The pupil can be narrowed or dilated with changes in the intensity of external light to regulate the light entering the eye and ensure clear retinal imaging. Patients with traumatic optic neuropathy often have dilated pupils on the injured side, when the affected eye is directly illuminated with light, the dilated pupil does not shrink (known as the direct response to light disappeared); and when the light is shone on the opposite side of the healthy eye, the dilated pupil of the affected side shrinks (known as the indirect response to light exists). However, monocular pupil dilation after trauma does not necessarily mean optic neuropathy. Ocular trauma that results in damage to the pupillary sphincter may also result in pupil dilation, in which case both the direct and indirect light responses of the dilated pupil are lost. Particularly need to be vigilant, when the craniocerebral injury occurs after intracranial hematoma caused by patients with increased intracranial pressure, the affected side of the cerebral hemisphere to increase the pressure so that the medial temporal lobe of the brain tissue downward displacement into the dural fissure and formation of cerebral herniation, the compression of the motor nerve can also cause the pupil of the same side of the pupil dilatation. At this time, the patient is comatose and has hemiparesis of the opposite side of the limbs. If the hematoma is not removed in time by craniotomy and decompression, the patient’s life will be in danger.