Stereopsis was brought to the fore by its stunning development in a virtual element, in movies or game devices. The mechanisms used to produce 3D artificially are very similar to those involved in natural depth perception. They include binocular stereopsis, generated by the simultaneous perception of two images with a slight horizontal shift, together with the interpretation of monocular clues (perspective, distribution of light and shadow,...). Because virtual 3D uses the same mechanisms as natural perception, there is no reason to believe that 3D movies might be dangerous for the eyes.