Part 35 (1/2)
OBSTRUCTION OF THE LACRIMAL APPARATUS, OR WATERING EYE.
The escape of tears on the side of the cheek is a symptom of external inflammation of the eye, but it may also occur from any disease of the lacrimal apparatus which interferes with the normal progress of the tears to the nose; hence, in all cases when this symptom is not attended with special redness or swelling of the eyelids, it is well to examine the lacrimal apparatus. In some instances the orifice of the lacrimal duct on the floor of the nasal chamber and close to its anterior outlet will be found blocked by a portion of dry mucopurulent matter, on the removal of which tears may begin to escape. This implies an inflammation of the ca.n.a.l, which may be helped by occasional sponging out of the nose with warm water, and the application of the same on the face. Another remedy is to feed warm mashes of wheat bran from a nosebag, so that the relaxing effects of the water vapor may be secured.
The two lacrimal openings, situated at the inner angle of the eye, may fail to admit the tears by reason of their deviation outward in connection with the eversion of the lower lid or by reason of their constriction in inflammation of the mucous membrane. The lacrimal sac, into which the lacrimal ducts open, may fail to discharge its contents by reason of constriction or closure of the duct leading to the nose, and it then forms a rounded swelling beneath the inner angle of the eye.
The duct leading from the sac to the nose may be compressed or obliterated by fractures of the bones of the face, and in disease of these bones (osteosarcoma, so-called osteoporosis, diseased teeth, glanders of the nasal sinuses, abscess of the same cavities).
The narrowed or obstructed ducts may be made pervious by a fine, silver probe pa.s.sed down to the lacrimal sac, and any existing inflammation of the pa.s.sages may be counteracted by the use of steaming mashes of wheat bran, by fomentations or wet cloths over the face, and even by the use of astringent eyewashes and the injection of similar liquids into the lacrimal ca.n.a.l from its nasal opening. The ordinary eyewash may be used for this purpose, or it may be injected after dilution to half its strength. The fractures and diseases of the bones and teeth must be treated according to their special demands when, if the ca.n.a.l is still left pervious, it may be again rendered useful.
EXTERNAL OPHTHALMIA, OR CONJUNCTIVITIS.
In inflammation of the outer parts of the eyeball the exposed vascular and sensitive mucous membrane (conjunctiva) which covers the ball, the eyelids, the haw, and the lacrimal apparatus, is usually the most deeply involved, yet adjacent parts are more or less implicated, and when disease is concentrated on these contiguous parts it const.i.tutes a phase of external opththalmia which demands a special notice. These have accordingly been already treated of.
_Causes._--The causes of external opththalmia are mainly those that act locally--blows with whips, clubs, and twigs, the presence of foreign bodies, like hayseed, chaff, dust, lime, sand, snuff, pollen of plants, flies attracted by the brilliancy of the eye, wounds of the bridle, the migration of the scabies (mange) insect into the eye, smoke, ammonia arising from the excretions, irritant emanations from drying marshes, etc. Road dust containing infecting microbes is a common factor. A very dry air is alleged to act injuriously by drying the eye as well as by favoring the production of irritant dust; the undue exposure to bright suns.h.i.+ne through a window in front of the stall, or to the reflection from snow or water, also is undoubtedly injurious. The unprotected exposure of the eyes to suns.h.i.+ne through the use of a very short overdraw check is to be condemned, and the keeping of the horse in a very dark stall, from which it is habitually led into the glare of full sunlight, intensified by reflection from snow or white limestone, must be set down among the locally acting causes. Exposure to cold and wet, to wet and snow storms, to cold drafts and wet lairs must also be accepted as causes of conjunctivitis, the general disorder which they produce affecting the eye, if that happens to be the weakest and most susceptible organ of the body, or if it has been subjected to any special local injury, like dust, irritant gases, or excess of light.
Again, external opththalmia is a constant concomitant of inflammation of the contiguous and continuous mucous membranes, as those of the nose and throat--hence the red, watery eyes that attend on nasal catarrh, sore throat, influenza, strangles, nasal glanders, and the like. In such cases, however, the affection of the eye is subsidiary and is manifestly overshadowed by the primary and predominating disease.
_Symptoms._--The symptoms are watering of the eye, swollen lids, redness of the mucous membrane exposed by the separation of the lids--it may be a mere pink blush with more or less branching redness, or it may be a deep, dark red, as from effusion of blood--and a bluish opacity of the cornea, which is normally clear and translucent. Except when resulting from wounds and actual extravasation of blood, however, the redness is seen to be superficial, and if the opacity is confined to the edges, and does not involve the entire cornea, the aqueous humor behind is seen to be still clear and limpid. The fever is always less severe than in internal ophthalmia, and runs high only in the worst cases. The eyelids may be kept closed, the eyeball retracted, and the haw protruded over one-third or one-half of the ball, but this is due to the pain only and not to any excessive sensibility to light, as shown by the comparatively widely dilated pupil. In internal ophthalmia, on the contrary, the narrow, contracted pupil is the measure of the pain caused by the falling of light on the inflamed and sensitive optic nerve (retina) and choroid.
If the affection has resulted from a wound of the cornea, not only is that the point of greatest opacity, forming a white speck or fleecy cloud, but too often blood vessels begin to extend from the adjacent vascular covering of the eye (sclerotic) to the white spot, and that portion of the cornea is rendered permanently opaque. Again, if the wound has been severe, though still short of cutting into the anterior layers of the cornea, the injury may lead to ulceration that may penetrate more or less deeply and leave a breach in the tissue which, if filled up at all, is repaired by opaque fibrous tissue in place of the transparent cellular structure. Pus may form, and the cornea a.s.sumes a yellowish tinge and bursts, giving rise to a deep sore which is liable to extend as an ulcer, and may be in its turn followed by bulging of the cornea at that point (staphyloma). This inflammation of the conjunctiva may be simply catarrhal, with profuse mucopurulent discharge; it may be granular, the surface being covered with minute reddish elevations, or it may become the seat of a false membrane (diphtheria).
_Treatment._--In treating external ophthalmia the first object is the removal of the cause. Remove any dust, chaff, thorn, or other foreign body from the conjunctiva, purify the stable from all sources of ammoniacal or other irritant gas; keep the horse from dusty roads, and, above all, from the proximity of a leading wagon and its attendant cloud of dust; remove from pasture and feed from a rack which is neither so high as to drop seeds, etc., into the eyes nor so low as to favor the acc.u.mulation of blood in the head; avoid equally excess of light from a sunny window in front of the stall and excess of darkness from the absence of windows; preserve from cold drafts and rains and wet bedding, and apply curative measures for inflammation of the adjacent mucous membranes or skin. If the irritant has been of a caustic nature, remove any remnant of it by persistent bathing with tepid water and a soft sponge, or with water mixed with white of egg, or a gla.s.s filled with the liquid may be inverted over the eye so that its contents may dilute and remove the irritant. If the suffering is very severe, a lotion with a few grains of extract of belladonna or of morphia in an ounce of water may be applied, or, if it is available, a few drops of 4 per cent solution of cocaine may be instilled into the eye.
In strong, vigorous patients benefit will usually be obtained from a laxative, such as 2 tablespoonfuls of Glauber's salt daily, and if the fever runs high from a daily dose of half an ounce of saltpeter. As local applications, astringent solutions are usually the best, as 30 grains of borax or of sulphate of zinc in a quart of water, to be applied constantly on a cloth, as advised under ”Inflammation of the eyelids.” In the absence of anything better, cold water may serve every purpose. Above all, adhesive and oily agents (mola.s.ses, sugar, fats) are to be avoided, as only adding to the irritation. By way of suggesting agents that may be used with good effect, salt and sulphate of soda may be named, in solutions double the strength of sulphate of zinc, or 7 grains of nitrate of silver may be added to a quart of distilled water, and will be found especially applicable in granular conjunctivitis, diphtheria, or commencing ulceration. A cantharides blister (1 part of Spanish fly to 4 parts lard) may be rubbed on the side of the face 3 inches below the eye, and washed off next morning with soapsuds and oiled daily till the scabs are dropped.
WHITE SPECKS AND CLOUDINESS OF THE CORNEA.
As a result of external ophthalmia, opaque specks, clouds, or haziness are too often left on the cornea and require for their removal that they be daily touched with a soft feather dipped in a solution of 3 grains nitrate of silver in 1 ounce distilled water. This should be applied until all inflammation has subsided, and until its contact is comparatively painless. It is rarely successful with an old, thick scar following an ulcer, nor with an opacity having red blood vessels running across it.
ULCERS OF THE CORNEA.
These may be treated with nitrate of silver lotion of twice the strength used for opacities. Powdered gentian, one-half ounce, and sulphate of iron, one-fourth ounce, daily, may improve the general health and increase the reparatory power.
INTERNAL OPHTHALMIA (IRITIS, CHOROIDITIS, AND RETINITIS).
Although inflammations of the iris, choroid, and retina--the inner, vascular, and nervous coats of the eye--occur to a certain extent independently of each other, yet one usually supervenes upon the other, and, as the symptoms are thus made to coincide, it will be best for our present purposes to treat the three as one disease.
_Causes._--The causes of internal ophthalmia are largely those of the external form only, acting with greater intensity or on a more susceptible eye. Severe blows, bruises, punctures, etc., of the eye, the penetration of foreign bodies into the eye (thorns, splinters of iron, etc.), sudden transition from a dark stall to bright suns.h.i.+ne, to the glare of snow or water, constant glare from a sunny window, abuse of the overdraw checkrein, vivid lightning flashes, drafts of cold, damp air; above all, when the animal is perspiring, exposure in cold rain or snowstorms, swimming cold rivers; also certain general diseases like rheumatism, arthritis, influenza, and disorders of the digestive organs, may become complicated by this affection. From the close relation between the brain and eye--alike in the blood vessels and nerves--disorders of the first lead to affection of the second, and the same remark applies to the persistent irritation to which the jaws are subjected in the course of dent.i.tion. So potent is the last agency that we dread a recurrence of ophthalmia so long as dent.i.tion is incomplete, and hope for immunity if the animal completes its dent.i.tion without any permanent structural change in the eye.
_Symptoms._--The symptoms will vary according to the cause. If the attack is due to direct physical injury, the inflammation of the eyelids and superficial structures may be quite as marked as that of the interior of the eye. If, on the other hand, from general causes, or as a complication of some distant disease, the affection may be largely confined to the deeper structures, and the swelling, redness, and tenderness of the superficial structures will be less marked. When the external coats thus comparatively escape, the extreme anterior edge of the white or sclerotic coat, where it overlaps the border of the transparent cornea, is in a measure free from congestion, and, in the absence of the obscuring dark pigment, forms a whitish ring around the cornea. This is partly due to the fact that a series of arteries (ciliary) pa.s.sing to the inflamed iris penetrate the sclerotic coat a short distance behind its anterior border, and there is therefore a marked difference in color between the general sclerotic occupied between these congested vessels and the anterior rim from which they are absent. Unfortunately, the pigment is often so abundant in the anterior part of the sclerotic as to hide this symptom. In internal ophthalmia the opacity of the cornea may be confined to a zone around the outer margin of the cornea, and even this may be a bluish haze rather than a deep, fleecy white. In consequence it becomes impossible to see the interior of the chamber for the aqueous humor and the condition of the iris and pupil. The aqueous humor is usually turbid, and has numerous yellowish-white flakes floating on its substance or deposited in the lower part of the chamber, so as to cut off the view of the lower portion of the iris. The still visible portion of the iris has lost its natural, clear, dark l.u.s.ter, which is replaced by a brownish or yellowish sere-leaf color. This is more marked in proportion as the iris is inflamed, and less so as the inflammation is confined to the choroid.
The quant.i.ty of flocculent deposit in the chamber of the aqueous humor is also in direct ratio to the inflammation of the iris. Perhaps the most marked feature of internal ophthalmia is the extreme and painful sensitiveness to light. On this account the lids are usually closed, but when opened the pupil is seen to be narrowly closed, even if the animal has been kept in a darkened stall. Exceptions to this are seen when inflammatory effusion has overfilled the globe of the eye, and by pressure on the retina has paralyzed it, or when the exudation into the substance of the retina itself has similarly led to its paralysis. Then the pupil may be dilated, and frequently its margin loses its regular, ovoid outline and becomes uneven by reason of the adhesions which it has contracted with the capsule of the lens, through its inflammatory exudations. In the case of excessive effusion into the globe of the eye that is found to have become tense and hard so that it can not be indented with the tip of the finger, paralysis of the retina is liable to result. With such paralysis of the retina, vision is heavily clouded or entirely lost; hence, in spite of the open pupil, the finger may be approached to the eye without the animal's becoming conscious of it until it touches the surface, and if the nose on the affected side is gently struck and a feint made to repeat the blow the patient makes no effort to evade it. Sometimes the edges of the contracted pupil become adherent to each other by an intervening plastic exudation, and the opening becomes virtually abolished. In severe inflammations pus may form in the choroid or iris, and escaping into the cavity of the aqueous humor show as a yellowish-white stratum below. In nearly all cases there is resulting exudation into the lens or its capsule, const.i.tuting a cloudiness or opacity (cataract), which in severe and old-standing cases appears as a white, fleecy ma.s.s behind a widely dilated pupil. In the slighter cases cataract is to be recognized by examination of the eye in a dark chamber, with an oblique side light, as described in the introduction to this article. Cataracts that appear as a simple haze or indefinite, fleecy cloud are usually on the capsule (capsular), while those that show a radiating arrangement are in the lens (lenticular), the radiating fibers of which the exudate follows. Black cataracts are formed by the adhesion of the pigment on the back of the iris to the front of the lens, and by the subsequent tearing loose of the iris, leaving a portion of its pigment adherent to the capsule of the lens. If the pupil is so contracted that it is impossible to see the lens, it may be dilated by applying to the front of the eye with a feather some drops of a solution of 4 grains of atropia in an ounce of water.
_Treatment._--The treatment of internal ophthalmia should embrace, first, the removal of all existing causes or sources of aggravation of the disease, which need not be repeated here. Special care to protect the patient against strong light, cold, wet weather, and active exertion must, however, be insisted on. A dark stall and a cloth hung over the eye are important, while cleanliness, warmth, dryness, and rest are equally demanded. If the patient is strong and vigorous, a dose of 4 drams of Barbados aloes may be given, and if there is any reason to suspect a rheumatic origin one-half a dram powdered colchic.u.m and one-half ounce salicylate of soda may be given daily. Locally the astringent lotions advised for external ophthalmia may be resorted to, especially when the superficial inflammation is well marked. More important, however, is to instill into the eye, a few drops at a time, a solution of 4 grains of atropia in 1 ounce of distilled water. This may be effected with the aid of a soft feather, and may be repeated at intervals of 10 minutes until the pupil is widely dilated. As the horse is to be kept in a dark stall, the consequent admission of light will be harmless, and the dilation of the pupil prevents adhesion between the iris and lens, relieves the constant tension of the eye in the effort to adapt the pupil to the light, and solicits the contraction of the blood vessels of the eye and the lessening of congestion, exudation, and intraocular pressure. Should atropia not agree with the case, it may be replaced by morphia (same strength) or cocaine in 4 per cent solution.
Another local measure is a blister, which can usually be applied to advantage on the side of the nose or beneath the ear. Spanish flies may be used as for external ophthalmia. In very severe cases the parts beneath the eye may be shaved and three or four leeches applied. Setons are sometimes beneficial, and even puncture of the eyeball, but these should be reserved for professional hands.
The diet throughout should be easily digestible and moderate in quant.i.ty--bran mash, middlings, gra.s.s, steamed hay, etc.
Even after the active inflammation has subsided the atropia lotion should be continued for several weeks to keep the eye in a state of rest in its still weak and irritable condition, and during this period the patient should be kept in semidarkness, or taken out only with a dark shade over the eye. For the same reason heavy drafts and, rapid paces, which would cause congestion of the head, should be carefully avoided.