Patent ID: 8821371

Claim:
An apparatus for treating a disease, comprising a hydraulically operable surgical implant, and an implantable pump for pumping hydraulic fluid to or from the surgical implant, the pump including a wall forming a chamber for the hydraulic fluid, the wall including a first wall portion and a second wall portion, which is displaceable relative to the first wall portion to change the volume of the chamber to pump the hydraulic fluid between the chamber and the surgical implant, wherein the second wall portion includes a displaceable membrane that is penetrable by an injection needle to add hydraulic fluid to or withdraw hydraulic fluid from the chamber of the pump, wherein the membrane includes a first layer and a second layer attached to each other, the first layer having better strength properties than the second layer and the second layer having better sealing properties than the first layer, wherein the first layer is harder than the second layer, wherein the second layer is situated between the first layer and the chamber, and wherein the membrane comprises a third layer harder than the second layer, the third layer being situated between the second layer and the chamber.