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 drugs is not used topically for treatment of open angle glaucoma? 
Select and explain. 
A. Lanatoprost, B. Brimonidine, C. Acetazolamide, D. Dorazolamide
C: Acetazolamide
Answer: C: Acetazolamide 
Explanation: Ans. is 'c' i.e., Acetazolamide