Contributor. Gordon K. Klintworth
A coloboma of the iris is characterized by the absence of a sector of the iris. It may be congenital or acquired. The remainder of the iris is normal. An iris coloboma may be typical [coloboma - typical] or atypical [coloboma - atypical]. Some iris colobomas are due to mutation in the SHH gene. Another common iris coloboma results from the sugical removal of iris tissue during a peripheral iridectomy as in a cataract extraction or in the surgical treatment of congenital glaucoma [glaucoma - congenital].