ng farsightedness or astigmatism, since both
are often present at birth.

The power of accommodation is sufficient to overcome the optical
defect of the eye, providing that the general health is good and the
eye is not used much for near work. If, on the other hand, excessive
use of the eyes in reading, writing, figuring, sewing, or other fine
work is required, and especially if the health becomes impaired, it
happens that the constant drain on the eye center in the brain will
result in a group of symptoms which we will consider later. Failure of
accommodation comes on at about forty, and gradually increases until
all accommodation is lost at the age of seventy-five.

For this reason it is necessary for persons over forty-five years of
age, having normal or farsighted eyes, to wear convex glasses in
reading or doing near work, and these should be changed for stronger
ones every year or two. These convex glasses save the eyes in their
attempt to make the lens more convex when looking at near objects in
farsightedness, and also prove serviceable in the same manner when
accommodation begins to fail in the case of what is called "old
sight." The neglect to provide proper glasses for reading any time
after the age of forty-five, and the failure to replace them by
stronger lenses when required, distinctly favor the occurrence of
cataract in later life.

In the act of accommodation, in addition to the muscular action by
which the lens is made more convex, there is the tendency for the
action of another group of muscles outside the eyeball, which turn the
eyes inward when they are directed toward a near object. Here then is
another source of trouble resulting from farsightedness, i. e., the
not infrequent occurrence of inward "squint" occasioned by the
constant use of the muscles pulling the eyes inward during
accommodation for near objects. Again, inflammation of the eyelids,
and sometimes of deeper parts of the eyeball, follows untreated
hyperopia. Early distaste for reading is often acquired by farsighted
persons, owing to the strain on the accommodative apparatus. The
convex lens is that used to correct farsightedness.

=NEARSIGHTED EYE.=--In the nearsighted eye the eyeball is too long for
parallel rays entering the eye to be focused upon the retina; they are
bent, instead, to a point in front of the retina, and then diverge
making the vision blurred. (Plate I, p. 30.) The act of accommodation
in making the lens more