The invention provides a switchable lens element comprising an inverse lens structure formed by an isotropic material and an isotropic cover sheet wherein the resulting lens structure comprises an electrically switchable polymer stabilized blue phase LC medium having the same refractive index in its isotropic state. Furthermore, the present invention relates to the use of such a lens element in an electro-optical device i.e. an autostereoscopic display device operable in a 2D mode or a 3D mode, in which a lens arrangement directs the output from different pixels to different spatial positions to enable a stereoscopic image to be viewed and wherein the lens arrangement comprises a plurality of said switchable lens elements.