(Kah-Luh-BOH-Muh). Congenital Anomaly. Cleft Or Defect in the Normal Continuity

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Coloboma 1

Coloboma

Jodi McQueen

Stephen F. Austin University

Coloboma

(kah-luh-BOH-muh). Congenital anomaly. Cleft or defect in the normal continuity

of a part of the eye.

What is Coloboma?

A coloboma (also part of the rare cat eye syndrome)is a hole in one of the structures of the eye, such as the lens, eyelid, iris, retina, choroid or optic disc.

Coloboma is a Greek word, which means mutilation. People with Coloboma are missing a portion of the structure of the eye.

Coloboma is congenital. The human eye develops between the fourth and fifteenth week of pregnancy. As the eye starts to develop, a gap opens on the underside of each eye bud. This gap provides a way for the developing eye to be nourished. This gap, called the optic fissure, has to close before the eye is fully developed. The coloboma is formed when this gap fails to close up completely before a child is born. Coloboma occurs in about 1 in 10,000 births.

The classical description in medical literature is of a key-hole shaped defect. A coloboma can occur in one or both eyes.

What parts of the visual system is affected?

Coloboma is the incomplete closer of the optic fissure. Gaps can occur in the eye lid, iris, ciliary body, lens, retina, macula, choroid and optic disc.

The effects of Coloboma

The effects a coloboma has on the vision can be mild or more severe depending on the size and location of the gap. If only a small part of the iris is missing, vision might still be normal, if a large part of the retina or optic nerve is missing, vision may be poor and a large part of the visual field may be missing. This is more likely to cause problems with mobility if the lower visual field is absent. It can cause from mild to sever vision loss.

Other conditions can be associated with a coloboma. Sometimes the eye may be reduced in size, a condition called microphthalmia, or there may be glaucoma, nystagmus or strabismus(squint).

Common treatments of Coloboma

As of yet there is no treatment for the visual impairment caused by coloboma. Specialized contact lenses can be used later in life.

Functional problems

The visual consequences of this condition results in processing (CVI) and a visual acuity of 20/20 to 20/400. It affects of the peripheral visual field depending on the retinal area involved; superior is the most common.

Sources:

1.  http://en.wikipedia.org/wiki/Coloboma

2.  Dictionary of Eye Terminology 5th Ed., Barbara Cassin and Melvin Rubin, MD, Editor, 2006, Gainsville, FL., pg. 69

3.  http://marylandgeneralhospital.com/imagepages/1130.htm

4.  http://groups.yahoo.com/group/coloboma/

5.  Functional Vision., Amanda Hall Lueck, Editor, 2004, New York, NY.,pg.476-7