A display device (1) has a photon source (20) that displays an image scene in which the user perceives points at differents distances, resulting in optical stimulation of the eye's accommodative response. This is achieved by an intermediate optical system (21) forming the photons into pencils and a variable power optical system (22) positioned for convergence of the pencils. A control system (8) controls the variable power optical system (22) to modulate photon wavefront curvature according to image pixel co-ordinate and intensity data and data representing required perceived pixel distance.