Anatomic Classification of Uveitis

Wendy M. Smith

Lisa J. Faia

Sunir J. Garg

H. Nida Sen

The uvea—made up of the iris, ciliary body, and choroid—is a pigmented, vascular structure of the eye. These anatomic components can be used to divide the uveal tract into anterior (iris and ciliary body), intermediate (ciliary body and pars plana), and posterior (choroid) locations. Inflammation of the uveal tract, or uveitis, may also involve the retina and the retinal vasculature.

CLASSIFICATION

In 2004, the First International Workshop on Standardization of Uveitis Nomenclature (SUN) endorsed an anatomic classification of uveitis based on the International Uveitis Study Group criteria.

Before these working groups, there were several grading systems in use. Standardization of classification criteria, inflammation grading schema, and outcomes allows comparisons of clinical research from different centers. The use of these criteria confers several advantages, including better definition of the clinical course of disease and more efficient evaluation of new therapies. The SUN classification contains several important features.

• The type of uveitis is determined by the predominant site(s) of uveal inflammation.

The anatomic localizations are anterior, intermediate, posterior, and panuveitis (Table 2-1).
Identifying the predominant site of inflammation also helps narrow the differential diagnosis (Table 2-2). Significant inflammation of the anterior chamber and vitreous is not panuveitis. (These should be classified as anterior and intermediate uveitis, respectively.)

• Anatomic classification is not influenced by the presence of structural complications.

For example, the presence of macular edema or optic disc edema alone is not enough to classify an eye as “posterior uveitis.” Macular edema due to anterior chamber inflammation would be correctly categorized as anterior uveitis.
Vitritis plus peripheral vascular sheathing or macular edema is defined as intermediate uveitis because this is the predominant site of inflammation.

• Pars planitis is a specific, idiopathic disease entity defined by the presence of snowball or snowbank formation in the absence of an associated infection or systemic disease; otherwise, the correct term is intermediate uveitis. The SUN working group criteria currently have a few limitations:

TABLE 2-1. SUN Working Group Anatomic Classification of Uveitis

Type	Primary Site of Inflammation	Includes
Anterior uveitis	Anterior chamber	Iritis, iridocyclitis, anterior cyclitis
Intermediate uveitis	Vitreous	Pars planitis, posterior cyclitis, hyalitis
Posterior uveitis	Retina or choroid	Focal, multifocal, or diffuse choroiditis; chorioretinitis, retinochoroiditis, retinitis, neuroretinitis
Panuveitis	Involves all compartments of the eye without one location predominating
SUN, Standardization of Uveitis Nomenclature.
Adapted from Jabs DA, Nussenblatt RB, Rosenbaum JT; Standardization of Uveitis Nomenclature (SUN) Working Group.
Standardization of uveitis nomenclature for reporting clinical data. Results of the First International Workshop. Am J Ophthalmol. 2005;140(3):509-516.

TABLE 2-2. Differential Diagnosis of the Major Causes of Uveitis

ANTERIOR UVEITIS^*
	Granulomatous	Nongranulomatous
	Sarcoidosis	Human leukocyte antigen (HLA) B27-associated (including ankylosing spondylitis, reactive arthritis, inflammatory bowel disease, and psoriatic arthritis)
	Syphilis
	Tuberculosis
	Herpes simplex	Juvenile rheumatoid arthritis
	Leptospirosis	Fuchs heterochromic iridocyclitis
	Brucellosis	Posner-Schlossman (glaucomatocyclitic crisis)
	Lens associated	Masquerade syndromes
	Idiopathic	Uveitis-glaucoma-hyphema syndrome
		Trauma
		Kawasaki disease
		Drug induced (rifabutin, cidofovir)
INTERMEDIATE UVEITIS
	Sarcoid,
	syphilis
	Inflammatory bowel disease
	Multiple sclerosis
	Pars planitis (idiopathic)
	Lymphoma, lyme
	Other (tuberculosis, Behçet disease, Vogt-Koyanagi-Harada disease, Whipple disease, toxoplasmosis, endophthalmitis)
POSTERIOR UVEITIS
	Focal Retinitis	Multifocal Retinitis
	Toxoplasmosis	Syphilis
	Onchocerciasis	Herpes simplex virus (acute retinal necrosis)
	Cysticercosis	Cytomegalovirus
	Masquerade syndromes	Sarcoidosis
		Masquerade syndromes
		Candidiasis
		Progressive outer retinal necrosis
		Eales disease
		Diffuse unilateral subacute neuroretinitis
PANUVEITIS
	Sympathetic ophthalmia
	Vogt-Koyanagi-Harada
	Behçet disease
	Endophthalmitis
	Sarcoidosis
	Lens associated
	Lyme disease
	Masquerade syndromes
	Toxoplasmosis
	Syphilis
	Tuberculosis
CHOROIDITIS
	Focal Choroiditis	Multifocal Choroiditis
	Tuberculosis	Histoplasmosis
	Toxocariasis	Pneumocystis choroiditis
	Nocardia	Serpiginous choroiditis
	Candidiasis	Birdshot
	Masquerade syndromes	Lymphoma
		Acute posterior multifocal placoid pigment epitheliopathy
		Multifocal choroiditis/punctate inner choroiditis
		Masquerade syndromes
		Cryptococcus
		Mycobacterium
^*This category is usually divided into granulomatous (mutton fat keratic precipitates) and nongranulomatous uveitis. All of the granulomatous entities can look nongranulomatous (especially with chronicity), but the nongranulomatous ones do not look granulomatous.
Pearl: Sarcoidosis, syphilis, tuberculosis, lyme, and lymphoma can look like anything.