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: Ophthalmology
Which of the following drugs is not used topically for treatment of open angle glaucoma – 
Select and explain. 
A. Latanoprost, B. Brimonidine, C. Acetazolamide, D. Dorzolamide
C: Acetazolamide
Answer: C: Acetazolamide 
Explanation: Pharmacological agents used for POAG
A) Topical drugs

β-blockers :- Timolol, betaxolol, levobunolol, carteolol.
Prostaglandin analogues :- Latanoprost, bimatoprost, travoprost.
Alpha agonists :- Non-selective (epipherine, dipivefrine); selective a2 (Apraclonidine, Brimonidine).
Carbonic anhydrase inhibitors :- Dorzolamide, brinzolamide.
Cholinomimetic agents :- Pilocarpine, physostigmine, echothiophate, carbachol.

B) Systemic drugs

Carbonic anhydrase inhibitors :- Acetazolamide, dichlorphenamide, methazolamide.
Hyperosmotic agents :- Mannitol, glycerol.