<qa>  What is the purpose of this study?The purpose of this study is to compare the fixed combination BID Brinzolamide 10 mgmL Brimonidine 2 mgmL eyes drops, suspension to the unfixed combination BID Brinzolamide 10 mgmL eye drops, suspension plus Brimonidine 2 mgmL eyes drops, solution with respect to intraocular pressure IOP-lowering efficacy. 