A light direction switching apparatus and method is described. The light direction switching apparatus comprises a passive birefringent lens (138), e.g. a birefringent lenticular screen, and a switchable polariser (146). By switching the polariser (146), different directional distributions of output light are provided. The light direction switching apparatus may be used with or incorporated in a display device, such as a liquid crystal display device, to provide a display device switchable between a two dimensional mode and an autostereoscopic three dimensional mode, or to provide a multi-user display device where different images are displayed to different viewers. The light direction switching apparatus may also be used to provide switchable brightness enhancement of reflective or transflective display devices. The light direction switching apparatus may also be used to provide a fiber-optic switching apparatus. The switchable polariser may be mechanically switchable or electrically switchable.