optic neuritis

Introduction

a demyelinating inflammation of the optic nerve that often occurs in association with multiple sclerosis (MS) and neuromyelitis optica (NMO)
women 2x more than men
4-5 cases per 100,000 people per year in Scandinavia - maybe more frequent in temperate regions
Caucasians more predisposed
1st onset of MS-related cases tends to be at 20-45 yrs

rapid onset visual impairment in one eye (may be bilat) with dyschromatopsia (change in color perception)
usually associated with retro-orbital pain and pain on moving eye, these often precede the visual impairment
Uhthoff phenomenon, in which vision loss is exacerbated by heat or exercise
Pulfrich phenomenon, in which objects moving in a straight line appear to have a curved trajectory: Presumably caused by asymmetrical conduction between the optic nerves

multiple sclerosis (MS)
- the most common cause of optic neuritis
temporal arteritis / polyarthralgia rheumatica may cause arteritic anterior ischemic optic neuropathy (AAION)
uncommonly:
- infectious processes involving the orbits or paranasal sinuses
- systemic viral illnesses
- chronic, isolated optic neuritis
rarely:
- syphilis
- Neuromyelitis Optica Spectrum Disorder (NMOSD)
  - aka Devic's disease or Devic's syndrome
  - chronic, relapsing condition with worldwide prevalence of 0.5–4.4 cases per 100,000 people
  - associated with the presence of a specific serum, NMO IgG autoantibody, which targets the water channel aquaporin-4
  - thought to be due to autoimmune attack on the astrocytes of the optic nerves and spinal cord causing optic neuritis and spinal cord lesions lead to varying degrees of weakness or paralysis in the legs or arms, loss of sensation, and/or bladder and bowel dysfunction