Uveitis refers to inflammation within the eye. This inflammation is mainly within the uveal tract (the vascular layer including the choroid, ciliary body and iris) but can also refer to inflammation of the retina and vitreous.
Uveitis in the iris and cilliary body (the front of the eye) is known as anterior uveitis. If the uveitis is in the ciliary body, then vitreous humour in middle of the eye can be affected (and become cloudy) and this is known as intermediate uveitis. Inflammation in the choroid, involving the retina or retinal vessels, is known as posterior uveitis and can also cause clouding of the vitreous humour.
Juvenile Idiopathic Arthritis (JIA) is the commonest systemic disease associated with uveitis and affects 15% of children with JIA. There are many other causes of uveitis however. JIA associated uveitis is usually chronic anterior uveitis (CAU) and can occur before or after the onset of the arthritis (usually up to 7 years after the onset of arthritis). CAU is invariably asymptomatic (i.e. no pain, blurring or photophobia) and the eye is not red. It can be bilateral and is only detected by eye screening. Once a child develops symptoms (e.g., blurring, floaters) then the visual outcome is worse. JIA uveitis can cause irreversible blindness if not detected and treated. Uveitis can occur in any subtype of JIA and at any time (even before onset of arthritis) but typically affects young children (under 7 years) with oligoarticular JIA rather than polyarticular onset and those carrying antinuclear antibody (ANA).
Uveitis is much less common in systemic JIA and chronic anterior uveitis is not typically associated with childhood onset enthesitis related arthritis (ERA) or Rheumatoid factor positive JIA. The presence of psoriasis may increase the risk of chronic anterior uveitis.
All children with suspected JIA should have eye screening with a slit lamp examination performed by an ophthalmologist although in some health care contexts this can be done by an experienced optician. Screening is required at regular intervals and often for several years as uveitis can occur at any time and be asymptomatic. Flares may occur during changes or breaks in systemic treatment and even when there is no active arthritis. Poor prognostic features for visual outcomes include onset of visual symptoms before being detected by screening and uveitis prior to arthritis. Visual loss occurs due to cataract, band keratopathy and glaucoma.
Children with JIA who carry HLA B27 (such as ERA patients) may develop an acute uveitis with a painful red often photophobic eye - this is rather like acute anterior uveitis that develops in ankylosing spondylitis in adults. Children with HLA B27 and ERA do not need regular eye screening as they will present with acute uveitis flares.
The photograph below shows acute uveitis in HLA B27 related Enthesitis Related Arthritis - the eye is painful, inflamed, and photophobic.
The photograph below shows an eye that is blind from cataract and keratopathy.