Optic neuritis

This condition typically affects patients in the 20 - 45 age group.

Presentation:

  • Impaired vision 
  • Central field defect
Examination:
  • Visual acuity may be as poor as perception of light
  • Central scotoma is typical
  • Impaired colour discrimination (best demonstrated with red object, the affected 

    • eye will see the red object less bright than the unaffected eye)
     
    Impaired colour discrimination. 
    Note the red circle changes from bright 
    red in the normal eye to darker colour 
    when viewed with the eye with optic
    neuritis
  • Relative afferent pupillary defect of the affected eye

    •  

    Swinging light test showing left relative afferent 
    pupillary defect. Note the dilatation of the pupil 
    when the light is shone at the left eye.
  • Pain on eye movement especially on adduction.
  • Fundal examination is normal as most cases have retrobulbar neuritis.
Management:
  • Refer the patient within 24 hours for confirmation of the diagnosis
  • Normal or near-normal vision usually returns within 6 weeks
  • As treatment does not affect the outcome, unilateral optic neuritis is not treated by 

    • most ophthalmologists. However, follow-up is important as radiological investigation 
    may be needed to exclude compressive lesion in cases where spontaneous recovery 
    fails to recur.
     
Figure 1
Optic atrophy in a patient with a past history of optic neuritis. Optic atrophy is a late 
sign. In acute optic neuritis, the optic disc is typically normal.

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