From the Guidelines
Anisocoria, or unequal pupil size, is a significant clinical finding that may indicate a pathological process, such as Horner syndrome, Adie tonic pupil, or a pupil-involving third-cranial-nerve palsy.
Key Points
- A difference in pupil size of more than 1 millimeter may be clinically significant 1.
- Anisocoria can be caused by various conditions, including neurologic disorders, traumatic sphincter damage, iritis, or congenital abnormalities 1.
- Pupillary evaluation in infants and children may be challenging due to frequent shifts in fixation and focusing 1.
- A relative afferent pupillary defect (RAPD) may indicate a unilateral problem with the optic nerve or other areas in the anterior visual pathway 1.
Clinical Significance
Anisocoria can be a sign of a serious underlying condition, and its presence warrants further evaluation to determine the cause. A comprehensive pupillary examination, including assessment of size, shape, symmetry, and reactivity to light, is essential in identifying potential pathological processes 1.
From the Research
Significance of Anisocoria
The significance of anisocoria, or unequal pupil size, can be indicated by the following points:
- Anisocoria may be physiological, pathological, or pharmacological in nature 2, 3, 4, 5, 6
- It can indicate underlying disease of the eye, orbit, brain, neck, or chest 2, 6
- Examination of the pupils is a crucial part of any eye examination to determine whether a patient with anisocoria can be reassured or requires referral for further investigation 2
Causes of Anisocoria
The causes of anisocoria can be diverse, including:
- Physiological anisocoria 3
- Horner syndrome 3
- Adie pupil 3
- Pharmacological anisocoria 3, 5
- Third nerve palsy 3
- Benign episodic unilateral mydriasis 4
Diagnostic Approach
A structured approach to examination of the pupils is necessary to determine the cause of anisocoria, including:
- Pupil testing and astute observation 2
- Pharmacological aids, such as cocaine 10% eye drops, hydroxyamphetamine eye drops, pilocarpine 0.1% eye drops, pilocarpine 1% eye drops, and apraclonidine 3
- Analysis of important Pilocarpin pharmacological tests 4
- Strictly taken patient's history with targeted questions searching for recent contact with some drugs, plants, or medications 4