Health Information

Coloboma of the iris

Coloboma of the iris


Keyhole pupil; Iris defect

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

I Would Like to Learn About:

  • Considerations

    Coloboma of the iris can look like a second pupil or a black notch 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. This may cause:

    • Blurred vision
    • Decreased visual acuity
    • Double vision
    • Ghost image

    If it is congenital the defect may include the retina, choroid, or optic nerve.

    Most colobomas are diagnosed at birth or shortly afterward.

  • 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 number 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.

    You may also need to see an eye specialist (ophthalmologist).

  • What to Expect at Your Office Visit

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

    Since the problem is most often diagnosed in infants, knowing about the family history is very important.

    The health care provider will do a detailed eye exam that includes looking into the back of the eye while the eye is dilated. An MRI of the brain, eyes, and connecting nerves may be done if other problems are suspected.

Related Information

  IrisVision problems    


Slamovits TL, Mbekeani JN,Glaser JS. The Pupils and Accommodation. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 2013 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013: vol 2, chap 15.

Olitsky SE, Hug D, Plummer LS, Stass-Isern M. Abnormalities of pupil and iris. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 614.


Review Date: 11/12/2013  

Reviewed By: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.

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