BIRDSHOT CHORIORETINITIS

Birdshot is a rare form of posterior uveitis - an inflammation of the uvea, the part of the eye that provides the retina (the light-sensitive layer of cells at the back of the eye necessary for vision) with most of its blood supply.

It is not known exactly how many people have birdshot but it is more common in Caucasian people and in those who are aged 45 to 50 years old though it can also affect people who are much younger.

Birdshot often starts with floaters and/or blurred vision. These are also symptoms of a number of other conditions as well which can make birdshot difficult to diagnose early on.

People with birdshot may go on to experience other symptoms including:

• Night blindness
• Problems with colour vision
• Sensitivity to bright lights
• Seeing flashing lights
• Distortions in vision
• Pain in the eyes
• Loss of depth perception and/or peripheral (side) vision

After some time it may also be possible for an ophthalmologist to see cream or orange oval-shaped spots in the retina, the distinctive pattern which gives this condition its name.

The severity of birdshot symptoms varies from person to person but most people will experience flare ups of inflammation in the eye. If uncontrolled, flare ups can lead to macular oedema, a swelling in the region of the eye responsible for central vision, causing potentially blinding damage to the eye.

The exact cause of birdshot is unknown but it is thought to be an autoimmune disease. An autoimmune disease is when the body’s immune system gets confused and begins to attacks its own tissues. Currently, researchers are trying to determine what ‘triggers’ birdshot and to what extent problems with the immune system might be responsible.

In the beginning, it is usual for people with birdshot to be treated with high doses of steroids to get the inflammation in the eye under control after which the dose will be taken as low as possible. Many people will also require long-term treatment with an immunosuppressant to help stop their immune system attacking their eyes.

Unfortunately, long-term steroid and immunosuppressant use can have side effects like bone problems or stomach complaints so patients are closely monitored and may receive other medications to manage these side effects.

There is no treatment regimen that suits all people with birdshot so patients will need to work with their doctor to find out what works best for them. Moorfields Eye Hospital and others are conducting research to develop new and better approaches towards treatment for people with birdshot. 

Moorfields Eye Hospital, England.