Optic neuritis (ON) may involve the retrobulbar (retrobulbar neuritis) or the intrabulbar (papillitis) portion of the optic nerve, or both

Most common type - Idiopathic ON (a primary demyelinating disease occurring in isolation or as part of multiple sclerosis

Causes:

• MS (most commonly associated disease)
• diabetes
• syphillis

Risk factors:

• Age 30 to 50
• Female
• White ethnicity
• HLA DRB1*1501 genotype - R/F for ON, and for conversion to MS
• EBV
• Presence of autoimmune diseases

PC

• Unilateral loss of visual acuity over hours or days
• Loss of visual acuity with central scotoma - “seeing through cloud, fog, rainy window”
• Eye pain: peri-orbital or retro-occular, exacerbated by eye movements. Intensity varies