Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1914-07-24
PEcULIARITIES OF THE EYE
Interesting Study that Reveals Valua'
BILE Information.


Interesting Study that Reveals Valua-
BILE information.
The exercise Of the sense of sight
is attended by more possibilities for
improvement than that Of any other
of the five senses. The tapering
finger and the stubby one may be
equally sensitive in touch; the sense
Of taste is not dependent on the size
Of the tongue; small and large noses
may be equally keen of scent; the
shape of the ear has little or nothing
to do with the ability to hear-but
the eye is different. 1t partakes
more of the character Of a fine me-
chanical instrument
Light enters the pupil Of the eye,
spans the diameter Of the ball, and
order that this focus may be proper
ly placed the eyeball must have GER
tain exact proportions. 1t must have
a definite shape; and, if it lacks so
little as one-hundredth part of an
inch, difficulties in seeing will occur.
In fact. many eyes seemingly perfect
to outward appearance, fall short in
a little detail of shape and the sight
is not at all satisfactory. This con-
dition is in no respect a disease.
When light entering the eye fails
to come to a correct focus, this de-
feet may be remedied by placing a
lense before the eye. That is to
say, the focal error may be meas
ured and a lens ground to correct 1t.
Thus we see that the problem present
ed is purely one of optical adjustment
and the solution depends upon the eX-
act measurements Of focus. In order
to determine just what an eye can or
cannot do, these measurements should
be made when the eye is in its usual
working condition. If any function
of the eye is impaired by the use Of
drugs-such as dilating the pupil,
ETC., the resulting measurements are
likely to be inaccurate and improper
ly fitted glasses may be given.
The principal defects Of sight may
be classified under three heads: Hy-
permetropia (far-sightedness), my
opia (near- -sightedness and an unsym-
metrical form called astigmatism.
Hypermetropia is a defect where
the eyeball is not deep enough to al
low the rays of light to come to a
correct focus With an eye Of this
kind the far-away sight is often near
ly normal, whereas the reading vision
may be accomplished only by unusual
strain of the focusing muscles. In
deed, in some cases, reading near at
hand is impossible without the aid of
glasses In hypermetropia certain
muscles are under strain practical
ly every moment that the eye is in
use. This produces discomfort about
the eyes and often results in head
aches. Properly fitted glasses is the
only permanent remedy.
Myopia is a focal arrangement
caused by the eyeball being too deep.
The distant sight is bad, yet the near
vision may be almost normal. The
focusing muscles are seldom brought
into play in myopia, so there is little
occasion to strain them. For this
reason headaches are rarely caused
by myopic eyes. People having such
eyes derive wonderful pleasure from
correctly fitted glasses, which enable
them to enjoy clear vision.
Astigmatism is a arrangement of
focus that may be said to lie between
the other two forms-for in the astig-
matte eye part of the rays of light
focus on the retina and part do not.
This is usually brought about by an
unsymmetrical shape Of the front
aspect (cornea) of the eye. small
degree of astigmatism will not ma
terially affect the sharpness of sight,
but often causes great discomfort and
aching in and about the eyes. These
symptoms have often led the unin-
formed to think that aStigmatiSm is
some form of disease. Astigmatism
is in no respect a disease, and it is a
serious mistake to use drugs in the
eyes when examining for it, as the ac-
ton of the drug interferes with ac-
curate measurement of the defect.
This focal defect is often associated
with myopia, and hyperemetropia,
thus producing what is known as
compounded astigmatism.
Besides these defects of vision.
another and very different kind should
be mentioned which develops in mid
die life 1t is universal. When view
ing objects near at hand the contents
of the eyeball are in constant notion
delicate muscles contracting, and the
jelly-like mass pulsating with action
instant adjustment being made for
any focus. But time, which changes
cartilage to bone and causes a gen.
eral hardening of the tissues, "Vul-
caniZes' the eye-lenses. Little by lit
tie the motion is checked, and finally
ceases altogether. In the proportion
that this ocular activity is lessened
by age, we have to hold our book or
paper further away to see the print
clearly. In extreme old age all in
ternal motion stops, and glasses alone
makes reading possible. When this
change begins it is folly to abuse the
sight by trying to force the eye to see
without glaSseS-for glasses are the
only thing that will restore normal
vision.
When using the two eyes in seeing
it is. of course, necessary that both
eyes be directed exactly toward the
object viewed. This calls a certain
tension of the muscles that move the
eyeballs. If for any reason these mus
cles are lacking in strength, vision
will be painful, and crosse
even, may finally result. The COM
petent optometrist, when examining
for cyeStrain, always tests the strength
of these muscles to find if they are
concerned in the trouble. as well as
learn if there is danger Of Gross
eyes" When needed, special lenses
are prescribed to relieve weak mus