Anterior uveitis primarily involves inflammation of the iris and ciliary body. When the anterior chamber is the primary site where inflammation is observed, the term iritis may be used for this inflammation. When inflammation is also observed in the anterior vitreous, the term iridocyclitis may be used.
Juvenile Idiopathic Arthritis
Juvenile idiopathic arthritis (JIA) (formerly, juvenile rheumatoid arthritis) is the most common identifiable etiology of childhood anterior uveitis. JIA is defined as arthritis of at least 6 weeks’ duration without an identifiable cause in children younger than 16 years. There are several subtypes of JIA, which are listed in Table 24-2.
Table 24-2 Subtypes of Juvenile Idiopathic Arthritis
Overall, the prevalence of uveitis in JIA varies from 2% to 34%. The subtypes of JIA that are particularly associated with uveitis are pauciarticular (oligoarthritis), polyarticular, psoriatic arthritis, and enthesitis-related arthritis. Uveitis almost never occurs in children with systemic arthritis and is very rare in those with rheumatoid factor–positive polyarticular subtype. In contrast to most forms of anterior uveitis, the uveitis associated with pauciarticular JIA and polyarticular JIA is initially asymptomatic. It has been described as “white iritis” because of the absence of a red eye. Screening for uveitis among children with JIA is therefore of great importance.
Pauciarticular is the most frequent type of JIA in children in North America and Europe. By definition, pauciarticular JIA affects 4 or fewer joints during the first 6 months of the disease. It occurs predominantly in young girls. Anterior uveitis is most likely to occur with this type of arthritis, developing in 10%–30% of patients. Laboratory markers include a high prevalence of antinuclear antibodies (ANA). Rheumatoid factor is almost always absent.
Children with polyarticular JIA show involvement of more than 4 inflamed joints during the first 6 months of the disease. This disease is more common in girls, and the mean age at onset is higher compared with pauciarticular JIA. Uveitis occurs in approximately 10% of these children. Affected patients may have a positive ANA test result, which is associated with an increased risk of uveitis. Human leukocyte antigen (HLA) associations have not been consistently documented.
The pathogenesis of the anterior uveitis associated with JIA is unknown, but it is likely to have an immunologic basis. The risk for development of uveitis is highest during the first 4 years after diagnosis of JIA. Among patients with JIA, 90% of uveitis cases develop within 7 years of onset of arthritis. Occasionally, uveitis is diagnosed before or at the onset of joint symptoms; in these cases, unfortunately, the prognosis is often poorer because the initially asymptomatic nature of the ocular inflammation often delays diagnosis and thus treatment. A shorter interval between the onset of arthritis and uveitis is also associated with a more aggressive course.
JIA-associated uveitis is usually bilateral and nongranulomatous with fine to medium-sized keratic precipitates, but a minority of children, especially African Americans, may have granulomatous precipitates. Chronic inflammation may produce band keratopathy (Fig 24-1), posterior synechiae, ciliary membrane formation, hypotony, cataract, glaucoma, and phthisis. Vitritis and macular edema occur infrequently.
Figure 24-1 Slit-lamp photograph from a patient with uveitis associated with juvenile idiopathic arthritis (JIA). As is typical in pauciarticular or polyarticular JIA, the conjunctiva is “white.” Band keratopathy is present.
(Courtesy of Amy Hutchinson, MD.)
Screening for uveitis
Recognition of the importance of screening for uveitis in children with JIA has resulted in an improved prognosis for this disorder. However, visual impairment has been reported in up to 40% of children with JIA-associated uveitis, and blindness may occur in as many as 10% of affected eyes. Screening guidelines continue to undergo revision but are based on 4 factors that are associated with an increased risk of uveitis:
Table 24-3 outlines the eye examination schedule for pauciarticular and polyarticular JIA, as recommended by the American Academy of Pediatrics. After 4 years, the eye examinations become less frequent. Although female sex is associated with a higher incidence of uveitis, this factor is not incorporated in the guidelines. Initial ophthalmologic examination should occur within 6 weeks of diagnosis.
Table 24-3 Frequency of Eye Examination in Patients With Pauciarticular or Polyarticular JIA
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.