Diseases of the Uveal Tract

Diseases of the Uveal Tract

UVEITIS

IRIDOCYCLITIS
Etiology

• Allergic uveitis is the most common variety.
• Hypersensitivity to tubercular proteins is an important cause in developing countries (most common).
• HLA associated uveitis;
– HLA-B27 : Acute anterior uveitis associated with ankylosing spondylitis and Reiter’s syndrome.
– HLA-B5 : Behcet’s disease
– HLA-DR4 : Vogt-Koyanagi-Harada’s syndrome
• Reiter’s syndrome is being considered to be caused by chlamydial infection.
• Granulomatous uveitis is seen in:
– Tuberculosis – Syphilis
– Sarcoidosis – Toxoplasmosis
– Sympathetic ophthalmia – Vogt-Koyanagi- Harada syndrome
• Common systemic disorders associated with acute non-granulomatous anterior uveitis are; sacroilitis, ankylosing spondylitis, Reiter’s syndrome, psoriasis, ulcerative colitis and Crohn’s disease.
• Retinal detachment, intraocular tumours, CNS lymphomas and multiple sclerosis may all masquerade as uveitis.
• Fungal uveitis is most commonly due to Candida

Clinical features

• Endothelial bedewing of the cornea is the earliest sign of iritis
• Keratic precipitates (KPs) i.e., proteinaceous cellular deposits at the back of the cornea are an important feature of cyclitis. They may be the only sign in insidious cases of cyclitis. KPs are seldom present in simple iritis.
– Mutton fat KPs are pathognomonic of granulomatous iridocyclitis
– Small and medium KPs are seen in nongranulomatous iridocyclitis
– Very fine KPs occur in Fuch’s heterochromic cyclitis
– KPs are arranged in a triangular fashion due to convection current.
• Aqueous flare is the earliest sign of iridocyclitis. Is best seen with slit lamp examination. Occurs due to leakage of proteins and leucocytes into the anterior chamber as a result of breakdown of blood-aqueous barrier.
• Aqueous cells are sign of active inflammation.
• Iris nodules are a feature of granulomatous iridocyclitis. Koeppe’s nodules are situated at the pupillary border. Bussaca’s nodules are situated near the collarette.
• Small and irregular pupil in iridocyclitis results from sphincter irritation due to toxins and engorgement of the radial blood vessels of the iris.
• Iris bombe results from annular posterior synechiae. In it, anterior chamber becomes funnel shaped.

Diseases of the Uveal Tract

• Atropine is the most important topical drag (of choice) for the management of a case of acute iridocyclitis.
• Steroids, topical as well as systemic are effective in most cases.
• Immunosuppressive drugs are specially useful in severe cases of Behcet’s disease, sympathetic ophthalmitis, pars planitis, and Vogt-Koyanagi- Harada syndrome.

Choroiditis

• Diffuse choroiditis refers to a large spreading lesion involving most of the choroidal tissue. It is usually tubercular or syphilitic in origin.

• Disseminated choroiditis is characterised by multiple small areas of inflammation scattered over the greater part of choroid, usually tubercular or syphilitic in origin.

• Central choroiditis involves macular area, common causes are: toxoplasmosis, histoplasmosis, tuberculosis, syphilis, and visceral larva migrans.

• Juxtacaecal choroiditis involves the area adjoining optic disc, typical example is Jensen’s choroiditis.

• Anterior peripheral choroiditis is usualy syphilitic in origin.

• In late stages of choroiditis-negative scotoma occurs in field of vision.

ENDOPHTHALMITIS

• Inflammation of inner structures of the eyeball (which include; uveal tissue, retina, vitreous) with pouring of exudates into the anterior and posterior chamber of the eye.

• Exogenous infection is the most common mode for purulent endophthalmitis.

• Puff ball opacities in the vitreous are pathognomonic of fungal endophthalmitis.

• Antibiotics should be given by all the routes viz. topical, subconjunctival, intravitreal and intravenously in bacterial endophthalmitis.

• Steroids should be started after 12-24 hours of intensive antibiotic therapy.

• Vitrectomy is the treatment of choice for fungal endophthalmitis. In bacterial endophthalmitis, it should be performed when the condition does not improve with intensive conservative therapy for 48 hours.

SPECIFIC CLINICO-ETIOLOGICAL VARITIES OF NON-SUPPURATIVE UVEITIS

I. Uveitis in chronic systemic bacterial infections

Tubercular uveitis

• Accounts for 1 percent of uveitis patients in developed countries. However, it is a very common cause of uveitis in developing countries.
• Most frequent feature is chronic granulomatous uveitis.
• Isoniazid test (300 mg/day for 3 weeks) for suspected ocular involvement is a useful diagnostic test.
• Systemic treatment consists of a course of isoniazid, pyridoxine and rifampicin for 12 months.

Acquired syphilitic uveitis

• Acute plastic iritis, typically occurs in secondary syphilis.
• Gummatous anterior uveitis occurs in late secondary syphilis and is characterised by yellowish red highly vascularized nodules arranged near the pupillary or ciliary border of iris.
• Chorioretinitis may be peripheral, disseminated or diffuse.
• Neuroretinitis may cause optic atrophy.

Leprotic uveitis

• Uveitis (predominantly anterior) occurs more commonly in lepromatous than the tuberculoid form of leprosy.
• Chronic granulomatous iritis is characterised by presence of small glistening ‘iris pearls’ near the pupillary margin in necklace form.

II. Uveitis in non-infectious systemic diseases

Sarcoid uveitis

Sarcoid uveitis accounts for 2 percent cases of uveitis and may occur as:

• Acute unilateral non-granulomatous anterior uveitis occurs in young patients with acute sarcoidosis.
• Chronic bilateral granulomatous iridocyclitis occurs in older patients with chronic lung disease.
• Uveoparotid fever (Heerfordt’s syndrome): Bilateral granulomatous panuveitis, painful enlargement of parotid glands, cranial nerve palsies, skin rashes, fever and malaise.
• Fundus changes include:
– Periphlebitis-advanced stage of vascular sheathing leads to Candle-wax drippings.
– Retinal granulomata
– Pre-retinal nodules (Lander’s sign)
– Retinal haemorrhages (in acute sarcoid retinopathy
– Choroidal granulomata
– Optic disc may show granuloma, neovascularization, papilloedema or optic atrophy.

Behcet’s disease

• Typically affects young men who are positive for HLA-B5.
• Ocular features are bilateral, recurrent, acute non-granulomatous iridocyclitis associated with transient hypopyon.

Vogt-Koyanagl-Harada (VKH) syndrome

It is more common in Japanese who are usually positive for HLA-DR4. Clinical features include:

• Cutaneous lesions—alopecia, poliosis, and vitiligo
• Neurological lesions are meningism, encephalopathy, tinnitus, vertigo, and deafness.
• Ocular features are chronic granulomatous anterior uveitis, posterior uveitis, and exudative retinal detachment.

III. Uveitis with arthritis

Uveitis with ankylosing spondylitis

• Ankylosing spondylitis is a common, chronic, sero-negative inflammatory arthritis which usually involves sacroiliac and posterior intervertebral joints.
• Typically affects HLA-B27 positive young males.
• About 30% cases develop a recurrent, unilateral, non-granulomatous, acute anterior uveitis.

Reiter’s syndrome

• Characterised by a triad of urethritis, arthritis and conjunctivitis.
• Acute non-granulomatous iridocyclitis occurs in 20-30 percent cases.
• Typically affects young males, 70 percent of whom are positive for HLA-B27.

Juvenile chronic arthritis (JCA)

• Anterior uveitis associated with JCA is chronic bilateral non-granulomatous with insidious onset.
• Bilateral in 70% cases (white uveitis).
• Uveitis is much more common in pauciarticular JCA than polyarticular JCA.
• About half of the cases are positive for HLA- DW5 and 75 percent are positive for antinuclear antibodies (ANA).
• Complications include posterior synechiae, complicated cataract and band-shaped keratopathy (commonest).

IV. Parasitic uveitis

Toxoplasmosis

Congenital toxoplasmosis
• Foetus gets infestation from the involved mother through transplacental route.
• Characteristic triad includes convulsions, calcification (intra-cranial), and chorioretinitis.
• Chorioretinitis at birth may be: (1) Inactive (more common) — bilateral punched out heavily pigmented scar at macula, or (2) Active (rare) – necrotic granulomatous retino-choroiditis.

Acquired toxoplasmosis

• Very rare.
• Most of the cases are subclinical (asymptomatic).

Recurrent toxoplasmic retinochoroiditis

• Most common cause of a focal retinochoroiditis.
• Characterised by a whitish-yellow, slightly raised area near the margin of old punched out scar of healed chorioretinitis.
• There may be associated non-granulomatous type of mild anterior uveitis.

Antitoxoplasmic drugs
• Clindamycin
• Spiramycin
• Pyrimethamine
• Sulphadiazine

Toxocariasis

• Infestation occurs in childhood by accidental ingestion of ova of toxocara canis shed in faeces of cats.
• Visceral larva migrans produces following ocular lesions (usually unilateral):
– Toxocara chronic endophthalmitis which presents between 2 and 10 years of age as leukocoria.
– Posterior pole granuloma – between 5 and 15 years of age.
– Peripheral granuloma – between 6 and 40 years of age.

V. Fungal uveitis

Presumed ocular histoplasmosis syndrome (POHS)

• Presumed to be caused by histoplasma capsulatum.
• Lesions (usually bilateral) include:
– Histospots: atrophic spots scattered in the midretina] periphery.
—Neovascular maculopathy ending in disciform scarring.

Candidiasis

An opportunistic infection occuring in:
• Immuno-compromised patients (e.g., those suffering from AIDS or malignancies)
• Patients with long-term indwelling catheter
• Drug addicts using infected needles.

Ocular lesions

• Anterior uveitis associated with hypopyon.
• Multifocal chorioretinitis with Roth’s spots.
• Endophthalmitis – characterised by ‘puffball’ or ‘cotton ball’ colonies, which joined by exudative strands form a ‘string of pearls’.

VI. Viral uveitis

Herpes zoster uveitis

• Unilateral non-granulomatous acute anterior uveitis occurs in about 50 percent cases with herpes zoster ophthalmicus.
• Complications include:
– Large segmental iris atrophy in 20 percent.
– Secondary glaucoma due to trabeculitis in 10 percent.
– Complicated cataract may occur in late stages.

Acquired cytomegalovirus (CMV) retinitis

• Occurs in immuno-compromised patients (e.g., patients with AIDS and those on cytotoxic therapy for malignancies etc.)
• Ocular lesions includes: Cotton-wool spots, areas of retina] necrosis, and areas of vasculitis and haemorrhage (sauce and cheese retinopathy).
• Complications are exudative retinal detachment, retinal atrophy and optic atrophy.

VII. Idiopathic specific uveitis syndromes

Fuch’s uveitis syndrome

Unilateral mild grade, non-granulomatous, anterior uveitis occurring between 20 and 40 years of age, characterised by:

• Heterochromia of iris due to diffuse stromal atrophy
• Fine KPs
• Faint aqueous flare
• No posterior synechiae
• Neovascularization of the angle
• Early development of the complicated cataract (usually the presenting sign)
• Secondary glaucoma (uncommon)

Intermediate uveitis (pars planitls)

• Patients presents with floaters or defective vision.
• Eye usually looks quiet.
• ‘Snow ball’ vitreous opacities in the inferior quadrant, which may coalesce to form ‘snow banking’.

Glaucomatocyclltis crisis (Posner Schlossman syndrome)

• Typically affects young adults, 40 percent of whom are positive for HLA-BW 54.
• Recurrent attacks of acute rise of the intraocular pressure (40-50 mm of Hg) without shallowing of anterior chamber (secondary open-angle glaucoma).
• Fine KPs but no synechiae.
• Epithelial corneal oedema.
• Dilated pupil.
• White eye (no or minimal congestion).

HETEROCHROMIA

Congenital causes
• Waardenburg’s syndrome
• Homer’s syndrome
• Naevus of Ota
• Congenital ocular melanocytosis

Acquired causes
• Chronic iritis
• Fuch’s heterochromic cyclitis
• Iris naevus or melanoma
• Siderosis
• Rubeosis
• Topical latanoprost

WHITE-DOT SYNDROME

Characterized by multiple white dots in fundus

Inflammatory causes

• Presumed ocular histoplasmosis syndrome (POHS)
• Multiple evanescent white dot syndrome (MEWDS)
• Bird-shot retinochoroidopathy
• Multifocal choroiditis
• VKH syndrome
• Sympathetic ophthalmitis
• Serpiginous choroidopathy
• HIV retinopathy
• Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)

Degenerative dystrophic causes

• Stargardt’s disease
• Retinitis punctata albescens
• Cystinosis
• Drusen

Neoplastic causes

• Leukemic retinopathy
• Metastatic tumours
• Large-cell lymphoma (Non-Hodgkin’s lymphoma)

Traumatic causes
• Purtscher’s retinopathy

Miscellaneous causes

• Choroquine or tamoxifen toxicity
• Photocoagulation spots

MALIGNANT MELANOMA OF CHOROID

• Most common primary intraocular tumour of the adults
• Extremely rare in Negroes
• Commonly seen between 6th and 9th decade of life.
• It arises from the pigment cells derived from the neural crest (neuroectodermal).
• May arise from the pre-existing naevus or de- novo from the mature melanocytes present in the, stroma.
• Earliest pathognomic sign is appearance of orange patch due to accumulation of lipofuscin in the retinal pigment epithelium.
• Associated are intraretinal or vitreous haemorrhage.

Glaucoma may develop with or without uveitis due to any of the following:

• Obstruction of vortex veins
• Angle blockage by forward displacement of the lens iris diaphragm.
• Neovascularization of the angle
• Infiltration of the angle by tumour cells.

MISCELLANEOUS POINTS

• Patients with aniridia have a higher prevalence of Wilms’ tumour.
• Coloboma of the uveal tract is the commonest congenital anomaly of the eye.
• Typical iris coloboma occurs in the inferonasal quadrant. It results from failure of closure of the embryonic fissure.
• Albinism results from tyrosinase deficiency.
• Blue iris occurs due to the absence of pigment in the iris stroma.
• Sarcoidosis and Behcet’s syndrome show increased Ig A levels.
• Persistent pupillary membrane is a remnant of anterior vascular sheath of the lens. It is characterised by the stellate-shaped shreds of the pigmented tissue attached at the collarette
• The lesions in the choroid are restricted to isolated areas because of segmental blood supply to choroid.