1. In reading, a book or newspaper should be held at a distance of
from ten to fifteen inches from the eyes. It is hardly necessary to
caution anybody not to hold the print further away than fifteen
inches. The only objection to holding ordinary print too far away is
that in so doing the pictures formed on the back wall of the eye are
too small to be readily and easily perceived, and the close attention
consequently necessary causes both the eyes and the brain to tire.
Most persons quickly find this out themselves, and the tendency is
rather to hold the book too near, for the nearer the object to the
eye, the larger its picture upon the retina, or back eye wall. But
here we encounter another danger. The nearer the object the eyes are
concentrated upon, the greater the muscular effort necessary; so that
by holding the book too near, the labor of reading is greatly
increased, and the long persistence in such a habit is likely to
produce weak eyes, and may, in some instances, lead to real
near-sightedness. When children are observed to have acquired this
habit and cannot be persuaded out of it, they should always be taken
to a physician skilled in the treatment of the eye for examination and
advice. A little attention at such a time may save them from a whole
lifetime of trouble with their eyes. Of course, the larger the print,
the farther it may be held from the eyes.