This invention relates to potent potassium channel blocker compounds of Formula (I) or a formulation thereof for the treatment of glaucoma and other conditions which leads to elevated intraoccular pressure in the eye of a patient. This invention also relates to the use of such compounds to provide a neuroprotective effect to the eye of mammalian species, particularly humans, or a pharmaceutically acceptable salt, in vivo hydrolysable ester, enantiomer, diastereomer or mixture thereof: formula (II) represents C6-10 aryl or C3-10 heterocyclyl, said aryl or heterocyclyl optionally substituted with 1-3 groups selected from Ra; Z represents (CH2)nPO(OR)(OR*).