Iris coloboma is a condition in which the iris ( colored portion of the eye) has a hole in it. The condition may be unilateral, and almost always occurs in merles. In the normal eye the pupil appears round and black. The black color is an opening through which light is admitted into the eye. The pupil will constrict to restrict the amount of light entering the eye, or dilate to admit more light. With the precense of an Iris Coloboma, extra light is continually admitted to the eye. Common complications resulting from an Iris coloboma is squinting in bright sunlight. Iris coloboma does not progress nor does it lead to blindness. It can be detected by an ophthalmic exam very early. Large colobomas are detectible with the naked eye, but small ones may escape detection unless examined by a certified veterinary ophthalmologist. Screening for iris coloboma is a part of a normal CERF exam.