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metric determinations, the relations of these scales must be evaluated.
Coburn's instrument is more accurate than mast tonometers because
applantatiou can be positively determined, and as the readings are
made on a mercury manometer the values are absolute and jiot relative.
The apparatus consists of a glass tube about 6 mm. in diameter but
drawn down to about 1 mm. in the center and to about 3 or 4 mm. at
one end. This is protected by a fenestrated brass sleeve, through the
opening in which the constricted part of the tube can be seen, and in
which a sliding marker, pointing towards the capillary tube, is placed.
The wider end of the tube is covered with a thin rubber membrane
while the other end is connected by a rubber tube to a mercurial
« manometer. From the middle of the rubber tube a lateral branch
leads to a rubber ball.

The method of using it is as follows: The glass tube is filled to the
lower end of the constricted part with colored water. The diaphragm
closing its end is pressed against a fiat surface and the indicator
moved so as to mark the top of the fluid in the tube when the dia-
phragm is plane. The diaphragm is applied to the eye with just
sufficient force to barely dimple the surface of the ocular tissues. As
the diaphragm is thus pushed inwards the fluid rises in the capillary
tube. Pressure is now made on the rubber ball until the fluid returns
to its original level as marked by the indicator, and then the mano-
metric reading is taken. The pressure as shown by the manometer
indicates the ocular tension. Corrections may be made for the elas-
ticity of the rubber diaphragm and the weight of the water indicator,
but these are very small and may be neglected when only relative
results are required. See, also, Tonometer; also p. 7595, Vol. X of
this Encyclopedia.

Ophthalmomanometry. Measurement of the intraocular pressure by
means of a manometer. See p. 7595, Vol. X of this Encyclopedia.
See, also, Ophthalmomanometer.

Ophthalmometer. Kebatometer. Astigmometer. This subject has al-
ready been treated on p. 4709, Vol. VI of this Encyclopedia, and to
some further extent under other captions. In addition it may here
be said that Kagenaar, Brudzewski (Tscherning's Physiological Optics,
p. 59), Sutcliffe {Ophthalmic Record, Mar., 1908) and a number of
others (opticians, physiologists, ophthalmologists) have designed
models, parts of which are now represented in the latest and most
efficient instruments. It must be remembered, however, in all these
corneal astigmometers that the readings of the instrument are only
approximate so far as regards the strength of the lens indicated for



OPHTHALMOMETER



8927




The Javal-Schiotz Ophthalmometer.



8928 OPHTHALMOMETER

the neutralization of the total astigmatism, although the indicated axis
is almost invariably correct.

It is well to remind the reader, both by reference to the accompany-
ing illustration and by quotation from the following text, that the orig-
inal Javal-Schiotz ophthalmometer still holds its place among instru-
ments for measuring the total corneal astigmatism which, as is well
knowai, is uniformly less than the total astigmatism of the human
dioptric apparatus.

The optical system of the Javal-Schiotz ophthalmometer includes a
Wollaston bi-refringent quartz prism and achromatic objectives.
The targets or mires are the parallelogram and steps devised by Java]
and Schiotz years ago. In spite of numerous experiments with other




The Javal-Schiotz Ophthalmometer.

forms, no better mire has been devised. This mire is particularly sen-
sitive in determining the continuity, or lack of it, of the central black
line.

The telescope (see the illustration) is supported in a sleeve at the
upper end of the column in which it may be racked back and forth for
focussing by means of a milled wheel at side. x

The telescope is raised or lowered to bring it to the level of the
patient's eye by means of a lever concealed in the base and operated
by the milled wheel and vertical shaft placed near the end of the
instrument.

The chin-rest of rubber enamelled covered metal is raised and low-
ered by means of a horizontal shaft, and can be operated from the
examiner 's end of the instrument.

The mires are controlled through an entirely new method, origina
in this instrument. The large dial is made to revolve independent!;



OPHTHALMOMETER



8929



of the telescope and arc, and has mounted on its concave face two
spiral tracks. On the back of each of the mire boxes is a ^oove-like
attachment engaging* one of these spiral tracks. As the dial is revolved,
therefore, the mires, following the spiral, are moved along the arc to




The Sutcliffe Keratometer, showiiii;' also the Form of tlio Mires.

or from the center, according to the direction of the rotation of tlie
dial. Small posts are mounted at short intervals near the periphery
of the dial on its convex side so that it may be conveniently revolved
from any point — the operator is relieved of the necessity of visually
locating this control.



8930 OPHTHALMOMETER

From the outer scale is obtained the amount of astigmatism in
diopters. It is graduated to quarter diopters. Two pointers (with
double oval openings) are provided, one of them, indicating the focus
of the primary position, the other one the focus of the secondary
position, the difference being the astigmatism. The primary pointer
is stationary with regard to the scale. It does not change its read-
ing unless moved by hand. The secondary pointer changes its reading
with every movement of the mires.

The inner circle shows the axis scale. The small pointer moves with
the telescope and records the position of the mires.

In Sutcliff'e's keratometer there is but one mire. Once the axis is
found there is no rotating to a second position. When the focus and
axis are determined the instrument automatically gives a reading on
scales. G. Young {Fractical Medicine Series, Eye, p. 179, 1911) has
compared the instrument with that of Javal in 60 cases and found it
to be just as accurate as that instrument.

In Hardy's improved ophthalmometer the targets, reflectors or
mires, one of which is triangular shaped, is bisected by a black space,
the other being arranged in steps and spaces on either side of a longi-
tudinal white space, are fixed on the large disc at a certain distance
apart, are stationary, and are in the same plane as the deviation of the
birefringent prism. They are translucent and are illuminated from
behind by incandescent lamps, contained within cups on the back of
the large disc, thus shutting out the light from the eyes of the operator
and avoiding the heat generated by large lamps. They may also be
sufficiently illuminated by daylight if the instrument is placed near
to and facing a window.

This method of electric illumination and the shape of the mires,
which are peculiarily adapted to the purpose, together with superior
lenses and biprism, give a clearness and perfection of definition which
enable the observer to locate the principal meridians accurately and
to read a quarter of a diopter of astigmatisai with exactness. (See
the cuts.)

The Bausch and Lomb keratometer differs from other models.

The accompanying figure represents a longitudinal section of the
optical arrangement of the keratometer constructed in this manner ;
F indicates the principal focus of the plano-convex lens with a power
of -f- 6.00 D, the principal focus appearing within the plane of the
aperture of the diaphragm through which the observer is looking; m
represents the scale in the keratometer, marked in millimeters; °1, °2,
objects appearing within the parallel beam of light, 0.

When an instrument is constructed on this principle and an obser-



OPHTHALMOMETER



8931




y^^mx^




■ii +



-ii'r




111! L



-"F




The Targets or Mires of the Hardy Ophthalmometer.



*NOTE. — The amount of the overlapping and the proportionate size of the
images are exaggerated for the purpose of clear illustration.



8932



OPHTHALMOMETER



vatioii is made through the ocular diaphragm situated in the posterior
focal plane of the lens, as shown in the illustration, it follows that
the rays proceeding from the object to the lens will be parallel to its
axis. If now a scale be placed in front of the object, as indicated




O i a!

Bausch and Lomb Keratometer.



between the letters m, a correct reading of the size of the object will
be obtained regardless of its position, and the parallax noticeable when
an object is measured with an ordinary rule (the rule, however, not
being in exactly the same plane as the object) is entirely eliminated.
In the next figure an external view of the keratometer is illustrated
showing the ocular diaphragm (1) which is fitted to a metal tube (2)
on the one end, while on the other end an eyepiece cap (3) is situ-
ated by means of which the instrument may be rested upon the mar-




R-4



Bausch and Lonib Keratometer.



gin of the orbital cavity of the patient's eye. Within the ring of the
eyepiece cap a scale (4), divided into one-half millimeters, is so
mounted that its upper edge may pass accurately through the center
of the ring. In front of the ring the metal tube has a large excision
through which sufficient light may reach the scale and the patient's
eye. The scale (4) is situated near the anterior focus of the lens, and
the same applies to the cornea which is to be measured; hence both
the scale and the cornea can easily be seen magnified 1.5 times by an
eye in front of the ocular diaphragm (1) . At the end of the tube fitted



OPHTHALMOMETER 8933

with the ocular diaphragm an excision (5) is made to allow for the
illumination of the white mark (6) , which illumination may be adjusted
by means of the white screen (7). The white mark (6) serves as a
fixing mark for the eye of the patient under examination. It goes
without saying that a cornea of any diameter may be measured with
this instrument, and by rotating the apparatus the diameter of the
cornea in any direction may be ascertained.

It is best steadied by the third and fourth fingers of the left hand,
with which the operator holds the farthest end of the tube upon the
patient's temple. In the case of bi-convex spectacle lenses there should
be no difficulty in measuring the distance from apex of cornea to
vertex of lens direct. With weak positive lenses or negative lenses,
measurements are best taken from the apex of cornea to the surface of
trial frame facing the eyes of the patient, and the distance from this
trial frame to the vertex of the trial frame lens is then ascertained by
an ordinary depth gauge. The two readings together then represent
the entire distance from apex of cornea to vertex of trial case lens.
The measurement of the vertical distance of the objects °1, °2 (shown
diagrammatically in the first figure) , will not fail to be correct, even
though the objects are not in one plane and do not coincide with the
scale, since, as explained above, the rays proceeding from the object
and scale are parallel.

The so-called new Jceratometer of Spiller has, according to the mak-
ers, certain advantages. There is only one simple mire consisting of
a cross enclosed in a circle, the narrow limbs of which are made to
coincide with the principal meridians. The intersecting images of the
circle enclose the short contact limbs, so that no confusion can arise
as to what the operator must look for.

There can thus be no distortion of the image such as is found with
the step or solid mire. The area of cornea utilized is moderate, and
therefore peripheral variations in curvature cannot confuse the result,
because it must not be forgotten that the cornea is only truly spherical
or (in astigmatism) only truly toroidal over a small central area not
exceeding some 3 mm. in diameter. It follows that definition in the
zone occupied by the cross limbs is good with a moderate size mire,
and contact easily made to the greatest nicety. In addition, the micro-
scope gives a higher magnification than is usually employed. There
is no arc and no secondary position visible to the patient. No effort
of memory is demanded in the least; the axis, readings and nature of
the astigmatism (with or against the riTle) arc simultaneously and
automatically recorded. The small lever gives an exact rotation of the
images through 90°, so that the observer need not remove his eye



8934 OPHTHALMOMETROSCOPE

from the microscope to secure the secondary position. On account of
the translucent dial no external illuminant is required in the room.
The Scheiner device ensures an absolute focus, and the slightest depar-
ture from the correct position immediately results in the ''splitting"
of the images. The chin-rest is abolished and for it is substituted a,
brow-rest. This alteration ensures a perfectly natural position of the
head together with freedom to answer questions on the part of the
patient.

Ophthalmometroscope. An ophthalmoscope with an attachment for
measuring the refraction of the eye.

Ophthalmometry. Measurement or examination of the eye by means of
the ophthalmometer.

Ophthalmomyiasis. See Myiasis.

Ophthalmomyitis. Ophtiialmomyositis. A term used by old writers
to define inflammation of the muscles of the eyeball.

Ophthalmomyositis. Inflammation of the extrinsic eye muscles.

Ophthalmomyotomy. Surgical division of the muscles of the eye.

Ophthalmoncus. (Obs.) Sw^elling of the eye.

Ophthalmoneuritis. Inflammation of the ophthalmic nerve.

Ophthalmoneuromyelite. (P.) A term applied by de Lapersonne to
the rather rare symptom-complex accompanying the optic neuritis of
myelitis, which Devic called nenromy elite optique aigue. See Mye-
litis; also the same (sub) title under Neurolog'y of the eye.

Ophthalmoneuromyelitis. See Myelitis, under Neurology of the eye.

Ophthalmonosology. The pathology of the eye.

Ophthalmopathy. Any disease of the eye.

Ophthalmopathy, External. An affection of the eyelids, cornea, con-
junctiva, or muscles of the eye.

Ophthalmopathy, Internal. Any affection of the deep or more essential
parts of the eye.

Ophthalmophakometer. OphthzVlmophacometer. The ophthalmome-
ter of Tscherning (Optics, p. 44) for measuring the two surfaces of
the lens and the posterior surface of the cornea.

Ophthalmophantom. A model of the eye used in demonstration ; or an
apparatus for holding animals' eyes for operation. See Phantom;
as well as under the section on Operative skill in ophthalmic surgery.

Ophthalmophlebotomy. Phlebotomy to relieve congestion of the con-
junctival veins.

Ophthalmophobia. Fear of the eye. A nervous affection, in the begin-
ning of which the patient is simply ill at ease whenever anyone is
gazing at him intently. Later, he cannot bear the society of his
fellow human beings, a condition not greatly dissimilar to that which



OPHTHALMOPHOROMETER 8935

is known as agoraphobia, but. having only this one special cause.
Finally, the victim falls actually ill. Seliguiann (Ko.fmos, Stuttgart,
Sep. 15, 1914) declares that ophthalmophobia is, at bottom, the cause
of the widely-spread superstition knowai as "the evil eye." He also
believes that the nervous affection in question is based upon the mis-
taken optical theory, "once universal and still adhered to by the
ignorant . . . that sight is the result of radiation proceeding
from the eye to the object seen."

Seligmann divides ophthalmophobiacs into three groups. Mild oph-
thalmophobia includes persons who when they notice anybody looking
at them, at once begin to wonder whether their hats are on straight
or whether in some other way they appear peculiar. The severe type
makes the sufferers perfectly miserable. If a woman is afflicted with
severe ophthalmophobia, she wears a thick veil or hides her face be-
hind a fan ; a man uses a newspaper or gets into the shadow of a
piece of furniture, his hands get cold, and his face perspires freely.
The third section of the subject is the "evil eye." Even in Germany,
a trace of this superstition is evident. Seligmann says that even
"cultured" persons when praised, tap three times under the table,
and say "Unberufen."— (T. H. S.) See, also, p. 4554, Vol. VI of this
Encyclopedia.

Ophthalmophorometer. A name given by Ostwalt {Bericht der Oph.
(lesclhch., 1895) to his phorometer in which the ^Maddox prism is the
chief agent in determining the kind and degree of muscle imbalance.

Ophthalmophthisis. Phthisis bulbi, or ophthalmomalacia; atrophy of
the whole eyeball.

Ophthalmoplasty. Plastic surgery of the eye or of its ai^pendages.

Ophthalmoplegia. Nuclear palsy. This form of oculomuscular paral-
ysis is the result of a lesion affecting the nuclei of the ocular muscles
in the floor of the fourth ventricle and in the aqueduct of Sylvius.
The external muscles alone may be involved (external ophthalmo-
plegia) or the internal muscles alone (internal oph1halino])legia), or
both groups together may be affected (mixed ophthalmoplegia). It
may be congenital or acquired. The acquired type appears in two
forms, acute and chronic. — (J. M. B.)

See, also, the various Ophthalmoplegia headings ; as well Congenital
anomalies. There is also a familial form of the disease.

Ophthalmoplegia, Asthenic. A name given by Karplus to a form that
sinndates a true bulbar ])aralysis hut in which the central lesion is
lacking. It is really an exaggerated form of muscular asthenopia;
or it may represent an early stage of multiple sclerosis.



8936 OPHTHALMOPLEGIA EXTERNA

Ophthalmoplegia externa. External ophthalmoplexia. Ophthalmo-
plegia EXTERIOR. Paralysis or paresis of one or more of the orbital
or external muscles of the eye. See Muscles, Ocular; Tabes dorsalis;
Syphilis of the eye; and such other captions as Diplopia, p. 4006, Vol.
VI of this Encyclopedia; also various sub-headings under Neurology
of the eye.

Ophthalmoplegia, Fascicular. Ophthalmoplegia due to lesion in the pons
varolii. ,

Ophthalmoplegia, Graux-Fereol type of. Associated paralysis of the
muscles affecting the right internal of one side and the right external
of the opposite side.

Ophthalmoplegia interna. Ophthalmoplegia interior. Paralysis of
the iridic and ciliary muscles. When it is complete a central lesion
is (apart from drugs and trauma) uniformly the cause.

M. G-rossman (Journ. Am. Med. Assocn., p. 963, Mar. 31, 1917)
believes this symptom-complex to be the rarest form of pupillary dis-
turbance found in congenital or acquired syphilis of the nervous
system. It manifests itself clinically as a paralysis of the intrinsic
muscles of the eye. The pupillary phenomena may be unilateral or
bilateral, the unilateral being encountered about twice as frequently
as the bilateral. The phenomena consist of widely dilated pupils
which do not react to accommodation, convergence or light retiex.
Such pupils do not contract when physostigmin or other miotics are
dropped into the eye. In the syphilitic cases, the pupils are, in addi-
tion, unequal in size and irregular in outline.

This writer says: "It is of interest to note that when the pupillary
activity returned in my cases, during the course of antispecific treat-
ment, the response to physostigmin was the first to appear. This was
followed by the return of the reaction to convergence, next accommo-
dation, and last of all light reflex. The same sequence was noted in
three of the patients, two of whom have almost completely recovered
their pupillary reactions. ' '

The importance of early recognition of these cases of latent con-
genital syphilis is evident. It is highly probable that some further
involvement of the central nervous system may occur if treatment is
not instituted in these cases.

Speaking of the pathology of ophthalmoplegia interna, the lesion is
presumably nuclear. In syphilitic cases, it is most probably either a
gumma or a degenerative process, due to endarteritic changes in the
region of the third nerve nucleus.

The most common cause of ophthalmoplegia interna is syphilis of
the central nervous system. Among the less frequent causes may be



OPHTHALMOPLEGIA INTIMA 8937

mentioned post-diphtheritie paralysis, trauma, and overstimulation
with mydriatics, as atropin.

When a syphilitic infection occurs, the local spirochele inoculation
is soon followed hy a general infection.

Of the tissues which are equally accessible in a general infection,
the most vulnerable will be the first attacked. At the same time this
tissue heals, it develoj^s a resistance against the infecting agent. In
ether words, it becomes less vulnerable, a property which tlic unaffected
tissues do not as yet possess. This is illustrated by the definite line of
invasion which we constantly find in a general syphilitic infection. It
begins with the local site of inoculation, followed by invasion of the
glands, mucous membranes and deeper tissues, each usually separated
by periods of apparent perfect quiescence. Only exceptionally is
the central nervous system invaded, and then this is usually the last
tissue to be attacked.

Wile and Stokes demonstrated biologic changes in tlie cerebrospinal
fluid in 63 per cent, of their cases presenting secondary syphilis. They
concluded, however, that not more than 5 per cent, of these cases later
gave destructive manifestations of central nervous syphilis.

Grossman regards ophthalmoplegia interna as a rare condition; it
may be familial. It may be the only objective evidence of congenital
syphilis of the central nervous system. All offspring should be care-
fully examined for latent syphilis when the parents are knowai to be
infected. AYhen evidence of latent syphilis is found, treatment should
be instituted ; it must be continued until all clinical and biologic evi-
dence of the disease disappears. In the writer's cases, the condition
was due to a strain of spirochete which probably possess a selective
property for nerve tissue. See, also, Iridoplegia, p. (JGIO, Vol. IX; as
well as Cycloplegia, p. 3641, Vol. V of this Encyclopedia; also several
minor ca])tions under Neurology of the eye.

Ophthalmoplegia intima (Hutchinson). Paralysis of the internal mus-
cles, or combined iridoplegia and cj^cloplegia. See Ophthalmoplegia
Interna.

Ophthalmoplegia mixta. That form in which both the internal and
external oculomuscular groups are affected.

Ophthalmoplegia, Parinaud's. Paralj'sis (of peripheral origin) of the
external rectus muscle of one eye associated with spasm of the in-
ternal rectus of the other.

Ophthalmoplegia, Recurrent. A name for ophthalmic migraine. See p.
76i)7, Vol. X of this Eiictjclopedki: also under Migraine in Neurology
of the eye.

Ophthalmoplegia, Sauvineau's. Paralysis of the internal rectus muscle

A'ol. xir 3



8938 OPHTHALMOPLEGIA, TOTAL

of one side and spasm of the external rectus of the opposite side.
This affection is the reverse of Parinaud's ophthalmoplegia.

Ophthalmoplegia, Total. A form of the disease that affects both the
extrinsic and the intrinsic muscular apparatus of the eye.

Ophthalmoplegia, Wernicke's pseudo-. . See under Neurology of the eye.

Ophthalmoprosepsis. A little-used term, to define the accommodating
power of the eye for both near and distant vision.

Ophthalmoprostatometer, Exophthalmometer. The name originally
given by (John to his exophthalmometer (q. v.).

Ophthalmoptosis. A synonym of exophthalmos.

Ophthalmo-reaction. Local reaction of the conjunctiva following in-
stillation into the eye of toxins of typhoid fever and tuberculosis.
The reaction is much more severe in persons affected with these
diseases than in the healthy or those affected with some other disease.
Called, also, Calmette's ophthalmoreaction, p. 1361, Vol. II of this
Encyclopedia.

Ophthalmorrhagia. Hemorrhage from the eye.

Ophthalmorrhea. A watery or sanguineous discharge from the eye.

Ophthalmorrhea externa. A discharge from the eyelids.

Ophthalmorrhea interna. A discharge from the eyeball.

Ophthalmorrhexis. Rupture of the eyeball.

Ophthalmo-sanitary legislation in various lands. See Legal relations of
ophthalmology, in the last third of the section.

Ophthalmoscope. The chief facts concerning the discovery of the
ophthalmoscope, and information regarding the seve-ral modifications
of the original device to the present time, have already been to
some extent discussed under Helmholtz, p. 5753, Vol. VIII ; Examina-
tion of the eye, p. 4748, Vol. VI; Coccius's ophthalmoscope, p. 2310,
Vol. IV.; Demonstration ophthalmoscope, p. 3814, Vol. V; Arlt's
orthoscope, p. 591, Vol. I ; Electric ophthalmoscope, p. 4230, Vol. VI ;



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