http://www.visionsofjoy.org/pdfs/BatesPerfectSightWG.pdf http://www.i-see.org/perfect_sight/
William Horatio Bates (1860-1931) first published his treatise, The Cure of Imperfect Sight by Treatment Without Glasses (title page), also known as Perfect Sight Without Glasses (cover), in 1920.
This guy has some kind of crazy ideas; but the general thing I learned from him is that the shape of the lens of the eye is a function of three sets of muscles that can be trained/relaxed to help vision come back to 'normal'.
A great read. The HN worthy title would be "hacking your crappy vision"