Diagnosis of internal ophthalmias difficult. Causes: as in
conjunctivitis, extension of conjunctivitis or keratitis to iris,
choroid, ciliary circle, retina; Lymphatic constitution, damp soil,
air and stable, pit life, dentition, grain feeding, training.
Symptoms: ophthalmic symptoms generally, enlarged ciliary vessels in
sclera not movable; white zone around corneal margin; iris dull,
brownish, sluggish; intraocular tension increased: flocculi in aqueous
humor: photophobia: oblique focal illumination: sudden change from
darkness to light: synechia: ophthalmoscope. Cyclitis. Diagnosis: from
keratitis, recurrent ophthalmia. Lesions: according to chief seat of
the disease: inflammation of Descemet’s membrane, iris, choroid,
ciliary circle, lens, vitreous and retina in variable degree. Opacity
of aqueous, lens, capsules, or vitreous. Prognosis: always grave,
often vision impaired or lost. Treatment: rest, pure air, apart from
strong sunshine, removal of causes, local bleeding or cupping,
derivation, purgative, cooling diuretics: locally astringent
antiseptic lotions, cocaine, homatropine, blister, undue tension
antiseptic puncture, mercury oxide ointment; in rheumatic cases
salicin or sodium salicylate.
In the domestic animals it is not always possible to distinguish between
inflammations affecting different portions of the inner and middle coats
of the eye (iritis, cyclitis, choroiditis, retinitis), so that it is
convenient to give in general terms the phenomena and treatment of the
class known as _ophthalmia internus_. This is all the more appropriate
that inflammation of one of these divisions so frequently extends to the
others producing _panophthalmitis_, that the disease in one usually
implies an early implication of all.
_Causes._ Many of the causes of conjunctivitis, when acting with special
intensity, or for too long a time, may cause internal ophthalmia. Severe
blows, bruises, punctures, lacerations, sand, cinders, dust, lime,
foreign bodies inducing traumas, sudden transitions from darkness to
bright sunshine, habitual exposure to sunshine or to the reflection from
snow, ice or water, through a window in front of the stall, the abuse of
the overdraw check rein, the glare of electric light or of lightning
flashes, draughts of cold damp air between windows or doors, the beating
of cold storms on the eyes and skin, a sudden chill from plunging in
water or standing in a cold draught when perspiring, blows with
branches, pine cones or needles in the eye, the constant irritation from
entropion, trichiases, burdocks or thistles in the forelock, irritant
gases, etc., are among the factors which coöperate in setting up the
disease. Again diseases of the digestive organs, rheumatism, influenza,
canine distemper, brust-seuche, petechial fever, variola, eczema, and
aphthous fever may be direct causes. Conjunctivitis and keratitis are
liable to merge into irido-choroiditis by extension, and above all when
owing to perforation of the cornea a direct channel is opened for the
easy entrance of infective, pathogenic microbes. A lymphatic
constitution, connected with low breeding, or living in a low, damp,
cloudy region, or in dark, damp, impure stables, has a strongly
predisposing influence. The period of dentition, connected as it usually
is with domestication, stabling, grain feeding, and training is often a
potent accessory cause.
_Symptoms._ With the general phenomena of superficial or external
ophthalmia there are some indications which may be called pathognomonic.
These may be summarized as follows: in eyes devoid of pigment the
_enlarged ciliary vessels run deeply and are not tortuous, nor mobile
when rubbed; the scleral redness increases toward the margin of the
cornea, but leaves a white zone in front of the penetration of the
ciliary vessels; the iris has lost its clear reflection, appearing dull
or brownish; the pupil is contracted and sluggish in response to light
and darkness, it may be fixed or may show marked unevenness in its
margin: the tension of the eye ball is often increased, flocculi of
lymph may be seen in the aqueous humor settling into the lower part of
the anterior chamber_. This deposit may be white or yellowish or it may
even be reddened by extravasated blood especially in traumatic injuries.
In traumas, too, the cornea and even the aqueous or vitreous humor may
be opaque. In cases resulting from exposure to cold or from internal
causes, the media of the eye are at first clear and transparent. The
condition of the interior of the eye is usually to be learned by
examining the patient as he stands facing the light from a dark back
ground. A stable door or window will afford the requisite amount of rays
falling from above and from each side upon the interior of the eye. The
observer looks indirectly or obliquely and under favorable conditions
can see the iris and through the pupil. If the pupil is unduly closed it
may often be dilated by instilling a few drops of a 5 per cent. solution
of atropia and waiting for fifteen or twenty minutes.
The examination is made more satisfactorily with a candle or other
single source of light in a dark chamber. If this light is surrounded by
a chimney opaque except at one side which is directed toward the eye,
the results are much more satisfactory. Focal illumination with a
biconvex lens, or oblique illumination will show a swollen condition of
the iris with uneven bulging swellings at different points, and
generally a lack of the clear dark surface which marks the healthy iris.
It may be yellowish or brownish, rather than dark, or blue, or yellow,
but is always duller than normal. The pupil may be contracted or
dilated, but is always uneven at the margin according to the degree of
congestion of the different portions. It may be quite immovable under
the stimulus of light and darkness, and is always sluggish as compared
with the healthy condition. To test this reflex action, the one eye may
be bandaged, and the other eye covered with the palm of the hand for one
or two minutes. When exposed the pupil will be found to be widely
dilated, and in the healthy eye it will rapidly contract and dilate
alternately until it has reached a condition of adaptation to the
intensity of the light when it will remain immovable. With the inflamed
iris these contractions and dilatations will be lacking altogether, or
they will be sluggish and imperfect in various degrees according to the
intensity of the inflammation, the degree of congestion or the tension
of the liquid media of the eye. Restricted movement may also be due to
adhesion to the cornea, (_synechia anterior_) or to the capsule of the
lens (_synechia posterior_).
When viewed with the ophthalmoscope properly focused the choroid may
show a lack of its normal lustre and an unevenness due to the formation
of small rounded elevations in connection with congestion, or exudation,
and patches of yellowish red or whitish discoloration together with
lines of the same color following the course of the blood-vessels. It
may also reveal dark spots of opacity in the lens (_cataract_) or clouds
in the anterior region of the vitreous, the result of exudations. The
blood-vessels may appear enlarged and tortuous.
In some cases the exudate may form a false membrane which completely
closes the pupil.
A special tenderness around the margin of the cornea is suggestive of
_cyclitis_. Internal ophthalmia is usually accompanied by a variable
amount of fever.
_Diagnosis._ From simple keratitis, it is distinguished by the
thickening, discoloration and sluggishness of the iris, by the absence,
in many cases, of corneal opacity, and of free lachrymation, and in some
instances by increased tension of the eyeball.
Recurring ophthalmia, which is usually also an internal inflammation,
appears more abruptly and often at first with greater severity, and
accompanied by more hyperthermia. There is almost always a bluish white
opacity around the margin of the cornea, the eye is retracted in its
sheath so as to appear smaller, and the upper lid usually shows a marked
angle between its inner and middle thirds in place of the evenly curved
arch of the healthy palpebra. It usually appears for the first time in
the young and in those that have inherited the susceptibility and have
been kept on damp soils, in cloudy districts, or dark buildings.
_Lesions._ These are necessarily varied according as the inflammation is
concentrated on particular parts of the interior of the eye. The
secreting membrane of the aqueous humor is nearly always inflamed giving
rise to an exudate and a milky opacity of the aqueous humor. The iris is
the seat of congestion exudation, thickening, cell proliferation and
investment by false membranes. The capsule of the lens is early clouded,
may be covered by exudate and is rendered vascular in some cases. The
choroid is also the seat of congestion, exudation and discoloration with
the covering up at points of its pigmentary layer. The vitreous and lens
finally become the seat of exudation and opacity which is liable to
prove permanent.
_Prognosis._ The internal ophthalmias are always to be dreaded. In other
organs exudates may take place and become organized as permanent
structures without abolishing the function or rendering the organ
physiologically useless, but in the delicate and transparent tissues of
the eye, any such permanent product almost infallibly causes opacity and
loss, or serious impairment of vision. In the retina the displacement,
derangement, or covering up of the cones and rods necessarily interferes
with or abolishes sight, the opacity of the cornea, lens, capsule, or
vitreous interrupts the rays of light, and the destruction, or coating
over of the pigment of the choroid leads to undue reflection and
destroys vision. Beside this the destruction or impairment of one part
of the eye, changes the refraction and blurs the vision, or interferes
with accommodation and destroys the utility of the organ. Unless
therefore the disease can be cut short in its early stages and a
complete resolution effected it is likely to leave the patient very much
deteriorated in value. Fortunately it is only in the most violent cases
or in very susceptible animals that the disease in the one eye is
transmitted to the other by sympathy and leads to destruction of that
eye as well.
In the _treatment_ of internal ophthalmia, rest in pure air and moderate
warmth, away from a fierce glare of light is imperative. The causes
should as far as possible be removed. Next, it is desirable to establish
derivation. Leblanc and Trasbot attach great importance to phlebotomy
from the jugular on the same side. A more direct local action with less
loss of blood may be obtained from opening the angular vein of the eye
or applying a leech beneath the lower lid. In most cases a sufficient
derivative action can be secured by an active purgative which may be
followed by daily doses of cooling diuretics. Locally astringent lotions
(lead acetate or zinc sulphate 1 dr. to 1 qt. water; mercuric chloride,
1 ∶ 5000; boric acid, 2 ∶ 100; pyoktannin, 1 ∶ 1000) in combination with
cocaine hydrochlorate, homatropin, atropia sulphate, duboisia or
hyoscyamin (1 ∶ 1000) would be appropriate. These may be applied over
the eye on a soft cloth, and in cases of infective inflammation the more
antiseptic agents may be injected under the lids. When the inflammation
is very severe the atropia or other sedative agent may be made of the
strength of 1 ∶ 100 and a drop or two placed inside the lids with a
dropper every two or three hours.
A blister of biniodide of mercury may be applied to a space the size of
a dollar above the anterior end of the zygomatic ridge, or in dogs back
of the ear on the side of the neck: or a seton may be passed through the
skin in the same situation.
When the eyeball is unduly tense, puncture through the margin of the
cornea with a fine aseptic lancet will relieve the tension and in some
cases induce a more healthy action. Assiduous antisepsis is needful
until the wound has healed.
In other cases benefit can be obtained from the use of an ointment of
yellow oxide of mercury 1 part, in vaseline 10 parts, or of iodoform of
the same strength. A small portion the size of a grain of wheat is put
under the lid, and the latter manipulated with the finger to bring it in
contact with all parts of the surface. In case of a rheumatic origin
salicin and salicylate of soda are demanded.