Controlled reduction of intraocular pressure is a main issue in treatment of glaucoma. A novel approach of glaucoma implant is based on a silicone microstent draining the aqueous humor from the anterior chamber of the eye into the suprachoroidal space. The paper presents micro particle-image velocimetry as a method to characterize the fluidmechanical function of the micromechanical valve. The current field around the valve region was measured quantitatively. The flow velocity ranged from 1E-6 to 2.5E-2 m/s depending on pressure difference. The valve opening pressure was Δp=4 mmHg indicated by an elevation of flow velocity by almost two orders of magnitude at this pressure difference. Further improvements of μPIV method will be a powerful tool for development and in particular for investigation of flow phenomena at pressure differences around the opening pressure as well as for new valve designs.