Anisocoria
Anisocoria
Anisocoria is an inequality of pupil size. This may be physiological (said to occur in up to 15% of the population), in which case the inequality is usually mild and does not vary with degree of ambient illumination; or pathological, with many possible causes.
- Structural:
- Ocular infection, trauma, inflammation, surgery
- Neurological:
- Anisocoria greater in dim light or darkness suggests sympathetic innervation defect (darkness stimulates dilatation of normal pupil). Affected pupil constricted (miosis; oculosympathetic paresis):
- Horner’s syndrome
Argyll Robertson pupil
Cluster headache
- Horner’s syndrome
- Anisocoria greater in bright light/less in dim light suggests defect in parasympathetic innervation to the pupil. Affected pupil dilated (mydriasis; oculoparasympathetic paresis):
- Holmes-Adie pupil (vermiform movements of the pupil margin may be visible with a slit-lamp)
Oculomotor (III) nerve palsy (efferent path from Edinger-Westphal nucleus)
Mydriatic agents (phenylephrine, tropicamide)
Anticholinergic agents (e.g., asthma inhaler accidentally puffed into one eye)
- Holmes-Adie pupil (vermiform movements of the pupil margin may be visible with a slit-lamp)
- Anisocoria greater in dim light or darkness suggests sympathetic innervation defect (darkness stimulates dilatation of normal pupil). Affected pupil constricted (miosis; oculosympathetic paresis):
Clinical characteristics and pharmacological testing may help to establish the underlying diagnosis in anisocoria.
References
Kawasaki A. Approach to the patient with abnormal pupils. In: Biller J (ed.). Practical neurology (2nd edition). Philadelphia: Lippincott Williams & Wilkins, 2002: 135-146
Cross References
Argyll Robertson pupil; Holmes-Adie pupil, Holmesadie syndrome; Horner’s syndrome; Miosis; Mydriasis
