Causes of uveitis

Uveitis occurs in all countries. Its etiology and distribution are closely related to the living conditions of the population, the circulation of pathogens, and the presence of conditions for the transmission of infection to susceptible individuals.

Data on the frequency of uveitis of various etiologies vary widely, which is due to the epidemiological situation in different areas, methods and assessment criteria used for diagnosis. Over the past twenty years, many reports have appeared on damage to the uveal tract, retina and optic nerve caused by viruses, but it is very difficult to accurately determine the percentage of viral uveitis due to the ambiguous approach to their diagnosis.

Infections play a leading role as causal and trigger factors of uveitis, and uveitis also develops in systemic and syndromic diseases. Among infectious agents, tuberculosis, toxoplasmosis, streptococcal and viral infections are of the greatest importance. Infectious uveitis accounts for 43.5% of uveitis.

Subsequently, the following changes occurred in the epidemiology and clinical presentation of bacterial uveitis:

• a decrease in the incidence of metastatic tuberculosis of the visual organ with an increase in tuberculosis-allergic lesions of the anterior and posterior segments of the eye. Chronic forms of tuberculosis play a leading role;
• relatively high incidence of uveitis in toxoplasmosis and streptococcal infection;
• a tendency towards an increase in the frequency of uveitis in systemic and syndromic diseases in children and adults against the background of hypersensitivity of the eye to streptococcus and suppression of cellular immunity;
• an increase in the frequency of infectious-allergic uveitis against the background of bacterial and herpesvirus polyallergy, tissue sensitization and various reactivity disorders.

Currently, the most acceptable pathological classification of uveitis is the following.

1. Infectious and infectious-allergic uveitis:
   • viral;
   • bacterial;
   • parasitic;
   • fungal:
2. Allergic non-infectious uveitis arising from hereditary allergies to external and internal environmental factors (atopic), uveitis due to drug and food allergies, serum uveitis due to the administration of various vaccines, serums and other non-infectious antigens, Fuchs' heterochromic cyclitis.
3. Uveitis in systemic and syndromic diseases - with diffuse damage to connective tissue (rheumatism, rheumatoid arthritis, spondyloarthritis, sarcoidosis, Vogt-Koyanachi-Harada, Reiter syndromes), multiple sclerosis, psoriasis, glomerulonephritis, ulcerative colitis, autoimmune thyroiditis.
4. Post-traumatic uveitis developing after penetrating eye injury, contusion and postoperative, phacogenic iridocyclitis, systematic ophthalmia.
5. Uveitis in other pathological conditions of the body: in metabolic disorders and disorders of the neurohormonal system (menopause, diabetes), toxic-allergic iridocyclitis (in the decay of a tumor, blood clots, retinal detachment, blood diseases).

With the introduction of the cycloscopic method into practice, they began to distinguish inflammation of the flat part of the ciliary body and the extreme periphery of the vascular membrane itself - peripheral uveitis.

Panuveitis and peripheral uveitis are relatively rare; anterior uveitis or iridocyclitis are more common.

There are primary, secondary and endogenous forms of inflammation. Primary uveitis occurs due to general diseases of the body, and secondary uveitis develops with eye diseases (keratitis, scleritis, retinitis, etc.). The main cause of vascular tract disease is endogenous uveitis. Vascular tract diseases caused by general diseases of the body can be both metastatic and toxic-allergic (with sensitization of the body and eye). Exogenous uveitis develops with penetrating wounds of the eyeball, after operations, perforating ulcer of the cornea.

According to the clinical course, uveitis is divided into acute and chronic. However, this division is conditional, since acute uveitis can become chronic or chronically recurrent. There are also focal and diffuse uveitis, and according to the morphological picture of inflammation - granulomatous and non-granulomatous. Granulomatous uveitis includes metastatic hematogenous uveitis, and non-granulomatous uveitis, which is caused by toxic or toxic-allergenic effects. There are also mixed forms of uveitis.

Depending on the nature of the process or inflammation, the following forms of uveitis are distinguished:

1. fibrous-lamellar;
2. serous;
3. purulent;
4. hemorrhagic;
5. mixed.

Posterior uveitis, or choroiditis, is usually classified by the localization of the process, distinguishing central, paranential, equatorial and peripheral. Limited and disseminated choroiditis are also distinguished. Acute inflammation most often corresponds to an exudative-infiltrative process, chronic inflammation - to an infiltrative-productive one.

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