Microsoft recently filed for a patent which could bring Virtual Reality to the Hololens.
“The technology provides a dimming module for a near-eye display (NED) device that controls an amount of ambient light that passes through the transmissive near-eye display to a user. The dimming module includes at least one electrochromic cell that enables variable density dimming so that the NED device may be used in an augmented reality and/or virtual reality application. The electrochromic cell may be a monochrome electrochromic cell having stacked layers of a monochrome electrochromic compound layer and insulator sandwiched between a pair of transparent substrates and conductors. A current may be applied to the conductor layers to control the amount of dimming in response to a dimming value. A NED device having a dimming module may be included in a visor, or other type of head-mounted display (HMD). The dimming module may be flat and supported by a flat waveguide mount in the user’s field of view.
We have yet to see what this all actually means.