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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).

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.

In addition to your child, you may also need to see an eye specialist (ophthalmologist).

 

What to Expect at Your Office Visit

 

Your 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 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.

 

 

References

Brodsky MC. Congenital optic disc anomalies. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 9.5.

Olitsky SE, Hug D, Plummer LS, et al. Abnormalities of pupil and iris. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 622.

 
  • Eye

    Eye - illustration

    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.

    Eye

    illustration

  • Cat eye

    Cat eye - illustration

    A cat eye is a type of coloboma. Any defect in the iris that allows light to enter the eye, other than through the pupil, is called a coloboma. An extra hole or slit may be present from birth, or may result from trauma. Colobomas may also exist in the eyelid, a defect which interrupts the border of the eyelid.

    Cat eye

    illustration

  • Coloboma of the iris

    Coloboma of the iris - illustration

    A coloboma is a defect in the iris of the eye. It can appear as a black notch of varying depth at the edge of the pupil, giving the pupil an irregular shape. Coloboma may be associated with hereditary conditions, trauma to the eye, or eye surgery.

    Coloboma of the iris

    illustration

    • Eye

      Eye - illustration

      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.

      Eye

      illustration

    • Cat eye

      Cat eye - illustration

      A cat eye is a type of coloboma. Any defect in the iris that allows light to enter the eye, other than through the pupil, is called a coloboma. An extra hole or slit may be present from birth, or may result from trauma. Colobomas may also exist in the eyelid, a defect which interrupts the border of the eyelid.

      Cat eye

      illustration

    • Coloboma of the iris

      Coloboma of the iris - illustration

      A coloboma is a defect in the iris of the eye. It can appear as a black notch of varying depth at the edge of the pupil, giving the pupil an irregular shape. Coloboma may be associated with hereditary conditions, trauma to the eye, or eye surgery.

      Coloboma of the iris

      illustration

    A Closer Look

     

      Tests for Coloboma of the iris

       

         

        Review Date: 11/4/2015

        Reviewed By: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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