In which region of the iris does an iris coloboma usually result in a defect?

An iris coloboma typically results in a defect in the inferonasal region of the iris. This is due to the process of embryological development where a failure of closure of the embryonic fissure can occur. When this fissure does not close completely, it can lead to a gap or defect in the iris, most commonly located in the inferonasal part.

The inferonasal region is significant because it is the area where colobomas are most frequently observed in cases of congenital iris anomalies. As a result, when evaluating a patient for potential coloboma, the inferonasal quadrant is the area clinically monitored for this specific defect. Understanding this anatomical and developmental context is critical for recognizing and diagnosing iris colobomas effectively.