bed-bug) and its various residing-places are well known. It gives rise
to a cutaneous lesion of the nature of an urticarial wheal, with a
central hemorrhagic point which remains after the swelling has
subsided. As a result of the scratching to which the irritation and
itching give rise excoriations are often observed. A larger species
(Conorhinus sauguisuga), known as the blood-sucking cone-nose and big
bed-bug, has been met with in Southern Illinois and Ohio; its bite is
said to produce severe inflammation of the skin. For the relief of
bed-bug bites lotions containing alcohol, vinegar, lead-water,
ammonia-water, and similar remedies may be sponged upon the parts.
Pyrethrum powder and corrosive sublimate are the best preventives
against bugs in beds.
* * * * *
PULEX IRRITANS.--This, the common flea, is found universally,
especially in hot and warm climates. As a result of its bite
erythematous spots with minute central hemorrhagic points are seen. The
presence of the areola distinguishes the lesions from those of simple
purpura, which at times they may resemble. The cutaneous disturbance is
usually slight, but in some individuals, and especially in tropical
countries, the discomfort to which these creatures give rise is often
considerable.
* * * * *
CULEX.--Gnats, or mosquitoes, are often productive of considerable
cutaneous irritation, the typical lesion being a wheal-like elevation.
The itching is best relieved with ammonia-water.
* * * * *
IXODES.--There are several species of wood-ticks met with in our woods
which are liable to attach themselves to the human skin. Inserting
their proboscis and head deeply into the tissues, they suck blood until
often they swell up several times their natural size. They should be
induced to relinquish their firm hold by dropping olive oil or one of
the essential oils upon the skin; they should never be extracted with
violence.
{734}
{735}
MEDICAL OPHTHALMOLOGY.
{736}
{737}
MEDICAL OPHTHALMOLOGY.
BY WM. F. NORRIS, M.D.
INTRODUCTION.--The object of the following essay is to give, as far as
practicable in the limits of an encyclopædic article, an account of the
eye symptoms which may be seen in the course of diseases of the general
system and in connection with the pathological conditions of the
various organs of the body. The eye has always been looked on as a
valuable indicator of general systemic disturbance. Its expression has
been noted as showing the general vigor or feebleness of the patient,
as well as his varying mental moods, while paralysis of its external
and internal muscles has in all times been regarded as a sign of
disturbed intracranial action or disease. In order to judge of the
state of the circulation the physician habitually looks at the lips,
the tongue, and the nails, where the capillaries are covered by
translucent material, to appreciate the state of the circulation. How
much better are we enabled to do this when, by the use of the
ophthalmoscope, we look at the interior of the eye and see the
blood-columns in the veins and arteries of the head of the optic nerve
and the retina laid bare to our view without any opaque covering
whatever! Such an examination, besides showing the state of the
circulation, will frequently reveal a neuritis which may be due to some
intracranial disease, or show a degeneration of the optic nerve which
may point to impaired power and tissue-change in the spinal cord or the
brain; or there may be characteristic retinal changes associated, as,
for instance, with disease of the kidneys, or extravasation of blood
which may be dependent on general or local causes; these frequently
serving as important indices of the state of the nerves and vascular
tissues in other organs in the body.
In so vast a field, and in one so new as regards ophthalmoscopic
appearances, there remains still much to be accomplished. Useful
knowledge has accumulated slowly, but numerous enigmatical appearances
have been referred to their true causes, while many which at first
sight seemed important have been proved to be either anomalies of
formation or to have no pathological import. A complete and accurate
description of all the eye symptoms in all diseases is an herculean
task, because it presupposes the careful study of vast numbers of cases
in every department of medicine: it is therefore out of the question
for any one man to complete such a description from his individual
efforts, and he must either remain content with a mere sketch or
collate the combined experiences of many observers in different fields
in order that it may be in any way reasonably {738} perfect. To keep
such an article within any moderate limits it has been necessary to
condense much, and to consider only those points which the combined
testimony of many observers shows to be important and of frequent
occurrence. For similar reasons the writer has abstained from giving a
complete list of all authorities treating of the subjects herein
discussed, and has referred only to those which appeared to him to be
some of the most important. Those readers who wish a more complete
bibliography can readily obtain it by referring to the various
monographs hereinafter quoted, and also by consulting the well-known
essays of Foerster,[1] Robin,[2] and of Mauthner,[3] or the treatises
of Albutt[4] and of Gowers.[5]
[Footnote 1: "Beziehungen der Allgemein-Leiden und Organ-Erkrankungen
zu Veränderungen und Krankheiten des Sehorgans," in _Graefe und
Saemisch's Handbuch der Augenheilkunde_, Bd. vii., 1877.]
[Footnote 2: _Des Troubles oculaires dans les Maladies de l'Encephale_,
Paris, 1880.]
[Footnote 3: _Lehrbuch der Ophthalmoscopie_, Vienna, 1868, and _Gehirn
und Auge_, Wiesbaden, 1881.]
[Footnote 4: _On the Use of the Ophthalmoscope_, London, 1871.]
[Footnote 5: _Medical Ophthalmoscopy_, London, 1879.]
Such an article is necessarily a chapter on symptomatology, giving the
eye symptoms in various diseases and pathological conditions, and the
reader will therefore look in vain in it for any directions as to the
treatment of such maladies, or for formulæ showing advantageous modes
of administering medicines. The writer has intended, by describing and
grouping eye symptoms, to enable the practitioner more readily to
diagnosticate the various pathological conditions of other parts of the
economy. The reader should look for a description of treatment in the
various articles of this work which are devoted to the discussion of
such diseases and morbid states. Local diseases of the eye, except so
far as they are manifestly related to or caused by general disease,
have been avoided in this paper, these topics being appropriate to a
treatise on the diseases of the eye.
Changes in the Eye-ground and its Appendages due to Diseases of the
Circulatory Apparatus--Heart, Blood-vessels, and Blood.
The ophthalmoscope has laid bare to our view a living nerve of special
sense, the highly-developed end-organ in which it terminates, and the
blood-columns circulating in them. In no other part of the body has
Nature vouchsafed to us so clear an insight into her mysteries. In a
state of health the index of refraction of the walls of the retinal
blood-vessels is so nearly coincident with that of the surrounding
media that they either entirely escape our observation or are only
slightly indicated, thus allowing us to see only the blood-columns
which circulate within them. Owing to the distance from the heart and
to the restraining influence of the intraocular pressure, as well as to
the minute size of the vessels in question, the pulse-wave has so far
died out as to be ordinarily invisible, even by the aid of the
eye-lenses which Nature has so kindly placed as magnifying-glasses to
assist us in the study of intraocular phenomena. Even where we avail
ourselves of the upright image in examining the normal eye-ground, by
which an amplifying power of seven to fifteen {739} diameters is
obtained, we cannot usually detect any pulsation in the vessels,
although exceptionally we may observe pulsation which is always venous
and confined to the larger twigs of the venæ centrales as they pass
over the disc and dip into the nerve-substance. By slight pressure on
the eyeball with the finger venous pulse can always be produced. This
phenomenon consists of an emptying of the vein from the optic pylorus
toward the periphery, followed by a rush of return blood in an opposite
direction, which takes place in eyes where the intravenous and
intraocular pressures are nearly balanced. Under these circumstances
the injection of a fresh quantity of arterial blood into the eye causes
a temporary increase of intraocular pressure, which is transmitted
through the vitreous to the main trunks of the veins, compressing them
at the point nearest the heart (where the intravenous pressure is
least) before the column of entering blood which has been hindered by
the capillary resistance has had time to flow around to re-establish
the current. Stronger pressure on the eye will produce an arterial
pulsation by causing the intraocular pressure to become so high that
the blood enters only during the systole of the heart and diastole of
the arteries. This is not infrequently seen in glaucoma, where there is
an augmentation of the intraocular pressure, but is never visible in
the normal eye of a healthy individual. It should be kept in mind that
the venous pulse often produces a slight change in the adjacent
arteries which ought not be mistaken for arterial pulsation.[6]
Wadsworth and Putnam[7] describe an intermittent variation in the size
of the retinal veins independent of the pulsation produced by the
heart's action, and having a period of about five respirations,
analogous to the variation of arterial tension found in animals.
Besides the arterial pulse already alluded to, produced by augmented
intraocular tension, where the normal force of the circulation is not
sufficient to drive the blood in a continuous stream into the tense
eyeball, we have an analogous condition where the intraocular tension
may be normal, but the arterial tension is diminished, and a full
stream of blood can enter only during the diastole of the arteries or
maximum of intravascular pressure. We may notice examples of this in
_insufficiency of the aortic valves_, and in some very rare cases
described by Quincke[8] and Becker,[9] who found it accompanied by an
alternate flushing and pallor of the optic disc analogous to the
capillary pulse which may at times be observed in the finger-nail under
similar conditions of the general circulation. The arterial pulse may
also accompany any cause which permanently or temporarily reduces the
blood-pressure in the arterial system, such as pressure of a tumor on
the ophthalmic artery or of a swollen nerve on the central retinal
artery (as in neuritis): or, again, by feeble impulse of the heart, as
in cases of fainting or in degeneration and dilatation of the walls of
the blood-vessels.[10] Becker relates[11] a case of arterial pulsation
in a left eye, supposed to be due to aneurism of the aorta at a point
where the left carotid is given off, whilst {740} the other eye
presented the usual appearance of healthy retinal circulation: an
aneurism at the origin of the innominate might reverse this and give
arterial pulsation in the right eye. Usually, the pulse-phenomena in
the retina are confined to the vessels on the optic disc and its
immediate vicinity, but both Jaeger[12] and Becker[13] give cases where
it was visible over the entire eye-ground. In cases of _congenital
malformation of the heart_ with cyanosis, such as defective closure of
the foramen ovale or stenosis of the pulmonary artery, the retinal
vessels show markedly the general distension of the veins and the
change of color of the blood. Liebreich[14] gives a striking picture of
such a case, and Leber[15] remarks that in two cases observed by him
the dilatation affected the arteries as well as the veins. Knapp[16]
describes a case of swelling of the discs, with a vast number of
thickened arteries and veins which radiated from them, many twigs
reaching the fovea centralis. The autopsy showed general enlargement
and hypertrophy of the whole vascular system without disease of the
heart. Arcus senilis is often an accompaniment of fatty heart and an
indication of extensive fatty degeneration of other tissues of the
body, such as the small arteries of the brain and the recti muscles of
the eye.[17]
[Footnote 6: For a minute study of the phenomenon, vide Jaeger, _Med.
Zeitschrift_, 1854. See also his _Ergebnisse des Untersuchung mit dem
Augenspiegel, etc._, 1876, pp. 60, 61. See also Becker, _Arch. f.
Oph._, vol. xviii., part 1, p. 270.]
[Footnote 7: Vide _Trans. of the Amer. Oph. Society_, 1878, pp.
435-439.]
[Footnote 8: H. Quincke, _Berl. klin. Wochenschrift_, No. 34, 1868.]
[Footnote 9: O. Becker, _Arch. f. Ophth._, vol. xviii., 1, pp.
207-296.]
[Footnote 10: Wordsworth, _R. L. O. II. Rep._, vol. iv. p. 111.]
[Footnote 11: _Loc. cit._, pp. 253-256.]
[Footnote 12: _Ophth. Hand Atlas_, p. 75, Fig. 52.]
[Footnote 13: _Loc. cit._, pp. 220, 221.]
[Footnote 14: _Liebreich's Atlas_, Tab. ix. Fig. 3.]
[Footnote 15: _Graefe und Saemisch_, vol. v. pp. 524-526.]
[Footnote 16: _Trans. Amer. Ophth. Soc._, 1870, p. 120.]
[Footnote 17: Canton, _The Arcus Senilis_, London, 1863.]
Since 1859, when Graefe[18] by means of the ophthalmoscope first
diagnosticated this condition of the retina (which Schweigger[19] a
year and a half later substantiated by anatomical proof, demonstrating
a closure of the central artery by an embolus in it just behind the
lamina cribrosa), embolism of the central artery of the retina has been
a favorite explanation of all cases of sudden one-sided blindness.
Since that date Sichel,[20] Nettleship,[21] Priestly Smith,[22] and
Schmidt[23] have all published careful clinical studies of similar
cases with autopsies. Embolism is less frequent in this situation than
in many other parts of the body, and this, as has been pointed out by
Foerster, is probably due to the fact that the ophthalmic artery is
given off from the external carotid nearly at a right angle, and while
it in turn again sends off its smallest branch--the central retinal
artery--at nearly the same angle; consequently, emboli are more readily
carried past their orifices into some other vascular area supplied by
the main stem. Mauthner has suggested that the transitory but complete
blindness which sometimes precedes embolism of the central artery may
be due to the stoppage of the orifice of the artery (where it comes off
from the ophthalmic artery) by a previous embolus which has been too
large to enter the artery, and which, owing to the favorable position
of the orifice, has been washed beyond into some of the other branches.
In the majority of such cases the ophthalmoscope shows that the retinal
arteries are diminished in size and partially filled with blood, while
a white opacity of the fibre-layer of the retina extends centrifugally
from the disc and between it and the macula lutea. When the opacity
surrounds the latter, the fovea centralis (where the fibre-layer dies
out) shows {741} by contrast as a reddish or at times a cherry-red
spot. The state of the disc itself appears to differ in different
cases: some authors have described it as unusually pallid, whilst
others claim that it still retains more or less of its natural pinkish
hue. In cases reported,[24] where the disc is said to be of normal
color, this circumstance is probably due to collateral circulation
which has been established with the ciliary vessels at the optic
entrance. Where the obstruction of the artery is complete the blindness
is permanent, and the disc and retina become atrophic. Embolism also
occurs in the branches of the central retinal artery, and in such
instances there is loss of a corresponding part of the field of vision.
In some cases there is hemorrhagic infarction.[25] It is never present
in embolism of the main stem of the central retinal artery. Inasmuch as
this latter vessel is an end-artery, the absence of infarction and
subsequent sphacelus is interesting. The intraocular pressure probably
prevents the back current of venous blood into the obstructed area,
while the nearness of the vessels of the chorio-capillaris allows the
retina to obtain sufficient nutriment to prevent death without allowing
it to carry on its functions. In the case of embolism of a branch, all
the retinal blood being under the intraocular pressure, there would be
no hindrance to the entrance of venous blood from the areas of the
retina supplied by other arterial branches, although, as above
mentioned, the infarction is not present in all such cases. _Thrombosis
of the central retinal vein_ is also a rare affection, only recognized
and diagnosticated of late years. Michel[26] reports 7 cases, with
plates of the ophthalmoscopic appearances in 4 of them. The patients
were all between fifty-one and eighty-one years of age, and all had
rigidity of the peripheral arteries. The suddenness of the attack
recalls the symptoms of embolism, but in thrombosis the blindness is
said never to be absolute. The ophthalmoscopic appearances are
described as consisting of a diffuse and intense reddish haze of the
fibre-layer of the retina, hiding the outlines of the disc and usually
extending one and a half disc-diameters from it. This area of haze
shows numerous small hemorrhages, mostly linear, in the direction of
the retinal fibres, and beyond it the arteries and veins of the retina
again become visible. The veins are dilated, excessively tortuous, and
carry dark blackish blood. In the periphery of the retina the
hemorrhages are rounded and splotchy, whilst a dark rounded hemorrhage
occupies the fovea centralis. There is no swelling or prominence of the
disc. When the thrombosis has been complete, atrophy of the intraocular
end of the optic nerve follows. Zehender[27] makes two classes of
cases--the marasmic in old people, and the phlebitic in
young--reporting an interesting case in a patient twenty-six years old.
Leber[28] details a case of hemorrhagic retinitis with thrombosis of
some of the venous trunks in the retina, which were swollen to two or
three times their usual calibre, and filled with very dark, almost
blackish, blood: as they approached the disc they rapidly diminished in
size, and were almost thread-like as they dipped into it.
Galezowski[29] {742} cites two instances--one in a case of injury to
the ciliary region, and one after injury to the eye by steam. In the
latter, the thrombosis affected the artery, and the subject was
forty-nine years of age.
[Footnote 18: _A. f. O._, v. 1, S. 136.]
[Footnote 19: _Vorlesunqen über den Gebrauch des Augenspiegels_, S.
140.]
[Footnote 20: A. Sichel, _Archiv der Phys. Norm. et Path._, No. 1, pp.
83-89 and pp. 207-218 (quoted by Leber).]
[Footnote 21: _R. L. O. H. Rep._, vol. viii., pp. 9-20.]
[Footnote 22: _Brit. Med. Journ._, 1874, April, p. 452.]
[Footnote 23: H. Schmidt, _A. f. O._, xx., 2, pp. 287-307.]
[Footnote 24: Vide case by Schmidt, _Archiv f. Ophthalm._, xx., 2, p.
288.]
[Footnote 25: Knapp, _Archives of Ophthalmology and Otology_, vol. i.
p. 84 (with plates), and Landesberg, in same journal, vol. iv. pp. 39,
40, have each given cases of embolism of a branch of the retinal
artery, with infarction.]
[Footnote 26: _A. f. O._, xxiv., 2, pp. 37-70.]
[Footnote 27: In clinical lecture reported by Angelucci, _Klin.
Monatsblätter f. Augenheilkunde_, 1880, p. 23.]
[Footnote 28: _Graefe und Saemisch_, vol. v. p. 531.]
[Footnote 29: _Gaz. méd. de Paris_, 1879, p. 217.]
Retinal hemorrhage is of frequent occurrence. It is often associated
with inflammation in cachectic conditions of the system, as in the
various forms of symptomatic retinitis, but is also found where there
is not any demonstrable constitutional disease. Here, as in the other
tissues of the body, apoplexies are favored by disease of the coats of
the vessels, by alteration in the state of the blood, and by increased
intravascular pressure. Anatomical examination has shown in the most
common form of disease in the retinal vessels fatty degeneration of
their walls, with calcareous deposits in them, and a condition
(denominated sclerosis) in which the coats become thickened,
homogeneous, and of a higher index of refraction. In this hardened
tissue there is a condition similar to amyloid degeneration, but no
reaction is to be obtained from iodine (Leber). No ruptures can be seen
with the ophthalmoscope, but the vessels appear to pass on in contact
with the hemorrhage without change of course or calibre. These
circumstances have led Leber[30] to suppose that most retinal
hemorrhages are due to diapedesis, and not to rhexis. When the blood
escapes into the fibre-layer of the retina, it frequently diffuses
itself along the course of the fibres and between them, and gives rise
to linear and striated hemorrhages, while in the deeper layers its
progress is barred by the connective-tissue elements--notably by the
radiating fibres of Müller--and forms irregular masses which appear as
more or less rounded clumps when looked at by the ophthalmoscope. Such
extravasations of blood are frequently absorbed, or, again, they may
leave black spots of pigment as the only marks of their presence. At
other times they produce yellowish-white masses which disappear slowly,
and often leave connective-tissue cicatrices behind them, dragging upon
and displacing the retinal elements. When the hemorrhage is
considerable, it may cause primary distortion of the images and
impairment of vision by pressure on the rods and cones. At times it
breaks through the limitans interna into the vitreous, giving rise to
floating opacities, more rarely spreading itself out in a layer between
the vitreous and the retina. The writer well remembers such an instance
in the case of an apparently healthy woman about forty years of age,
who, while sitting quietly in church, noticed that objects looked red
and that a dense cloud came before the eye. Examination with the
ophthalmoscope showed a large hemorrhage which covered the entire
region of the macula and extended far beyond it, overlapping the
temporal edge of the disc. This hemorrhage was slowly absorbed, and
four years later the patient had a vision of 20/xx, and no trace of
hemorrhage was visible in the entire eyeground. Liebreich[31] gives a
good illustration of a similar case in a woman of forty-five years of
age who, after suppression of the menses, had a similar state of
affairs. Leber[32] has seen several such cases, in one of which the
hemorrhage was changed into a brilliant white mass. This was entirely
absorbed, leaving only a small pigmented stripe at its lower border as
the sole trace of the previous large extravasation of blood.
Occasionally retinal hemorrhage {743} ushers in glaucoma. Retinal
apoplexies, like extravasations of blood in the conjunctiva of the
eyeball, often come without apparent cause. In many cases they are
finger-posts pointing to grave disease of the vessels in other parts of
the body. The writer recalls a patient of seventy years of age who
believed himself in perfect health until alarmed by a retinal
hemorrhage, which a few months later was followed by a cerebral
apoplexy which caused his death.
[Footnote 30: _Graefe und Saemisch_, vol. v. p. 554.]
[Footnote 31: _Atlas_, Table viii. Fig. 2 (1863 ed.).]
[Footnote 32: _Graefe und Saemisch_, v. p. 553.]