This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
A patient presented with pain in left eye associated with visual distrubance, also a history of blunt trauma to eye 4 month back, first investingation of choice is 
Select and explain. 
A. Introcular tension, B. Ophthalmoscopy, C. Perimetry, D. Ultrasound
A: Introcular tension
Answer: A: Introcular tension 
Explanation: A i.e. Intraocular tension This is a case of angle recession glaucoma