Coloboma of the iris

Considerations:
Colobomas of the iris may appear as a black, round hole located in or adjacent to the iris (colored portion 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. 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 secondary image to focus on the back of the eye, causing some blurred vision or decreased visual acuity .

Coloboma may be associated with hereditary conditions, trauma to the eye, or eye surgery.

Common Causes:

Note: There may be other causes of coloboma of the iris. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for coloboma of the iris, occurring alone or in combination with other problems.

Home Care:
The person with a coloboma of the iris should be questioned about the presence of blurred vision or decreased visual acuity .

Call Your Healthcare Provider If:

  • you notice that your child has what appears to be a hole in the iris or an unusual-shaped pupil.
  • vision becomes blurred or decreased vision is noted.

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

What to expect at your health care provider's office:
The medical history will be obtained and a physical examination performed.

Medical history questions documenting a coloboma in detail may include:

  • time pattern
    • When did you first notice that the iris looked unusual?

  • location
    • Does the iris look unusual in one or both eyes?
    • What part of the eye is affected (iris or pupil)?

  • quality
    • What is the size and shape of the dark area?

  • other
    • What other symptoms are also present?
    • Is there any change in the vision?

The physical examination will include a detailed eye examination.

Diagnostic tests may include:

After seeing your health care provider:
You may want to add a diagnosis related to a coloboma to your personal medical record.


This is an illustration of a cross-section and frontal view of the eye.



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.