Uveitis

Anterior uveitis (iritis)

Anterior uveitis affects the front of the eye (usually the iris) and is the most common type of uveitis. It can affect one or both eyes depending on the cause.

Anterior uveitis symptoms include:

• An aching, painful, red eye. The pain can range from a mild ache to intense discomfort,
• Blurred or cloudy vision
• A small pupil or a distortion of the shape of the pupil
• An iris (the coloured part of the eye) that may have a slightly different colour
• Sensitivity to light (photophobia)
• Headaches.

These symptoms may develop gradually over hours or days and may gradually increase in intensity.

Intermediate uveitis

Intermediate uveitis is the second most common type of ocular inflammation. It predominantly affects the vitreous, a gel like structure found in the cavity just behind the ciliary body and in front of the retna in the middle part of the eye, both eyes tend to be affected and it is usually painless. Intermediate uveitis symptoms can include:

• Floaters (dots that move across the field of vision)
• Blurred vision due to cells and protein from the blood vessels leaking into the gel of the eye due to inflammation of the retinal blood vessel walls (retinal vasculitis)or deposits just behind the cilliary body (parsplanitis)
• Mild redness (although the inflamed eye may look completely normal despite having symptoms)

Posterior uveitis

Posterior uveitis affects the choroid, a layer of blood vessels supplying the retina (the nerve tissue responsible for vision). The choroid forms the middle layer of the wall of the eye, with the retina comprising the inner layer and the sclera the outer layer. One or both eyes may be affected and it is usually painless. However posterior uveitis is a more serious form of ocular inflammation than anterior uveitis.

Posterior uveitis usually causes decreased vision and floaters, and sometimes retinal detachment. Posterior uveitis symptoms are slower to develop and often last longer than those of anterior uveitis. It can be more damaging to the eye than other types of uveitis and can sometimes cause visual loss.

Scleritis

Scleritis, is a form of inflammation affecting predominantly the sclera, or outer white coat of the eye.

Scleritis may affect the front and/or back of the eye. It causes a very red eye and intense ocular pain, which can sometimes even prevent sleep.

If you experience any uveitis symptoms, you should immediately contact your GP who may refer you to an ophthalmologist for further investigation. An optometrist may also be able to detect uveitis, if very severe and recommend referral to a uveitis expert for investgation and treatment. It is recommended that urgent attention from an ophthalmologist is sought if signs of uveitis is accompanied by sudden or pronounced blurred vision, as this may represent the severe form of uveitis.

What are the types of uveitis?

The type of uveitis may be categorised according to which part of the eye is affected

• Anterior uveitis: Refers to inflammation of the iris (iritis) or inflammation of the iris and the ciliary body (iridocyclitis). It is the most common type of uveitis, accounting for 75% of cases in adults.

• Intermediate uveitis: This affects the area behind the ciliary body and the retina. It tends to occur in children, teenagers and young adults.

• Posterior uveitis: This is a severe form of uveitis which affects the back of the eye i.e. the choroid and the retina, and can seriously affect vision.Panuveitis is a type of uveitis that affects the entire uveal tract i.e. inflammation of both the front and the back of the eye at the same time. This form of uveitis can be sight threatening and should be reviewed without undue delay

Uveitis may also be categorised in accordance with the length of time that it lasts

• Acute uveitis lasts for a few weeks and can recur
• Chronic uveitis lasts for more than three months, with symptoms that can vary over time.Recurrent uveitis is when there are repeat episodes of inflammation in the eye, with gaps of a few months between each.

What are the causes of uveitis?

The cause of uveitis is often unknown, with approximately 40% of patients not having a determined cause after clinical investigation. Many cases are linked to the immune system, when it becomes overactive in the eye for unknown reasons. Uveitis can also be caused by infection, injury or surgery, although this is less common.

Uveitis is broadly divided into infectious and non-infectious causes.

Increased uveitis risk factors can also be related to the following health conditions:

• An inflammatory or autoimmune condition (when the body attacks its own organs). HLA B-27 positivity is the most common association. This may also be associated with rheumatoid arthritis, ankylosing spondylitis (arthritis of the lower back), psoriasis or inflammatory bowel disease. Other systemic condition associted with uveitis include Behçet’s disease, sarcoidosis and Reiters
• Bacterial, viral, fungal and parasitic infection such as toxoplasmosis, Herpes Simplex, Herpes Zoster(shingles), tuberculosis (TB), Lyme disease and syphilis are all causes of uveitis. Immunodeficiency in susceptible with a known underlying condition such as leukaemia, lymphoma, HIV/AIDS may make these groups of patients vulnerable to opportunistic infections in the eye e.g. cytomegalovirus retinitis
• Juvenile Idiopathic Arthritis (JIA) is the most common identifiable cause of uveitis in children