The low contrast between light and shadow on the model combined with the high contrast between the entire model and the background make the 3D preview more of a strain to view than it needs to be.
simply increasing the contrast of the model i.e. making the shadows much darker would make it a much more comfortable to viewing experience.
It might also help to lighten the background a little to reduce eye strain. Either the background or the model could also be given a colure tint to retain a strong delineation between model and background without the high contrast.