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: Pharmacology
Which of the following is the longest acting ocular beta blocker ? 
Select and explain. 
A. Timolol, B. Betaxolol, C. Carteolol, D. Metoprolol
B: Betaxolol
Answer: B: Betaxolol 
Explanation: Beta blockers used in Glaucoma- Timolol, levobunolol, Carteolol, betaxolol
Metoprolol, though a beta blocker is not used for glaucoma because of its local anaesthetic property. Drugs having local anaesthetic property will increase the risk of corneal ulcers.
Betaxolol is longer acting than Timolol or others.