Also, it is useful in eye diseases like cataracts, glaucoma, macular degeneration, etc. But, in disease cases The Bates Method is complementary with medicine, so the student must be under the care of a medical doctor.

When one's mind is under a strain one unconsciously tightens the muscles which encircle the eyeball, and consequently squeeze it out of shape and out of focus.  But when the mind is at rest these muscles are relaxed and the eyeball is allowed to assume its proper shape and focus.

William H Bates, M.D., Better Eyesight magazine, May 1923