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PATHOLOGY OF UVEITIS

Inflammation of the uvea fundamentally has the same

characteristics as any other tissue of the body, i.e, avascular and a cellular response. However, due to

extreme vascularity and looseness of the uveal tissue,

the inflammatory responses are exaggerated and thus

produce special results.

Pathologically, inflammations of the uveal tract

may be divided into suppurative (purulent) and nonsuppurative

(non-purulent) varieties. ood has

further classified non-suppurative uveitis into a nongranulomatous

and granulomatous types. !lthough

morphologic description is still of some value, therigid division of uveitis by ood into these two

categories has been "uestioned on both clinical and

pathological grounds. #ertain transitional forms of

uveitis have also been recognised. $ome of these

(e.g., phacoanaphylactic endophthalmitis andsympathetic ophthalmia) showing pathological

features of granulomatous uveitis are caused by

hypersensitivity reactions. hile uveitis due to

tissue invasion by leptospirae presents themanifestation of non-granulomatous uveitis.

%onetheless, the classification is often useful in

getting oriented towards the sub&ect of uveitis, its

wor'up and therapy. herefore, it is worthwhile to

describe the pathological features of these

overlapping (both clinically and pathologically)

conditions as distinct varieties.

1.Pathology of suppurative uveitis. Purulentinflammation of the uvea is usually a part of

endophthalmitis or panophthalmitis occurring as a

result, of exogenous infection by pyogenic organisms

which include staphylococcus, streptococcus,

psuedomonas, pneumococcus and gonococcus.he pathological reaction is characterised by an

outpouring of purulent exudate and infiltration by

polymorphonuclear cells of uveal tissue, anterior

chamber, posterior chamber and vitreous cavity. !s a

result, the whole uveal tissue is thic'ened andnecrotic and the cavities of eye become filled with

pus.2.Pathology of non-granulomatous uveitis.%ongranulomatous

uveitis may be an acute or chronic

exudative inflammation of uveal tissue (predominantly

iris and ciliary body), usually occurring due either to

a physical and toxic insult to the tissue, or as a result

of different hypersensitivity reactions.he pathological alterations of the nongranulomatous

reaction consists of mar'ed dilatation and

increased permeability of vessels, brea'down of blood

a"ueous barrier with an outpouring of fibrinous

exudate and infiltration by lymphocytes, plasma cells

and large macrophages of the uveal tissue, anterior

chamber, posterior chamber and vitreous cavity. he

inflammation is usually diffuse.!s a result of these pathological reactions iris

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becomes waterlogged, oedematous, muddy with

blurring of crypts and furrows. !s a conse"uence its

mobility is reduced, pupil becomes small in sie due

to sphincter irritation and engorgement of radial

vessels of iris. *xudates and lymphocytes poured intothe anterior chamber result in a"ueous flare and

deposition of fine +Ps at the bac' of cornea. ue toexudates in the posterior chamber, the posterior

surface of iris adheres to the anterior capsule of lensleading to posterior synechiae formation. In severe

inflammation, due to pouring of exudate from ciliary

processes, behind the lens, an exudative membrane

called cyclitic membrane may be formed.

!fter healing, pin-point areas of necrosis or atrophyare evident. $ubse"uent attac's lead to structural

changes li'e atrophy, gliosis and fibrosis which cause

adhesions, scarring and eventually destruction of

eye.3.Pathology of granulomatous uveitis. ranulomatous

uveitis is a chronic inflammation of

proliferative nature which typically occurs in

response to anything which acts as an irritant foreignbody, whether it be inorganic or organic material

introduced from outside, a haemorrhage or necrotictissue within the eye, or one of the certain specific

organisms of non-pyogenic and relatively nonvirulent

character. he common organisms which

excite this type of inflammation are those responsible

for tuberculosis, leprosy, syphilis, brucellosis, leptospirosis, as well as most viral, mycotic, protooal

and helminthic infections. ! typical granulomatous

inflammation is also seen in sarcoidosis, sympathetic

ophthalmitis and ogt-+oyanagi-Harada/s disease.he pathological reaction in granulomatous uveitis

is characterised by infiltration with lymphocytes,

plasma cells, with mobiliation and proliferation oflarge mononuclear cells which eventually become

epithelioid and giant cells and aggregate into nodules.

Iris nodules are usually formed near pupillary border

(Koeppes nodules). $imilar nodular collection of the

cells is deposited at the bac' of cornea in the form ofmutton fat 'eratic precipitates and a"ueous flare is

minimal. %ecrosis in the ad&acent structures leads to

a repairative process resulting in fibrosis and gliosis

of the involved area.