Which of the following is an iris abnormality?

Aniridia is an iris abnormality characterized by the absence of the iris, which is the colored part of the eye that regulates the amount of light entering the pupil. This condition is typically congenital, meaning individuals are born with it, and can significantly affect vision as it allows uncontrolled light to enter the eye and can lead to sensitivity to bright lights. Additionally, individuals with aniridia may develop other ocular issues, such as glaucoma or corneal problems, due to the lack of iris tissue.

In contrast, diabetic retinopathy involves damage to the retina due to diabetes, cataract refers to the clouding of the lens inside the eye, and anisometropia is a condition where there is a significant difference in refractive power between the two eyes. While these conditions can impact vision, they do not directly involve abnormalities of the iris itself.