The goals of glaucoma treatment are to halt the progress of the disease and to preserve vision. For most patients, single drug therapy is adequate to reach a desirable IOP. In many patients β –blockers have been used as a first line of therapy since they are effective and usually topically well tolerated. Over the past few years there has been a gradual shift in the choice of first line therapy. PGs analogues have superceded β –blockers as the first choice.PGs analogues/prostamides include latanoprost, travoprost; unoprostone and bimatoprost are available in the treatment of glaucoma as an initial and continuing therapy. These drugs appear to lower IOP by stimulating the release of metalloproteases that degrade the extra-cellular matrix of the cells along the uveoscleral outflow pathways. This in turn promotes the outflow of aqueous humor and the reduction of IOP, although not all these drugs may work via the same receptors.