With an injury to the eye, the muscles that control the pupil size and shape can be damaged. These muscles control the ability of the pupil to change in size and keep its round shape.
An injury that punctures the eyeball may tear the colored part (iris) of the eye, causing it to lose its round shape.
An injury to the eye may also cause the pupils to react differently to light or to be different sizes.
Call your doctor for an evaluation if you have a change in the size or shape of your pupil after an injury to your eye.