Anisocoria

Anisocoria is present when an individual's pupils differ in size. If a person's pupils are symmetric there is said to be isocoria.

Epidemiology

The prevalence of transient physiological anisocoria of >0.4 mm is found in up to 20% population. However persistent anisocoria seems to be rarer, in the same study it was only found in 3% subjects .

Pathology

Etiology

Most cases are benign, the two diagnoses of concern are third nerve palsy and Horner syndrome, each of which has multiple causes (see individual articles).

• third nerve palsy
• Horner syndrome
• medication
  • mydriatics (dilating agents) are more commonly the cause than miotics (constricting agents)
  • mydriatics
    • vasoconstrictors, hyoscine, glycopyrrolate antiperspirant, Jimson weed, angel's trumpet, blue nightshade
  • miotics
    • opiates, clonidine, organophosphates, pilocarpine, prostaglandins
• physiological
• local pathology of the iris (rare) e.g. trauma