Anisocoria

Anisocoria

An example of anisocoria, where the pupils are of unequal sizes.

Anisocoria is a condition characterized by an unequal size of the pupils. It is a common condition, occurring in approximately 20% of the population. Anisocoria can be a benign finding or a sign of more serious medical conditions.

Causes

Anisocoria can result from a variety of causes, which can be broadly categorized into physiological and pathological causes.

Physiological Anisocoria

Physiological anisocoria is a benign condition where the difference in pupil size is usually less than 1 mm and does not change with different lighting conditions. It is often idiopathic and does not require treatment.

Pathological Anisocoria

Pathological anisocoria can be due to:

• Horner's syndrome: A condition caused by disruption of the sympathetic nerves supplying the eye, leading to ptosis, miosis, and anhidrosis.
• Adie's tonic pupil: A neurological disorder where one pupil is larger than normal and reacts slowly to light.
• Third nerve palsy: A condition affecting the third cranial nerve, leading to ptosis, "down and out" eye position, and pupil dilation.
• Iritis or uveitis: Inflammation of the iris or uveal tract can cause anisocoria due to irregular pupil shape or size.
• Pharmacological agents: Certain medications or drugs can cause anisocoria by affecting the muscles of the iris.

Diagnosis

The diagnosis of anisocoria involves a thorough medical history and physical examination. Key steps include:

• Observation in different lighting conditions: To determine if the anisocoria is more pronounced in bright or dim light.
• Slit-lamp examination: To assess the anterior segment of the eye for any abnormalities.
• Neurological examination: To check for any associated neurological signs that might indicate a more serious underlying condition.

Treatment

Treatment of anisocoria depends on the underlying cause. Physiological anisocoria does not require treatment. Pathological anisocoria requires addressing the underlying condition, which may involve:

• Medications: For conditions like uveitis or iritis.
• Surgery: In cases of structural abnormalities or tumors.
• Observation: In cases where the cause is benign and self-limiting.

Related pages

• Pupil
• Horner's syndrome
• Adie's tonic pupil
• Third nerve palsy
• Iritis
• Uveitis