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
The first line of treatment of open angle glaucoma is - 
Select and explain. 
A. Timolol, B. Pilocarpine, C. Epinephrine, D. Carbonic anhydrase inhibitor
A: Timolol
Answer: A: Timolol 
Explanation: Topical Beta blockers are being recommended as the first drug of choice for medical therapy of POAG in poor and average income patients.These lower IOP by reducing the aqueous secretion due to their effect on beta 2 receptors in the ciliary processes. Ref :Ophthalmology A K Khurana 6th edition chapter-10 page no :236