Allergic keratitis

The range of allergic reactions and diseases of the cornea is still less clearly defined than allergies of the accessory apparatus of the eye. The situation is complicated by the fact that the cornea is exposed not only to exo- and endoallergens, but also to allergens from its own tissue, which arise when it is damaged.

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Causes of allergic keratitis

A classic example of an allergic process in the cornea is the Wessely phenomenon: the development of marginal keratitis in an animal sensitized by the introduction of a heterogeneous serum into the center of the cornea.

In the clinic, a reaction similar in its pathogenesis to the Wessel phenomenon occurs in the cornea during its burns, although it is caused by autoallergens. The layering of autoallergy causes the expansion of the damage zone beyond the area of the cornea exposed to the burning substance, which aggravates the severity of the burn. The affinity of antibodies that occur during corneal and skin burns served as the basis for the creation of an effective method for treating eye burns with the blood serum of burn convalescents.

The highest autoimmune organ specificity is possessed by the epithelium and endothelium of the cornea, damage to which during inflammation, trauma, surgical intervention is fraught with the formation of antibodies, and the allergic reactions that develop after this worsen the course of the above processes. The desire to reduce these unfavorable effects is one of the reasons for the tendency observed in modern eye surgery to spare the corneal endothelium as much as possible during operations. Many ophthalmic surgeons, for example, due to damage to the corneal endothelium by ultrasound, refrain from cataract phacoemulsification.

Allergic reactions of the cornea can be caused by essentially any exo- and endoallergens to which the eyes and auxiliary apparatus react. Of the exogenous allergens, medications are of the greatest importance. According to scientists, they caused changes in the cornea in 20.4% of patients with drug allergy of the eye, with local applications causing mainly epithelial lesions (64.9%), and taking medications orally or parenterally leads to stromal keratitis (13.4%).

Corneal epitheliopathy, its central erosion, epithelial, filamentous, stromal and marginal keratitis, according to the classification of the above authors, represent the main clinical forms of drug allergy of the cornea. This allergy is in many ways similar to reactions of the cornea to other allergens, in particular pollen, cosmetics, chemicals, etc. In such patients, punctate subepithelial infiltrates of the cornea, its erosions, perilimbal opacities and ulcerations of the corneal tissue are often detected. Even with weak manifestations of the disease, histological changes and desquamation of the epithelium are detected, Bowman's membrane and lymphocytic tissue reaction are absent in places. Staining of the cornea (fluorescein, fuscin) and biomicroscopy help to identify such often weakly expressed changes in the clinic.

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Symptoms of allergic keratitis

Clinically observed allergic reactions of the cornea to exogenous allergens are usually limited to changes in its anterior layers: the epithelium, Bowman's membrane, and superficial stroma layers are affected. More often, such lesions are complications of allergic diseases of the eyelids and conjunctiva. For example, Pillat's corneal eczema begins with pronounced serous abacterial conjunctivitis, which is joined by vesicular epithelial keratitis, and then deeper corneal infiltrates in the presence of skin eczema at the same time.

Repeated contacts of the cornea with an allergen are not always limited to avascular reactions. In patients with eczema, circular corneal pannus may develop. Congenital syphilitic parenchymatous keratitis, which is extremely rare at present, occurs with pronounced ingrowth of vessels into the cornea, in which antibodies to spirochetes are formed, and the antigens are altered corneal proteins. Rosacea keratitis is vascular, in the development of which endocrine allergic factors, in particular testosterone, are now given great importance.

A common eye lesion is marginal allergic keratitis. It begins with the appearance of one or more gray superficial infiltrates of an elongated shape arranged in a chain along the limbus. Later, the intensity of the infiltrates increases, they ulcerate, and if recovery is delayed, superficial vessels appear coming from the limbus. Unlike the catarrhal ulcer caused by the Morax-Lexenfold bacillus, there is no intact area between the infiltrate and the limbus, nor a depression along the limbus with bulging of the thinned posterior layers of the cornea into it. On the contrary, infiltrates of allergic genesis are often distinguished by their "volatility": having remained in one area for several days, they disappear here, to soon appear in other places. Eye irritation is pronounced. Treatment is similar to that for other allergic diseases of the cornea. In this pathology, G. Gunther particularly emphasizes the role of focal infection with its chronic foci in the paranasal sinuses, teeth, and nasopharynx. Microbial allergens coming from here cause superficial and ulcerous, less often parenchymatous marginal and central inflammations of the cornea. Elimination of infectious foci leads to rapid healing of the eyes of such patients.

Treatment of allergic keratitis

Effective therapy of pronounced manifestations of eye allergy and its accessory apparatus requires local and general complex impact on the body, taking into account the whole variety of etiological and pathogenetic factors, complexity of pathogenesis, disorders of the endocrine, central and autonomic nervous systems. The most effective in treatment is prevention of contact with the allergen, its elimination, which often leads to a quick recovery.

However, it is not possible to identify and turn off the allergen in time for every patient. In such cases, without stopping the search for the cause of the disease, it is necessary to influence certain links in the pathogenetic chain of the allergic process in order to slow down the formation, neutralize antibodies or suppress the pathochemical phase of the allergy. Also needed are means that increase the body's resistance and reduce its allergic reactivity, normalize metabolism, permeability of blood vessels, nervous and endocrine regulation.

The first task - inhibition of antibody formation and the allergen-antibody reaction - is solved by prescribing desensitizing drugs, primarily steroid hormones. Glucocorticoids reduce antibody production, decrease capillary permeability, delay the breakdown of complex mucopolysaccharides, and have a pronounced anti-inflammatory effect. Their therapeutic effect is most clearly manifested in delayed-type allergic reactions.

In ophthalmology, these potent drugs with serious side effects are indicated for patients with severe eye allergies (either an independent process or a complication of another pathology) that are difficult to treat with other methods. These are usually eyeball diseases. In the case of allergic lesions of the accessory apparatus of the eye, it is recommended to avoid steroids if possible.

For the treatment of ocular manifestations of allergy, the most recommended are dexamethasone instillations (0.4% solution) or adrezone 4-6 times a day, the use of prednisolone, hydrocortisone and cortisone ointments (0.5-1%), dexamethasone (0.1%), in severe cases of the disease, dexamethasone or dexazone injections into the conjunctiva, as well as prescribing prednisolone (5 mg), triamcinolone (4 mg), dexamethasone (0.5 mg per dose), medrysone, fluoromethalone orally 3-4 times a day. Treatment is usually carried out in short courses with a gradual reduction in doses, calculated so that after 10-15 days the oral administration of the drug can be discontinued. The withdrawal syndrome with such courses, if it manifests itself, is only a slight exacerbation of the eye disease, requiring an extension of glucotherapy for some more short time.

Long courses of treatment (1.5-2 months or more) and higher doses of steroid hormones (up to 60-70 mg of prednisolone per day at the beginning of treatment) are prescribed to patients with chronic, recurrent, more often infectious-allergic eye diseases, as well as in the treatment of sympathetic ophthalmia. In microdoses, dexamethasone (0.001% aqueous solution) Yu. F. Maychuk (1971) recommends for the treatment of allergic reactions in Sjögren's syndrome, chronic conjunctivitis of unknown etiology, viral eye lesions, etc. Since salicylic and pyrazolone drugs have certain immunosuppressant properties, they are successfully used in medium doses in the treatment of allergic eye diseases, especially in allergies of the eyelids and conjunctiva, avoiding the use of corticosteroids. The similarity in the mechanisms of antiallergic action also determines the possibility of replacing steroids with these drugs in patients for whom they are contraindicated. Treatment is carried out in courses lasting 3-5 weeks.

In recent years, special immunosuppressive agents, mainly from the arsenal of tumor chemotherapy, have been tested with positive results in allergic eye diseases.

Suppression of the pathochemical phase of an allergic reaction is mainly carried out by antihistamines, which have the greatest effect on immediate-type allergies. The number of these drugs is large. Most often, ophthalmologists use diphenhydramine (0.05 g 3 times a day), suprastin (0.025 g 2-3 times a day), diprazine (pipolfen 0.025 g 2-3 times a day), levomepromazine (Hungarian tizercin 0.05-0.1 g 3-4 times a day), diazolin (0.1-0.2 g 2 times a day), tavegil (0.001 g 2 times a day), fenkarol (0.025-0.05 g 3-4 times a day). The last three drugs, which do not have a hypnotic effect, are suitable for outpatient treatment. When choosing drugs, their tolerability by patients is of primary importance; if the effect of one remedy is weak, it is recommended to replace it with another.

For local therapy, the following medications are used: diphenhydramine in drops. Depending on the patient's reaction, instillations of 0.2%, 0.5% and 1% solutions are prescribed 2-3 times a day. Drops are useful for patients with both severe and mild manifestations of conjunctival and anterior eye allergy. The mechanism of action of antihistamines has not been sufficiently studied. It is believed that they block histamine on recipient cells, reduce vascular permeability, contract capillaries, and inhibit the formation of hyaluropidase, which promotes the spread of histamine. Their noticeable anti-inflammatory effect is also important.

L.D. Ldo distinguishes three stages of action of antihistamines during their long-term use:

1. therapeutic stage (maximum effect);
2. the stage of habituation (there is no effect or it is weak);
3. stage of allergic complications (the appearance of hypersensitivity to the drug used in some patients).

Such dynamics limit the course of treatment to 3-4 weeks and confirm the advisability of changing drugs due to addiction to them.

In addition to the above medications, histoglobulin (a mixture of gamma globulin and histamine) helps to inactivate histamine and reduce sensitivity to it. It is administered subcutaneously at 1-3 ml once every 2-4 days; a total of 4-10 injections per course. Significant improvement in the course of the disease is observed only after 1-2 months. Combining this agent with corticosteroids is not recommended.

The complex treatment of severe manifestations of eye allergies can also include intravenous infusions of 0.5% novocaine solution by drip, 150 ml per day for 8-10 days. 10 ml of 5% ascorbic acid solution is added to the drip, and rutin is prescribed orally.

Of the general agents for the body to mobilize its defense mechanisms to combat allergies, ophthalmology widely prescribes calcium chloride orally (5-10% solution, 1 tablespoon 3-4 times a day after meals), less often intravenously (10% solution, 5-15 ml daily) or calcium gluconate orally (1-3 g 2-3 times a day). For the same purposes, A. D. Ado et al. (1976) recommend sodium thiosulfate (30% solution, 5-10 ml intravenously; 7-10 injections per course). All these medications combine well with antihistamines.

_{Vitamins C and B2} (riboflavin) and sedatives are also useful for patients with eye manifestations of allergy. Sanitation of infection foci, treatment of other general somatic processes, normalization of mental status, sleep, etc. are strictly necessary. Predisposition to allergies, including eyes, is reduced by hardening the body, doing physical education and sports. This is essentially what prevention of allergic diseases in general and eye allergies in particular consists of.

A very difficult task is the treatment of eye patients suffering from polyvalent allergies, who often give a pronounced local and sometimes general reaction to the local use of almost any medication. Allergens for them can even be the same glucocorticoids and antihistamines that treat allergies. In such cases, it is necessary to cancel all medications, no matter what they are needed to treat the underlying disease, and then very carefully, preferably by setting preliminary tests, select tolerated medications.

While suppressing allergic reactions in one way or another, the ophthalmologist has no right to forget that the entire immune system of the body suffers, and its protection against infectious and other agents worsens.

Effective, but difficult to implement in widespread practice, specific desensitization with tuberculin, toxoplasmin and other antigens is described in detail in the works of A. Ya. Samoilov, I. I. Shpak and others.

Depending on the nature of the allergic pathology of the eye, along with antiallergic therapy, symptomatic treatment is carried out, mainly locally, with drying, disinfecting, astringent and other medications, mydriatics or miotics are prescribed, etc.

In particular, in case of ocular manifestations of Quincke's edema, if it is not possible to identify and eliminate the allergen, then symptomatic treatment is carried out mainly with antihistamines. Diphenhydramine is used locally; it or other histamines are prescribed orally. In case of pronounced symptoms of the disease, amidopyrine, brufen, aminocaproic acid are indicated (from 0.5 to 2.5-5 g depending on age, washed down with sweetened water). Treatment of complications is usual. Corticosteroids, as a rule, are not indicated.

In cases of severe allergic dermatitis and eczemas, along with possible elimination of the allergen, symptomatic therapy is carried out similar to that recommended above for Quincke's edema. Prescription of antihistamines in combination with this therapy is indicated, since mixed allergy of the delayed-immediate, and sometimes only immediate type, cannot be excluded. Calcium, sodium thiosulfate or magnesium thiosulfate preparations are also recommended. Corticosteroids are prescribed only to patients with very severe manifestations of the disease.

In case of maceration and oozing, drying lotions ("compresses") are indicated for 10-15 minutes 3-4 times a day with various solutions: 1-2% boric acid solution, 1% resorcinol solution, 0.25% amidopyrine solution, 0.25-0.5% silver nitrate solution, 0.25% tannin solution. Crusts are removed after softening with sterile fish oil or olive oil, cracks and deep efflorescences are cauterized pointwise with 2-5% silver nitrate solution. Treatment is without dressings (light-protective glasses). To reduce maceration of the skin with discharge from the eye, disinfectant, astringent, vasoconstrictor drops are used, and at night - lubrication of the ciliary edge of the eyelids with ointment.

As the inflammatory phenomena weaken, disinfectant ointments on an eye base without Vaseline and a specially prepared salicylic-zinc paste are indicated. Branded ointments such as "Geocortop", "Sinalar", "Oxicort", "Dermatolon", "Lokakortei" and others, which are made without taking into account the characteristics of the eye tissues and its auxiliary apparatus, are suitable only for external use. By applying them to the skin of the eyelids 1-2 times a day for 1-2 days, Yu. F. Maychuk (1983) obtained an effect in those cases where other corticosteroids did not help.

In the treatment of contact allergic conjunctivitis and dermatoconjunctivitis, antihistamines are ineffective, vasoconstrictors do not work. Such patients are prescribed disinfectants in drops, ointments or films (GLN), corticoids, calcium chloride or calcium gluconate taken orally, acetylsalicylic acid, amidopyrine, and in case of a protracted disease - short courses of glucocorticoids in medium doses.

According to research, glucocorticoids are the most effective in treating spring catarrh. Given their better tolerance at a young age, they are prescribed in drops 2-3 times a day during the entire period of exacerbation of the disease, and are also used to prevent relapses before the onset of warm weather. Severe manifestations of the disease require supplementing local corticosteroid therapy with general intermittent courses of treatment with these drugs in medium doses. The effectiveness of treatment is increased by cryoapplications of conjunctival and limbal growths, sometimes their excision. Along with steroids, calcium chloride or calcium gluconate, riboflavin, and sodium cromolyn (Intal) are useful. To reduce itching and thin the secretion, 3-5% sodium bicarbonate is instilled 3-5 times a day, zinc sulfate with adrenaline, sometimes 0.1-0.25% dicaine solution, etc. During the period of remission, patients are subject to dispensary observation and anti-relapse treatment; in case of relapse, they are treated on an outpatient basis or in ophthalmological hospitals.

When administering medications or conducting testing, the ophthalmologist may observe the most severe general manifestation of allergy - anaphylactic shock. A patient with suspected shock, especially with obvious signs of it, is immediately placed in a strictly horizontal position. 0.5 ml of 0.1% adrenaline solution, dexamethasone (4-20 mg) or prednisone (0.5-1 mg per 1 kg of body weight), euphyllin (1-2 ml of 2.4% solution), shik diprophyllin (5 ml of 10% solution) and diphenhydramine (5 ml of 1% solution) or another antihistamine are administered intramuscularly. If these and other anti-shock agents are insufficient, they are administered intravenously).