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.
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 (IUSG) criteria.
Prior to 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. 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 to 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 disk 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, as this is the predominant site of inflammation.
|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 predominating|
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.
|Human leukocyte antigen-B27–associated (including ankylosing spondylitis, Reiter’s syndrome, inflammatory bowel disease, psoriatic arthritis)|
Juvenile rheumatoid arthritis
Fuchs’ heterochromic iridocyclitis
Posner-Schlossman (glaucomatocyclitic crisis)
Drug-induced (rifabutin, cidofovir)
Inflammatory bowel disease
Pars planitis (idiopathic)
Other (tuberculosis, Behçet’s, Vogt-Koyanagi-Harada, Whipple’s disease, toxoplasmosis, endophthalmitis)
|Focal Retinitis||Multifocal Retinitis|
Herpes simplex virus (acute retinal necrosis)
Progressive outer retinal necrosis
Diffuse unilateral subacute neuroretinitis
|Focal Choroiditis||Multifocal Choroiditis|
Acute multifocal placoid pigment epitheliopathy
Multifocal choroiditis/punctate inner choroiditis
*This category is usually divided up into granulomatous (mutton fat KP) and nongranulomatous uveitis. All of the granulomatous ones can look nongranulomatous, but the nongranulomatous ones do not look granulomatous.
Pearl: Sarcoid, syphilis, tuberculosis, Lyme, and lymphoma can look like anything.
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 has a few limitations:
It does not provide criteria for diagnosis of specific uveitic entities.
It does not address the classification of neuroretinitis.
It is still undergoing validation.
The SUN working group also standardized the descriptors of uveitis in order to facilitate clinical descriptions of diseases both for clinical care as well as for research purposes.
Limited (≤3 months)
Persistent (>3 months)
Course of disease
Acute (sudden onset and limited duration)
Chronic (persistent uveitis with relapse <>3 months after discontinuing therapy)
Recurrent (repeat episodes of uveitis separated by at least 3 months without treatment)
Presence of hypopyon should be noted separately
A more recent grading system using calibrated Bangerter diffusion filters and color photographs for assessing vitreous haze is a promising technique that requires further validation (Davis et al.).