The Swinging Cure

The Swinging Cure

[...The Swinging Cure

If you see a letter perfectly, you may note that it appears to
pulsate, or move slightly in various directions. If your sight is
imperfect, the letter will appear to be stationary. The apparent
movement is caused by the unconscious shifting of the eye. The lack of
movement is due to the fact that the eye stares, or looks too long at
one point. This is an invariable symptom of imperfect sight, and may
often be relieved by the following method:

Close your eyes and cover them with the palms of the hands so as to
exclude all the light, and shift mentally from one side of a black
letter to the other. As you do this, the mental picture of the letter
will appear to move back and forth In a direction contrary to the
imagined movement of the eye. Just so long as you imagine that the
letter is moving, or swinging, you will find that you are able to
remember it, and the shorter and more regular the swing, the blacker
and more distinct the letter will appear. If you are able to imagine
the letter stationary, which may be difficult, you will find that your
memory of it will be much less perfect.

Now open your eyes and look first at one side and then at the other of
the real letter. If it appears to move in a direction opposite to the
movement of the eye, you will find that your vision has improved. If
you can imagine the swing of the letter as well with your eyes open as
with your eyes closed, as short, as regular and as continuous, your
vision will be normal...]

- Dr. W. H. Bates, September 1919