This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glaucoma, Subject name: Ophthalmology
[{'content': 'A lady presented with reddish eye and watering over left eye with a shallow anterior chamber. What is the next best investigation? \nSelect and explain. \nA. Tonometry, B. Cup disc ratio, C. Gonioscopy, D. Ophthalmoscopy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) TonometryShallow AC with redness- points towards PACG in a female. In acute stages, IOP is markedly raised - Do tonometry followed by gonioscopy & fundus examination.', 'role': 'assistant'}]