Көздің ұйқыбас қабынуы

Inflammation of the uvea of the eye

Uveitis (,/juː//v//i//.//aɪ//t//I//s/) is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and includes the iris, ciliary body, and choroid. Uveitis is described anatomically, by the part of the eye affected, as anterior, intermediate or posterior, or panuveitic if all parts are involved. Anterior uveitis (iridocyclitis) is the most common, with the incidence of uveitis overall affecting approximately 1:4500, most commonly those between the ages of 20 60. Symptoms include eye pain, eye redness, floaters and blurred vision, and ophthalmic examination may show dilated ciliary blood vessels and the presence of cells in the anterior chamber. Uveitis may arise spontaneously, have a genetic component, or be associated with an autoimmune disease or infection. While the eye is a relatively protected environment, its immune mechanisms may be overcome resulting in inflammation and tissue destruction associated with T cell activation. Uveitis is an ophthalmic emergency that requires urgent control of the inflammation to prevent vision loss. Treatment typically involves the use of topical eye drop steroids, intravitreal injection, newer biologics, and treating any underlying disease. While initial treatment is usually successful, complications include other ocular disorders, such as uveitic glaucoma, retinal detachment, optic nerve damage, cataracts, and in some cases, a permanent loss of vision. In the United States uveitis accounts for about 10% 20% of cases of blindness.

Uveitis is classified anatomically into anterior, intermediate, posterior, and panuveitis forms—based on the part of the eye primarily affected. Before the twentieth century, uveitis was typically referred to in English as "ophthalmia." Anterior uveitis includes iridocyclitis and iritis. Iritis is the inflammation of the anterior chamber and iris. Iridocyclitis is inflammation of the iris and ciliary body with inflammation predominantly confined to the ciliary body. Between 66% and 90% of uveitis cases are anterior in location (iritis). This condition can occur as a single episode and subside with proper treatment or may take on a recurrent or chronic nature. Intermediate uveitis, also known as pars planitis, consists of vitritis—which is inflammation of cells in the vitreous cavity, sometimes with snowbanking, or deposition of inflammatory material on the pars plana. There are also "snowballs," which are inflammatory cells in the vitreous. Posterior uveitis or chorioretinitis is the inflammation of the retina and choroid. Panuveitis is the inflammation of all layers of the uvea.

Uveitis is usually an isolated illness, but can be associated with many other medical conditions. The most common form of uveitis is acute anterior uveitis (AAU). It is most commonly associated with HLA B27, which has important features: HLA B27 AAU can be associated with ocular inflammation alone or in association with systemic disease. HLA B27 AAU has characteristic clinical features including male preponderance, unilateral alternating acute onset, a non granulomatous appearance, and frequent recurrences, whereas HLA B27 negative AAU has an equivalent male to female onset, bilateral chronic course, and more frequent granulomatous appearance.

Rifabutin, a derivative of Rifampin, has been shown to cause uveitis. Several reports suggest the use of quinolones, especially Moxifloxacin, may lead to uveitis.

Onset of uveitis can broadly be described as a failure of the ocular immune system and the disease results from inflammation and tissue destruction. Uveitis is driven by the Th17 T cell sub population that bear T cell receptors specific for proteins found in the eye. Serum TNF α is significantly elevated in cases while IL 6 and IL 8 are present in significantly higher quantities in the aqueous humour in patients with both quiescent and active uveitis. These are inflammatory markers that non specifically activate local macrophages causing tissue damage.

The cause of non infectious uveitis is unknown but there are some strong genetic factors that predispose disease onset including HLA B27 and the PTPN22 genotype.

Recent evidence has pointed to reactivation of herpes simplex, varicella zoster and other viruses as important causes of developing what was previously described as idiopathic anterior uveitis. Bacterial infection is another significant contributing factor in developing uveitis.

Uveitis is assessed as part of a dilated eye exam. Prior to the administration of corticosteroids, corneal ulcers must be ruled out. This is typically done using a fluorescence dye test. In addition to corticosteroids, topical cycloplegics, such as atropine or homatropine, may be used. Successful treatment of active uveitis increases T regulatory cells in the eye, which likely contributes to disease regression. In severe cases an injection of posterior subtenon triamcinolone acetate may also be given to reduce the swelling of the eye. Intravitrial injection of steroid has proven to be a newer useful way to control inflammation for longer without the need for daily eyedrops. Dexamethasone and fluocinolone acetonide are two more commonly used options for noninfectious uveitis. Non biologic, steroid sparing therapies for noninfectious uveitis in adults are now more available. These include the disease modifying antirheumatic drugs (DMARDs) methotrexate, mycophenolate, cyclosporine, azathioprine, and tacrolimus. In comparing various studies, methotrexate is more efficacious than mycophenolate in inflammatory control for most forms of panuveitis. Methotrexate also had little to no differences in safety outcomes compared to mycophenolate. In the case of herpetic uveitis, anti viral medications, such as valaciclovir or aciclovir, may be administered to treat the causative viral infection.