Uveitis

Definition: it is an inflammation of the uveal tract (Iris, Ciliary body and choroid) and adjacent structures, most probably the retina. Classification: - Anatomical. - Clinical. - Aetiological.

Anatomical Classification: 1- Anterior uveitis: which is subdivided into: a- Iritis: in which inflammation predominantly affects the iris. b- Iridocyclitis: in which both the iris and anterior part of the ciliary body (pars plicata) are equally involved. 2- Intermediate uveitis: It is characterized by involvement predominantly of the posterior part of the ciliary body (pars plana), periphery of the retina and the underlying periphery of the choroid. 3- Posterior uveitis: Inflammation of the choroid and retina posterior to the equator of the eye. 4- Panuveitis: Involvement of the entire uveal tract.

Clinical classification: 1- Acute uveitis: usually has a sudden, symptomatic onset and persists for up to 3 months. If the inflammation recurs following the initial attack it is referred as recurrent acute uveitis. 2- Chronic uveitis: the onset is frequently insidious and may be asymptomatic. It usually persists for longer than 3 months. Acute or subacute exacerbations on chronic may occur.

Aetiological classification: 1- Idiopathic: which forms more than 50% of cases of uveitis. 2- Associated with a systemic disease, e.g.: a- Spondyloarthopathies: ankylosing spodylitis, Reiter's syndrome, psoriatic arthritis and chronic juvenile arthritis. b- Inflammatory bowel disease: ulcerative colitis, Crohn's disease, Whipple's disease. c- Nephritis. d- Non-infectious multi-system disease: sarcoidosis, Behçet's disease. e- Infectious systemic disease: e.g. TB, syphilis f- Diabetes. 3- Infections: a- Bacterial: tuberculosis. b- Fungal: Candidiasis. c- Viral: Herpes Zoster. 4- Infestations: a- Protozoa: Toxoplasmosis. b- Nematodes: Toxocariasis.

Clinical Features: Anterior uveitis Symptoms: Acute anterior uveitis: Photophobia, pain, redness, decreased visual acuity and lacrimation. Chronic anterior uveitis: may be asymptomatic or give rise to mild redness and the perception of floaters.

Signs: 1- Circumcorneal injection: acute anterior uveitis has a violaceous hue. 2- Miosis 3- Keratic precipitates: cellular deposits on the corneal endothelium (deposition of inflammatory cells into corneal endothelium). Their characteristics and distribution may indicate the probable cause of uveitis. 4- Cells: indicative of acute inflammation: it is graded from 1 to 4. a- Aqueous cells. b- Anterior vitreous cells. 5- Aqueous flare: is seen due to scattering of light by proteins that have leaked into aqueous humour by break down of blood-aqueous barrier. It is graded from 1 to 4 according to its haziness or obscuration to the details of iris. 6- Iris nodule: which is a feature of chronic granulomatous inflammation. 7- Hypopyon

  Complications of anterior uveitis: 1- Posterior synechiae: 360° (seclusio pupillae) causes iris bombé that leads to closure of the angle of anterior chamber and ends with secondary angle closure glaucoma. 2- Cataract. 3- Glaucoma: inflammatory or secondary angle closure glaucoma. 4- Cyclitic membrane formation which leads to traction and then detachment of the Ciliary body which causing phthisis bulbi.

Intermediate Uveitis Symptoms: Initially, floaters (inflammatory cells in anterior vitreous) and later, decreased visual acuity due to macular edema (due to associated vitritis). Signs: Cellular infiltration of vitreous (vitritis). Vitreous snowballs Peripheral periphlebitis Snowbanking is characterized by a grey-white fibrovascular plaque which may occur in all quadrants, but is most frequently inferior

Complications: Cystoid macular oedema. Cyclitic membrane and phthisis bulbi. Cataract. Tractional retinal detachment.

  Posterior uveitis Symptoms: 1- Floaters (due to cells and flare in the vitreous). 2- Impairment of visual acuity (due to macular oedema). Signs: 1- Cells, flare, opacities and posterior vitreous detachment (inflammatory process of vitreous (vitritis) leads to its shrinkage and then separation of posterior vitreous face from the retina). 2- Retinitis: ill-defined, focal, white, cloudy appearance of retina with obscuration of retinal vessels. 3- Vasculitis: acute vasculitis, which is characterized by a fluffy white haziness surrounding the blood vessels.

Complications: 1- Cystoid macular oedema. 2- Macular ischaemia. 3- Epiretinal membrane formation. 4- Vascular occlusion. 5- Retinal detachment (tractional). 6- Consecutive optic neuropathy (due to ischaemia that affects the ganglion cells layer, nerve fiber layer and the optic disc itself).

Special investigations for patients with uveitis: 1- X-Ray: - Sacroiliac joint (for ankylosing spondylitis). - Chest x-ray (for TB and sarcoidosis). - Skull calcification: toxoplasmosis. 2- Skin test: histoplasmosis, Mantoux and kveim (for sarcoidosis). 3- Serum tests: ANA (Anti-Nuclear Antibodies) as in chronic juvenile arthritis, VDRL, toxoplasmosis test (IFAT) and ELISA. 4- HLA-typing: HLA-B27 for ankylosing spondylitis and B5, B51 for Behçet's disease.

Treatment: 1- Mydriatics: Short acting: Tropicamide 0.5% (for <1y) & 1% (for > 1y), the duration of action is 6 hours. Cyclopentolate 0.5% (for <1y) & 1% (for > 1y), the duration of is 24hours. Phenylnephrine (sympathetic agonist) Long acting: Atropine 0.5% (for <1y) & 1% (for > 1y), it is the most powerful cycloplegic and mydriatic, its duration of action is 2 weeks.

Indications for these mydriatic and cycloplegic drugs: a- To promote comfort through muscles paralysis (except phenynephrine). b- To prevent formation of posterior synechiae through continuous movement of the pupil. c- To break down recently formed synechiae.

2- Steroids: -Topical steroids: only for anterior uveitis, because they do not reach therapeutic levels behind the lens. Potent steroids are: prednisolone acetate, dexamethasone and betamethasone. Side effects of topical steroids (especially after prolonged use): a- Glaucoma. b- Cataract. c- Corneal complications: they are rare, e.g. bacterial and fungal keratitis and recurrence of herpes simplex keratitis. d- Systemic side effects.

-Periocular injection of steroids: Indications: a- Severe acute anterior uveitis. b- As an adjunct to topical or systemic steroid in resistant cases. c- Intermediate uveitis. d- Poor patient compliance with topical or systemic steroids. -Intravitreal injection of steroids: Injection of triamcinolone acetonide (2mg in 0.05ml) in resistant uveitic chronic cystoid macular oedema.

-Systemic steroids: Prednisolone tablets Indications: a- Intractable anterior uveitis resistant to topical and periocular steroids. b- Intermediate uveitis unresponsive to preiocular injection. c- Posterior ueveitis or panuveitis, particularly with severe bilateral involvement.

3- Immunosuppressive agents: Either Antimetabolites (cytotoxic) as Azathioprine and Methotrexate, Or T-cell inhibitors as ciclosporin. Indications: a- Sight (vision)-threatening uveitis: Which is usually bilateral, non-infectious and has failed to response to adequate steroid therapy. b- in patients with intolerable side effect from systemic steroids.