…optometrist Ruth Perrott, who claims James Cameron’s sci-fi movie picks up eye problems such as strabismus, when the eyes do not align when focusing, or amblyopia, the loss of one eye’s ability to see details.

She said: “About five to ten per cent of people don’t have true depth perception, and far more may have trouble with their binocular vision, which is needed to see the 3D images in movies.”

Ruth, a practitioner specially trained to help patients improve their visual performance, said: she understood that to make movies such as Avatar, filmmakers used special 3D cameras that captured two images, simulating the different perspectives of the left and right eye. …