A drainage device for implantation in an eye of a patient to treat an ocular condition, that includes an implant body portion comprising of a valve portion. The valve portion may comprise a flexible membrane disposed and arranged in a manner to affect flow of aqueous humor through the implant body portion. The device may also include a reed valve disposed downstream of the flexible membrane. The reed valve may be configured to prevent backflow of aqueous humor toward the membrane and configured to stabilize flow by affecting pressure at the flexible membrane. In one aspect, the reed valve is configured to create backpressure at the membrane that affects the rate of flow at the flexible membrane.