A theory of refractive error based on muscular functioning
In the 1930s a group of optometrists led by A.M. Skeffington held that refractive error was a matter of muscular function. Here is the so-called "New Optometry" as laid out by Des Moines, Iowa, practitioner Milton M. Izdal in the Optical Journal and Review of Optometry in 1935. He explains various eye conditions as the result of energy habitually sent to the eye muscles, and challenges the "eye is too long / too short" concept of refractive error.
New Optometry: Making it Easy For Yourself[136K PDF]