Uveitis

Uvea is the vascular layer of the eye and comprises the iris, ciliary body, and choroid.

The ciliary body starts 1 mm from the limbus and extends posteriorly for about 6 mm. The first 2 mm consist of the pars plicata, and the remaining 4 mm comprises the flattened pars plana.

Uveitis, by strict definition, implies inflammation of the uveal tract. However, the term is commonly used to describe many forms of intraocular inflammation involving not only the uvea but also the retina and its vessels.

Anterior uveitis may be subdivided into:

• Iritis, in which the inflammation primarily involves the iris.
• Iridocyclitis, in which both the iris and the pars plicata of the ciliary body are involved.

Intermediate uveitis is defined as inflammation predominantly involving:

• The pars plana
• The peripheral retina
• The vitreous

Posterior uveitis involves the fundus posterior to the vitreous base.

• Retinitis with the primary focus in the retina.
• Choroiditis with the primary focus in the choroid.
• Vasculitis, which may involve veins, arteries, or both.

Panuveitis implies involvement of the entire uveal tract without a predominant site of inflammation.

Endophthalmitis implies inflammation, often purulent, involving all intraocular tissues except the sclera.

Panophthalmitis involves the entire globe, often with orbital extension.

• Acute Anterior Uveitis is the most common form of uveitis, accounting for three-quarters of cases.
• It is characterized by sudden onset and duration of 3 months or less.
• It is easily recognized due to the severity of symptoms, which will force the patient to seek medical attention.
• Presentation is typically with the sudden onset of unilateral pain, photophobia, and redness, which may be associated with lacrimation.
• Occasionally, patients may notice mild ocular discomfort a few days before the acute attack when clinical signs are absent.
• Visual acuity is usually good at presentation except in eyes with severe hypopyon.

Clinical Aspects and Examination Findings

• External examination shows ciliary (circumcorneal) injection.
• KP (keratic precipitates) are clusters of cellular deposits on the corneal endothelium composed of epithelioid cells, lymphocytes, and polymorphs. Their characteristics and distribution may indicate the probable type of uveitis.
• Miosis due to sphincter spasm may predispose to the formation of posterior synechiae unless the pupil is pharmacologically dilated.
• Anterior vitreous cells indicate iridocyclitis.
• Aqueous flare reflects the presence of protein due to a breakdown of the blood–aqueous barrier.
• Hypopyon is a feature of intense inflammation in which cells settle in the inferior part of the anterior chamber (AC) and form a horizontal level.
• Posterior synechiae may develop quickly and must be broken down before they become permanent.
• Low intraocular pressure (IOP) may occur as a result of reduced secretion of aqueous by the ciliary epithelium. Occasionally, the intraocular pressure may be elevated (hypertensive uveitis).
• Fundus examination is usually normal but should always be performed to exclude ‘spillover’ anterior uveitis associated with a posterior focus, notably toxoplasmosis.

Treatment

Steroid + Cycloplegia

Prognosis

The prognosis is usually very good. Complications and poor visual prognosis are related to delayed or inadequate management. Steroid-induced hypertension may occur, but glaucomatous damage is uncommon.

• It encompasses retinitis, choroiditis, and retinal vasculitis.
• Some lesions may originate primarily in the retina or choroid, but often there is involvement of both (retinochoroiditis and chorioretinitis).
• Presentation varies according to the location of the inflammatory focus and the presence of vitritis.
• For example, a patient with a peripheral lesion may complain of floaters, whereas a patient with a lesion involving the macula will predominantly complain of impaired central vision.
• Retinitis may be focal (solitary), multifocal, geographic, or diffuse. Active lesions are characterized by whitish retinal opacities with indistinct borders due to surrounding edema.
• Choroiditis may also be focal, multifocal, geographic, or diffuse. It does not usually induce vitritis in the absence of concomitant retinal involvement. Active choroiditis is characterized by a round, yellow nodule.
• Vasculitis may occur as a primary condition or as a secondary phenomenon adjacent to a focus of retinitis. Both arteries (periarteritis) and veins (periphlebitis) may be affected.