The Eye in its Relation to Health
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By Chalmer Prentice, M.D.
Chicago, A.C. McClurg & Company, 1895
Transcription (c) A. Wik, 2004

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        | Chapter IX |  pages 137-152
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								137

ABNORMAL innervation of the ciliary muscle
is very common.  This muscle, surround-
ing the crystalline lens, exactly as the metal rim
surrounds a spectacle, possesses the power to con-
tract itself around the lens, thus increasing its
antero-posterior convexities, and thereby raising
its magnifying power, whenever that is deficient.
This defect in the lens constitutes hypermetro-
pia--or shorter, hyperopia--a condition in which
the rays of light are brought to a focus behind the
retina, or would be if there were a suspension of
innervation.  A stimulus for perfect vision, or a
clearly defined impression in the visual centers of
the brain, is awakened by the imperfect picture,
and the impulse is sent through the ciliary nerves
to the muscle, thus causing it to contract, so that
the magnifying power of this little glass brings
the rays of light to a perfect focus, producing a
clearly defined image on the retina.  The impact
here sends impulses to the visual nerve-centers,
giving rise to the feeling of perfect sight, which
is the most instructive and the most continuously
enjoyable of all our senses.  If the crystalline
lens possessed just the proper curvatures to bring

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about perfect refraction at an infinite distance
without any effort on the part of the ciliary mus-
cle, it would still require an effort of this muscle
to increase the refractive power for all nearer dis-
tances than twenty feet.  This is called accom-
modation.  Such an eye would be natural or
emmetropic.
  When imperfect vision is due to a deficiency
of refraction in the crystalline lens, say 2 D, or
when an eye whose vision is practically perfect
will accept a 2 D spherical lens without impair-
ment of vision, we have what is termed manifest
hypermetropia to the extent of 2 D.  We might
well discriminate between these two forms of
manifest hyperopia, naming the first Non-func-
tional Manifest, and the second Functional Mani-
fest Hyperopia, for the reason that in the first
form, the function of vision is not perfectly per-
formed, while in the latter it is.  By using some
drug to suspend the action of the ciliary, such as
atropine, hyoscyamine, and their congeners, we
may perhaps find that the same patient cannot see
well with the 2 D glasses, but now requires 4 D,
under its influence, to bring about the best possi-
ble vision.  Without the drug, we had 2 D of
deficiency of refraction; with it, 4 D.  The 2 D
is called manifest, the extra 2 D developed under
the drug is called latent hypermetropia.  It has
been the aim of the profession always to deter-

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mine the full amount of latent hyperopia.  The
advice given in all text books has been to put on
the strongest convex glasses with which the
patient could make out twenty-twentieths of
vision, also the weakest concave glasses, thus
recognizing the fact that it is always advisable to
suspend as much ciliary strain as possible.  This
idea is not new, it is a time-honored method in all
text books of the past as well as the present.
The fact that mydriatics in some cases are variable
in their action on the same patient at different
times and under various conditions of health, is
known to every oculist.
  Latent hyperopia may exist to a high degree
and yet be undiscoverable by the use of mydri-
atics.  In many cases where mydriatics fail, fog-
ging will reveal a high state of hyperopia.  This
relaxation of the ciliary by repression is often
temporarily much enhanced by the administration
of lobelia, wine of antimony, ipecac and similar
general systemic depressants of the nervous sys-
tem.  Conversely, repression is retarded by stim-
ulants.
  In some cases of hypermetropia, hyoscyamine
and atropine act, at different times, quite uniformly
in discovering various amounts of deficient refrac-
tion; in others, their action is uncertain and vari-
able to a considerable extent; while in some
cases, these drugs have failed to give the slight-

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est evidence of hypermetropia, which has been
revealed afterwards by the process of fogging.
  As in case No. 2, page 81, a two grain solution
of atropine was dropped into the eyes twice a day
for one week, as a test for hyperopia, but no
hyperopia was developed.  The solution was
increased in strength to four grains to the ounce
and continued for three days.  The constitutional
effect of the drug was so prominent, that I was
obliged to discontinue it at this time.  On exam-
ining the eyes, I again found no indication of
hypermetropia.  Vision without the glasses was
twenty-twentieths or normal.  I prescribed a +1
D glass for outdoor use, which gave twenty-fif-
tieths of vision at twenty feet.  For house, read-
ing, writing, and all close purposes, I prescribed a
+4 D, which was 1 D more than an absolute sus-
pension of the accommodation at thirteen inches.
This rendered the patient artificially myopic.  At
the expiration of three months, through the +1
D glasses at twenty feet, vision was twenty-twen-
tieths, and though the glasses were removed,
vision continued normal, but when they were
returned to the eyes, the vision through the
glasses was reduced to twenty-thirtieths, and
required about half an hour to regain its normal
condition.  I now increased the power of both
pairs of glasses .75 of a dioptre, which again gave
twenty-fiftieths of vision for objects at a distance,

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and for objects at twelve inches the same amount
of artificial myopia that the first pair of reading
glasses gave.  At the expiration of six months
more, vision under the 1.75 D, at twenty feet, was
normal.  On removing these glasses, some five min-
utes were now required for normal vision to take
place, indicating that the reduction of ciliary in-
nervation was becoming somewhat fixed.  The
glasses were continued as well as the above
modus operandi for a period of three years, since
which time the patient has been wearing +2.75
for all general purposes.  With these glasses
vision is twenty-twentieths at all distances, but
for the purpose of resting the accommodation, a
+5 D is frequently resorted to for long and con-
tinued close work.
  If serious nervous disturbances have been held
in check by the above process, it is not advisable,
after any given length of time, to prescribe glasses
which will give fully twenty-twentieths of vision,
but to increase their power .25 or .50 of a dioptre
so as to produce about twenty-thirtieths, when
practicable with the patient.  Fogging fulfills a
double purpose; first, the tendency to repress
ciliary innervation is continued; next, the visual
centers are relieved from taking impressions of
numerous definable points, and great rest is often
so attained.
  Fogging, for the discovery of high degrees of

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latent hyperopia where mydriatics fail, I believe
to be entirely new.  Naturally the criticism might
be made that it would break down the accommo-
dation.  It certainly does break down a laborious
accommodation that always exists where there is
a high degree of latent hyperopia, which is mak-
ing a constant and extravagant call on the nerve-
centers.  It breaks down a state of perfect
accommodation that under highly abnormal con-
ditions not only exists, but often proves very
injurious to health.  This is what it has always
been our purpose to do with mydriatics.  A new
and more perfect accommodation is soon estab-
lished, which is more favorable to conditions of
health.
  In such localities as England, the northwest
coast of North America, and similar sections of
country where during a great part of the time the
atmosphere is humid and foggy, nervous ailments
are not so common, because the sharpness of
vision is much diminished by the haziness of the
atmosphere, and the sight centers of the brain are
not exercised to the same extent as in a clear,
bright view, where the most minute objects are
distinctly seen, and constantly taxing the nerve-
centers with their impressions.  For vision is an
active function even when it is the easiest pos-
sible.  It will often be found that besides
repression, one of the results of fogging with

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glasses is a state of rest and quiet, and sometimes
sleep.
  A question naturally rises here--Are the con-
ditions which we are seeking to alleviate by re-
pression of the ciliary, as well as by laborious
attempts to repress the long muscles, of sufficient
gravity to warrant the inconvenience to the
patient?  The reply must depend on the state of
the patient's health.
  Latent hyperopia is a condition of more or less
perfect vision that is sustained by a constant and
firmly fixed excess of innervation to the ciliary
muscle.  We still, in this immediate connection,
consider myopia or near-sightedness, for I believe
it properly belongs to the same line of thought.
It is often the case that where the superior rectus
is too short, the inferior rectus, instead of draw-
ing the eye down to a balance with its fellow,
draws it beyond, through an excess of nerve-
force; and myopia is a condition depending at
first on a similar spasm.  In my opinion this
defect takes its origin nearly, if not always, as
hypermetropia, but the nerve-impulse that in-
creases the convexity of the lens to correct the
hypermetropia, exceeds that office; it passes the
point where the refraction would produce clear
and distinct vision, and near-sightedness is the
result.  It becomes an excessive impulse, fixed or
progressive, arising from deranged nerve-centers.

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Thus myopia is the result of a nervous disturb-
ance which causes an associated disarrangement
in the impulses of assimilation in various parts of
the eye, especially in the sclerotic coat.  This dis-
turbance in the nutrition of the sclerotic and
other parts, tending to soften them and lessen
their mechanical support, together with the press-
ure of the rectus muscles, probably brings about
that elongation of the eye that we find in axial
myopia.  The further these abnormal conditions
proceed, the greater the source of irritation to the
nerve-centers.  In hereditary myopia, as in other
hereditary diseases, there is undoubtedly trans-
mitted a condition of the nerve-centers which
tends to produce the difficulty.  All evidence
bears out the fact that myopes generally are
people of a higher civilization, who exercise their
eyes at the near point, and thus establish an
abnormal impulse in the ciliary centers during
such use of the eyes.  The stimulus has been so
constant for a long period that the impulse to the
ciliary is unable to suspend itself and bring about
distant vision again.  The motive-impulse keeps
coming.  The ciliary will not relax from its con-
tracted condition, the refraction remains high,
and the patient near-sighted.  This exercise of
the ciliary centers through years, in one or more
generations, causes a differentiation tending to
produce an excessive ciliary impulse.

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  IN HYPEROPIA, THE NERVE-IMPULSE THAT CAUSES
THE CILIARY MUSCLE TO CONTRACT AND INCREASE
THE REFRACTION OF THE CRYSTALLINE LENS, IS
ABNORMAL, YET IT PERFORMS A NORMAL FUNCTION;
WHEREAS IN MYOPIA THE FUNCTION AND THE IM-
PULSE ARE BOTH ABNORMAL.  The circular fibres of
the ciliary are hypertrophied in hypermetropia;
they are hypertrophied also in myopia previous to
its becoming axial, but atrophied after it becomes
axial, that is, when the eye begins to elongate;
for this elongation necessitates the suspension of
ciliary contraction to maintain distinct vision even
at the near point.  As the eye elongates, the
repression that goes on in the ciliary is of the
highest type, being exercised at the near point,
thus suspending the action of the circular fibres of
the ciliary muscle, and their atrophy naturally
follows.
  This natural forced repression, which increases
with the progress of axial myopia, suspends the
ciliary impulse more or less completely, and in
such a case we should not expect those nervous dis-
turbances that depend on ciliary strain; but in a
mixed case, where concave glasses are worn for
all distances, and the ciliary is taxed with the
accommodative effort of the near point, I have
sometimes found that the removal of the concave
glasses for reading suspended some accompany-
ing nervous condition.
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  The following are some very interesting exper-
iments in myopia which can be verified by any
operator, and which prove that refractive myopia
depends on ciliary spasm, and that, even in axial
myopia, considerable repression can sometimes be
made at the near point.  In either class of cases,
repression must be made at the near point.  In
various lengths of time, we shall be able to reduce
the myopia one or two dioptres, sometimes more.
In most cases satisfactory results will require con-
siderable time and patience; but a few experi-
ments after the following example will suffice to
show that in some very advanced stages of
myopia, it is possible to suppress, or at least
check, its onward course by repression at the
near point.  This fact renders the fitting of minus
glasses to myopic eyes an open question.
  M. S., age thirty-five; has been wearing minus
glasses since the age of twelve; obliged at various
times to increase the power.  When I saw the
patient, she was wearing -5 D for all purposes.
Vision with each eye, at twenty feet, was twenty-
twentieths, or normal.  The addition of half a
dioptre increased the acuity of vision to twenty-
fifteenths, or above normal.  A reduction of the
power of the -5 D glass to -4.75 reduced the
distant vision to twenty one-hundredths.  This
glass was worn one week, and the vision, instead
of having been improved, was reduced to twenty

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two-hundredths.  A return to the -5 D restored
the vision to twenty-twentieths.  Vision was also
normal at the near point.  On removing the glasses
she was able in a few minutes to read ordinary
type at eight inches, but no farther.  Repeated
tests for half an hour resulted similarly.  A +3
D was now put on the patient, necessitating the
holding of the type somewhat nearer to the eyes.
After twenty-five minutes, she was able to read
with +3 D at eight inches.  After continuing
them for an hour, and then removing them, the
patient was able to read the same type at twelve
inches; but this condition was of short duration,
necessitating the gradual approach of the letters
until, within five minutes, the type was again eight
inches distant.  Under the high fusion power of
the near point, the ciliary spasm had become
repressed or partially suspended while the +3 D
glasses were before the eyes, and it did not return
immediately on removal of the glasses; conse-
quently the same print could be seen at twelve
inches, but within five minutes the old innervation
of the ciliary had re-established itself, necessitat-
ing the holding of the print to within eight inches
again.  At the far point, in this test, the fusion
power was not sufficiently high to permit of a
reduction of .25 D in the -5 D glasses.  We see
that it required fully twenty-twentieths of vision
to bring about fusion power enough to prevent the

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ciliary spasm from increasing, for when it was
reduced .25 D the myopia increased rapidly in one
week.
  The patient was a constant reader, which it
will be seen was a great aid to the results of my
following effort.
  I prescribed a +3 D glass for all reading.
This continued for thirty days during which time
no concave glasses were worn for out-door or dis-
tant purposes.  When I again tested the vision for
the far point, the patient could with -4.25 D,
bring out twenty-twentieths of vision, being a
reduction of .75 D in one month.  The same trial
was continued for another month with a still fur-
ther reduction of .25 D, making in all 1 D in two
months.  During this time, some favorable changes
took place in the condition of the nervous system.
Just how far we could have succeeded in time in
reducing this case of myopia, we do not know.
Impatience and the inconvenience necessary to this
procedure, influenced the patient at this point to
abandon the effort.  Neither is it possible to state
just how much of this myopia was axial, which
amount, of course, would not have been influenced
by the repression process.
  Age forty-three; myopia; had been wearing
over the right eye -1.25 D, left eye -1 D, with
little or no change for the space of two years;
eyes in use more or less at the near point.  I

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recommended the removal of the concave glasses
for distant vision and prescribed +3.50 D for
reading, writing and other office work.  After
reading in these glasses for several days, the
patient was able to read print twelve inches from
the eyes.  This patient was of more than ordinary
intelligence and understood the aim of the effort.
In six months I changed the glasses for reading
and writing to a +4 D without seeing the patient.
After using the +4 D glasses for several months
he again came under my care for an examination,
when the left eye gave twenty-twentieths of vision,
while the right eye was very nearly the same, but
the acuity was just perceptibly less.  During this
time the general health had improved somewhat,
including considerable gain in the nervous condi-
tion.  Similar results have been attained in thir-
ty-four like cases; but the process is very tedious
for the patients, and unless their understanding is
clear on the subject, it is almost impossible to
induce them to undergo the trial.
  The foregoing in connection with limited tests
of more than two hundred similar cases suggests
an answer to that most important question, 'What
shall we do to prevent myopia in school children
and students?'
  In a nomad, who is reared out of doors, who
follows such pursuits that his vision is mostly used
at twenty feet and greater distances, the nerve-

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impulses to the ciliary muscle become established
so that the easiest vision is for the far point, and
in many years of such use, these impulses become
more or less fixed; while the child of a higher
civilization spends its life within doors, amuses
itself with toys, picture books, kindergarten
amusements and learning to read.  We will assume
that such a child generally holds its book or toy
ten inches from the eyes, in which case the crys-
talline lens requires a much greater convexity, or
higher state of refraction to bring about perfect
vision; and this is brought about by an increase
in the ciliary nerve-impulse which contracts the
ciliary muscle.  Through long continued use, this
excessive impulse becomes comparatively fixed,
and in some instances refuses to suspend itself
sufficiently to bring about distant vision again,
and so myopia has set in.  The regular work of
the student and those other pursuits which re-
quire the use of the eye at the near point, tend to
perpetuate this disease and make it progressive.
  Again, the important question, 'How are the
advantages of a high civilization to be attained
without the foregoing disadvantages?'  If the
eyes are to be used at a distance of ten inches, aid
them artificially by a ten inch magnifying glass;
then the nerve-impulses to the ciliary muscle
will be no more than if the patient were leading
an outdoor life and viewing objects at twenty feet

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or more.  The nerve-centers are not called upon
for so excessive an impulse, and they become
habituated to sending the same amount of nerve-
force as if an outdoor life were led.  In conjunc-
tion with this artificial aid to the ciliary centers,
it may be found advantageous to suspend, in
a measure, the excessive nerve-impulses to the
interni, by the use of prisms, base in.  Under
these artificial conditions, the eyes may be used
in the attainment of all the advantages of the
highest civilization while the nerve-centers are no
more taxed than if out of door pursuits were being
followed.  If the little student at school or any
other person using the eyes at the near point,
were to be supplied with such glasses during
the hours of study, on leaving the school room
they could be taken off and the natural use
of the eye at all other times would be quite
sufficient to cultivate and establish the habit of
accommodation.  At least the danger of disturb-
ing the accommodation would be much less than
the dangers resulting to the eyes and nerve-
centers without such aid.
  I simply suggest the above as a possible
answer to one of the most important questions of
the day.
  Astigmatism, or that condition in which the
refraction of the eye is different in various meri-
dians.  Illustration:  In the horizontal meridian,

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+2 D is required to correct the irregularity of
refraction, while in the opposite or vertical meri-
dian, +4 D is needed.  Astigmatism is generally
due to an irregularity of the spherical contour of
the cornea, its curvatures being different in vari-
ous meridians, requiring a stronger lens to correct
it in one direction than the other.  Corneal astig-
matism is almost always due to the fact that some
of the muscles of the eye ball are exerting greater
tension in one meridian than another.  For in-
stance:  A shortness of the internal or external
muscle, inducing considerably more stress later-
ally than the superior and inferior muscles exert
in a vertical direction, would cause the cornea to
be distorted horizontally, and vice versa.  The
many possible varying conditions of tension in the
muscles produce corresponding deformities in the
contour of the cornea, resulting in various forms
of astigmatism.  Wherever corneal astigmatism
exists, it is fairly safe to conclude that is is due to
some muscular strain.  After correction of mus-
cular defects, it is quite common for large amounts
of astigmatism to disappear, and leave the eye in
perfect, spherical shape.  In the foregoing
remarks, I refer to corneal astigmatism only.





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        | End of Chapter IX |  pages 137-152
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