Contributor: Jesse Vislisel, MD
Photographer: Stefani Karakas, CRA
"Typical" iris colobomas are located in the inferonasal quadrant. They are caused by failure of the embryonic fissure to close in the 5th week of gestation, resulting in a "keyhole-shaped" pupil. They may be associated with colobomas of the ciliary body, choroid, retina, or optic nerve. "Atypical" iris colobomas are not caused by embryonic fissure closure defects and thus are not associated with other colobomas.
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