Background:
Approximately 6% of all
cases of uveitis arise in children. The most frequent cause of chronic
intraocular inflammation among children is juvenile rheumatoid arthritis
(JRA)-associated uveitis. Chronic iridocyclitis occurs in 10-20% of all patients
with JRA. Chronic uveitis characteristically is asymptomatic in children with
JRA, leading to insidious but progressive morbidity and possible blindness. The
involved eyes often are white and quiet appearing, yet 30-40% of patients with
JRA-associated uveitis experience severe loss of vision as a consequence of
their condition.
JRA, as defined by the American Rheumatism Association (ARA), is the presence
of arthritis (chronic, seronegative, and peripheral) before age 16 years, of at
least 3 months duration, when other causes have been excluded. It is classified
by 1 of 3 types of onset.
Oligoarticular (pauciarticular) onset JRA (40-60%) is common in girls (5:1).
Peak age of onset is at age 2 years. Four or fewer joints are involved during
the first 6 months of the disease (often asymmetric). Oligoarticular onset
commonly involves the knees and, less frequently, the ankles and wrists. The
arthritis may be evanescent, rarely destructive, and radiologically
insignificant. Approximately 75% of these patients test positive for antinuclear
antibody (ANA). This mode of onset rarely is associated with systemic signs. A
high risk for uveitis exists.
Polyarticular onset JRA (20-40%) is common in girls (3:1). Peak age of onset
is at age 3 years. It involves 5 or more joints during the first 6 months of the
disease. Polyarticular onset commonly involves the small joints of the hand and,
less frequently, the larger joints of the knee, ankle, or wrist. Asymmetric
arthritis may be acute or chronic and may be destructive in 15% of patients.
Immunoglobulin M (IgM) rheumatoid factor (RF) is present in 10% of children with
this JRA subgroup. It is associated with subcutaneous nodules, erosions, and a
poor prognosis. Approximately 40% of these patients test positive for ANA.
Systemic symptoms, including anorexia, anemia, and growth retardation, are
moderate. An intermediate risk for uveitis exists.
Systemic onset JRA (10-20%) is equal frequency in boys and girls and can
appear at any age. Symmetric polyarthritis is present and may be destructive in
25% of patients. Hands, wrists, feet, ankles, elbows, knees, hips, shoulders,
cervical spine, and jaw may be involved. ANA is positive in only 10% of the
patients. Systemic onset is associated with fever (high in evening and normal in
morning), macular rash, leukocytosis, lymphadenopathy, and hepatomegaly.
Pericarditis, pleuritis, splenomegaly, and abdominal pain less commonly are
observed. A low risk for uveitis exists.
Pathophysiology:
The cause of uveitis
and arthritis in JRA remains unknown. Akin to many other autoimmune diseases,
the target antigen is unidentified. Immune reactions to ocular antigens (S
antigen or iris antigen) have been studied; however, their actual role (active
or passive) is unknown. The course of the disease may be short and limited or
progressive and severe.
Frequency:
-
In the US:
JRA has an estimated prevalence of about 113
cases per 100,000 children. It is estimated that JRA afflicts 60,000-70,000
children, but only a minority develop eye disease. Incidence of eye disease in
the JRA population is uncertain but is believed to be around 10%.
Mortality/Morbidity:
Morbidity in JRA-associated uveitis may
result either from lack of treatment or from overzealous treatment. Mortality
may result from the latter.
Race: No known racial predilection exists.
Sex: A strong predilection exists for girls. The girl-to-boy
ratio is 4:1.
Age: JRA is a childhood disease.
