Question:easy
Iris coloboma is most commonly located in which quadrant?
Iris coloboma is most commonly located in which quadrant?
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Colobomas follow the line of the embryonic fissure.
Updated On: Jun 24, 2026
- Inferotemporal
- Superotemporal
- Inferonasal
- Superonasal
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Trace the cause. Colobomas, whether of the iris, choroid, retina, or optic disc, arise when the fetal (embryonic) fissure does not seal properly.
Step 2: That fissure runs along the inferonasal aspect of the optic cup, so any gap from incomplete closure appears in the inferonasal region.
Step 3: For the iris this presents as a typical coloboma producing a downward-and-inward keyhole or inverted-teardrop pupil.
Step 4: Since the inferotemporal, superotemporal, and superonasal positions do not lie on the fissure, they are ruled out, confirming inferonasal as the answer.
\[\boxed{\text{Inferonasal}}\]
Step 2: That fissure runs along the inferonasal aspect of the optic cup, so any gap from incomplete closure appears in the inferonasal region.
Step 3: For the iris this presents as a typical coloboma producing a downward-and-inward keyhole or inverted-teardrop pupil.
Step 4: Since the inferotemporal, superotemporal, and superonasal positions do not lie on the fissure, they are ruled out, confirming inferonasal as the answer.
\[\boxed{\text{Inferonasal}}\]
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