This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Trauma, Subject name: Ophthalmology
In a patient of head injury, who presents with headache and increased intracranial pressure, the effect on pupil is: 
Select and explain. 
A. Ipsilateral mydriasis, B. Contralateral mydriasis, C. Ipsilateral miosis, D. Contralateral miosis
A: Ipsilateral mydriasis
Answer: A: Ipsilateral mydriasis 
Explanation: 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