**Core Concept**
Coloboma of the iris is a congenital anomaly characterized by a defect in the iris, typically resulting from incomplete closure of the embryonic fissure. This condition can lead to various ocular manifestations, including vision impairment.

**Why the Correct Answer is Right**
Coloboma of the iris is a result of the incomplete closure of the embryonic fissure during fetal development. The embryonic fissure is a slit-like opening in the anterior segment of the eye, which eventually closes to form the iris. Failure of this fissure to close results in a coloboma, leading to a defect in the iris. This can cause problems such as irregular pupil shape, vision impairment, and increased risk of glaucoma.

**Why Each Wrong Option is Incorrect**
**Option A:** Coloboma of the iris is not the same as a coloboma of the retina, which is a different type of congenital anomaly affecting the posterior segment of the eye.
**Option B:** Coloboma of the iris is not defined by the presence of a cataract, which is a separate ocular condition characterized by clouding of the lens.
**Option C:** Coloboma of the iris is not the result of a traumatic injury to the eye, which can cause a different type of iris defect.

**Clinical Pearl / High-Yield Fact**
In addition to coloboma, other embryonic fissure anomalies include microphthalmia (small eye) and anophthalmia (absence of an eye). These conditions can be associated with systemic syndromes and genetic disorders.

**Correct Answer:** C. A defect in the iris resulting from incomplete closure of the embryonic fissure.