A vision prosthesis (17) includes a first detector (24) disposed to detect apolarization state of light reflected from a retina, and a controller (26) incommunication with the first detector (24). The controller (26) is configuredto receive, from the detector (24), a measurement signal indicative of thepolarization state. In response thereto, the controller (26) generates acontrol signal for causing a change to an optical properly of an opticalsystem in optical communication with the retina.
