Part 72

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.

SIMPLE IRITIS.

Causes. Symptoms: redness of sclera, in dogs, cats, birds, pigs, with a narrow zone of white next the cornea, red scleral vessels immovable, iris dull gray or brown, uneven, sluggish in response to light, synechia anterior or posterior, lens and capsule clouded or clear, pupillary margin uneven, myosis or midriasis, black cataract. Treatment: rest, dark stall or covering, head elevated, midriatics, cocaine, antiseptic puncture, purgation, leeches, seton, cooling astringent lotions, diuretics, for tension in convalescence iridectomy. In traumatic cases careful antisepsis.

This may come from any one or more of the causes of internal ophthalmia above named. The inflammation, however, concentrates itself on the iris so as to overshadow the disease in the adjacent organs.

The more distinctive symptoms are the redness of the sclerotic in unpigmented organs (swine, birds, dogs, cats), the redness increasing as it approaches the margin of the cornea but leaving a narrow white zone surrounding the edge. The red vessels on the sclerotic are not moved with the conjunctiva when the lid is moved over the front of the eye. The front of the iris is dull, grayish or brownish, it is thickened unevenly and very sluggish in response to light and darkness. Not infrequently it is adherent to the back of the cornea (synechia anterior) or to the front of the lenticular capsule (synechia posterior). The lens and its capsule may or may not be clouded, but if the interior of the vitreous can be seen it is found to be clear. The pupil is more or less uneven in outline and sometimes it is torn at its inner edge so as to form shreds and projecting tongues. Myosis (contraction of the pupil) or midriasis (dilatation) may be present. If the latter has been preceded by adhesion a portion of the uvea may remain attached to the lenticular capsule constituting =black cataract=. The lens or its capsule may become opaque, and a fibrinous membrane may form over the pupil.

Treatment. Rest for body and eye are essential. A dark stall, or a thick covering for the eye is desirable. The head should be kept moderately elevated to facilitate the return of blood. The pupil should be kept widely dilated to prevent adhesions to the lens. Sulphate of atropia 5 grs. to the oz. of water should be applied a few drops at a time, thrice a day, or as often as may be necessary to secure dilatation. In case the atropia fails to secure dilatation a 5 per cent. solution of cocaine should be dropped into the eye every three or four minutes for four or five times and then another application of atropia may be tried warm. Should it still fail and should there be indications of extra congestion and swelling of the iris or of excessive tension of the eyeball, relief may be obtained by puncturing the cornea. With the reduction of the tension the iris will often respond to the midriatic. Benefit may also be obtained from an active purgative, or the application of leeches in the vicinity of the eye.

Cooling astringent applications may be kept up over the eye, or warm antiseptic applications will often give great relief.

In obstinate cases the yellow oxide of mercury ointment may be applied as advised for internal ophthalmia.

Cooling diuretics may also be of essential advantage.

If, after a fair recovery the bulb remains unduly tense, iridectomy may be resorted to as a prophylactic measure for the future. An incision is made with a lancet close in front of the margin of the cornea, and the iris seized and withdrawn with a pair of fine forceps, and a portion snipped off with fine scissors. The eye and instruments must be rendered absolutely aseptic by carbolic acid and boiling water, and the antisepsis of the eye must be carefully maintained until the wound is healed. This tends to relieve congestion in the iris and to moderate the secretion in the anterior chamber, so that the former extreme tension does not recur. In making choice of the seat of the iridectomy a selection may be made which will do away with adhesions, or one that will expose a portion of the lens which is still transparent, and which may restore vision when obscured by a cataract.

In traumatic cases there should be extra care in maintaining a thorough antisepsis of the eye as the great danger is that of infective panophthalmitis. The injection of antiseptic liquids under the eyelids, and the covering of the eye with antiseptic cotton wool or with a soft rag wet with an antiseptic lotion are important factors in treatment.

SYMPTOMATIC OR METASTATIC IRITIS.

Complications of infectious diseases, influenza, contagious pneumonia, strangles, tuberculosis, omphalitis. Symptoms: exudation of fibrine and blood, with those of simple iritis. Treatment: as in iritis, plus measures for the specific primary disease. When second eye is threatened enucleation.

Under this head Möller describes those forms of iritis which occur as complications of various infectious diseases. It has long been observed that iritis and other ophthalmias, occurred as complications of the acute infectious diseases of the respiratory organs of the horse formerly known under the general name of “influenza.” More recently many veterinarians and others have classed these influenza iritis separately under the name of “pinkeye.” The same can be said of “contagious pneumonia” (brustsenche) of horses which is distinctly caused by the diplococcus (streptococcus) pneumoniæ equina. Attention was called to the iritic complication of this disease in 1881 by Siedamgrotzky and it has been often noticed since. Conjunctivitis is however a more frequent complication of this disease than iritis. In both influenza and contagious pneumonia the iritis often supervenes when convalescence has apparently set in. Strangles is another affection in which the iris occasionally suffers. Mathieu has described tuberculosis of the iris in cattle, and Möller mentions with some hesitancy cases of iritis which complicated the infection of the navel in new born animals.

The symptoms of symptomatic iritis vary according to the particular infection. In addition to the fibrinous exudate the infections of the respiratory organs are liable to be complicated by blood extravasations. In influenza this may show as deep blotches on the bulbar conjunctiva and in chemosis. In contagious pneumonia Schütz met with iritis of a distinctly hæmorrhagic character.

In Matthieu’s cases of tubercle of the iris there was first a slight lachrymation, and soon the iris assumed a grayish tint, and became uneven and unduly approximated to the cornea though it failed to become adherent to it. The swellings of the iris increased and became of a grayish yellow color, and the pupil was usually contracted and varied little in size. Post mortem examination showed the presence of tubercles. The same condition has become familiar in connection with experimental inoculation in the eye. As in ordinary iritis adhesion to the capsule of the lens and cataract are common results.

Apart from the treatment of the specific primary disease this type of iritis demands the same treatment as other forms. Strong atropia lotions to prevent or break up adhesions and antiseptic astringents are especially indicated. When implication of the second eye is threatened it may be desirable to remove the first by enucleation. (See Panophthalmitis).

FOREIGN BODIES IN THE IRIS.

These are sometimes fine shot particularly in dogs, and splinters of iron and steel in other animals. Their presence can sometimes be made out by careful focal illumination. If septic they cause violent iritis and panophthalmia. If aseptic they may sometimes cause little trouble. If they can be exactly located, they should be removed at once before the aqueous humor and cornea become clouded. If the offending body is a piece of iron or steel and can be reached by a magnet introduced through the original wound or through one made with a lancet in the edge of the cornea it may be extracted by this means. If it is shot or other body that is not attracted by a magnet the portion of the iris in which it is entangled may be drawn out with forceps and snipped off with fine scissors. Due antiseptic precaution must be exercised.