Introduction

Uvea is the collective term traditionally used to describe the central vascular layer of the eye. The uvea is divided anatomically into three parts: anterior iris, intermediate ciliary body, and the posterior choroid (188). The ciliary body is further delineated by an anterior portion, the pars plicata, and a posterior portion, the pars plana. The functions of the uvea include thermoregulation, production of the aqueous fluid, and nutritional support for the structures of the eye. Over 95% of the blood flow to the eye is distributed throughout the uvea with a majority transported through the choroid.

Uveitis is a collective term, used to describe intraocular inflammatory diseases that affect the uveal tract. Many of these diseases also affect other ocular tissues, and many are ocular manifestations of systemic diseases. Uveitis is an uncommon disease with a prevalence of 0.5% in the general population, of which 5–10% is classified as pediatric uveitis. It is important for the pediatrician to recognize a potential case of uveitis because it is an often treatable, visionthreatening disease that has the best prognosis when discovered early in its course.

The most common clinical symptoms of uveitis include blurred vision, photophobia, pain, and conjunctival/scleral redness. Some patients or parents may only notice epiphora (increased tearing). Patients with posterior or intermediate disease may complain of floaters or decreased vision from swelling of their macula (189). Many of these symptoms may not be present in the pediatric patient and often an asymptomatic pediatric uveitis is discovered by routine ophthalmologic screening. In some pediatric patients, the presenting complaint is decreased vision that is secondary to longstanding uveitis with cataract formation.

Early uveitis in a child may not be apparent on routine examination by a pediatrician. By the time clinical signs of uveitis become visible without a slit-lamp, significant damage may have already occurred.

External examination of a child with uveitis may show redness around the limbus, called ciliary flush (190), or may be normal. Ciliary flush is more commonly seen in cases of adult uveitis and frequently the external examination in pediatric uveitis is normal.

Optic nerve

Central retinal artery and vein

Area of the

optic disk

Vitreous chamber

Corneal signs common to uveitis include keratic precipitates (191), which are collections of white blood cells on the posterior corneal surface, and corneal edema (192) may be present if there is an elevation in the intraocular pressure (IOP). Keratic precipitates can often be seen in the red reflex of a direct ophthalmoscope (193).

189

189 Uveitic swelling of the macula.(Courtesy of Peter Buch,CRA.)

190 Ciliary flush and uveitis with retained lens fragment in the anterior chamber after cataract extraction.(Courtesy of Peter Buch,CRA.)

191 Collections of white blood cells on the posterior cornea (keratic precipitates). (Courtesy of Hasan M.Bahrani,MD.)

192 Corneal edema in a patient with chronic uveitis.(Courtesy of Peter Buch,CRA.)

193 Retroillumination of keratic precipitates. (Courtesy of Peter Buch,CRA.)

194

194 White blood cells and leaked protein (flare) in the anterior chamber.(Courtesy of Hasan M. Bahrani,MD.)

195

195 Severe intraocular inflammation with hypopyon formation.(Courtesy of Peter Buch, CRA.)

The hallmark of uveitis in the anterior chamber is visualization of cells (white blood cells) and flare (protein that has leaked from inflamed vessels) (194). When the inflammation is significant, the white blood cells can layer out inferiorly in the anterior chamber in a hypopyon (195).

With chronic inflammation that has continued for a long period of time (months to years), it is common for scarring of the iris to occur along with development of cataract. When the iris scars to the cornea it is termed anterior synechia. When the iris scars to the lens it is termed posterior synechia (196, 197).

Classification

There is no universally accepted technique for classifying uveitis. Many authors choose to classify uveitis based on causative factor. Those texts generally group uveitis into inflammatory or infective categories. Classification can also be based on time course of the disease, with acute, subacute, and chronic types as the major subclassifications. Many ophthalmic texts also classify uveitis in terms of white cell types using granulomatous and nongranulomatous as the major subclassifications. In terms of recognition and diagnosis, the pediatrician will likely find it easier to classify uveitis based on the anatomical structures involved. For the purposes of this text, uveitis will be classified into four categories: anterior uveitis, intermediate uveitis, posterior uveitis, and masquerade syndromes (Table 14).

196 Scarring of the iris (synechiae) to both the cornea (anterior) and the lens (posterior). (Courtesy of Hasan M.Bahrani,MD.)

197 Severe posterior synechiae with cataract formation.(Courtesy of Peter Buch,CRA.)