This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
In open-angle glaucoma investigation least done is 
Select and explain. 
A. Indirect ophthalmoscopy, B. Tonometry, C. Direct ophthalmoscopy, D. Perimetry
A: Indirect ophthalmoscopy
Answer: A: Indirect ophthalmoscopy 
Explanation: Investigations to be done in open-angle glaucoma are :Slit lamp examinationTonometryGonioscopyDirect ophthalmoscopyPerimetry