Coloboma of the iris is a congenital (present since birth) defect of the iris of the eye.

Coloboma of the iris may appear as a black, round hole located in or next to the colored portion of the eye (iris). 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:

• Blurred vision
• Decreased visual acuity
• Ghost image

The defect may extend to the retina, choroid, or optic nerve.

Colobomas are generally diagnosed at, or shortly after birth.

Coloboma can occur due to:

• Eye surgery
• Hereditary conditions
• Trauma to the eye

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