The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1877-03-31
OLD EYES AND SPECTACLES.


Numerous errors respecting the condi-
ton of eyes that have become affected with
age, and concerning the use of spectacles,
are prevalent, not only among the laity,
but also among the mass of medical prac-
titioners themselves. This, however, is not
to be wondered at, since the more precise
physiological knowledge of the parts of the
visual apparatus involved has come to us
within comparatively recent years, and only
those who have been working in that par
ticular line have kept pace with the ad.
vance of that knowledge. Eyes that have
become affected through age were formerly,
and are now by a large number, incorrectly
regarded as being in the same condition as
far-sighted eyes. Persons of all ages may
be far sighted, but presbyopia-or old eyes
is limited to those who have reached the
meridian of life and are travelling the down.
ward slope. Farsi ghtedness, or hyperme-
tropia, is dependent upon faulty construc-
ton of the eye balm general it is an eye
that is too short while presbyopia is sim
ply the result of the decline of the vital
| powers from age.
Presbyopia consists essentially in an ina
bility to see distinctly small objects close at
hand. Our ability to distinguish fine oh.
jects within a few inches of the eyes is due
| to the fact that we have the power to in
crease the curvature of the crystalline lens,
and thus to unite the rays, which come in
divergent manner from those objects, upon
the retina. Two factors enter into the pro-
duction of this; first, the Elasticity of the
lens, and second, the contraction of a mus
Gle acting upon it. Both of these factors
undergo modification with age; the lens
becomes firmer and less plastic, and the
muscle gets stiff and less active
Now, while these changes have in reality
been going forward since childhood, they
do not, under ordinary circumstances make
| themselves appreciably felt until about the
fortieth year. I'VE speak now of eyes that
are in other respects healthy.) At about
that age-or between that and the fiftieth
year-most individuals experience difficulty
in recognizing small objects, especially I'M
der bad illumination. In the evening the
book or newspaper is laid aside earlier than
formerly and casual remarks are made not
complimentary to the printers of this gen.
GRAFTON. The page is instinctively held at
a greater distance from the eyes and turned
Sc as to have the light fall upon it most
advantageously. This sort of thing grow
ing from bad to worse, you happen Incl
dentally to mention it to an elder friend,
who astonishes you perhaps by saying:
My dear fellow, you need glasses" The
fact is now forced upon you, for the first
time it may be, that you are growing old,
But it is the course of Nature, and you
must accept the fat. She now declares
that she is no longer able of herself to do
her work properly, and that art must lend
its aid.
And just here comes in very generally
accepted error, 1t is currently believed
that the use of glasses should be put off as
long as possible; that too early use of
them is injurious, and that when once be-
gun it becomes, earlier than it should be, a
necessity. AS the office of the glass is to
supply the refracting power which the eye,
through age, can no longer furnish, it is
evident that SO soon as need of this arti-
fetal power is felt we should resort to it,
By failing to do so, we deprive ourselves of
much useful work of the organ, while the
work it does is done under a disadvantage
and with greater or less risk.
but how shall | know when | need
them you may ask. When you can no
longer read, with ease, the finest print of
your newspaper, at distance of 80 cent?
meters 1s inches).
Inconvenience will first be felt in the use
Of the eyes in the evening, and for year
or more you may contine the use of your
glasses to work at that time. But soon
they will become necessary during the day,
especially if you have work requiring close
and accurate attention, and the light is not
good.
Under ordinary circumstances, and when
the eyes are in other respects healthy, the
first glasses should be weak-say about No.
GO, according to the numbering in this
country. Such number, however, should
be selected as will enable you to read the
finest print at so centimeters az inches)
After the lapse of a year or two you will
find it necessary to increase the number of
your glasses to about As, and you will find
that these will serve both for evening and
day work. AS regards the frequency with |
WHICH the glasses have to be changed, it |
differs in different individuals. As gen
eral rule, however, they should be increased |
every five or seven years-always keeping |
the ''near point" of good, clear vision at |
about 12 inches. The general health will |
influence this largely, the weak, nervous
woman feeling the need of an increase in
the strength of her glasses much sooner
than a robust, healthy man. Those who
use their eyes much, especially if at trying
work, will also experience demand for a
more frequent change.
These rules apply, as previously men-
toned, to eyes in a perfectly normal condi-
ton. Short sghtedness and far-sighted-
ness influence the necessity for glasses to
great degree. Short-sighted persons can
dispense with glasses for near work for a
much longer time than those having nor
NAL eyes, and if their short -sightedness is
of even moderate degree, they may live
to green old age without ever having occa-
ton to use them. On the other hand, far
sighted persons feel the need of assistance
very early-often as early as the 25th or
30th year.
A few words now as to the glasses them
selves. In the first place, bear in mind that
60 pebble glasses are humbug. Even if
they are what they are represented to be,
and are made of pure crystal, they can
serve no better purpose than if made of
good clear glass. They are harder than
ordinary glass, and thus less liable to be
INIT hot VII