Which condition involves an irregular pupil?

• A. Aniridia
• B. Ptosis
• C. Coloboma
• D. Mydriasis

Answer: (C)

An irregular pupil is most often due to iris coloboma, a congenital defect where part of the iris tissue fails to form because the embryonic fissure doesn’t close properly. This leaves a notch at the pupillary border, giving a crescent-shaped or otherwise irregular pupil. Coloboma can involve other eye structures too, but iris involvement directly alters the pupil’s shape.

Aniridia is a near-complete or partial absence of the iris, which changes iris color and depth but doesn’t create the classic notch in the pupil. Ptosis is drooping of the eyelid and doesn’t affect the pupil’s contour. Mydriasis is dilation of the pupil, producing a larger round pupil rather than an irregular edge.