Glaucoma drainage devices including vario-stable valves and associated systems and methods are disclosed. A glaucoma drainage device includes a drainage lumen and a valve system coupled to the drainage lumen to control the flow of fluid through the drainage lumen. The valve system includes an adjustable valve with a diaphragm that is in communication with the drainage lumen and is movable to occupy varying amounts of the drainage lumen. In some embodiments, the valve system is maintained in a desired position without the use of power such that power is only needed when changing a position of the adjustable valve.