Effect on pupil is ipsilateral mydriasis. - In this patient of head injury bleeding occurs, which increases Intra cranial pressure- This increased intra cranial pressure compresses and damages the 3rd nerve- 3rd nerve carry the parasympathetic fibers which is responsible for pupillary constriction- So, the unopposed sympathetic fibers mediated by the 5th nerve dilate the pupil - Hence patient comes with ipsilateral mydriasis Hutchinson's pupil is an ipsilateral mydriasis due to 3rd cranial nerve compression by an intracranial mass lesion including intracranial bleeds