Wessington Springs herald. (Wessington Springs, Aurora County, Dakota [S.D.]) 1883-1891, 1885-01-09
HUMAN VISION.
Something About the Eyesight, Which
Should he Read and Remembered.

l SuIucUlluk ADoub ia
Should he Read and Remembered.
Persons speak of their eyes being ia
tigued, meaning thereby that the seeing
portion of the brain is fatigued,
but in that, says DR.. W. w.
Seely, they are mistaken. So men say
| their brains are tired. Brains seldom
| become tired. The retina of the eye,
which is a part of the brain and an Off
shoot from it, hardly ever is tired.
The fatigue is in the inner and outer
! muscles attached to the eye and in the
muscle of accommodation. The eye
ball, resting in a bed of fat, has at
| tached to it six muscles for turning it
in any desired direction, and the mus
| Gle attached to the side nearest the nose
and one at the outer angle of the eye
should, in every normal eye, be bal
anced. They are used in converging
the eye on the object to be viewed, and
the inner muscles are used the more
when the object is the nearer. The
muscle of accommodation is n which
surrounds the lens of the eye. When it
is wanted to gaze at objects near at
hand, this muscle relaXes and allows
the lens to thicken, increasing
its retroactive power at the same
time that the muscles on the in
ner or nasal side of the eye contract and
direct the eyes to the point gazed at.
1t is in these muscles that the fatigue is
felt, and one finds relief in closing the
eyes or in gazing at objects at a dis
lance. The chief source of fatigue is
H. 1,o1r IS l,11-,, -, IL, {,vo ,.&, -
inner and outer muscles of accommo-
dation. 1t may be set down that there
is something wrong when the eye be-
comes fatigued. The detective eye, as
i. gives out sooner, is really safer from
severe strains. The usual indication of
strain is a redncss of the rim of the eye
lid, betokening a congested state OF the
inner surface, accompanied with some
pain. When it, is shown that the eye is
not equal to the work required Of it, the
proper remedy is not rest, for that is
fatal to its strength, but the use of!
glasses Of sufficient power to render
necessary so much effort in accommo-
dating the eye to vision. 1t is not good,
sense to waste time in resting the eye,'
and that practice does not strength,
en- it. !:
Eyes begin to age at about the tenth
or twelfth year of life, when they have
reached their full Development. At the
age Of forty-five or fifty years the lenses
cease to thicken, when the pressure is;
removed and their presbyopia, or old
sight, begins. When a child is COM
PEELED to use or require the use Of
glasses, there is little reason to hope
that it will outgrow the need; but The
person will use these glasses as a basis,
adding other glasses as he reaches the
age when old sight begins, or using
thicker glasses. DR.. Seely, however,
mentioned one ease he had observed
where a child had outgrown the need
of glasses, but in the mean time he had
grown from a small and puny child to
a large and well developed man.
Second sight, or the apparent re-
covery of strength Of vision, which is
sometimes seen in the aged, the lee
turer explained as a change, an clon-
cation, in the shape of the eyeball, by
which the person became nearsightcd,
accompanied by a change in the lens
caused by the appearance Of cataract.
Scientific american.