The symptoms of a coloboma depend on where it occurs. An iris coloboma will be visibly noticeable due to the keyhole or cat-eye appearance of the eye. An eyelid coloboma will also be noticeable. People with a coloboma affecting the front of the eye will not have any decreased vision as a result of it.
Other types of coloboma can cause vision loss, depending on their size. A child with a coloboma affecting the macula or the optic nerve will 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.
Image reproduced, with permission, from Holds JB, Basic and Clinical Science Course, Section 7, American Academy of Ophthalmology, 2011-2012.
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