This study will evaluate the efficacy and safety of either bimatoprost 0.01% ophthalmic solution (Lumigan®) alone or bimatoprost 0.01% ophthalmic solution (Lumigan®) and brimonidine tartrate 0.1% ophthalmic solution (Alphagan® P) in combination in patients previously treated with latanoprost 0.005% ophthalmic solution monotherapy who require additional intraocular pressure (IOP) lowering medication.