uvea

uvea

1. UVEA OPTOM FASLU MUHAMMED

2. Uveal tissue constitutes the middle vascular coat of the eyeball. From anterior to posterior it can be divided into three parts, namely, iris, ciliary body and choroid.

3. CONGENITAL ANOMALIES OF UVEAL TRACT HETEROCHROMIA OF IRIS It refers to variations in the iris color and is a common congenital anomaly. In heterochromia iridium colour of one iris differs from the other. Sometimes, one sector of the iris may differ from the remainder of iris; such a condition is called heterochromia iridis.

4. CORECTOPIA It refers to abnormally eccentric placed pupil. Normally pupil is placed slightly nasal to the centre. POLYCORIA In this condition, there are more than one pupil

5. CONGENITAL ANIRIDIA (IRIDREMIA) It refers to congenital absence of iris. True aniridia, i.e., complete absence of the iris is extremely rare. Usually, a peripheral rim of iris is present and this condition is called ‘Clinical aniridia'. Zonules of the lens and ciliary processes are often visible.

6. PERSISTENT PUPILLARY MEMBRANE It represents the remnants of the vascular sheath of the lens. It is characterized by thread like-shaped shreds of the pigmented tissue coming from anterior surface of the iris (attached at collarets). These float freely in the anterior chamber or may be attached to the anterior surface of the lens

7. CONGENITAL COLOBOMA OF THE UVEAL TRACT Congenital coloboma (absence of tissue) of iris, ciliary body and choroid may be seen in association or independently. Coloboma may be typical or atypical. Typical coloboma is seen in the inferonasal quadrant and occurs due to defective closure of the embryonic fissure. Atypical coloboma is occasionally found in other positions.

8. UVEITIS The term uveitis strictly means inflammation of the uveal tissue only. However, practically there is always some associated inflammation of the adjacent structures such as retina, vitreous, sclera and cornea.

9. CLASSIFICATION I. ANATOMICAL CLASSIFICATION 1. Anterior uveitis. It is inflammation of the uveal tissue from iris up to pars plicata of ciliary body. It may be subdivided into : Iritis, in which inflammation predominantly affects the iris. Iridocyctitis in which iris and pars plicata part of ciliary body are equally involved, and Cyclitis, in which pars plicata part of ciliary body is predominantly affected.

10. 2. Intermediate uveitis. It includes inflammation of the pars plana and peripheral part of the retina and underlying ‘choroid’. It is also called ‘pars planitis'. 3. Posterior uveitis. It refers to inflammation of the choroid (choroiditis). Always there is associated inflammation of retina and hence the term ‘chorioretinitis’ is used. 4. Panuveitis. It is inflammation of the whole uvea

11. II. CLINICAL CLASSIFICATION 1. Acute uveitis . It has got a sudden symptomatic onset and the disease lasts for about six weeks to 3 months. 2. Chronic uveitis . It frequently has an insidious and asymptomatic onset. It persists longer than 3 months to even years and is usually diagnosed when it causes defective vision.

12. III. PATHOLOGICAL CLASSIFICATION 1. Supportive or purulent uveitis. 2. Non- suppurative uveitis. It has been further

13. IV. 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

14. ETIOLOGY OF UVEITIS 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.

15. 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 postoperatively (after intraocular operations). Secondary infection of the uvea occurs by spread of infection from neighboring structures,

16. e.g., acute purulent conjunctivitis. (pneumococcal and gonococcie), kératites, scleraitis etc. . Endogenous infections are caused by the entrance of organisms from some source situated elsewhere in the body, by way of the bloodstream.

17. 2. Allergic (hypersensitivity linked) uveitis 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 sensitization of the uveal tissue with formation of antibodies.

18. ii. Anaphylactic uveitis. It is said to accompany the systemic anaphylactic reactions like serum sickness and angioneurotic edema . 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 dander's of cats, chicken feather, house dust.

19. iv. Autoimmune uveitis. It is found in association with autoimmune disorders

20. 3. Toxic uveitis Toxins responsible for uveitis can be endotoxins, endocular toxins or exogenous toxins i . Endotoxins 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.

21. ii. Endocular toxins - are produced from the ocular tissues. Uveitis seen in patients with blind eyes, long-standing retinal detachment and intraocular hemorrhages is said to be due to endocular toxins.

22. iii. Exogenous toxins - causing uveitis are irritant chemical substances of inorganic, animal or vegetative origin.

23. 4. Traumatic uveitis . Direct mechanical effects of trauma. Microbial invasion. Chemical effects of retained intraocular foreign bodies; and Sympathetic ophthalmia in the other eye.