IF you’ve been to see the 3D blockbuster film Avatar and emerged from the cinema with a headache, it could be time to get your eyes checked – and you might even need surgery.

So says Acomb 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.

“The two slightly different images are projected on to a custom screen. When seen through the lenses of the special 3D glasses, each eye sees the proper perspective and the brain fuses them into a 3D or stereoptic image. People whose eyes aren't perfectly aligned because of strabismus or amblyopia, or who struggle to keep their eyes lined up and moving together, will likely have difficulty fusing the images into a 3D experience. Moreover, the challenge may cause eyestrain – dry, irritated, or painful eyes which may lead to headache.”