Coloboma of the iris
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.
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.
When to Contact a Medical Professional
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 Office Visit
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.
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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