the orthodox explanations, even where such explana tions were available. It seemed to me that if a state ment is a truth it must always be a truth. There can be no exceptions. If errors of refraction are incurable, they should not recover, or change their form, spon taneously.
In the course of time I discovered that myopia and hypermetropia, like astigmatism, could be produced at will; that myopia was not, as we have so long believed, associated with the use of the eyes at the near-point, but with a strain to see distant objects, strain at the near-point being associated with hypermetropia; that no error of refraction was ever a constant condition; and that the lower degrees of refractive error were curable, while higher degrees could be improved.
In seeking for light upon these problems I examined tens of thousands of eyes, and the more facts I accumu lated the more difficult it became to reconcile them with the accepted views. Finally, about half a dozen years ago, I undertook a series of observations upon the eyes of human beings and the lower animals the results of which convinced both myself and others that the lens is not a factor in accommodation, and that the ad justment necessary for vision at different distances is affected in the eye, precisely as it is in the camera, by a change in the length of the organ, this alteration being brought about by the action of the muscles on the out side of the globe. Equally convincing was the demon stration that errors of refraction, including presbyopia, are due, not to an organic change in the shape of the eyeball, or in the constitution of the lens, but to a func tional and therefore curable derangement in the action of the extrinsic muscles.