the signs and symptoms of recurrence and seek immediate help if they recur, including if recurrence is in the other eye

Complications

  • Development of multiple sclerosis
    • Optic neuritis may be the first presentation of multiple sclerosis alongside fatigue
  • Recurrence of disease
  • Reduced visual acuity

Prognosis

  • Optic neuritis is usually self-limiting and resolves over several weeks to months
  • The visual prognosis is generally good

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