Devices and methods are provided for administering a fluid to a neuronal
site. The device comprises a reservoir, an aperture in fluid connection
to the reservoir, and electrical means for moving to the fluid to or
through the aperture. The electrical means may take the form of
electroosmotic force, piezoelectric movement of a diaphragm or
electrolysis of a solution. The electrical means may be external to the
host, implanted in the host or may be photodiodes activated by light,
particularly where the neuronal site is associated with the retina.