The visual pathway and visual afferent pathway, which part of these two aspects are affected, may cause pupil dilation, as follows: 1. The pupil is innervated by the pupillary sphincter and pupillary dilator muscles in both directions, and when trauma occurs, it may cause paralysis of the pupillary sphincter, which can cause pupil dilation, or cause iris avulsion, which may also cause irregular pupil dilation, resulting in ciliary muscle paralysis. 2. Pupil dilation can be caused by the use of ciliary muscle paralysis medications, frequent dilated eye examinations, and the use of compound tropicamide or atropine drops. 3. Central nervous system pathologies, such as cerebral hemorrhage and cerebral bruising, can also cause pupil narrowing or dilation.