<prompt> Initial drug in open angle glaucoma -b-blockerPilocarpineAnticholinergicsc Physostigmine  <response>: Ans. is a i.e., b-blocker o Topical b-blockers timolol, betaxolol, levobunolol, carteolol are the drugs of choice for POAG. Treatment of primary open angle glaucoma o Following treatment options are available for POAG o Medical therapyTotal medical therapy is the treatment of choice for POAG. Topical ji-blockers Timolol, Betoxalol, Levobunolol, carteolol are the drugs of choice. Topical prostaglandin analogues Latanoprost, bimatoprost, travoprost are the second choice drugs. Other topical drugs for POAG are : - Alpha agonists non - selective : epinephrine, dipivefrine; and Selective - a2: apraclonidine, brimonidine Carbonic anhydrase inhibitors fDorzalamide, brinzolamide Cholinomimetic drugs Pilocarpine, physostigmine, echothiophate, carbachol Pilocarpire has several drawbacks, therefore, is being considered as an adjunctive therapy only as a last resort. Approach to treatment of POAG o Start monotherapy with topical b-blocker or latanoprost. o If target IOT is not attained either change over to the alternative drug or use both the above concurrently, o Brimonidinedorazolamidedipivefrine are used only when there are contraindications to PG analogues or b-blockers. o Topical miotics and oral acetazolamide are added only as the last resort. Systemic therapy is considered only as a last resort. Drugs used for systemic therapy are :- i Carbonic anhydrase inhibitors .dcefflzoamrrfetDichlorphenamide, methazolamide, ii Hyperosmotic agents mannitol, glycerol. 