Diseases Of The Cornea And Sclera
Diseases Of The Cornea And ScleraBy SWAN M. BURNETT, M. D., PH. D
OF WASHINGTON, D. C.
Inflammation of the Cornea (Keratitis). The cornea, having no vascularization of its own, depends for its nutritive supply on the blood vessels of the conjunctiva, sclera, iris, and ciliary body. From this it happens first, that inflammations of these tissues are nearly always accompanied by some change in the nutrition of the cornea; and, second, that defective general nutrition is apt to be felt early in the cornea as a tissue far from the base of supplies. Keratitis, therefore, when not the direct result of a traumatism, is in the vast majority of cases the expression of some depressed general vitality or is the effect or accompaniment of an inflammation in the adjacent parts. A primary and isolated keratitis is a rare affection, though the participation of other tissues may be so slight as to escape detection or be veiled by the intensity of the corneal affection.
Corneal inflammations may be studied clinically from the standpoint either of their supposed etiology or by following the anatomical divisions of the affected part. For practical purposes sometimes the one method and sometimes the other has been found the more convenient.
Anatomically, the cornea is a direct continuation of other coats of the eyeball of the conjunctiva, through its epithelial laver; of the sclera, through the substantia propria; and of the uveal tract, through the endothelial laver of Descemet's membrane. The pathological importance of this connection will be apparent when we come to consider the various individual forms of keratitis.
Superficial Keratitis. The most common form of this affection is that known as phlyctenular conjunctivitis, phlyctenular kerato conjunctivitis, or herpes cornea, but more properly as strumous or scrofulous Ophthalmia, because it is usually limited to the conjunctival or epithelial layer of the cornea, and is always associated with the strumous diathesis or some form of defective assimilation.
Etiology. The disease is confined almost entirely to childhood. One eye or both may be affected at the same time, and a recurrence of the affection from time to time is the rule. Evidences of a strumous diathesis are seldom lacking in its subjects. There is often swelling of the preauricular and submaxillary glands; the patients are badly nourished, even when not positively anemic, and the appetite is bad or capricious. In the worst cases the scrofulous cachexia is very pronounced. Running from the nostrils, which are clogged up with dried secretions, swollen aloe nasi, thick upper lip, and excoriated cheeks make the diagnosis before the eyes are inspected. Naso pharyngeal disease, inflammatory or obstructive, which most frequently accompanies the affection, is the etiological factor in many instances. Phlyctenular disease often follows in the wake of measles and other exanthemata. It is more aggravated in warm and moist weather.
Micro organisms have been described, but their etiological relationship to this disease has not been established (compare with page 286). 0
Objective Symptoms. The disease manifests itself by a small yellowish white elevation (the phlyctenule) on the surface of' the cornea, varying in size from I to 2 or 3 mm. in diameter. It may occur at any place on the corneal surface, but its usual seat is near the scleral edge, and commonly on the limbus itself. It is Dot uncommon for two or more of these phlyctenules to appear at the same time, and on rare occasions they are so numerous as to form a circlet around the corneal base (marginal phlyctenular keratitis). The accompanying injection of the conjunctival vessels may be very slight, and is commonly limited to a leash of vessels running tip to and ending in the phlyctenule (Fig. 202).
On the other hand, and especially when the spot is farther in on the corneal surface and the deeper structures are involved, the conjunctival congestion is more general. Oftentimes the accompanying conjunctivitis assumes the form of a more or less muco purulent type. The intensity of the accompanying conjunctival participation, however, bears, as a rule, no proportion to the local lesion on the cornea.
Subjective Symptoms. The subjective symptoms vary greatly in intensity. In the milder cases there is little or no pain, and a feeling of discomfort and an inability to use the eyes as much as customary are about all that is complained of.
In severe eases, which occur especially in children, the symptoms are of the most intense kind. There is a photophobia which makes the child keep the eyes tightly shut (blepharospasm), and which may persist for weeks, render even forcible separation of the lids difficult (see also page 253). The child seeks the darkest corner of the room, buries its bead deep in the pillow, and violently resists every effort to bring it into the light. The lachrymation is profuse, and the cheeks are excoriated with the constant overflow of irritating tears.
Between this and the mildest form there is every gradation; moreover, the intensity of the symptoms does Dot bear any proportion to the extent of the pathological change. A single phlyctenule may be attended with more pronounced subjective symptoms than three or four, and the severity differs in different attacks in the same person. This can be accounted for partly, no doubt, by the fact that in the one case the exudate presses on the terminal filaments of the nerve distributed among the cells of the epithelial layer, causing these intense reflex phenomena, and in the other it does not. Another important factor, too, is the generally hyperesthetic condition of the patient, due, most likely, to defective nutrition of the nerve centers.
Pathology. Pathologically, the phlyetenute is not a vesicle with fluid contents, as its appearance would indicate. Under the epithelium there is found a collection of small round lymphoid cells, as shown in Fig. 203. The anterior epithelial wall of the phlyctenule breaks down; tile cells are discharged, leaving a small, superficial ulcer (phlyctenular ulcer), which is generally rapidly covered over by a fresh layer of' epithelium, and the diseased process is ended for the time, usually leaving no trace unless the deeper structures of the cornea are involved, when there is likely to be more or less opacity remaining for a time or, it may be, permanently.
Diagnosis and Prognosis. Direct inspection reveals the nature of the disease. The prognosis depends on the type. It is essentially a relapsing disease; repeated attacks may leave the corneal epithelium roughened and scarred, and sometimes covered with vessels, the so called phyetenular pannus.
Treatment. In the treatment of the affection attention to the general condition is of' greatest importance. A persistent and long continued use of tonics and nutrients among which iron (syrup of the iodid) and cod liver oil are perhaps the best is the first requisite as regards medication. But most important is the regulation of the diet and habits of the child. Only nutritious food should be allowed milk, meat (except pork and veal) in moderate quantity, vegetables (except potatoes in excess), with abstinence from sweets and pastries. Good fruit may be allowed in proper quantities.
The child should live out of doors as much as possible in spite of the photophobia, and the function of the skin should be kept in proper order by frequent bathing. Any associated nasal affection should receive prompt and thorough attention, and the naso lachrymal passages should be kept patulous.
Locally, in the first or acute stage, atropin drops (gr. gr.iv 3j) are to be used, and where there is much photophobia all equal amount of muriate of cocain can be added. A drop of this solution is to be put in the eye three times a day or every four hours according to the intensity of the symptoms. The eye should be bathed in water as hot as can be borne for five minutes every four hours.
In the second stage, after the rupture of the phlyctenule and the process of restoration has begun, the insufflation of finely powdered calomel is a timehonored remedy, as is also Pagenstecher's salve (hydrarg. oxid. flav., gr. j, petrolat. 3j or ij) put under the eyelid and rubbed over the ball. In very mild cases, where there is no photophobia, lachrymation, or other sign of irritation, a simple antiseptic collyrium, such as boric acid or biborate of odium, gr. x to 3j, will suffice, with care in the use of the eyes. The eyes should never be bandaged, protection from the excessive light being secured by colored glasses or a shade.
In the severest cases the blepharospasm is so intense as to require especial attention. When it has once become a fixed habit it is difficult to break up, and its presence undoubtedly prolongs the disease. It sometimes yields to the instillation of cocain, but in long standing cases this will not suffice. In these instances the most efficient means is to plunge the face in a basin of cold water and hold it there a few moments. The shock of this violent procedure will usually relieve the spasm, and the child will, on removal from the water, open its eyes widely. Forcible dilatation of the eyelids by an eyespeculum for a short period each day has been recommended. The excoriations at the angles of the lids no doubt keep up the blepharospasm. through reflex action, and should be cured as promptly as possible. After the disease has subsided any refractive error should be corrected, as eye strain may excite an attack in an eye predisposed to this disorder.
Pannus. Vascularity of the superficial layers of the cornea is often an accompaniment of trachoma or of one of its sequels cicatricial entropion or trichiasis.
When the vascularity and thickening accompany the first stages of the disease, before the period of cicatrization has arrived, there are grounds for believing that the pannus is but an expression of the trachomatous process itself i. e. a true trachoma of the conjunctival layer of the cornea and not a secondary effect. In such cases the thickening is much greater than when it is due to mechanical irritation by trichiasis or the rough cicatricial conjunctiva (see also page 291).
The denser forms of pannus have been called pannus crassus the thinner, pannus tenuis. In pannus tennis the blood vessels are confined to the superficial layers, and there is not much infiltration or thickening of the epithelial layer; but in the denser form the infiltration may involve the deeper layers of the substantia propria (Fig. 204). The entire surface of the cornea may be covered, and the thickening so dense that the iris can DO longer be distin In the lighter forms only a part of the cornea may be involved, and in that case it is usually the upper portion.
It is seldom that a case of pannus runs its course without more or less loss of tissue, or ulceration. Occasionally, however, the pathological condition is one only of hypernutrition, characterized by the formation of new bloodvessels and connective tissue, and if there is no destruction of the substantia propria, the process may end with a complete absorption of the foreign material, leaving the cornea quite clear.
Treatment. As the condition is usually secondary to some other pathological process trachoma, trichiasis, etc. the treatment must be mainly directed against these affections. The existence of a pannus is no bar to the prompt and energetic treatment of these conditions; on the contrary, it improves pari passu with the amelioration of the original cause. Atropin, with cocain sometimes added (atrop. sulph. cocain. mur., aa. gr. iv ,3j), and hot applications are the remedies proper to the relief of the symptoms of pain and photophobia, of which the corneal trouble is the immediate cause.
When the vascularization and opacity persist in any degree after the removal of the original cause, remedial measures addressed to the condition itself become necessary. These consist in diminishing, or in some manner cutting off, the blood supply to the newly formed tissue in the cornea or assisting in its absorption by the natural processes. The former may be accomplished directly by dissecting a narrow band of conjunctival tissue, 2 mm. wide, from around the base of the cornea (peritomy), or, as has been suggested, by cauterizing the tissues deeply with the actual or galvano.
The production of a violent inflammation of the conjunctiva by means of an infusion of or the powder of the jequirity bean had at one time quite a vogue in the treatment of pannus, but some unfortunate cases of total destruction of the cornea from its excessive action have caused it to fall into disuse except among a very few surgeons. The same may be said of inoculations with gonorrheal matter, which at one time were used, particularly in Belgium.
Curetting the surface of the cornea, especially in the earlier stages and before entropion or trichiasis has set in, can be practised with great benefit. For the less serious cases the ointment of the yellow amorphous oxid of mercury (gr. j 3ij), rubbed under the lids once or twice a day, assists in the process of absorption. For the same purpose insufflation of finelypowdered calomel is a remedy of old and established value.
Resorption or Transparent 'Ulcer of the Cornea. A loss of tissue on the corneal surface, usually not very deep nor extensive, and not associated with any opacity of the corneal substance, is known as a "resorption ulcer."
The distinguishing characteristics are its transparency and the smoothness of its surface, which is covered bv normal epithelium.
The usual seat of the ulcer is near the center of the cornea. There is commonly but little lachrymation or photophobia, and there is scarcely any increased vascularization of the conjunctiva. An ulcer of this character is most common among the old and enfeebled, and is usually slow in healing. A slight traumatism is most probably the originating cause.
The ulcer usually heals without other interference than protection with atropin and hot applications when the subjective symptoms are more pronounced than usual. In the chronic cases eserin has been found useful. The lesion may become converted into a true ulcer, with a tendency to spread through necrosis of the tissue.
When situated over the pupil a transparent ulcer gives rise to great disturbance of vision, quite as much so as an opacity of the same size, on account of the diffraction and diffusion of light through its irregular surface.
Herpes Cornea (Vesicular keratitis). In those cases of herpes frontalis where the nasal twig of the fifth pair is affected and a vesicle is formed along the side of the nose, it is rare to have the cornea unaffected.
A vesicle containing a clear fluid form on the surface of the cornea, ruptures early, and leaves a superficial ulcer or epithelial denudation, with infiltration and opacity of the surrounding parts. It is accompanied with much pain of a neuralgic character, photophobia, and lachrymation. Occasionally, however, these violent symptoms are absent. The cornea itself is usually more or less anesthetic to touch, and the tension of the eyeball is diminished.
The vesicle differs from a phlyctenule of scrofulous conjunctivitis, with which it is sometimes confounded on account of the name herpes conjunctiva by which the latter was formerly known, in that it is larger and its contents are fluid. Some opacity of the cornea nearly always remains (see also page 287).
Treatment. The treatment is palliative atropin alone or combined with cocain, hot applications, and an anodyne internally when the pain is exhausting. The general condition usually requires tonics and a sustaining nourishment. The author has found the salicylate of sodium in large doses useful in controlling pain and mitigating the severity of the disease. It has been suggested to scrape the ulcers and cauterize them, but unless they show a marked tendency to spread this course is not advisable.
Vesicles on the cornea have sometimes been found associated with herpes labialis or nasalis, especially in children, to which the name herpes febrilis has been given. The symptonis exhibit less intensity than those just described; there is little or no anesthesia of the cornea, and the globe tension is Dot changed. These vesicles have been seen during malarial fevers. They all, however, seem to depend on some derangement of the central nervous system.
Dendritic Keratitis. This name has been given to a species of superficial keratitis of a peculiar arborescent form (Fig. 205).
It begins as a small vesicle, and continues its growth by a series of newly formed contiguous vesicles which break down into small ulcers, forming irregular lines which give the distinctive name to the disease (Galenga, Horner)
Etiology. Some authors regard the affection as mycotic, and no doubt micro organisms are found in it, but none that are peculiar to it. It has been found associated with malaria (Kipp and others), and syphilis has been assigned as a cause by some writers. It seems most probable that the disease is the expression of a dyscrasia of some kind.
The ulceration occupies by preference the central portion of the cornea. The course of the disease is usually slow, and though, for the most part, not very annoying, is occasionally very painful and associated with severe supraorbital neuralgia and tenderness, depending on the depth of the ulceration and the amount of involvement of the terminal filaments of the nerves.
Treatment. This consists in rest, protective spectacles, atropin, and hot applications. Should there be a marked tendency to spread or obstinacy in healing under the above treatment, the ulcer should be scraped and I: 60 formalin solutions applied, or in severe cases the actual cautery. Quinin and arsenic internally are useful. Galvanism along the supraorbital nerve has been suggested.
Filamentous Keratitis. On rare' occasions, after rupture of corneal vesicles, a rope like body is seen attached to the surface of the ulcer, its free end being frayed (Fig. 206). This is the filamentous keratitis of Leber and Nuel. It consists of epithelial cells and coagulated fibrin twisted into the form of a cord.
Superficial Punctate Keratitis. Under the bead of superficial keratitis must also be admitted a form of corneal inflammation called by Fuchs keratitis punctata superficialis (Syns.: Keratitis subepithelialis centralis; Keratitis maculosa; Noduli cornea; Relapsing herpes cornea).
The alterations in the cornea consist of small gray dots arranged in groups or short rows in the superficial layers, mostly near the center. The disease begins with a rather pronounced catarrhal conjunctivitis, and is usually associated with catarrhal disease of the respiratory tract. The dots remain sometimes for weeks. Stellwag has described a similar affection, the foci of larger size being found in the periphery of the cornea. There is much pain, and iritis may develop (nummular keratitis).
Treatment. Hot applications, atropin, and protection of the eye with dark glasses.
Fascicular Keratitis (Keratitis in Bandelette). This affection, which bears a resemblance to the phlyetenular form of keratitis, and of which it may be a modified form, is characterized by a band or leash of vessels, with a narrow border of opaque corneal tissue, which traverses the surface of the cornea to end near the center in a small round whitish yellow head (Fig. 207).
On disappearance of the vessels a more or less opaque band or Streak is usually left on the cornea. More than one of these bands may appear at the same time or develop consecutively. The treatment is the same as that suited to keratitis in general.
Bullous Keratitis. In eyes whose nutrition has been seriously interfered with, as it is likely to be in glaucoma, irido cyclitis, or choroiditis, an extensive elevation of the epithelium is sometimes observed at or near the center of the cornea. The bleb, thus formed, is usually partially filled with a clear fluid which gravitates to the bottom, giving it a baggy appearance. The same phenomenon has also been observed a few times in eyes that are not thus disorganized. There is slight pericorneal injection, but the pain is usually quite severe and of a more or less intermittent character. The anterior layers of the cornea are seldom exempt from implication.
The disease seems to be purely local in character, not depending upon the, general condition, as does, for instance, vesicular keratitis.
A recurrent form following injuries has been noted by Hansen Grut.
Fuchs and some others seem to think that the elevation of the epithelium is due to an obstruction in the lymph circulation.
Treatment. The disease is to be treated by instillations of atropin, except where glaucoma is present or feared when eserin (I/2 to 1/4 gr. 3j) can be used instead, and by hot applications for the mitigation of pain, with an opiate or other anodyne if it does not yield to these mild measures. Should an ulcer form with a tendency to spread, it can be touched with formalin, I: 60, or with the actual cauterv. In the milder forms insufflations of iodoform act with good effect on the ulcer and the pain. Cocain can be used in mode A protective bandage is usually beneficial.
Suppurative Inflammations of the Cornea or Suppurative Kera inflammations of the cornea form the most important Category of its diseases, because of their immediate and remote dangers.
Suppuration of the corneal tissue is always followed by ulceration or destruction of the substance, leaving invariably an opaque cicatrix as a sequel, thus annulling one of its most necessary qualities its transparency.
These inflammations may Dot only eventuate in a total destruction of the cornea itself, but on occasion lead to an involvement of the whole eyeball, ending in its disorganization. They demand our most earnest attention, Moreover, from the fact that they are truly infectious in their nature, and are, thus far, to be classed among the preventable diseases.
Etiology and Pathology. We know, since the great work of Leber,' that for the genuine infecting process we must have a micro organism, and that usually it is introduced from without. For this reason these infectious affections of the cornea are common among those working out of doors and in the dust, as laborers, harvesters, etc. But not only must we have the organism, but also the soil made ready for the seed, and the tissue must be in a con to serve as a proper nidus for the growth and development of the particular micro organism present.
Few organisms are able to obtain a foothold upon a perfectly healthy tissue, with the power to throw out white blood corpuscles to act as phagocytes. The wounded normal corneal tissue always heals without suppuration when free from any infecting organism. The epithelium of the cornea, when intact, interposes an almost insuperable barrier to the entrance of germs, and when we find an infection we may be almost certain that a destruction of epithelium has preceded it. The important practical lesson to be learned from this is, that with proper precaution and early attention many, if not most, of these destructive suppurations can be avoided.
All injuries and wounds to the cornea should be promptly treated by disinfection, or at least by thorough and frequent cleansing with an aseptic liquid, as boric acid or mild bichlorid or weak formalin solutions. Bandaging the eye closely tinder these conditions is of doubtful wisdom. The heat of the bandage hastens the development of what germs may yet remain in the conjunctival sac or on the lid margins. An absolute disin of these parts has not yet been found possible by any safe procedure.
For clinical purposes suppurative diseases of the cornea can be considered under several heads, based on their etiology, course, particular complications, and special features ; but the general characteristics are the same in all, and all begin in essentially the same manner.
There is first noted at the place of infection an infiltration of a pearlygray color which rapidly turns to a creamy yellow. This infiltration spreads to a greater or less extent, remaining circumscribed only in a genuine" abscess." In the eroding or serpiginous forms this extension is sometimes very rapid. On the other hand, it may be slow, but steady in its progress. The part of the cornea affected loses its vitality, sloughs off, and an ulcer is formed. This destructive action of the micro organism is arrested, it is claimed, by the phagocytic power of the white blood corpuscles. A limit is thus set to the invasion of sound tissue, and the healing begins by the re forniation of epithelium at the edge of the ulcer. The process of reparation goes on, when the loss of tissue is not extensive, to a complete restoration Of the original form, but usually with a substance not of the nature of the true corneal tissue. It is cicatricial in character, and not transparent, except perhaps in those cases where the destruction is very limited in extent. The membrane of Bowman is never re formed when it is once destroyed, but the epithelium is very readily re established. While the pathological processes in all cases of suppuration are essentially those just recited, for the purposes of clinical study and treatment they have been classified tinder several distinct varieties.
Abscess of the Cornea. This is a simple circumscribed collection of pus in the corneal substance, usually some distance from the scleral edges.
It is most commonly seen as a sequel or continuation of a phlyetenule on the surface, the throwing off of the epithelium opening lip the way to an infection of the deeper parts. The subjective symptoms are the same as in other forms of keratitis. It terminates by a breaking down of its anterior wall and a discharge of its contents, becoming thereby an open ulcer, which under favorable circumstances heals in a few days, and, if' the loss of tissue is not great, leaving little opacity. It may be induced by any other means that destroy the epithelial laver, such as small wounds, foreign bodies, etc. The so called ring abscess, where the suppuration extends around the base of the cornea, is seen mostly after cataract operations.
Treatment. The proper treatment is hot applications, atropin solution (gr. iv 3j), a drop three times a day, with rest and protection of the eyes. A spontaneous rupture is usually allowed. When the ulcer is formed its healing is expedited by aseptic applications of weak formalin solution, 1 : 2000, or boric acid solution, or other means to be mentioned in succeeding paragraphs.
Ulceration of the cornea, or destruction of the corneal substance, is the essential feature of all forms of suppurative keratitis.
Varieties. The forms of corneal ulceration, from a clinical standpoint, depend upon its seat, its cause, its course, and its association with other pathological conditions. Thus we have the sthenic and asthenic ulceration, according as the accompanying vascularization and other symptoms of irritation are considerable or mild; marginal ulceration, when it is seated near the margin of the cornea; serpiginous ulceration, when it creeps over the surface of the cornea, invading successively the adjoining areas; keratitis with hypopyon, when associated with the presence of pus in the anterior chamber; and other distinctive titles. Moreover, all these varieties, or any number of them, may be only different or successive phases of the same attack. In all, the essential clinical features are the same, modified, however, by the particular circumstances of individual cases.
Under this head may be mentioned a rare form of chronic creeping ulcer, which begins near the margin of the cornea and progresses in a crescentic form without any pronounced suppuration or hypopyon, never leading to perforation, but followed by dense cicatricial opacities. To this the name rodent ulcer has been given.
A form of spreading keratitis is observed very often in those engaged in shucking oysters the so called ogster shucker's keratitis. It was thought to be a purely infectious disease until Randolph of Baltimore demonstrated that it was not, but a mechanical keratitis caused by the fine particles of lime of the oyster shell. The harvester's keratitis is probably first mechanical and afterward microbic
Etiology. The immediate causes of destructive ulcers of the cornea are usually infecting wounds or injuries of some kind, including operations, such as cataract extraction, iridectomy, and other operations involving the cornea. Anything that destroys the epithelium opens tip the way to the entrance of infecting microorganisms. These germs may be introduced at the time of injury or they may enter later. Two factors are necessary for development of the process the germ and the soil. As there are always germs in the conjunctival sac, or as they can easily get entrance there, some of which may be pyogenic, any injury of the cornea is liable to take on an ulcerative action if the tissue is in a condition of non resistance, as, for instance, in the case of weak, poorly nourished people. The progress of the ulceration may be very brief, the reparative process setting in in a few days, or it may continue for weeks without showing any tendency to heal or may extend itself slowly, but persistently, into the sound tissue.
The germs most commonly found as the active agents primary in corneal ulcerations are the usual pyogenic form s principally staphylococcus and streptococcus (see Figs. 192 and 197) but UhthoiT,, Axenfeld, and others have recentlv (1896) found the pneumococcus in great abun ance in serpent ulcers (Plate 2, Fig. IV.), and Leber has found a form of aspergillus in some cases. Probably the most frequent cause of large destruction of the cornea is the gonococcus of Neisser found in purulent ophthalmia of gonorrheal origin (see article on the Conjunctiva).
Symptoms and Course. An ulcer begins with a focus of infection, noticeable as a superficial defect with ragged edges of a yellow color and surrounded by a zone of infiltrated cornea. Its sides and bottom are covered by a detritus of dead corneal tissue, having a yellow pultaceous appearance. The accompanying vascularization of the conjunctiva varies greatly. In some instances it is pronounced, the swelling of the tissue around the base of the cornea in the vicinity of the ulcer being very marked.
There are at times great photophobia and much lachrymation and pain, which, however, in the indolent forms may be lacking almost entirely.
In the serpiginous form the ulceration spreads gradually over the surface, and usually with increasing depth. Then some time during its course there is an appearance of pus in the bottom of the anterior chamber hypopyon (Fig. 208). This may occur while the ulcer is still central and there is yet clear cornea between it and the scleral margin. It was held at one time that it was necessary to have a perforation of' the posterior wall of the ulcer through the membrane of Descemet in order that pus might find its way into the anterior chamber. The researches of Leber have shown, however, that the pus cells may gravitate down through the sound corneal tissue and pass into the anterior chamber at the iris angle, or they may originate at this point from a participation of the uveal tract in the inflammatory process. In certain cases no doubt there is a small perforation of Descemet’s membrane.
The destruction of tissue may be very extensive, covering the entire anterior surface, leaving the posterior layers and the membrane of Descemet intact; in which case there will be no perforation. In most cases, however, this is the event, and we have as a consequence a new set of phenomena and complications.
With the opening of the anterior chamber the aqueous humor escapes; the iris falls forward against the posterior wall of the cornea, plugs up the opening, and in course of time may become united to it by adhesive inflammation (anterior synechia). The anterior chamber then refills, leaving this portion of the iris in front of the mass of aqueous humor. If the opening is large enough, the pressure from behind is sufficient to push the iris through the opening and form a bag of greater or less size in the site of the ulcer, We then have perforation with. prolapse of the iris.
It may happen that the pyogenic germs entering the anterior chamber find a suitable nidus for their development in the iris, ciliarv body, and choroid, and, setting up a purulent inflammation in these tissues, bring about the condition of panophthalmitis, leading to final atrophy of the eyeball. There is no case of hypopyon probably in which the iris is not more or less affected.
Prognosis. From what has been said it may be inferred that the prognosis depends upon the activity of the morbific agent and the ability of the tissues to resist its encroachment. In the old and feeble it is much more serious than in the young and strong.
Treatment. Suppurative keratitis being an infection. , disease, the treatment should be both preventive and therapeutic. Every injury of the cornea should be considered as if it were infected. The conjunctival sac should be thoroughly cleansed with an aseptic liquid, as a saturated boric acid solution or formalin 1 : 2000, and kept as aseptic as possible. The seat of injury itself should be touched with a 1 : 60 formalin solution, or nitrate of silver (gr. xx ,3J), or tincture of iodin, when there is strong suspicion of infection, and, where it is reasonably certain, with the actual cautery. The treatment of the ulcer when it has declared itself should be antiseptic and palliative. The surface of the ulcer should be touched with a I : 60 formalin solution once a day so long as there seems to be any tendency to spread. Formerly the author was accustomed to use full strength carbolic acid for this purpose with good effect. A mule recommends iodoform applied on a wafer of gelatin directly to the ulcer, bandaging the eye to keep it in place. The iodoform may be dusted directly on the ulcer, but this is less efficacious. When the serpiginous character becomes pronounced, the actual cautery applied to the edges and bottom of the ulcer becomes necessary. This must be done under cocain. It is well to scrape away as much dead tissue as possible with a sharp spoon before applying either the cautery or the formalin caustic solution. Tincture of iodin and nitrate of silver (gr. xx f.3J) are also applied to tile curetted area. The cauterization may be repeated every two or three days, according to the urgency of the symptoms. Curetting of the ulcer while a fine spray of a 2 per cent., solution of boric acid is directed against its surface ha., been recommended. Samisch recommended an incision into the anterior chamber through the sides and bottom of the ulcer in the serpiginous form, and this operation is still performed by many surgeons. Its performance before a hypopyon is formed is in the majority of cases not advisable, since it makes easy the entrance of germs into the interior of the eye. In cases of hypopyon this objection does not hold to the same extent. It is often necessary to let out the pus when present in large quantity, and in these cases the incision should be made as low down as possible (see also p. 567).
Quite recently the subconjunctival injections of bieblorid of mercury have had many advocates. A few drops of I : 2000 solution are injected under the conjunctiva once a day or every other day. The operation is generally very painful, even under cocain.
Others have found the injection of a normal salt solution quite as effective. As palliatives atropin and cocain are the main reliance. The latter should be used only for the temporary relief of pain and the lowering of intraocular tension. Eserin in weak solution (I/2 to I02 gr. ad 3J) is used for the same purpose if iritis is not a complication.
As a palliative and curative agent beat is most valuable. As tile morbific process is to be stopped, or at least retarded, by the phagocytic action of the white blood corpuscles, a determination of fresh blood to the part, with dilatation of the vessels, is all important. Heat accomplishes this, and the best form of application is fomentation with water as hot as it can be borne for five minutes every three or four hours. The immersion of the eye in a goblet or glass of hot water, as recommended by Leartus Conner of Detroit, is an elegant and most efficient way of administering heat.
The eye should not be bandaged, except when the ulcer is very deep and there is danger of spontaneous rupture, under which circumstances the dry antiseptic pressure bandage is effective.
In cases of perforation the management is little different, except as to the treatment of the prolapse of the iris. When the prolapse is not large and is situated peripherally, and does Dot involve the sphincter, eserin should be substituted for atropin. Its myotic action tends to draw the iris out of the wound, and often quite successfully. If the condition of the conjunctiva warrants it, a pressure bandage aids in reducing a hernia of the iris. The prolapsed iris should Dot be excised or punctured, certainly not until the sup process has ended, and then only under strictest asepsis. Even very large prolapses smoothe down in time.
Careful attention must be paid to the general condition of the patient, particularly in the old and feeble. Tonics, and even stimulants, with the most nutritious diet, are indicated.
There are two forms of secondary purulent keratitis which require a brief separate mention:
(1) Ulcerations following Purulent Conjunctivitis. Under these circumstances the two most potent factors are united in the development of the disease in its most destructive form namely, the presence of an infecting germ and a denuded and macerated condition of the epithelium, with diminished nutrition of the cornea from the pressure of the chemosis on the surrounding nutritive vessels. The ulceration usually begins at the periphery of the cornea under a fold of overlapping chemosis. Quite often, however, it commences near the center, and occasionally there is a necrosis of the whole cornea at, once from the cutting off of its nutritive supply by pressure a true sphacelus cornea when the entire tissue becomes yellow and breaks down into a pul mass. The presence of the corneal ulcer, however great its extent, is not a bar to the most energetic treatment of the conjunctival disease (see also page 279). The ulceration is apt to be deeper than in other forms, especially at the periphery, and there is an earlier prolapse of the iris. Often the whole iris seems to bulge forward either as a mass keratocele or through numerous perforations in the apparently clear cornea the so called mulberry appear the eye seems doomed to destruction. There is, however, in manv of these cases quite a quantity of sound corneal tissue remaining. The membrane of Descemet resists destruction far a long while, and eyes that seemed lost regain their form and some part of their function.
In cases of peripheral perforation eserin is to be used, while in other forms atropin and antisepsis, with hot applications, should constitute the main local treatment.
(2) Neuro paralytic Keratitis. The other form of secondary keratitis is that associated with paralysis of the fifth pair of cranial nerves, the so called neuro paralytic keratitis. When the fifth nerve, particularly the part containing fibers of the sympathetic, is divided in animals, in a short time the cornea on that side begins to ulcerate, and soon passes on to total destruction. The same thing is likely to occur in man when the fifth nerve is from any cause paralyzed, and particularly when the branch of the seventh going to the orbicularis is at the same time involved.
It has been a point in dispute whether the ulceration is due to interference with nutrition from injury to the trophic filaments in the fifth pair, or is simply the result of the traumatic injuries inflicted on the insensitive cornea on ac~ount of its constant exposure from the paralysis of the orbicularis. It would seem from a careful sifting of the evidence that both factors play a part. Injury to the trophic nerves seriously impairs the resisting power of the corneal tissue, and, it may be in some instances, is of itself sufficient to bring about destructive inflammation, independent of serious injury, for we see the ulceration sometimes when the orbicularis is intact. On the other band, we have paralysis of the orbicularis without corneal ulceration.
The process usually begins as a marginal ulcer, with deep injection of the conjunctiva, and spreads gradually over the whole cornea, the tissue breaking down into a soft yellow mass. On occasion the process seems to arrest itself, and a small amount of clear cornea is left. It is usually painless, and not accompanied by photophobia or lachrymation.
The course is slow and prognosis serious, a total destruction of the cornea being the result to be expected.
Treatment is wholly palliative, protection of the eyes by bandage or stitching the lids and cleanliness being the main features in the therapeutics. Tonics and a nutritious diet are nearly always demanded.
After removal of the Gasserian ganglion Dr. W. W. Keen and Dr. de Schweinitz recommend primarily stitching of the lids, and when the first dressing is made the application of a Buller's shield, which remains for a week or more. With these precautions they have prevented corneal ulcer after complete excision of the ganglion. Destructive ulceration of the cornea is the result most to be feared in diphtheria of the conjunctiva (page 284).
Keratitis e Iagophthalmo. When the cornea is continuously exposed from any cause its epithelium desiccates and falls off, and there is a liability to the entrance of germs with an infective keratitis as a result.
The affection has been observed in excessive exophthalmos, destruction of, or cicatricial contraction of the eyelids, paralysis of the orbicularis, etc.
The keratitis pursues practically the same course as neuro paralytic Ophthalmia, though not usually with the same rapidity or malignancy, and responds more promptly to treatment.
Treatment. This consists in removing the cause when possible, and usually by some operation on the lids. In case this cannot be done a protective bandage must be constantly used. In the slighter forms of lag the bandage should always be applied at night, and all such eyes should be protected against dust, wind, smoke, and other irritating influences. The treatment of the keratitis itself is the same as that indicated for keratitis in general.
Corneal Ulcers in Small pox. In the days prior to vaccination destruction of the cornea from smallpox was one of the most common forms of blindness. Happily, it is not often encountered now.
True vaccinal abscess differs from ordinary abscess in that it is generally endogenous, being simply the appearance of a variolous pustule on the cornea itself. That it may be due to secondary infection is, however, possible, especially if the cornea becomes involved after the stage of eruption is passed.
The treatment is the same as that for other forms of purulent keratitis.
Keratomalacia. Tbis is a form of destructive corneal trouble met with mostly in badly nourished infants and children, though adults with vital powers greatly reduced by lack of proper food are also liable to be attacked. It is seen accompanying meningitis, variola, measles, and severe diarrhea or dysentery.
Symptoms. It is always associated with xerosis of the conjunctiva (page 296). There is great dryness of the conjunctiva, which is covered in spots with a froth like material that is found upon examination to consist of fatty matter and epithelial cells. The lachrymal secretion is deficient or entirely lacking. The cornea becomes dry and cloudy from a drying of its epithelium, and soon shows evidences of breaking down at the center. This disintegration is of the color of pus, and sometimes extends very rapidly, destroying the cornea in the course of a few hours. Sometimes, however, it requires several days to accomplish this. It may even happen in mild cases that the whole tissue is not destroyed. There is, in those who are old enough to express themselves, a pronounced night blindness at the beginning Of the affection. This, as well as the other characteristic symptoms, gives evidence of a lack of nutrition at the nerve centers.
Microbes of various kinds have been found in the secretions, but they are probably not the essential cause of the disease, but only find in it a nidus for growth. The one most frequently found is a small bacillus, the so called pseudo diphtheria bacillus, and is often present in large numbers.
The prognosis is most unfavorable; the patients frequently succumb to the disease which has caused the keratitis or to an intercurrent pneumonia.
Treatment. The first object in treatment is to improve the nutrition as rapidly as possible by the most nourishing foods, tonics, etc. The eye itself should be treated with hot fomentations, mild aseptic washes. Caustics are seldom called for. On account of the insensitiveness of the eyes and the tendency of the lids to remain open, a bandage is necessary for protection.
Tuberculosis of the Cornea. Primary tuberculosis of the cornea is a rare affection. The cornea, however, usually participates more or less in the conjunctival form of that affection (page 302).
Symptoms. In the few cases that have been reported it has begun as an interstitial opacification, commencing at the edge and progressing toward the center of the cornea. In this affected area there are to be seen small yellowish white granules like miliary tubercles, which coalesce and finally break down, and are thrown off, leaving an ulcer usually without hypopyon. A bacteriological examination or experimental inoculation will usually demonstrate the character of the disease.
The treatment is the same as that for other ulcers ' only demanding an early scraping or destruction by caustics of the affected tissues.
Interstitial or Parenchymatous Keratitis (Syphilitic, Inherited, Specific, Diffuse Interstitial K eratitiN). In contradistinction to the destructive forms of corneal inflammation we have been considering, this form does not lead, as a rule, to a loss of corneal tissue. Moreover, it is always the manifestation of a systemic derangement, and usually some form of dyscrasia, hereditary syphilis being the most common. Its association with acquired syphilis is uncommon, nor does scrofula usually manifest itself by this form of corneal inflammation.
Etiology. We owe to Hutchinson the discovery of the intimate connection of keratitis parenchymatosa with inherited syphilis. The ground taken by him nearly forty years ago is still maintained by a large part of the ablest chnicians.
Still, it may be questioned whether all cases of interstitial keratitis are syphilitic. Von Hipper has found the disease very frequent in people of a tuberculous taint with no history of inherited syphilis. Of 87 cases, 23 were syphilitic and 15 doubtful; 18 tuberculous and 8 doubtful other cases uncertain. Parinaud found 96 per cent. of his cases syphilitic; Despagnet, 14 per cent.; Scklassy, 30 per cent.; Bosse, 44 cases in 54.
The syphilitic cases are generally marked by definite and peculiar features. As regards the mother, there are rarely absent histories of abortions or early death of other children, and those now living show more or less evidence of being affected.
Probably the most characteristic appearance is on the part of the permanent teeth. The central upper incisors have notched edges and are peg shaped, the so called " Hutchinson's teeth." This shape is due to defective nutrition and the breaking away of the enamel. There are often nodosities on the tibia, and the frontal tuberosities are unusually prominent. There are often deep scars around the angles of the mouth and the alae nasi. It is usual to describe the skin as being coarse, but the author's observation is that it is commonly unusually fine and velvety in texture. This is particularly noticeable in the negro race. A less common accompaniment is that of deafness. Synovitis of the knee joint may be a complication, and there are likely to be' other evidences of faulty nutrition. The disease is commonest between the ages of five and fifteen, occurring occasionally as early as the third year and rarely as late as the sixtieth year. A congenital form has been described. In female children it is apt to appear about the supervention of menstruation.
Cases occurring in persons above thirty years of age are not, as a rule, due to syphilis, but to some other dyscrasia, as rheumatism, gout, and possibly tuberculosis, or the climacteric.
Symptoms. The disease begins as a grayish opacity in the substance of the cornea, sometimes at more than one place, and gradually extends in typical cases until the whole of the tissue is involved. This opacity is so dense in fully developed cases as to entirely veil the iris from view, and is generally quite uniform, though a close inspection will reveal foci of more intense filtration.
At the beginning the epithelium is intact and the surface of the cornea has its normal glistening look, but later it becomes rough like ground glass, showing a disturbance in the arrangement of its epithelial cells.
In a form to which the name circumscript or discrete has been given there may be several spots at some distance from each other and apparently unconnected. An examination with oblique illumination and a magnifier, however, will nearly always show some fine streaks of opacity connecting them.
In this discrete form, which is more frequently found in the rheumatic diathesis and in women about the climacteric, there is nearly always a permanent opacity remaining after the disease has subsided, more especially when the spots are near the scleral border (Fig. 211).
During the very early stage of the infiltration there is no great increase in the vascularization of the conjunctiva, nor are pbotopbobia and lachrymation very pronounced.
The second stage, that of vascularization, is almost always attended with symptoms of irritation. This vascularization of the infiltration is the nat¬process for its absorption. Its manner of invasion is characteristic and distinctive. The vessels, which are very fine and delicate, are seen to penetrate deeply into the substance of the cornea at its periphery. On account of their fineness and compactness they seem, as seen through the hazy corneal tissue, almost like an extrava of blood into its substancethe 11 salmon patch " of Hutchinson.
The vascularization usually advances pari pass it with the progress of the infiltration across the cornea, and that is usually from above downward, so that by the time the infiltration reaches the opposite side the cornea looks like a piece of raw beef the vascular keratitis of some writers. This may have required weeks or even months, for tediousness is a prime characteristic of the affection (Fig. 210).
The accompanying symptoms may be mild, giving rise to but little pain. In most cases, however, there are considerable pain of a neuralgic character and lachrymation, and there are generally indications of the involvement of the uveal tract. In fact, few cases run their course without an implication of the iris, ciliary body, or choroid, or all three. Stellwag designated the disease as "anterior uveitis." We must remember that the cornea is connected directly with the uveal tract through the endothelial laver of Descemet's membrane. Unfortunately, the condition of the cornea does not allow us to examine carefully into the state of the iris, but after the opacity has cleared up we are apt to find evidence of iritis. Retinitis and optic neuritis may occur, and secondary glaucoma is not uncommon.
All cases, however, do not run such a typical course. A part of the cornea may be attacked, vascularize , and clear up, and then another and another, until the whole tissue has been successively affected. The process may occasionally stop after an attack on a limited portion. A number of cases of an atypical form which are not properly forms of interstitial keratitis, have been reported in which the opacities are stripe like or ring like. These present the appearance of pus in the corneal layers, the so called abscess forms, or they may appear as a central annular lesion. On rare occasions ulceration and hypopyon are accompanying conditions, but should be regarded as incidental complications.
Prognosis. The course of the disease is invariably slow, and, as the eyes are liable to be affected in succession and the same eye experience more than one attack, manv months or even years may not see the end. And yet the prognosis quoad visum is generally good, and particularly is this so when the uveal tract is not seriously involved. In manv cases the cornea clears up almost perfectly, though an examination with oblique illumination and corneal loup will reveal some faint streaks of opacity ; indeed, years after an attack of interstitial keratitis minute vessel channels, nearly straight, branching at acute angles and short bends, may be detected in the cornea. These are best studied with the ophthalmoscope, after dilating the pupil, through a strong convex glass (+ 16 D.) (Fig. 213). The process of resolution always begins at the periphery of the cornea.
Treatment. The disease is essentially self limited, and we can do but little to shorten its course. Yet we are not without resource for the alleviation of its uncomfortable symptoms and measures to encourage a favorable issue of the disease. As resolution takes place through vascularization, means which increase this are in order, and chief among them are hot applications. The eye should be bathed in water as hot as can be borne for five minutes every four hours. This also assists in relieving any pain that may be present. Atropin, 1 per cent. solution, dropped in the eye three times a day is beneficial, not only for the corneal affection, but also for the iritis which may be present. When the long continued use of atropin sets up a papillary inflammation of the conjunctiva which it may do on very rare occasions hyoscyamin, scopolamin, or daturin may be substituted for it. Being a diathetic dis general treatment is all important, especially iron, arsenic, and cod liver oil. Tonics and good nourishment are called for in cases of debility, while rheumatism and gout and tuberculosis require their appropriate treatment. In those cases where hereditary syphilis is evident or suspected, specific treatment is demanded, but not of a vigorous kind. The simplest form of administration is bichlorid of mercury gr. 1 and iodid of potassium gr. ij, after each meal. These remedies are well borne for many months. Inunctions of mercury are not usually called for except in very severe and well pronounced cases. In the practice of some surgeons they constitute the basis of treatment in the majority of cases. The patient should be encouraged to go out of doors as much as possible, protecting the eyes with blue or gray glasses. Recently subconjunctival injection of bichlorid of mercury have been advocated quite strongly in certain quarters, as have those of normal salt solution, used in the same manner. The severe pain which has been found to accom their employment is a great bar to their general use.
Results of Corneal Inflammation. Opacities of the Cornea. The outcome of an inflammation of the cornea as regards its restitutio ad integrum of transparency depends largely upon whether it is of the destructive form or not. A pannus or interstitial keratitis can continue for months or even years, and yet the cornea clear up almost perfectly, provided there has been no loss of substance replaced by cicatricial tissue. But even in the interstitial form there can be an organization of the effused material, taking on the character of connective tissue, which does not become transparent. Indeed, in the most favorable cases there are always fine streaks of opacity to be discovered by oblique illumination and the magnifier (see page 146).
Where there has been any considerable loss of tissue the rule is for an opacity to remain, the cicatricial material which replaces the lost corneal tissue never becoming transparent. The presence or activity of the corneal epithelium seems to exercise a favorable influence on the reproduction of the clear corneal substance. The clearing up of the opacity proceeds from the periphery toward the center.
Opacities have always been classified, according to their intensities, into nebule or macula, the slighter forms, and leukomata, the denser forms. When after a perforation of the cornea there is prolapse of the iris, with adhesion to the wound, we have the condition known as adherent leukoma.
The amount of damage to perfect vision caused by an opacity depends largely upon its situation, and to some extent upon its density. A small, sharply defined, dense opacity over the pupil, however, will disturb vision less than a thinner one, which allows a greater amount of light to go through, but diffuses it more.
The course and final condition of a corneal opacity depend largely upon the age of the patient and the depth of the destructive process. In young people the chances of a clearing up are much better than in elderly ones, and the smaller and more superficial the ulcer the greater the probability of an ultimate clarification.
Treatment. The treatment of corneal opacities is directed to an assistance in the absorption of the effused material. This requires usually some means which increases temporarily the vascularization of the part and stimulates the absorbents. Insufflation of finely powdered calomel once a day is an old remedy. Another form of mercury much used is the yellow amorphous oxide gr. j ad 3j of cosmolin " Pagensteeher's ointment " a small bit to be rubbed under the lids once a day or every other day (massage of the cornea). Turpentine oil moderated with sweet oil has been used for the same purpose. In fact, everything which increases the blood supply of the conjunctiva has been used, and with some show of success. The value of the constant current of electricity applied to the cornea for this purpose has doubtless its basis in the same quality.
The attempt to remove opacities by operation is of course futile, since the removed tissue will be replaced by cicatricial tissue, except in those cases where the trouble is limited to the epithelial layer, as where there are deposits of lime, lead, etc., and in some cases of superficial pannus.
For cases of total leukoma of the cornea or large central opacities covering the pupil, with no room for an artificial pupil at the periphery, transplantation of a portion of the cornea of rabbits or other animals was first suggested by Reissinger in 1824, and revived by von Hippel in 1876. It cannot be said, however, that any brilliant permanent success has followed the attempts made thus far.
In case of leukoma adherens it may be necessary to loosen the iris from its adhesion to the cicatrix for optical purposes, or to free the eye from a source of constant irritation. An iridectomy is often called for when the opacity covers the pupil, even when there is Do incarceration of the iris, for optical purposes.
In permanent opacity the disfiguring appearance can be much mitigated by the process of tattooing the white spot with India ink.
Changes in the Form of the Cornea. While inflammations of the cornea may subside without any change in the form of the cornea, even when a considerable opacity remains, in a large number of cases, and especially in those where there has been a considerable loss of tissue or even long continued infiltration, the original shape is seldom retained, and sometimes the change is enormous. This alteration may be in the manner of flattening or of bulging stophyloma.
(1) Flattening of the cornea most frequently follows upon total destruction or large losses of the corneal tissue, and especially in those cases where the uveal tract has been involved and the nutrition of the eye interfered with, accompanied by reduced tension of the eyeball. The iris is found in such cases plastered against the posterior wall of the remnant of the cornea, some portion of which may still be transparent. The flattening may be of any grade, from that discernible only by means of the ophthalmometer to that associated with a more or less complete atrophy of the eyeball.
(2) Bulging of the Cornea. Staphyloma has various qualifying terms, denoting special characteristics. It may globose, or racemose, the latter name signifying a number of small protrusions linked together around the periphery of the cornea. A general enlargement of the eyeball (hydrophthalmos) (Fig. 214) is very often associated with these conditions and always indicates the participation of the iris and choroid in the inflammatory process. The iris may be attached to it either partially, as in adherent leukoma, or completed, as in some forms of keratoglobus.
All staphylomata indicate an in¬creased tension of the eyeball at some time. The structure of a staphyloma is by no means uniform. Its walls may be thin or very thick, and some the apex undergoes ulceration or degeneration of the calcareous or colloid form; and it is always liable to attacks of inflammation.
Treatment. Tbe therapeutics of staphylomata is preventive and surgical. The former is applicable only during its stage of formation, when a pressure bandage should be applied to support the weak tissue. Paracentesis, sometimes repeated, by lessening the intraocular tension, removes an important factor in its production. Eserin can be used for the same end.
When a staphyloma has become so large as to be unsightly, or is a source of annoyance or pain, surgical interference of some kind is the only remedy: enucleation of the eye, abscission of the staphyloma, or evisceration.
Enucleation should be avoided when possible in children, among whom staphyloma so frequently occurs as a consequence of conjunctivitis neonatorum. The presence of the eyeball seems to be necessary to the proper development of the orbit, and an artificial eye is difficult to adapt to very young children. In cases of excessive bydrophtlialmos the operation of evisceration finds its best field of application. Evisceration, with the introduction of a glass ball within the sclera (Mules's operation), gives an excellent support for an artificial eye (see page 572).
3) Cy8toid Cicatrix. The condition of union between the tissues at the scleral border in some cases of adherent leukoma can be such as to form a circumscribed cystic elevation the walls of which may give way at times, discharging the contents of the aqueous chamber the so called cystoid cicatrix; or the opening may Dot close at all, constituting a fistula, through which the aqueous humor constantly leaks, sometimes under the conjunctiva, causing a chemosis pallida. Similar phenomena may arise after the operation of iridectomy.
These conditions are usually very rebellious to treatment, which is for the most part surgical, consisting in cauterization, the formation of conjunctival flaps over the parts, or cutting away a part, of the walls of the cyst and procuring a firm adhesion between the edges of the wound. An iridectomy sometimes helps much.
(4) Astigmatism. The changes in the form of the cornea are commonly so irregular (irregular astigmatism) that it is not possible to correct tile optical defect by any form of lens in such manner as to improve vision materially. Changes are occasionally so regular, however, as to allow this to be done, and here the ophthalmometer becomes a valuable aid in diagnosis. With the sug afforded by this examination it is often possible to double or treble the visual acuteness (see also page 231).
When the intraocular pressure is reduced to any considerable degree tile cornea feels the diminished tension, and manifests it by an altered curvature, sometimes in the nature of wrinkling. This is very apparent in many forms of atrophy. In cyclitis associated with reduced eye tension it is nearly always demonstrable by the ophthalmometer, or Placido's disk. Fig. 215 gives the corneal reflection of Placido's disk in such a case. The cornea resumed its normal shapes when the tension was restored.
Sclerosing Keratitis. A special form of corneal opacity is associated with long continued scleritis and irido choroiditis. It begins in the former case as a triangular bit of bluish white tint, with its base on the sclera, its apex toward the center of the cornea. The change is interstitial, the epithelium seldom undergoing any alteration. When following long continued inflammation of the uveal tract, with depressed nutrition of the eyes, the opacity sometimes extends as a band wholly or partially around the corneal circumference, as shown in 'Fig. 216, taken from a case under the author's own observation. Baumgartner and Berlin have found that the corneal tissue has undergone fatty and hyalin degeneration with what appears to be in some instances adenoid tissue.
Treatment is of no avail, though the galvano cautery applied to the base of the lesion has been recommended.
Ribbon shaped Keratitis (Primary Transverse Opacity of Cornea; Zonular Opacity; Keratitis Bandelette). This is a rare form of corneal opacity, not due to an inflammation of the cornea itself, but associated with or following some kind of ocular malnutrition, caused by irido eboroiditis, glaucoma, or a gouty tendency.
The lesion is situated directly in the palpebral aperture, where the cornea is most exposed, and consists of finely punctiform opacities under the epithe¬lium of the cornea. It begins sometimes on one side, sometimes on the other, leaving a small area of clear tissue at the periphery, and. progresses steadily toward the pupil, over which the two bands usually meet in time (Fig. 217). Some cases have been observed in which it began in the center. Both cornea are liable to be affected in time. It occurs mostly in men. After the epithelium is removed the deposit can be flaked off, leaving, as a rule, clear cornea beneath. The deposit is either the phosphate or carbonate of lime. Its removal in this manner is the only treatment. Atropin should be avoided in such eyes, on account of their tendency to glaucoma
Striped keratitis. A peculiar form of opacity of the cornea is sometimes noticed after cataract extraction, but has been observed also after other forms of injury or inflammation of the cornea. It consists of fine, straight stripes 1/2 to I mm. in width, focussing toward the seat of in¬jury. The intervening corneal tissue may be comparatively clear, in which case the lines will appear as grayish stripes against the darker back of the iris (Fig. 218). There may be two or more sets of lines crossing each other, making a sort of panel figure (Fig. 219).
They were once thought to be dilated by lymph channels (Becker, Reeklinghausen) or infiltration of the large nerve canals (Alt). They are caused, however, by a folding Of the membrane of Descemet, due to a shrinking of the corneal tissue in cicatrization or its unequal swelling in infiltration. (Mull, Hess, Schirmer) (Fig. 220). They usually disappear, but traces of them may remain in the form of geometrical figures (Fridenberg). The folding of Bowman's membrane may give the same appearance.
Corneal Opacities due to Metallic Deposits. The salts of lead coming in contact with the albumin of the cornea denuded of its epithelium are sublimated in the form of an opaque abuminate. Such deposits were of much more frequent occurrence when lead lotions were used more commonly than now in corneal ulcers. The epithelium usually forms over it. The deposit can be scraped off after the epithelium is removed, leaving usually a moderately clear cornea beneath.
Nitrate of silver also leaves a stain when applied to the substantia propria for a long while. A brilliant metallic luster has also been observed in opacities of the cornea the results of injuries.
Arcus Senilis. An are of opacity 1 to 1.5 mm. in width is very commonly seen at the base of the cornea in old people. It may entirely circle the cornea. There is usually a narrow strip of clear cornea between it and the sclera. It is sometimes met with in comparatively young persons. In the negro race it is usually very pronounced. It is a colloid degeneration of the superficial layers of the cornea. When incised it heals as readily as normal corneal tissue.
Transient Corneal Opacities. Sudden and severe pressure oil the cornea causes a derangement of its fibers which impairs its transparency This is observed in severe blows directly on the cornea and in acute attacks of glaucoma. This disappears in a short time when the pressure is relieved.
Rampoldi (1881) has described a temporary form of opacity due to infiltration of the eorneal tissue with lymph. It occurs in anemic persons or those affected with lymphatism. It may extend to the anterior chamber, forming hypopyon, or into Tenon's capsule. It may be called up or increased by a dependent position of the head.
Cocain causes a dryness and opacity of the epithelium, and even its detachment from Bowman's membrane, when applied too long with exposure of the cornea to air. The corneal epithelium. in old glaucoma is nearly always dull and irregular.
Blood staining of the Cornea. A number of cases have been observed after traumatism in which the cornea has been infiltrated with blood; it is of a chocolate or greenish brown color at the central parts, passing off into a reddish tinge at the periphery. The appearances closely resemble those of an amber colored lens dislocated into the anterior chamber. The hema¬toidin deposited in the substantia propria, which gives this color, is absorbed very slowly, at least two years elapsing before its entire disappearance.
Keratitis Nodosa. When the poisonous spines of certain caterpillars get into the eye, they set up an inflammation which is peculiar in that it is in the form of nodules which very much resemble tubercles. While more commonly found in the conjunctiva, the nodules occur also in the cornea, and pass sometimes into the iris. They never break down and discharge, but in time disappear by absorption (see also page 296).
No attempt should be made to excise the nodes from the cornea. They should he treated as secondary keratitis with heat and atropin.
Keratitis punctata (Aquo casulitis, Descemetitis). Small whitish deposits are observed on the posterior surface of the cornea in that form of iritis known as serous iritis, and have been considered by some authors as a form of iritis or irido eyclitis. As the anterior surface of the iris and tile posterior surface of the cornea are lined by a continuous layer of endothelial cells, converting, in fact, the anterior chamber into a closed or serous sac, there is some ground for this view ; and in these cases, almost without exception both cornea and iris are involved, sometimes, however, one more than the other. In some instances there is a marked plastic iritis accompanying or following the appearance of the dot , in the cornea. Though the dots are usually arranged in a pyramidal shape, base down, they are. often irregularly placed (Fig. 221). The deposits vary in size from a millimeter or so in diameter to a microscopic point. They consist of inflammatory exudate with a quantity of endothelial cells (Fig. 222). Suellen, Jr., is reported to have found a microbe in the deposits, but this observation has not been confirmed by others. The exudate is sometimes found in the iris angle and in the choroid. Oblique illumination and a magnifier are often necessary to determine its presence in the cornea. A general haziness of the cornea or a limited part of it is manifest on illumination of the fundus with the ophthalmoscope. Usually there is no pain, the pupil is commonly somewhat dilated, and the intraocular tension slightly increased. Vision is usually much impaired.
Treatment. Atropin must be avoided unless there is an active plastic iritis. The progress of the disease is usually very slow, months sometimes being required for the disappearance of the deposits. Mild doses of bichlorid of mercury, continued for a long while, seem to be followed by better results than any other therapeutics.
Non inflammatory Changes in the Form of the Cornea. in the form of the cornea from the normal which is really that of a triaxial ellipsoid, but not very markedly departing from that of a sphereare known as astigmatisin. Those changes which influence the optical properties of the eye that can be neutralized are treated of in the chapter on Refraction. These forms usually are congenital, and remain unchanged during life.
There are other forms, however, which appear to be acquired, though Dot associated with any inflammatory affection. They are usually classed under the general heading of Keratoconus or Conical Cornea, from the fact that they always assume a form approximating that of a cone. The cone, however, is generally quite irregular. One case has fallen under the author's observation in which the curve of the vertical meridian was such that in the upper part of the pupil. There was myopic astigmatism, and in the lower half hyperopic astigmatism. The apex of the cone is not always in the center of the cornea.
Except in a few cases, perhaps, keratoconus is Dot congenital, but begins to develop usually about the seventh or eighth year, though often later, reaching its climax not long after the establishment of puberty. Women are more often affected than men. The appearance of a well marked case is shown in Fig. 223.
When less pronounced the abnormal curve cannot be detected by simple inspection, but is easily made manifest by the keratoscope (Placido's disk, see page 145). This is held in front of the eye or attached to the ophthalmometer of Javal, and its reflection on the cornea at its different parts observed. Instead of being approximately circular at the center, as it should be in the normal cornea, it has some modification of the appearances shown in Fig. 224.
Illumination of the fundus, as in examination by the 11 shadow test," shows, instead of a uniform reddish tint of the pupillary area, a dark spot, usually crescentic in form, in the red area, which changes with each movement of the mirror or eye.
The gradual change of form of the cornea is due to a weakening of the corneal tissue and an increase of the intraocular pressure. The determining cause is not known. Vision is much reduced, and, since both eyes are nearly always affected, though often in varying degree, these patients are always 11 near sighted," though not neces myopic, having to bold all objects close in order to obtain large retinal images.
Treatment. In many cases vision can be much improved by glasses, a certain amount of regular astigmatism being found by the ophthalmometer. The light coming through the sides of the cone is that generally used, and therefore, as a rule, plus cylinders are preferred. Raehlmann devised parabolic glasses to correspond to the corneal curve, but they have not been found of much practical use.
Surgical treatment in the way of flattening the cornea by the knife or atrephine, or burning it away with caustics, promises better. The stenopaic slit is often of benefit in obtaining better outlines of objects, but the diminution of field and illumination are its drawbacks.
Morbid Growths on the Cornea. Of benign growths, fibroma (Fig. 225) is the one most commonly found on the cornea. It may come on independently or it may develop on cicatricial tissue the result of a previous ulceration. There is a tendency to return after removal. Papilloma may also find its habitat here.
Malignant growths are usually, perhaps always, of the epithelial variety, at least at the beginning, and are commonly secondary to similar growths on the conjunctiva or sclera. A few cases of sarcoma appearing primarily on the cornea itself have been reported. Leprosy may attack the cornea.
Congenital Defects of the Cornea. The most common of these are dermoid tumors of various kinds (Fig. 226). Usually they are seated on the corneo seleral margin, and are sometimes associated with some other malformation of the eye, generally coloboma of the lid.
Congenital opacities are not common, but a number of cases have been recorded. They may be due to intra uterine inflammation or to arrest of development: in the latter ease the two eyes are apt to be affected in approximately the same manner. Congenital staphyloma has, been described. It may be associated with a dermoid growth.
Microphthalmos is that Condition in which the entire eye remains in a rudimentary state, and in which the cornea is reduced in all its diameters.
Megalophthalmos (see Buphthalmos, p. 385).
Sclerophthalmia is that condition in which, owing to an imperfect differentiation of the sclera and cornea, the former encroaches on the latter, so that only the central part of the cornea remains clear. Sometimes only the upper half of the cornea is affected.
DISEASES OF THE SCLERA.
Episcleritis. The most common form of scleral inflammation is that known as episcteritis, in which the subconjunctival tissue and superficial layers of the sclera are conjointly affected.
Symptoms. Episcleritis manifests itself as an ill defined spot of infiltration with an elevation of I to 1.5 mm. Its seat of election is from 2 to 6 mm. distance from the corneal edge and to the outer side. Its color is not of a pure deep red, but rather of a bluish or violet hue; it is not movable on the ball and is more or less sensitive to touch. The conjunctival vessels leading up to it are congested, but the remaining part of the scleral surface is usually clear. There are in most cases considerable photophobia and lachrymation. The disease is tedious in its course, sometimes running for several weeks, and is subject to recurrences, and it may be at different localities oil the ball.
A rheumatic or gouty diathesis usually lies at the bottom of it, but it also occurs from exposure and with scrofula and menstrual disorders.
Treatment. General treatment must be along these etiological lines. Large doses of meliorate of sodium often have a good effect on the pain and shorten the course of the disease; in some cases pilocarpin sweats are beneficial. Subconjunctival injections of bichlorid of mercury or physiological salt solution have been used with good effect. Scarification of the tissue has also been recommended. Heat is the best local remedy, and may be used in the form of hot bathing or the Japanese hot box. As iritis has beet) known to develop during its course, atropin should be used at the height of the disease; but if there is no iritis, pilocarpin or eserin locally (gr. 1 1/2, gr. ¼), combined with cocain, is most useful. Galvanism has been recommended.
Transitory Episcleral Congestion. This is the name given to a rather sudden and sometimes intense hyperemia of the sclera and overlying conjunctiva, lasting from a few hours to a day or two.
Fuchs (1895) calls it episeteritis partialis fugax. The author has called it a vaso motor dilatation of the vessels (1892). The " hot eye" of Hutchinson is probably of the same nature. The affection is liable to recur for years, and is not attended with danger to vision. It is usually painful and accompanied by photophobia and lachrymation. Exceptionally it occurs in children. Heat for the relief of pain is called for, and the careful employment of cocain may be of use. Any dyscrasic condition, especially rheumatism and gout, must be attended to.
Deep Scleritis. Inflammation of the sclera as a whole is very uncommon independently of a panophthalmitis. But the deeper layers of the sclera can become inflamed, though this is seldom the ease, except in connection with inflammation of the underlying uveal tract. A very common instance of deep scleritis is what is known as selerotico ehoroiditis Posterior, Dearly always found in high grades of myopia (posterior staphyloma) (see page 221). The inflammation affects the anterior part less commonly, when it is known as anterior scleritis.
The disease nearly always begins in the uveal tract, and the sclera, becoming soft, yields to the intraocular pressure and bulges, causing a ciliary staphyloma which may be equatorial. There may be more than one staphyloma, and they may invade the edge of the cornea. They are bluish in color from the pigment showing through the thin scleral tissue. There are considerable congestion, lachrymation, and photophobia, the intensity of the symptoms depending upon the amount of ciliary or iritic involvement.
In a less intense form the disease may be chronic and last for years, with recurrences. Rheumatism, gout, and syphilis (gummatous scleritis) are to be counted as its causes, and its general treatment must be directed to the correction of the demonstrated or suspected dyserasia. Locally, heat, atropin, and, when the staphyloma is thin, a pressure bandage, are indicated.
Tumors of the sclera generally are extensions from the neighboring conjunctiva or cornea. The benign ones are fibromas enehondromas, and the malignant ones are epitheliomas or sarcomas.
Melanosis of the sclera is usually congenital, and these dark spots are common in the Negro race. Melanosis may occur in Addison's disease.
Abscess of the sclera has been observed. It is usually the result of injury, and seldom idiopathic. One or two cases of osseous degeneration of the sclera have been reported.
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