A visual stress assessment device is provided comprising a plurality of coloured light sources, each adapted to produce light of a predetermined hue, and a white light source. The white light source and the coloured light sources each comprise a plurality of light emitting diodes. A chamber is provided having an interior comprising a viewable region configured to provide a sample for inducing visual stress, wherein said viewable region is arranged to be illuminated by the white light source and the coloured light sources. A controller is configured to selectively operate the white light source and coloured light sources such that only one or both of a first of the coloured light sources and a second of the coloured light sources are operated simultaneously with the white light source, whereby their respective emitted light is observable in the viewable region by a user at a predetermined hue and saturation.