UVEITIS
UVEITIS
GENERAL CONSIDERATIONS
DEFINITION
The term uveitis strictly means inflammation of the
uveal tissue only. However, clinically there is always
some associated inflammation of the adjacent
structures such as retina, vitreous, sclera and cornea.
Due to close relationship of the anatomically distinct
parts of the uveal tract, the inflammatory process
usually tends to involve the uvea as a whole.
ICLASSIFICATION
I. Anatomical classification
1. Anterior uveitis. It is inflammation of the uveal
tissue from iris up to pars plicata of membrane .
It may be subdivided into:
• Iritis, in which inflammation predominantly
affects the iris.
Iridocyclitis during which iris and pars plicata a part of
ciliary body are equally involved, and
• Anterior cyclitis, in which pars plicata part of
ciliary body is predominantly affected.
2. Intermediate uveitis. It includes inflammation of
the pars plana and peripheral a part of the retina and
underlying 'choroid! It is also called 'pars planitis
3. Posterior uveitis, It refers to inflammation of the
choroid (choroiditis). Almost always there i
associated inflammation of retina and hence the
term chorioretinitis' is used.
4. Panuveitis. It is inflammation of the whole uvea.
II. Clinical classification
1. Acute uveitis. It has got a sudden symptomatic
onset and the disease lasts for 3 months or less.
2. Chronic uveitis. It frequently has an insidious
and asymptomatic onset. It persists longer than 3
months and is usually diagnosed when it causes
defective vision.
3. Recurrent uveitis. This is characterised by repeated
episodes separated by inactive periods of >3
months without treatment.
III. Pathological classification
1. Suppurative or purulent uveitis.
2. Nonsuppurative uveitis. It has been further
subdivided into two groups (Wood's classification).
i. Nongranulomatous uveitis, and
ii. Granulomatous uveitis.
IV. Etiological (Duke Elder's) classification
1. Infective uveitis
2. Immune-related uveitis
3. Toxic uveitis
4. Traumatic uveitis
5. Uveitis associated with noninfective system
diseases
6. Idiopathic uveitis.
ETIOLOGY
Despite a great deal of experimental research and
many sophisticated methods of investigations
etiology and immunology of the uveltis is still largefy
not understood. Even today, the cause of many
clinical conditions is disputed (remains presumptive)
and in many others etiology is unknown, The
etiological concepts of uveitis as proposed by Duke
Elder, in general, are discussed here,
1. Infective uveitis
In this, inflammation of the uveal tissue is induced
by invasion of the organisms. Uveal infections may
1. Exogenous infection wherein the infecting organisms
directly gain entrance into the attention from outside, It Can
occur following penetrating injuries, perforation of
corneal ulcer and postoperatively (after intraocular
operations), Such infections usually result in an
acute iridocyclitis of suppurative (purulent) nature,
which soon turns into endophthalmitis or even
Il. Secondary infection of the uvea occurs by spread
of infection from neighbouring structures, e.g.,
gonococcal), keratitis, scleritis, retinitis, orbital
panophthalmitis.
te purulent conjunctivitis (pneumococcal and
ellulitis and orbital thrombophlebitis.
il. Endogenous infections are caused by the entrance
of organisms from some source of infection situated
elsewhere in the body, by way of the bloodstream.
Endogenous infections play important role in the
inflammations of uvea.
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.
il. Viral infections associated with uveitis are herpes
simplex, herpes zoster and cytomegalo virus (CMV).
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.
2. Immune related uveitis
mmune related uveitis is one of the commonest
oCcurrence in clinical practice. The complex subject
immune linked inflammation of uveal tissue is
following ways:
still not clearly understood. It may be caused by the
1. Microblal 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 the
formation of antibodies. At a later date a renewal
of infection within 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.
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 infecions in the teeth,
paranasal sinuses, tonsils, prostate, genitals and
urinary tract.
EmoticonEmoticon