Toxoplasmosis.

Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects. The infection can be congenital or acquired. Ocular symptoms are variable according to the age of the subject. For instance, young children present with reduced visual acuity, strabismus, nystagmus, and leucocoria, while teenagers and adults complain of decreased vision, floaters, photophobia, pain, and hyperemia. Toxoplasmic retinochoroiditis typically affects the posterior pole, and the lesions can be solitary, multiple or satellite to a pigmented retinal scar. Active lesions present as grey-white focus of retinal necrosis with adjacent choroiditis, vasculitis, hemorrhage and vitreitis. Cicatrization occurs from the periphery towards the center, with variable pigmentary hyperplasia. Anterior uveitis is a common finding, with mutton-fat keratic precipitates, fibrine, cells and flare, iris nodules and posterior synechiae. Atypical presentations include punctate outer retinitis, neuroretinitis, papillitis, pseudo-multiple retinochoroiditis, intraocular inflammation without retinochoroiditis, unilateral pigmentary retinopathy, Fuchs'-like anterior uveitis, scleritis and multifocal or diffuse necrotizing retinitis. The laboratory diagnosis of toxoplasmosis is based on detection of antibodies and T. gondii DNA using polymerase chain reaction (PCR). Toxoplasmosis therapy includes specific medication and corticosteroids. There are several regimens, with different drug combinations. Medications include pirimetamine, sulfadiazine, clindamycin, trimethoprime-sulphamethoxazol, spiramycin, azithromycin, atovaquone, tetracycline and minocycline. The prognosis of ocular toxoplasmosis is usually good in immunocompetent individuals, as long as the central macula is not directly involved.

Fuchs' heterochromic cyclitis.

Fuchs' heterochromic cyclitis (FHC) is a chronic anterior segment inflammatory syndrome that accounts for 2 to 3% of all uveitis cases. The etiology is unknown, but Herpes simplex, ocular toxoplasmosis and rubella infection have been implicated in the pathogenesis of the disease. It occurs more commonly in the third and fourth decades of life with an equal gender distribution. Patients are usually asymptomatic but may present with floaters and blurry vision. There is a mild but persistent anterior chamber reaction with diffuse and characteristic white stellate keratic precipitates. Iris and trabecular meshwork show abnormal vessels that may sometimes lead to a hyphema. Synechia formation is uncommon. Heterochromia is considered an important feature and accounts for the name, but it is variable depending on the intensity of the anterior stromal atrophy, initial iris color and amount of pigment in the iris pigmented epithelium. Progression of the disease is associated with cataract formation and glaucoma. Anti-inflammatory treatment is not indicated for the low-grade anterior chamber reaction seen in Fuchs' patients. Occasionally, a short course of corticosteroids is indicated if a symptomatic exacerbation occurs. The long-term prognosis is good, and patients usually maintain a visual acuity of 20/40 or better.

Intermediate uveitis.

Intermediate uveitis is an intraocular inflammation involving the anterior vitreous, peripheral retina and pars plana. It usually affects patients from 5 to 30 years old, without gender or racial preferences. The etiology is unknown but there are several associated diseases: multiple sclerosis, idiopathic optic neuritis, autoimmune corneal endotheliopathy, sarcoidosis, thyroid diseases and inflammatory bowel diseases. Symptoms are blurry vision, floaters and distortion of central vision. The syndrome is bilateral in 80% of the patients and chronic with periods of exacerbation and remission. Clinical presentation includes: mild to moderate anterior chamber inflammation, thin keratic precipitates in the inferior portion of the cornea, autoimmune endotheliopathy, vitreitis, vasculitis in the peripheral retina, intravitreal "snowballs," retinal "snowbanking," optic neuritis and cystoid macular edema. Cataract and glaucoma are frequent complications. Treatment of intermediate uveitis is based on periocular and oral corticosteroids. Cryotherapy or laser photocoagulation of the peripheral retina are options in patients with snowbanking when there is an insufficient response to periocular or systemic corticosteroids. Imunosuppression may also be used when other therapies fail, and Cyclosporin A is the first drug of choice. Pars plana vitrectomy is indicated in patients with chronic significant inflammation, non-responsive cystoid macular edema, non-clearing vitreous hemorrhage, tractional retinal detachment and epiretinal membranes. The long-term prognosis of intermediate uveitis is usually good, particularly with strict control of inflammation and with proper management of complications. Patients can often maintain a vision of 20/50 or better.

Acute retinal necrosis.

Acute retinal necrosis (ARN) is an uncommon intraocular inflammatory syndrome characterized by severe and diffuse uveitis, retinal vasculitis, and retinal necrosis. It is typically described to occur in immunocompetent patients, but can also be found in immunocompromised subjects. Varicella-zoster virus (VZV), herpes simplex virus (HSV 1 and 2), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) have been implicated in the etiology of ARN. The characteristic features of the disease include iridocyclitis, vitritis, retinal vasculitis, and retinal necrosis. Bilateral involvement occurs in two-thirds of the patients, frequently in the first six weeks, but sometimes months to years later. Retinal detachment occurs in 75% of the cases. The diagnosis of ARN is usually based in clinical features. The use of polymerase chain reaction (PCR) in aqueous humor samples is useful to identify the etiology of the disease. The treatment of ARN includes intravenous acyclovir, corticosteroids and aspirin. To prevent fellow eye involvement, intravenous acyclovir is followed by oral acyclovir for 14 weeks. Alternatives to acyclovir include ganciclovir, foscarnet, famcyclovir, brivudine, and valgancyclovir.

Tuberculosis.

Tuberculosis is caused by Mycobacterium tuberculosis, transmitted primarily by inhalation of aerosolized droplets containing the organisms. There is an infection of the respiratory tract and the tubercle bacilli spread via lymphatic system and bloodstream to many different organs. Generally, the pulmonary tuberculosis infections are asymptomatic and a positive skin test result is the only indication of it. Approximately 10% of infected individuals develop active disease. Immunosuppression caused by systemic diseases or medication increases the risk of developing tuberculosis. In addition to the pulmonary tract, tuberculosis may affect many organs and systems, including lymph nodes, larynge, middle ear, genitourinary tract, musculoskeletal system, central nervous system, gastrointestinal tract, pericardium, and skin. Ocular involvement is an uncommon event in tuberculous infection, and there are several presentations involving the iris, ciliary body, choroid, retina and optic nerve. The diagnosis is based in the detection of mycobacteria in fluids and tissues. If there is no available material for analysis, a presumptive diagnosis is made and therapeutic test initiated. The therapy is based in anti-tuberculous drugs and corticosteroids. The standard treatment protocol in Brazil includes isoniazid, rifampim, and pyrazinamid for two months, followed by isoniazid and rifampin for four months for susceptible organisms. Alternative regimens are necessary in the presence of drug resistance.

Sarcoidosis.

Sarcoidosis is a multisystem granulomatous disease with an unknown etiology, characterized by the presence of noncaseating granulomas in involved organs. It has a worldwide prevalence, but variable incidence among different geographical regions. The disease affects adults between 20 and 40 years of age, and it is slightly more common in women than men. Sarcoidosis is 3 to 4 times more prevalent in US blacks than whites. It usually presents with bilateral hilar adenopathy, pulmonary infiltrates and skin or eye involvement. The eye or adnexa are affected in 25 to 80% of the sarcoidosis patients. The disease can involve the orbit, lacrimal gland, anterior and posterior segments of the eye. Typical sarcoid uveitis presents with bilateral mutton-fat keratic precipitates, cells, flare, iris nodules, anterior and posterior synechia, and increased ocular pressure. Posterior involvement includes vitreitis, vasculitis, choroidal lesions, and optic neuropathy. Long term complications are common, and cystoid macular edema is the most important and sight-threatening consequence. Laboratory tests for the diagnosis of sarcoidosis include chest radiography or CT scan, bronchoscopy with bronchoalveolar lavage, angiotensin converting enzyme (ACE), Lysozyme, serum and urinary calcium, gallium scintigraphy, and biopsy. The only confirmatory test is biopsy showing classic noncaseating granulomas. Oral corticosteroids are the mainstay of treatment of sarcoidosis. Systemic cytotoxic agents like methrotrexate, azathioprine, and chlorambucil may be used in refractory cases. The visual prognosis of sarcoidosis is usually good.

Behçet's disease.

Behçet's disease is a chronic, relapsing vasculitis that can affect most organ systems. The prevalence varies geographically, and the disease is more common in countries along the ancient Silk Road, including Italy, Turkey, Israel, Saudi Arabia, Iran, China, Korea and Japan. Behçet's is more common in men than in women, and typically affects young adults. The classic finding in Behçet's patients is the presence of recurrent mucocutaneous ulcers, and oral aphthous ulcerations are usually the initial symptom. Other manifestations include genital ulcers, skin lesions, vascular, neurological, articular, and ocular disease. The disease can affect the anterior and/or posterior segments of the eye, and the main manifestations include iridocyclitis, hypopyon, mild to moderate vitreitis, retinal vasculitis and occlusion, optic disc hyperemia, and macular edema. There is no pathognomonic laboratory test in Behçet's disease, and the diagnosis is based in systemic and ocular clinical findings. Treatment of ocular Behçet is based in corticosteroids and immunosuppressive agents, to suppress acute inflammation and reduce its recurrence frequency. Ocular lesions may improve with immunosuppressive therapy, but usually are not fully reversible, and generally progress over time. The prognosis of anterior uveitis is usually good, but patients with posterior lesions tend to have some degree of visual loss, even with adequate treatment.