The symptoms of a coloboma depend on where it occurs. A coloboma of the iris will be visibly noticeable due to the keyhole or cat-eye appearance of the pupil. An eyelid coloboma will also be noticeable due to a notch or defect in the eyelid. People with a coloboma affecting the front of the eye may have problems with vision and should be evaluated in infancy.
Other types of coloboma can also cause vision loss, depending on their size and location. A child with a coloboma affecting the macula or the optic nerve will likely have reduced vision. Children who are missing a part of their retina will have a “field defect,” which means that they will not have vision in a specific location (for instance, the upper part of the field of vision). Vision impairment caused by a coloboma may not be noticeable at birth.
Sometimes children with a coloboma have increased sensitivity to light.