Mice lacking AQP1 showed reduced aqueous fluid production and reduction of IOP.20 AQP1 is also expressed in trabecular meshwork cells and has been shown to regulate cell volume of the trabecular meshwork cells,21, 22 as well as other types of cells.23, 24, 25 However, the role, if any, of AQP1 in regulating the physiology of TM tissue in the pathogenesis of POAG remains unclear. This evidence concerns the gene AQP1 and open-angle glaucoma.