Diagnosis of lepra of the eye

Leprosy is diagnosed only in the presence of clinical signs of the disease. As stated above, clinical symptoms of damage to the organ of vision in patients with leprosy are detected only many years after the onset of the disease. Consequently, the basis for establishing the leprosy etiology of eye disease is primarily the clinical manifestations of the disease, expressed mainly in a variety of dermatological and neurological symptoms and characterized by a chronic course with periodic exacerbations.

The diagnosis is established using data from epidemiological, radiological, functional and laboratory studies.

The main radiological signs are focal specific inflammatory destruction of bone tissue (leprosy), observed in the lepromatous type of leprosy, and periostitis, hyperostosis and trophic changes (osteoporosis and osteolysis), found in all types of leprosy.

As is known, leprosy mono- and polyneuritis are accompanied not only by sensory and motor, but also vasomotor, secretory and trophic disorders. For the purpose of diagnosing the latter, functional and pharmacodynamic tests are used: with histamine (or morphine, dionine), nicotinic acid, mustard plaster, as well as Minor's test.

A histamine test reveals damage to the peripheral nervous system. One drop of 0.1% histamine solution (or 1% morphine solution, 2% dionine solution) is applied to the affected area and to externally unchanged skin, and a superficial skin incision is made. Normally, three reaction phases are observed (Lewis triad): a small erythema appears at the site of the skin incision, after 1-2 minutes a significantly larger reflex erythema (several centimeters in diameter) develops, arising according to the axon reflex type, after a few more minutes a papule or vesicle forms in its center. On rashes of leprosy etiology (sometimes on externally unchanged skin) due to damage to the nerve endings in the skin, reflex erythema does not develop.

Using the nicotinic acid test proposed by N. F. Pavlov (1949), vasomotor disorders are detected. The patient is given 3-8 ml of a 1% aqueous solution of nicotinic acid intravenously. Normally, erythema of the entire skin is observed, which completely disappears after 10-15 minutes. In leprosy lesions, and sometimes in individual areas of outwardly unchanged skin due to capillary paresis, hyperemia persists for a long time (symptom of "inflammation").

The mustard plaster test is used in patients with hypopigmented skin spots, in which erythema does not appear due to vasomotor disorders.

The sweat test (Minor) is as follows. The skin area to be examined is lubricated with iodine-containing Minor reagent or 2-5% alcohol solution of iodine and powdered with starch. Sweating is then stimulated. On areas of healthy skin with normal sweating, a blue color appears. On leprous skin lesions due to anhidrosis, a blue color does not occur.

Examination of the visual organ in patients with leprosy should include an external examination of the eye and its accessory organs, determination of the mobility of the eyeballs, study of pupillary reactions to light, accommodation and convergence, study of refractive media in transmitted light, ophthalmoscopy, biomicroscopy, gonioscopy, biomicroophthalmoscopy, study of the sensitivity of the bulbar conjunctiva and cornea, determination of visual acuity, perimetry, campimetry, adaptometry and tonometry.

For early detection of fatigue of the orbicularis oculi muscle, Yu. I. Garus (1959) proposed a blinking test. The patient is asked to continuously blink the eyelids for 5 minutes. Normally, these movements stop after 5 minutes. When the orbicularis oculi muscle is affected, its fatigue, expressed in incomplete closure of the eyelids, occurs after 2-3 minutes.

When examining patients with suspected leprosy, bacterioscopic, histological and immunological research methods are used.

Bacterioscopic examination is performed on scrapings from the mucous membrane of the nasal septum, scarifications from affected skin areas, and lymph node punctures. In case of visual organ lesions, discharge from the conjunctival sac, scrapings from the conjunctiva of the eyeball and eyelids, from the cornea, and fluid from the anterior chamber of the eye are examined. Smears are stained according to Ziehl-Neelsen. The results of bacterioscopic examinations depend on the type and stage of leprosy, exacerbations, and the effectiveness of treatment for leprosy infection.

The material for histological studies is usually biopsied skin pieces. In case of enucleation of the eyeball, its membranes are examined. Histological sections are stained according to Romanovsky-Giemsa and Ziehl-Nielsen. The results of histological studies (most often biopsied skin pieces) are important for classifying the type of leprosy, studying the dynamics of the leprosy process, assessing the effectiveness of treatment, determining the duration of inpatient treatment and dispensary observation.

Serological diagnostics of leprosy using the RSK, RIGA, RNIF reactions, etc. is under study.

To determine the body's resistance to leprosy mycobacteria, a lepromin test is performed, proposed by K. Mitsuda in 1919. The reaction uses Mitsuda's lepromin-antihep (an autoclaved suspension of leprosy mycobacteria obtained from leprosy). This is the so-called integral antigen, which is used most often. Other antigens have also been proposed. 0.1 ml of lepromin is injected into the skin of the patient's shoulder or forearm. If the result is positive, hyperemia and a papule are detected at the site of antigen injection after 48 hours. This is an early reaction to lepromin (Fernandez reaction). After 2-4 weeks, a tubercle develops, sometimes an ulcerating nodule. This is a late reaction to lepromin (Mitsuda reaction). Within 3-4 months, a scar forms, usually hypopigmented, persisting for many years.

A positive Mitsuda reaction indicates a pronounced ability of the body to develop a response to the introduction of leprosy mycobacteria, which is observed in most healthy people.

A negative Mitsuda reaction indicates suppression of cellular immune responses.

In patients with the lepromatous type of leprosy, the lepromin test is negative, in the tuberculoid type it is positive, in the undifferentiated type it is positive in approximately 50% of cases, and in the borderline type it is usually negative. In children under 3 years of age, the Mitsuda reaction is negative.

Thus, the lepromin test is important for determining the type of leprosy, prognosis of the disease and the state of the body's resistance. Cellular immunity in leprosy is also studied in vitro reactions (lymphocyte blast transformation reaction, etc.).

Clinical manifestations of leprosy are varied and require careful differentiation from many diseases of the skin, mucous membrane of the upper respiratory tract, peripheral nervous system, lymph nodes and organ of vision, which have a number of entry features with manifestations of leprosy (nodular erythema, tuberculous syphilide, syphilitic gummas, tuberculous lupus, sarcoidosis, syringomyelia, myelodysplasia, multiple and lateral amyotrophic sclerosis, inflammatory diseases of the mucous membrane of the nose and larynx, lymph nodes, organ of vision of tuberculous and syphilitic etiology, etc.).

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