Coloboma of the iris

Eye — The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

Definition

Coloboma of the iris is a hole or defect of the iris of the eye. Most colobomas are present since birth (congenital).

Considerations

Coloboma of the iris may look like a black, round hole located in or next to the colored part of the eye (iris). It can look like a black notch of different depths at the edge of the pupil. This gives the pupil an irregular shape. It can also appear as a split in the iris from the pupil to the edge of the iris.

A small coloboma (especially if it is not attached to the pupil) may allow a second image to focus on the back of the eye, causing:

Blurred vision
Decreased visual acuity
Ghost image

The defect may include the retina, choroid, or optic nerve.

Colobomas are generally diagnosed at, or shortly after, birth.

Common Causes

Coloboma can occur due to:

Eye surgery
Inherited conditions
Trauma to the eye

Most cases of coloboma have no known cause and are not related to other abnormalities. A small percentage of people with coloboma have other inherited developmental problems.

Call your health care provider if

Contact your health care provider if:

You notice that your child has what appears to be a hole in the iris or an unusual-shaped pupil.
Your child's vision becomes blurred or decreased.

Note: It is appropriate to see an ophthalmologist for vision problems. Your primary health care provider may need to help rule out disorders associated with coloboma of the iris.

What to expect at your health care provider's office

Your health care provider will take a medical history and do an examination.

The patient is usually an infant, and the family history will be most important.

The physical examination will include a detailed eye examination, which may involve:

Dilated exam
MRI imaging of the brain and nerves connecting the eye to the brain

After seeing your health care provider:

You may want to add a diagnosis related to a coloboma to your personal medical record.

References

Olitsky SE, Hug D, Smith LP. Abnormalities of pupil and iris. In: Kliegman RM, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 621.

Guercio JR, Martyn LJ. Congenital malformations of the eye and orbit. Otolaryngol Clin N Am. 2007;40:113-140.

Review date:: October 31, 2009
Reviewed by:: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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