Anisocoria

Definition

Anisocoria is unequal pupil size. The pupil is the black part in the center of the eye. It gets larger in dim light and smaller in bright light.

Considerations

Slight differences in pupil sizes are found in up to 1 in 5 healthy people. Usually, the diameter difference is less than 0.5 mm, but it can be up to 1 mm (0.05 inch).

Babies born with different sized pupils may not have any underlying disorder. If other family members also have similar pupils, then the pupil size difference is possibly genetic and nothing to worry about.

Also, for unknown reasons, pupils may temporarily differ in size. If there are no other symptoms and if the pupils return to normal, then it is nothing to worry about.

Unequal pupil sizes of more than 1 mm that develop later in life and do NOT return to equal size may be a sign of an eye, brain, blood vessel, or nerve disease.

Causes

The use of eyedrops is a common cause of a harmless change in pupil size. Other medicines that get in the eyes, including medicine from asthma inhalers, can change pupil size.

Other causes of unequal pupil sizes may include:

Home Care

Treatment depends on the cause of the unequal pupil size. You should see a doctor if you have sudden changes in pupil size.

When to Contact a Medical Professional

You should see a doctor if you have persistent, unexplained, or sudden changes in pupil size. The new development of different sized pupils may be a sign of a very serious condition.

If you have differing pupil size after an eye or head injury, get medical help immediately.

Always seek immediate medical attention if differing pupil size occurs along with:

What to Expect at Your Office Visit

Your health care provider will perform a physical exam and ask questions about your symptoms and medical history, including:

Tests that may be done include:

Treatment depends on the cause of the problem.


Review Date: 4/30/2011
Reviewed By: Kevin Sheth, MD, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine;David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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