Aetiology and classification of uveitis.

Uvea consists of iris, ciliary body and choroid
•It is a major cause of visual loss both in the developed and developing nations of the world.
•Uveitis is defined as a group of inflammatory disorders that primarily involves the uvea but may also involve adjacent tissues such as the retina, vitreous, sclera and cornea.

1. AETIOLOGY AND CLASSIFICATION OF UVEITIS DR AISHA AHMAD BARWA DEPARTMENT OF O PTHALMOLOGY ATBUTH BAUCHI THURSDAY 17 TH JULY 2025

2. CONTENT Introduction E pidemiology C lassification E tiology Summary R efrences

3. INTRODUCTION Uvea consists of iris, ciliary body and choroid It is a major cause of visual loss both in the developed and developing nations of the world. Uveitis is defined as a group of inflammatory disorders that primarily involves the uvea but may also involve adjacent tissues such as the retina, vitreous, sclera and cornea .

4. EPIDEMIOLOGY Uveitis is an important cause of preventable blindness with it being the 5 th leading cause of blindness in the developing world.   Global incidence of 17 to 52 per 100,000 people annually prevalence of uveitis varies, with estimates ranging from 38 to 714 per 100,000 people.   About 2,359,242 people have uveitis globally.

5. EPIDEMIOLOGY In the U.S, estimates range from 80,000 to 168,000 cases annually.   Nigeria has 1.73% of it's population suffering from uveitis.   Uveitis can affect people of all ages, but it often affects young adults. Some studies suggest a slight predominance in women in developed countries while others report an equal distribution between men and women.

6. CLASSIFICATION ANATOMICAL C LINICAL P ATHOLOGICAL ETIOLOGICAL

7. ANATOMICAL CLASSIFICATION The standardization of uveitis nomenclature (SUN) system classifies uveitis based on the anatomical location of inflammation. Anterior uveitis: the anterior chamber is the primary site of inflammation. Intermediate uveitis: primarily vitreous inflammation

8. ANATOMICAL CLASSIFICATION iii. Posterior uveitis: retina and/ or choroid. iv. Panuveitis : all uveal structures are involved. However, uveitis affecting a given anatomic location may have distinct etiologies, clinical courses, prognoses, and treatment indications

9. ANATOMICAL CLASSIFICATION Type Primary Site of Inflammation Includes anterior uveitis anterior chamber Iritis Iridocyclitis anterior cyclitis Intermediate uveitis Vitreous pars planitis posterior cyclitis hyalitis posterior uveitis retina or choroid Focal, multifocal, or diffuse choroiditis Chorioretinitis retinochoroiditis retinitis Neuroretinitis panuveitis anterior chamber, vitreous, and retina or choroid

10. Anatomical classification of uveitis

11. CLINICAL CLASSIFICATION The SUN system further refines the anatomical classification of uveitis with discriptors based on clinical onset, duration and course Onset : sudden or insidious. Duration : limited (3 months or less) or persistent. Clinical course : acute (of sudden onset and limited duration), recurrent (repeated episodes separated by untreated inactive periods), or chronic (persistent duration, with relapse less than 3 months after discontinuation of treatment). Remission is defined as inactivity (no visible cells) for 3 months or longer.

12. Category Descriptor Comment Onset Sudden Insidious Duration Limited persistent ≤ 3 months’ duration > 3 months’ duration Course acute recurrent Chronic episode characterized by sudden onset and limited duration repeated episodes separated by periods of inactivity without treatment ≥ 3 months in duration persistent uveitis with relapse in < 3 months after discontinuing treatment

13. PATHOLOGICAL CLASSIFICATION Suppurative or purulent uveitis. Non-suppurative uveitis. It has been further subdivided in two groups (Wood’s classification). ( i ) Non-granulomatous uveitis, and (ii) Granulomatous uveitis

14. ETIOLOGICAL (DUKE ELDER'S) CLASSIFICATION 1. Infective uveitis 2. Allergic uveitis 3. Toxic uveitis 4. Traumatic uveitis 5. Uveitis associated with non-infective systemic diseases 6. Idiopathic uveitis

15. ETIOLOGY The etiologies of uveitis are known to vary in different populations depending on the country, race and socioeconomic status The etiological concepts of uveitis as proposed by Duke Elder includes 1. Infective uveitis 2. Allergic uveitis 3. Toxic uveitis 4. Traumatic uveitis 5. Uveitis associated with non-infective systemic diseases 6. Idiopathic uveitis

16. 1. INFECTIVE UVEITIS In this, inflammation of the uveal tissue is induced by invasion of the organisms. Uveal infections may be exogenous, secondary or endogenous. i Exogenous infection wherein the infecting organisms directly gain entrance into the eye from outside. It can occur following penetrating injuries, perforation of corneal ulcer and post- operatively (after intraocular operations). Such infections usually result in an acute iridocyclitis of suppurative (purulent) nature, which soon turns into endophthalmitis or even panophthalmitis.

17. INFECTIVE UVEITIS CONT… ii   Secondary infection of the uvea occurs by spread of infection from neighbouring structures, e.g., acute purulent conjunctivitis. (pneumo- coccal and gonococcal), keratitis, scleritis, retinitis, orbital cellulitis and orbital thrombophlebitis. iii   Endogenous infections are caused by the entrance of organisms from some source situated elsewhere in the body, by way of the bloodstream. Endogenous infections play important role in the inflammations of uvea.

18. TYPES OF INFECTIOUS UVEITIS Depending upon the causative organisms, the infectious uveitis may be classified as follows: i . Bacterial infections. These may be granulomatous e.g., tubercular, leprotic, syphilitic, brucellosis or pyogenic such as streptococci, staphylococci, pneumococci and gonococcus. ii. Viral infections associated with uveitis are herpes simplex, herpes zoster, cytomegalovirus (CMV), HIV, rubella, measles and mumps.

19. iii. Fungal uveitis is rare and may accompany systemic aspergillosis, candidiasis and blastomycosis. It also includes presumed ocular histoplasmosis syndrome. iv. Parasitic uveitis is known in toxoplasmosis, toxocariasis, onchocerciasis and amoebiasis. v. Rickettsial uveitis may occur in scrub typhus and epidemic typhus.

20. 2. ALLERGIC (HYPERSENSITIVITY LINKED) UVEITIS Allergic uveitis is of the commonest occurrence in clinical practice. The complex subject of hypersensitivity linked inflammation of uveal tissue is still not clearly understood. It may be caused by the following ways: i . Microbial allergy. In this, primary source of infection is somewhere else in the body and the escape of the organisms or their products into the bloodstream causes sensitisation of the uveal tissue with formation of antibodies. At a later date a renewal of infection in the original focus may again cause dissemination of the organisms or their products (antigens); which on meeting the sensitised uveal tissue excite an allergic inflammatory response.

21. ALLERGIC UVEITIS CONT… Primary focus of infection can be a minute tubercular lesion in the lymph nodes or lungs. Once it used to be the most common cause of uveitis worldwide, but now it is rare. However, in developing countries like India tubercular infections still play an important role. Other sources of primary focus are streptococcal and other infections in the teeth, paranasal sinuses, tonsils, prostate, genitals and urinary tract.

22. ALLERGIC UVEITIS CONT… ii. Anaphylactic uveitis. It is said to accompany the systemic anaphylactic reactions like serum sickness and angioneurotic oedema. iii. Atopic uveitis. It occurs due to airborne allergens and inhalants, e.g., seasonal iritis due to pollens. A similar reaction to such materials as cat dander, chicken feather, house dust, egg albumin and beef proteins has also been noted.

23. ALLERGIC UVEITIS CONT… iv. Autoimmune uveitis. It is found in association with autoimmune disorders such as Still’s disease, juvenile idiopathic arthritis, rheumatoid arthritis, Wegener’ s granulomatosis, systemic lupus erythematosus, Reiter’s disease and so on. In phacoanaphytic endophthalmitis, lens proteins play role of autoantigens. Similarly, sympathetic ophthalmitis has been attributed to be an autoimmune reaction to uveal pigments, by some workers.

24. ALLERGIC UVEITIS CONT… v. HLA-associated uveitis: Human leucocytic antigens (HLA) is the old name for the histocompatibility antigens. There are about 70 such antigens in human beings, on the basis of which an individual can be assigned to different HLA phenotypes. Recently, lot of stress is being laid on the role of HLA in uveitis, since a number of diseases associated with uveitis occur much more frequently in persons with certain specific HLA- phenotype.

25. ALLERGIC UVEITIS CONT… A few examples of HLA-associated diseases with uveitis are as follows:   HLA-B27. Acute anterior uveitis associated with ankylosing spondylitis and also in Reiter’s syndrome.  HLA-B5: Uveitis in Behcet’s disease.  HLA-DR4 and DW15: Vogt Koyanagi Harada’s disease.

26. 3. TOXIC UVEITIS Toxins responsible for uveitis can be endotoxins, endocular toxins or exogenous toxins. i . Endotoxins, produced inside the body play a major role. These may be autotoxins or microbial toxins (produced by organisms involving the body tissues). Toxic uveitis seen in patients with acute pneumococcal or gonococcal conjunctivitis and in patients with fungal corneal ulcer is thought to be due to microbial toxins.

27. TOXIC UVEITIS CONT… ii. Endocular toxins are produced from the ocular tissues. Uveitis seen in patients with blind eyes, long-standing retinal detachment and intraocular haemorrhages is said to be due to endocular toxins. Other examples are uveitis associated with intraocular tumours and phacotoxic uveitis. iii. Exogenous toxins causing uveitis are irritant chemical substances of inorganic, animal or vegetative origin. Certain drugs producing uveitis (such as miotics and cytotoxic drugs) are other examples of exogenous toxins.

28. 4. TRAUMATIC UVEITIS It is often seen in accidental or operative injuries to the uveal tissue. Different mechanisms which may produce uveitis following trauma include:  Direct mechanical effects of trauma.  Irritative effects of blood products after intraocular haemorrhage (haemophthalmitis).  Microbial invasion.  Chemical effects of retained intraocular foreign bodies; and  Sympathetic ophthalmia in the other eye.

29. 5. UVEITIS ASSOCIATED WITH NON-INFECTIVE SYSTEMIC DISEASES Certain systemic diseases frequently complicated by uveitis include: sarcoidosis, collagen related diseases (polyarteritis nodosa (PAN), disseminated lupus erythematosus (DLE), rheumatic and rheumatoid arthritis), metabolic diseases (diabetes mellitus and gout), disease of the central nervous system (e.g., disseminated sclerosis) and diseases of skin (psoriasis, lichen planus, erythema nodosum, pemphigus and so on).

30. 6. IDIOPATHIC UVEITIS It may be specific or non- specific. i . Idiopathic specific uveitis entities include the conditions which have certain special characteristics of their own e.g., pars planitis, sympathetic ophthalmitis and Fuchs’ hetero-chromic iridocyclitis. ii. Nonspecific idiopathic uveitis entities include the condition which do not belong to any of the known etiological groups. About more than 25 percent cases of uveitis fall in this group.

31. SUMMARY

32. REFERENCES AAO VOL 09 UVEITIS AND OCCULAR INFLAMMATION AK KHURANA COMPREHENSIVE O PTHALMOLOGY 4 TH EDITION EYEWIKI KANSKI CLINICAL O PHTHALMOLOGY A SYSTEMIC APPROACH 8 TH EDITION

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