Coloboma is a group of eye conditions where normal eye tissue in or around the eyes is missing from birth. It is also defined as an abnormal eye development caused by improper closure of the optic fissure. It occurs in approximately 1 of 10,000 live births and can also cause vision loss.The term coloboma originates from a Greek word which means “curtailed”.
Coloboma can be classified into different groups depending on the part of the eye which is missing. These generally affects the following parts of the eyes:
- Uvea
- Optic nerve
- Macula
- Lens
- Eyelids
Eyelid Coloboma: In this type, a portion of either the lower or upper eyelid is absent. It may be a part of some genetic syndrome. Otherwise, it may happen as a result of abrupt disruption of eyelid development in a baby. This syndrome is a collection of symptoms or birth defects present in one person.
Lens Coloboma: A portion of the lens is absent in this type of coloboma. The lens usually appears with a notch. This lens help in focusing light on the retina.
Macular Coloboma: When the macula doesn’t develop properly, macular coloboma occurs. Macula is the center of the eye’s retina. It is responsible for color, fine and daylight vision. This type of coloboma occurs when the retina gets inflamed during the development of the baby. Also, any kind of interruption during the normal eye development may cause macular coloboma.
Optic Nerve Coloboma: This type of coloboma usually refers to either of the two distinct conditions-
- An deformed optic nerve that is hollowed out or deeply “excavated”. Also, in some of the cases, it is reffered as an optic nerve pit. This optic nerve is a bunch of nerve fibers that is responsible for passing the light signals from the eye to the brain.
- Uveal coloboma which is so large that it involves the optic nerve. It either involves the complete optic disc or the part of the inferior optic disc.
