A portion of the eyeâ€™s structure has not fully developed. This gap can occur in a range of areas and be any size. The most common form of gap is caused by an imperfect closure of a cleft, present in the womb but usually closed by birth date. This gap can occur in the eyelid, iris, lens, retina, choroid or optic disc
Although no specific pattern has been identified there appears to be a strong hereditary factor in the incidence of this condition, which is sometimes linked to chromosomal disorders.
During the first three months of pregnancy, the eyes of the foetus are developing quickly, starting as a small bud which then sprouts out so that all the intricate parts of the inside of the eye can be formed and nourished. To aid this nourishment a gap, known as the foetal cleft, opens on the underside of each bud.
When the intricate development of the eye is completed, the gap closes but in some cases the gap either does not close or closes only partially and such gaps will remain throughout life. This gap is Coloboma. This does not mean that there is a hole in the eye, just that certain structures within the eye do not fully form.
The effects of the condition can be mild or severe and this will depend upon the extent and location of the gap (or incomplete closure). In most cases, the gap is usually at the bottom of the eye.
A lens coloboma, if large, may also include flaws in the iris and choroid and slightly increase risk of retinal tearing. In severe cases, the eye may be reduced in size. This condition is called Microphthalmia, a condition that may arise without coloboma.
Coloboma of the iris may sometimes gives a keyhole shape to the pupil. Central vision may be affected and may reflect the extent, location and shape of the gap. In some cases the problem may be accompanied by other problems in the body which may be neurological or chromosomal.
Further information about this condition can be obtained from any of our optometrists.