DISEASES OF THE EYE AND ITS APPENDAGES.

By M. R. Trumbower, D. V. S.

[Revised by Leonard Pearson, B. S., V. M. D.]

DESCRIPTION.

For the sake of gaining a clear comprehension of the diseases of the eye it becomes necessary to review the anatomy of this important organ. The essential organ of vision, or globe of the eye, will be first described, then its receptacle or orbital cavity, the muscles that move it, the protective membranes, or eyelids, the membrana nictitans, or accessory eyelids, and, lastly, the lacrimal apparatus.

The globe or ball of the eye is almost spherical in form. On closer inspection, however, it appears to be made up of two combined portions from spheres of different sizes. The posterior portion, forming about five-sixths of the ball, is a sphere of comparatively large size with a small segment cut off it in front, and at this point there is applied to it the anterior portion, which, being a segment of a smaller sphere, projects at the front of the ball with a greater convexity than the posterior portion.

The eyeball consists of concentrically arranged coats and of refracting media inclosed in them. The coats are three in number, namely, (1) an external protective tunic made up of the sclerotic and cornea; (2) a middle vascular and pigmentary tunic, the choroid; (3) an internal nervous layer, the retina. The sclerotic is the white, opaque part of the outer tunic, of which it forms about the posterior five-sixths, being coextensive with the larger sphere already mentioned. The cornea forms the remaining one-sixth of the outer tunic, being coextensive with the segment of the smaller sphere. It is distinguished from the sclerotic by being colorless and transparent. The choroid coat will be recognized as the black layer lying subjacent to the sclerotic. It does not line the cornea, but terminates behind the line of junction of that coat with the sclerotic by a thickened edge—the ciliary processes. At the line of junction of the sclerotic and cornea the iris passes across the interior of the eye. This (which may be viewed as a dependency of the choroid) is a muscular curtain perforated by an aperture termed the pupil. The retina will be recognized as a delicate, glassy layer, lining the greater part of the choroid.

The refracting media of the eye are three in number, namely (1) the aqueous humor, a watery fluid inclosed in a chamber behind the cornea; (2) the crystalline lens and its capsule, a transparent, soft solid of a biconvex form, and placed behind the iris; (3) the vitreous humor, a transparent material with a consistence like thin jelly, and occupying as much of the interior of the eye as is subjacent to the choroid.

The sclerotic is a strong, opaque, fibrous membrane, which, in a great measure, maintains the form of the eyeball and protects the more delicate structures within it. Its interior portion, which is covered by the ocular conjunctiva, is commonly known as the "white of the eye." In form it is bell-shaped, and the optic nerve pierces it behind like a handle, the perforation being a little to its inner side. In front, the rim of the bell becomes continuous with the cornea. The outer surface of the membrane receives the insertion of the muscles of the eyeball. The coat is thickest over the posterior part of the eyeball, and is thinnest a little behind its junction with the cornea.

The cornea is the anterior transparent portion of the outer coat of the eyeball. It may be viewed as a part of the sclerotic specially modified to permit the passage of light into the interior of the eye. Its outline is elliptical, nearly circular, and its greatest diameter is transverse. At its periphery it joins the sclerotic by continuity of tissue, and as the edge of the cornea is slightly beveled and has the fibrous sclerotic carried for a little distance forward on its outward surface, the cornea is generally said to be fitted into the sclerotic like a watch glass into its rim. The venous canal of Schlemm runs circularly around the eyeball at the line of junction of the sclerotic and cornea. The anterior surface of the cornea is exquisitely smooth, and is kept moist by the lacrimal secretions. Its posterior surface forms the anterior boundary of the chamber in which the aqueous humor is contained. The cornea is of uniform thickness and is of a dense, almost horny, consistence. Save a few capillary loops of blood vessels at its margin the cornea is without vessels. Its structure is comprised of five distinct layers.

The aqueous humor occupies a chamber which is bounded in front by the posterior surface of the cornea and behind by the capsule and suspensory ligament of the lens and by the ends of the ciliary processes. It is across this chamber that the iris extends. The aqueous humor is composed of water, with a small proportion of common salt in solution.

The iris is a muscular, pigmented curtain extending across the interior of the eye and having about its center an aperture termed the pupil. By variations in the size of this aperture the amount of light transmitted to the retina is regulated. It varies somewhat in color, but is most frequently of a yellowish-brown tint. Its anterior face is bathed by the aqueous humor. The greater part of the posterior surface is in contact with the capsule of the lens and glides on it during the movements of the curtain. The circumferential border is attached within the junction of the sclerotic cornea. The inner border circumscribes the pupil, which varies in outline according to its size. When much contracted the pupil is a very elongated ellipse, the long axis of which is in the line joining the nasal and temporal angles of the eyelids. It contains muscular tissue, which, by contracting or relaxing, lessens or dilates the pupillary opening.

The choroid coat is a bell-shaped, dark membrane which lines the sclerotic. Its outer surface has a shaggy appearance, caused by the tunica fusca, which unites the two coats. Between the two the ciliary vessels and nerves pass forward. Behind it is pierced by the optic nerve; in front it is continued as the ciliary processes, which form, as it were, the rim of the bell. The ciliary processes form a fringe around the slightly inverted rim of the choroid.

The retina is the most delicate of the coats of the eyeball. It is formed by the expansion of the optic nerve on the inner surface of the choroid, and, like that coat, it is bell-shaped. Its inner surface is molded on the vitreous humor. The nervous structures of the retina terminate at a wavy line, the ora serrata, behind the ciliary processes. Ten distinct layers are described as composing the thickness of the retina.

The lens is situated behind the pupil and is contained within a capsule of its own.

The capsule is a close-fitting, firm, transparent membrane. The anterior surface forms the posterior boundary of the cavity containing the aqueous humor, and the iris in its movement glides on it. The posterior surface is in contact with the vitreous humor.

The vitreous humor occupies four-fifths of the interior of the eyeball. It is globular in form, with a depression in front for the lodgment of the lens. It is colorless, transparent, and of a consistency like thin jelly. It is enveloped by a delicate capsule—the hyaloid membrane—which is connected in front with the suspensory ligament of the lens, and ends by joining the capsule behind the lens.

The orbital cavity, at the side of the head, is circumscribed by a bony margin; posteriorly, however, there are no bony walls, and the cavity is often confounded with the depression above and behind the orbit—the temporal fossa. A fibrous membrane completes this cavity and keeps it distinct from the temporal fossa. This membrane—the ocular sheath or periorbita—is attached posteriorly around the opening in the back part of the orbital cavity (the orbital hiatus) and anteriorly to its inner face; then it becomes prolonged beyond the margin to form the fibrous membrane of the eyelids. When complete the orbital cavity has the form of a regular hollow cone, open at its base and closed at the apex. The opening of this cone is directed forward, downward, and outward. Independently of the globe of the eye, this cavity lodges the muscles that move it, the membrana nictitans, and the lacrimal gland.

The muscles of the eye are seven in number—one retractor, four straight, and two oblique. The retractor oculi envelops the optic nerve between the brain and the ball of the eye and becomes attached upon the external face of the sclerotic tunic. When this muscle contracts, it draws the globe back into the orbit, away from the light. The superior, inferior, external, and internal recti or straight muscles are attached to the back part of the orbital sheath and spread forward in four bundles over the globe of the eye, where they are inserted by a fibrous expansion into the sclerotic at the margin of the cornea. When they act singly, they turn the globe either upward, downward, inward, or outward. The great oblique, by its action, pivots the eye inward and upward in the orbit. The small oblique turns the eye outward and downward.

The eyelids are two movable curtains, superior and inferior, which cover and protect the eye in front. They are attached to the circumference of the orbit and have a convex external face formed by the skin and a concave internal face molded on the anterior surface of the eye and are lined by the conjunctiva, which is reflected above and below on the eyeball. The border of each lid is slightly beveled on the inner side and shows the openings of the Meibomian glands. These glands secrete an unctuous fluid, which is thrown out on the border of the lids, the function of which is to facilitate their movements and enable them to retain the tears in the ocular cavity. The eyelid is composed of a fibrous inner membrane ending in a stiff arch near the border, a muscle to close the lid, another to open it, the skin externally, and the conjunctival mucous membrane internally. The border of each lid is covered and protected by long hairs to prevent floating particles of matter in the atmosphere from gaining entrance to the eye.

The membrana nictitans, which is also named the third eyelid, winking eyelid, haw, etc., is placed at the inner angle of the eye, whence it extends over the eyeball to relieve it from foreign bodies which may fall upon it. It has for its framework a fibro-cartilage, irregular in shape, thick, nearly prismatic at its base, and thin anteriorly where it is covered by the conjunctiva; behind, it is loosely attached to a fatty cushion.

The lacrimal gland is situated between the orbital process and the upper part of the eyeball. It secretes the tears destined to lubricate the anterior surface of the eye. This fluid escapes upon the organ at the outer angle of the lids and is carried between them and the eyeball toward the inner angle.

The caruncula lacrimalis is a small round body, frequently entirely or partially black, situated in the inner angle of the eye, and is designed to direct the tears toward the puncta lacrimalia.

The puncta lacrimalia are two little openings, situated one in each eyelid, a short distance from the inner corner, which admit the tears into the lacrimal ducts leading to the lacrimal canal, whence they are emptied into the nasal passages.

CONJUNCTIVITIS (SIMPLE OPHTHALMIA).

This is an inflammation of the conjunctival mucous membrane of the eyeball and lids; in severe cases the deeper coats of the eye are involved, seriously complicating the attack.

Causes.—It may result from a bruise of the eyelid; from the introduction of foreign matters into the eye, as chaff, hayseed, dust, gnats, etc.; from exposure to cold; poisonous or irritating vapors arising from filthiness of stable. Dust, cinders, or sand blown into the eyes during transportation frequently cause conjunctivitis.

Symptoms.—A profuse flow of tears, closure of the eyelids from intolerance of light, retraction of the eyeball and corresponding protrusion of the haw, disinclination to move, diminution of milk secretion, etc. On parting the lids the lining membrane is found injected with an excess of blood, giving it a red and swollen appearance; the sclerotic, or white of the eye, is bloodshot and the cornea may be cloudy. If the disease advances, keratitis results, with its train of unfavorable symptoms.

Treatment.—Careful examination should be made to discover particles of chaff, etc., which may have lodged in the eye, and upon the discovery of such a cause prompt removal is indicated. This may be accomplished by flushing the eye with warm water by means of a syringe, or, if the foreign substance is adherent to the eyeball or lid, it may be scooped out with the handle of a teaspoon or some other blunt instrument. To relieve the congestion and local irritation, a wash composed of boracic acid in freshly boiled water, 20 grains to the ounce, or acetate of zinc, 5 grains to the ounce of pure soft water, may be used, to which may be added 20 drops of laudanum. A few drops of this should be placed in the eye with a camel's-hair pencil or soft feather three or four times daily. The animal should be placed in a cool, darkened stable; then a cloth folded into several thicknesses should be fastened to the horns in such manner as to reach below the eyes. This should be kept wet with cold water during the day and removed at night. If there is much fever and constitutional disturbance, it becomes advisable to administer 1 pound of Epsom salt dissolved in 1 quart of water.

INFECTIOUS CATARRHAL CONJUNCTIVITIS (SPECIFIC OPHTHALMIA).

This generally appears in an enzootic or epizootic form and affects a considerable number in the herd. It is distinctly a contagious disease and may be brought into a previously healthy herd by one infected animal. It may continue in a herd for a season or for several years, affecting all newly purchased animals. It is seldom seen in the winter months. It affects old and young animals alike.

Symptoms.—This form of catarrh conjunctivitis is characterized chiefly by a mucopurulent discharge from the eyes, an intense degree of inflammation of the mucous membrane, accompanied with swelling of the eyelids and an early opacity of the cornea. The flow of tears is mixed with pus, sometimes streaked with blood, and the skin of the face is kept moist and soiled. The eyes are kept continually closed. The implication of the cornea in the disease frequently blinds the animal for a time, and occasionally suppurative keratitis, ulcers of the cornea, or staphyloma supervene. The attack is marked from the onset by fever, partial loss of appetite, partial loss of milk, suspended rumination, and separation from the herd.

Treatment.—The animal should be housed in a cool, dark stable, supplied with plenty of fresh water to drink and soft, succulent feed. Administer 1 pound of Epsom salt—if a very large animal, use 1½ pounds—dissolved in 2 or 3 pints of water. For an eyewash, take boracic acid, 1 dram, and pour 4 ounces of boiling water over it. Use this as often as is convenient, applying it directly to the eye. In the majority of cases improvement becomes manifest in a few days, and the eye becomes clear and free from inflammation in 10 days or 2 weeks. Where the disease develops ulceration of the cornea, or well-marked, deep-seated keratitis, the treatment recommended for those conditions should be adopted.

Prevention.—Whenever this affection appears in a herd all the unaffected animals should be moved to fields which possess a different character of soil and feed. The water should also be changed, especially if they have been obtaining it from a stagnant pond.

KERATITIS (CORNEITIS).

This is an inflammation of the cornea proper, although the sclerotic at the corneal border becomes involved to some extent. It may be divided into diffuse and suppurative.

Causes.—The cornea constitutes the most prominent portion of the eyeball, hence it is subject to a variety of injuries—scratches, pricks, contusions, lacerations, etc. Inflammation of the cornea may also be due to the extension of catarrhal conjunctivitis or intraocular disease, and it may occasionally occur without any perceptible cause.

Symptoms.—Diffuse keratitis is characterized by an exudation into and an opacity of the cornea. The swelling of the anterior part of the eyeball may be of an irregular form, in points resembling small bladders, or it may commence at the periphery of the cornea by an abrupt thickening, which gradually diminishes as it approaches the center. If the whole cornea is affected, it has a uniform gray or grayish-white appearance. The flow of tears is not so marked as in conjunctivitis, nor is the suffering so acute, though both conditions often exist together. Both eyes usually become affected, unless it is caused by an external injury.

In favorable cases the exudate within the cornea begins to disappear within a week or 10 days, the eye becomes clearer and regains its transparency, until it eventually is fully restored. In unfavorable cases blood vessels form and are seen to traverse the affected part from periphery to center, vision becomes entirely lost, and permanent opacity (albugo or leucoma) remains. When it arises from constitutional causes recurrence is frequent, leaving the corneal membrane more cloudy after each attack, until the sight is permanently lost.

Suppurative keratitis may be a sequel of diffuse keratitis; more commonly, however, it abruptly becomes manifest by a raised swelling on or near the center of the cornea that very soon assumes a yellow, turbid color, while the periphery of the swelling fades into an opaque ring. Suppurative keratitis is seldom noticed for the first day or two—not until distinct pus formation has occurred. When it is the result of diffuse keratitis, ulceration and the escape of the contained pus is inevitable; otherwise the pus may be absorbed. When the deeper membranes covering the anterior chamber of the eye become involved, the contents of this chamber may be evacuated and the sight permanently lost.

Treatment.—Place the animal in a darkened stable, give green or sloppy feed, and administer 4 ounces of Glauber's salt (sulphate of soda) dissolved in a quart of water once a day. If the animal is debilitated a tablespoonful of tonic powder should be mixed with the feed three times a day. This may be composed of equal parts by weight of powdered copperas (sulphate of iron), gentian, and ginger. As an application for the eye, nitrate of silver, 3 grains to the ounce of soft water, with the addition of 1 grain sulphate of morphia, may be used several times a day. If ulceration occurs, it is well to dust powdered calomel into the eye twice daily, or apply to the eyelids a salve of yellow oxid of mercury, 5 per cent in lanolin. Some of this may go on to the cornea and beneath the lids. Apply twice daily. (See "Ulcers of the cornea.")

To remove opacity, after the inflammation has subsided, apply a few drops of the following solution twice a day: Iodid of potassium, 15 grains; tincture sanguinaria, 20 drops; distilled water, 2 ounces; mix.

Sometimes keratitis exists in a herd as a transmissible disease, spreading like infectious conjunctivitis. Calomel, applied to the eye, is especially useful in such cases.

ULCERS OF THE CORNEA.

An ulcer comes from erosion or is the consequence of the bursting of a small abscess, which may have formed beneath the delicate layer of the conjunctiva, continued over the cornea; or, in the very substance of the cornea itself, after violent keratitis, or catarrhal conjunctivitis. At other times it is produced by bruises, scratches, or other direct injury of the cornea.

Symptoms.—The ulcer is generally at first of a pale gray color, with its edges high and irregular, discharges instead of pus an acrid, watery substance, and has a tendency to spread widely and deeply. If it spreads superficially upon the cornea, the transparency of this membrane is lost; if it proceeds deeply and penetrates the anterior chamber of the aqueous humor, this fluid escapes, the iris may prolapse, and the lens and the vitreous humor become expelled, thus producing destruction of the whole organ.

Treatment.—It is of the greatest importance, as soon as an ulcer appears upon the cornea, to prevent its growing larger. The corroding process must be converted into a healthy one. For this purpose nothing is more reliable than the use of solid nitrate of silver. A stick of this medicine should be scraped to a point; the animal's head should be firmly secured; an assistant should part the lids; if necessary, the haw must be secured within the corner of the eye and then all parts of the ulcer should be lightly touched with the silver. After waiting a few minutes the eye should be thoroughly washed out with a very weak solution of common salt. This operation generally has to be repeated at the end of three or four days. If healthy action succeeds, the ulcer assumes a delicate fleshy tint, and the former redness around the ulcer disappears in proportion as the ulcer heals.

In superficial abrasions of the cornea, where there is no distinct excavation, this caustic treatment is not needed. The eye should be bathed several times a day with sulphate of zinc, 30 grains to half a pint of soft water, and protected against exposure to cold air and sunlight. Excessive ulceration sometimes assumes the form of fungous excrescence upon the cornea, appearing to derive its nourishment from loops of blood vessels of the conjunctiva. Under these circumstances the fungoid mass must be cut away and the wound cauterized with the nitrate of silver, or else the eye will soon be destroyed. When ulcers of the cornea appear indolent, with a tendency to slough, in addition to the treatment already prescribed, tonic powders of copperas, gentian, and ginger, equal parts by weight, should be given twice a day, mixed with the feed; dose, one tablespoonful.

STAPHYLOMA.

This is a disease of the eyeball, in which the cornea loses its transparency, rises above the level of the eye, and even projects beyond the eyelids in the form of an elongated, whitish, or pearl-colored tumor, which is sometimes smooth, at other times uneven.

Causes.—Inflammation is the only known cause, although it may not occur immediately; it frequently follows catarrhal conjunctivitis and keratitis as a sequela.

Treatment.—In a few cases restoration of sight may be effected by puncturing the projecting tumor and treating it afterwards with nitrate of silver in the same manner as prescribed for ulceration of the cornea. In some cases spontaneous rupture has occurred, and healing without any treatment at all.

CATARACT.

In cataract the crystalline lens becomes opaque and loses its transparency, the power of refraction is lost—the animal can not see.

Causes.—Cataract generally arises from a diminution (atrophy) or other change in the nutrition of the lens; it may occur as a result of inflammation of the deep structures of the eye. Cataract may be simple, or complicated with amaurosis, adhesions, etc.

Symptoms.—It is known by the whiteness or loss of transparency of the lens, although the pupil dilates and contracts. Sight may be totally lost; however, evidence is usually manifested that the animal distinguishes light when brought out of a darkened stable. For the most part the formation of cataract takes place slowly, the cases in which it originates very quickly being but few.

Treatment.—There is only one method for the treatment of cataract—a surgical operation for the removal of the lens; but this is not advisable, for the sight can not be perfectly restored, and objects would be seen imperfectly without the aid of glasses.

AMAUROSIS.

This is a paralysis of the nerve of sight or the expansion of the retina.

Causes.—This is the result of concussion from a blow upon the forehead, fracture of bone over the eye (causing downward pressure), rheumatic inflammation of the optic nerve, or from extension of deep inflammation of the eye involving the retina. It sometimes occurs as the result of excessive loss of blood or of great debility.

Symptoms.—In this disease observation is seldom made until the animal in its gait and by its action indicates blindness. Generally both eyes are affected. The eyeball remains clear, and the pupil is permanently dilated. No response to light is manifested.

Treatment.—If caused by debility, loss of blood, or associated with rheumatism, general blood tonics may be given in the feed, namely, powdered sulphate of iron, 1 dram; gentian, 2 drams; nux vomica, one-half dram; to be given twice a day. In cases of rheumatism, one-half ounce of saltpeter may be added.

FILARIA OCULI (WORM IN THE EYE).

Filaria oculi (provisionally taken as the larva of F. cervina) is a small white worm, found swimming in the aqueous fluid in the anterior chamber. It may be apparently harmless for a long time, but will eventually induce keratitis with inflammatory exudations.

Treatment.—The cornea may be punctured at its upper and outer margin, and the worm squeezed out with the aqueous humor. The latter will be formed again. This operation results disastrously unless the greatest care and skill are employed.

CORNEAL DERMATOMA (HAIRY TUMOR ON THE EYEBALL).

In a few instances this has been seen as a congenital growth. The tumor arises from the cornea or the sclerotic, covered by its respective membrane, with a growth of hair upon its surface. These tumors may be quite prominent or flattened, and are dark in color; the hair may protrude between the eyelids, giving the animal the appearance of having a double eyelid.

Treatment.—A surgical operation becomes necessary for their removal— one requiring a skilled operator.

STRABISMUS (SQUINTING).

This is a very rare affection among cattle. Strabismus may be either single or double—affecting one eye or both. It is caused by a paralysis, or a weakening of one of the straight muscles of the eyeball. Generally it is a congenital defect, and the squinting is toward the nose—strabismus convergens. It is best not to attempt to remedy the defect, as the risk in an operation is greater than the chances of success warrant.

PTERYGIUM.

This term is applied to a flesh-colored membrane, triangular in form, which most frequently grows from the inner angle of the eye and extends over the cornea, thus interfering with vision. It may grow from the outer angle, or even from either the superior or inferior hemisphere of the eyeball. The figure is invariably that of a triangle, with its base on the white of the eye and its apex more or less advanced over the cornea toward its center.

The distinguishing characteristics are the constancy of the triangular form, and the facility with which the whole of it may be taken hold of with a pair of forceps and raised into a fold on the cornea. Every other kind of excrescence attached to this membrane continues firmly adherent to it, and can not be folded and raised from the surface of the cornea in any manner whatever.

Treatment.—Raise the fold and dissect it away from all points of attachment.

TRICHIASIS (INVERSION OF THE EYELASHES).

In the simplest form the eyelashes bend inwardly, touching the eyeball, causing irritation and simple conjunctivitis. It may be also associated with entropion.

Treatment.—The offending eyelashes should be cut off or pulled out. In case the natural growth of the eyelashes is directed inward, an operation similar to that for entropion becomes necessary.

ENTROPION (INVERSION OF THE EYELID).

In inversion of the eyelid the eyelashes soon irritate the anterior face of the cornea and produce more or less inflammation and opacity. The inversion may be due to the growth of a tumor within or without the lid, to abscess, laceration, or injury, causing the lid to lose its natural conformity to the eyeball, ulcerations, etc. Surgical interference in either case becomes necessary to restore the lid to its natural direction.

ECTROPION (EVERSION OF THE EYELID).

This serves to injure the eye by permitting dust or other foreign substances to enter the eye and interferes with the natural removal of them.

Treatment.—A delicate surgical operation—the removal of an elliptic section of the palpæbral conjunctiva—may remedy the defect.

TUMORS OF THE EYELIDS.

Occasionally tumors form upon or within the substance of the eyelid. They may be of a fibroid nature and arise from the follicles of the hair as sebaceous tumors or may be in the form of an abscess. In debilitating diseases the lids sometimes become swollen and puffy, a condition which may possibly be taken for the growth of a tumor. This generally disappears with the improvement of the health of the animal. Warts not uncommonly appear on or about the eyelids of cattle.

Treatment.—The removal of a tumor in the vicinity of so delicate an organ as the eye should not be attempted by anyone not qualified to perform the operation.

LACERATION OF THE EYELID.

This accident is not uncommon where cattle are fenced in by barbed wire; an animal may be caught under the eyelid by the horn of another, or the laceration may occur in the stable by means of a projecting nail or splinter of wood.

Treatment.—The edges of the wound should be brought together closely and correctly, by means of pins pushed through very nearly the whole thickness of the lid, extending through each lip of the torn part; then a waxed silk or linen thread must be wound over each end of the pin, crossing the torn line in the form of the figure 8 (Pl. XXVII, fig. 9); the pins should be placed about three-eighths of an inch apart. The projecting ends of the pins should be cut off close to the ligature, and the parts kept anointed with vaseline, to which 2 per cent of compound cresol has been added. In place of a pin suture, silver wire, catgut, or strong linen thread may be used in the way of an ordinary suture.

FOREIGN BODIES IN THE EYE.

Splinters of wood, hedge thorns, pieces of cornstalk or leaves, stems of hay or straw, twigs of trees, or weeds may penetrate into the eye, break off, and remain, causing inflammation, blindness, abscess, etc. These substances may penetrate the eyeball, but more frequently they glide off and enter between the eye and the ocular sheath.

Treatment.—Their removal becomes often a very difficult task, from the fact that the organ is so extremely sensitive, and the retracting power so strong as to necessitate casting the animal, or even the administration of sufficient chloroform to render it completely insensible. The removal, however, is of paramount importance, and the after treatment depends upon the extent and location of the injury—cold water compress over the injured eye, the application of mild astringent and cooling washes, such as acetate or sulphate of zinc, 5 grains to the ounce of water. When there is extreme suffering from pain a solution of atropia or morphia, 5 grains to the ounce of water, may be dropped into the eye, alternating with the cooling wash several times a day. When abscesses form within the orbit a free opening must be maintained for the discharge of pus. In deep penetrating wounds of the eye there is a great tendency to the formation of a fungous growth, which often necessitates the enucleation of the whole eyeball.

ORBITAL AND PERIORBITAL ABSCESS.

Orbital abscess may form outside the globe and within the orbital sheath, as the result of a previous wound of the parts or from fracture of the bony orbit, etc. Periorbital abscess commences outside the ocular sheath, beneath the periosteal membrane covering the bone, and is usually the result of a disease or fractured bone which enters into the formation of the orbital cavity.

Symptoms.—Orbital abscess is manifested by a pushing forward of the eyeball (exophthalmos), a swelling of the conjunctiva and eyelids. The bulging out of the eye is in proportion to the size of the abscess; the movement of the eye is fixed, due to the painfulness of any voluntary movement of the eyeball. Periorbital abscess generally pushes the eye to one side; otherwise the symptoms are similar to the foregoing. The pain generally is very great; paralysis of the nerve of sight may occur, and death may be caused by the abscess extending to the brain.

Treatment.—The treatment for either orbital or periorbital abscess is the same as that for abscess occurring in any other part of the body—a free opening for the escape of imprisoned pus. This should be made as soon as the true nature of the disease is recognized. Afterwards antiseptic injections may be needed to stimulate healthy granulation and to prevent septic infection of the ocular membranes. For this purpose a saturated solution of boric acid or listerine 1 part to 10 of water may be used. When the fever runs high, Glauber's salt (sulphate of soda) may be given in 4-ounce doses once a day. The animal should be kept in a darkened stable, on soft or green feed.

FRACTURE OF THE ORBIT.

This accident occasionally occurs among belligerent animals, or as the result of blows delivered by brutal attendants. The orbital process above the eye may be entirely crushed in, pressing down upon the eyeball. In such an event the depressed bone should be elevated into its proper place, and if it fails to unite it may have to be removed with saw or chisel. The margin of the orbit may be crushed at any point and cause periorbital abscess, or necrosis may result from the presence of a splinter of bone or the excessive destruction of bone. In all cases of fracture the animal should be kept by itself until the injured part heals.

NECROSIS OF THE BONY ORBIT.

As the result of fracture of the margin of the orbit a part of the injured bone may become necrosed (dead), and periostitis and periorbital abscess will follow as a consequence. The discovery of this disease will at first resemble abscess, but on making an examination with a probe after the abscess is open we find the bone rough and brittle at the point of disease. The discharge has a peculiar fetid odor, and is often mixed with blood.

Treatment.—The affected bone must be laid bare and all diseased portions removed by scraping or, if necessary, with saw or chisel, disregarding the extent of the injury or the size of the wound necessary to be inflicted. A large portion of the bony orbit may be removed without serious danger to the eye, provided the eyeball itself has not been previously affected by the disease or involved in the original injury.

TUMORS OF THE ORBIT.

A fungous tumor of the eyeball or orbit occasionally appears, which is designated fungus hæmatodes. This may arise without any appreciable cause, or as the result of a wound. It frequently commences within the eyeball as a small, red mass, eventually bursts through, and pushes its way outside the orbit as a large, dark-red mass, bleeding at the slightest touch. It has a peculiar, fetid odor, and early in its appearance destroys sight, involving all the contents of the orbit, not infrequently the bony wall itself.

Unless the tumor is totally removed in its early stage of growth, together with the eyeball, the disease will eventually cause emaciation and death of the animal. The enucleation of the eyeball should not be undertaken by anyone unacquainted with the anatomical structures involved in such an operation. When the operation is performed early enough the result is generally satisfactory.

Bony tumors of the orbit, the result of bruises, fractures, etc., are occasionally present in cattle. They may encroach upon the contents of the orbit, causing paralysis of the optic nerve—the condition known as amaurosis—or by pressure upon the posterior surface of the eyeball force it forward, or produce atrophy (shrinking). They may displace the eye in any direction, with or without disturbing vision.

Fibrous tumors growing within the orbit will produce symptoms similar to those of bony tumors.

Treatment.—When the outlines of the tumor, whether fungoid, bony, or fibrous, can be detected, an operation for its removal should be undertaken as soon as the sight of the eye is in any manner disturbed.

DISLOCATION OF THE EYEBALL.

The eyeball may be torn out of its socket by the horns of another animal, or it may be crowded out with the blunt end of a club, cane, or probe in the hands of a brutal attendant.

Treatment.—When the optic nerve is not lacerated and the retractor muscles at the back of the eye are intact, an attempt at reduction is advisable. This, however, must follow very soon after the injury—before swelling takes place. Divide the outer corner of the eyelid to enlarge the orifice, then by pressure with the fingers of both hands placed upon the sides of the eye the ball may be put into its place. Apply a firm compress over the injured eye and keep it constantly wet with cold water containing 1 dram of sugar of lead to each quart.

If the attempt at reduction proves unsuccessful the artery at the back of the eye should be ligated, and then the whole mass cut off as deep within the orbit as possible. The orbital cavity, after washing it out with a 3 per cent solution of carbolic acid or compound cresol, should be packed daily with fresh absorbent cotton.

INFLAMMATION AND ENLARGEMENT OF THE HAW.

The haw, or membrana nictitans, is subject to inflammation and swelling from the extension of conjunctivitis, or direct injury by foreign substances. It presents a red, swollen appearance, accompanied with considerable pain and a profuse flow of tears. A slight scarification with a sharp knife and the application of a cooling lotion, such as is recommended for conjunctivitis, will soon reduce the swelling and restore it to its normal function.

There is, however, a tendency for an inflammation of this membrane to take on a chronic character, which may eventually result in a permanent enlargement, resembling a tumor. When it attains sufficient size to protrude itself permanently over the eye, or project between the lids so as to obstruct the sight, its removal may become necessary. A threaded needle is passed through the body of the enlarged mass, by which the membrane is drawn out as far as possible, then with a blunt pair of scissors it may be dissected away from its attachments. The eye is afterwards treated with simple cooling lotions.