Trauma to the pupil can cause the pupil to dilate, and whether or not it will become larger depends on the severity of the injury to determine. The pupil is a circular hole made up of the iris, and the dilation and contraction of the pupil is controlled by the muscles within the iris; dilation requires the pupil dilator muscle, and contraction requires the pupil sphincter. Trauma can cause paralysis of the pupil sphincter, ciliary muscle, and innervating nerve, resulting in pupil dilation. Patients with trauma-induced pupil dilation experience a brief period of pupil narrowing followed by pupil dilation. Patients with mild eye trauma can be treated with antibiotic eye drops (chloramphenicol eye drops, Rensu eye drops, etc.), multivitamins, methylcobalamin, and other nerve-nourishing drugs, and most of the patients can recover well without special treatment. But serious eye trauma can cause pupil sphincter fiber damage, iris pupil rim laceration, this case of pupil dilation is generally more difficult to recover, but can be done by doing pupil formation surgery, the pupil with sutures to narrow. Patients with pupil injuries it is best to go to the hospital to do a checkup, under the guidance of the doctor, so as not to delay the condition.