A coloboma is a gap in part of the structures of the eye. This gap can occur in the iris, the retina, or the optic nerve and can be large or small. The most common form of gap is caused by an imperfect closure of a cleft, present in the womb but usually closed by birth. Coloboma of the eye is an important cause of childhood visual impairment and blindness. Colobomas can be seen in isolation or in an impressive number of multisystem syndromes, where the eye problem is seen in association with severe neurological or craniofacial anomalies or other systemic developmental defects such as congenital heart or gut abnormalities.

Colobomas affecting both eyes can be passed through families, although most cases appear without any previously known family history. During the first three months of pregnancy, the eyes of the fetus 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. A gap, known as the fetal cleft, opens on the underside of each bud, through which blood vessels pass, to aid in nourishment of the developing eye. This gap normally closes after the major components of the eye are formed. Failure of this gap to completely close results in coloboma. The effects of the condition can be quite mild or cause more visual problems if the back of the eye is affected. This will depend upon the extent and location of the gap, or incomplete closure.

Coloboma is often first detected by a keyhole-like shape of the pupil or by a white reflection in the pupil especially in flash photographs. If your child is suspected to have a coloboma, he or she will undergo a full eye examination. This will help determine how much of the eye has been affected by the coloboma. It may be difficult to tell how much a child’s sight has been affected until they are older because small children are not able to communicate about their vision.

There is no cure for coloboma. This condition should be monitored according to the complexity of the eye involvement. There is a small increased risk of detached retina or glaucoma. Children with colobomas frequently develop a need for glasses or contact lenses. Early detection and treatment can prevent further vision loss due to the child ignoring the eye that needs stronger glasses.