About Birdshot ChorioretinopathyBirdshot Chorioretinopathy or Retinochoroidopathy (normally shortened to 'Birdshot') is a rare, potentially blinding, chronic posterior uveitis which usually affects both eyes. It is believed to be an autoimmune disease. The usual age of onset is between 45 and 55, although it can first occur in much younger and older people.
HistoryBirdshot is a relatively new disease (first discovered in 1949 and only recognised as a 'Birdshot' in 1980). It is still widely misunderstood and unrecognised.
Course of the DiseaseUsually, the initial symptoms of Birdshot are floaters and/or blurred vision, often with little noticeable affect on your ability to see. However, there are cases where symptoms have appeared very rapidly and have included painful eyes, difficulty in seeing in the dark, flashing lights and aversion to bright lights.
The progress of the disease is usually gradual, with a slow and painless loss of vision, involving both eyes. In the initial stages, you may be able to continue to see well but may begin to experience night vision problems and defective colour vision.
Birdshot is usually chronic (it lasts a long time) and needs treatment to prevent ongoing inflammation which leads to permanent loss of vision. If left untreated, and the patient continues to have inflammation, it can lead to macular oedema, a swelling of the macula layer in the eye, which causes blindness.
Diagnosis and TestingBecause it is a rare disease, Birdshot can often be misdiagnosed or missed altogether particularly as the birdshot 'spots' are often not clearly visible in the initial stages. There is no single diagnostic test for Birdshot. Usually, more common eye diseases are ruled out and then a blood test is carried out to establish whether you are HLA A29 positive. HLA A29 is an antigen associated with Birdshot. Most people (though not all) who develop Birdshot carry this antigen.
If you have been diagnosed with Birdshot, or are being tested for Birdshot, you are likely to be asked to undertake some or all of the following tests which involve taking images of the back of the eye and finding out how much damage (if any) has already occurred to your vision: Fluorescein angiography, Indocyanine Green angiography, Optical Coherence Tomography, Electroretinogram (ERG) and Visual Field Test.
TreatmentThere are some people who seem to have a mild form of the disease, and who may not require treatment. If in need of treatment, the right treatment has to be tailored to suit the individual concerned, and will depend on the results of any of the above tests and the history of the patient.
The current protocol is to treat with a combination of steroids (to reduce the inflammation) and immuno-suppressants (to stop your immune system attacking your eyes). The goal of treatment is to find the lowest dosage of medication that will allow you to maintain your eyesight and stabilise your condition, or allow you to reach remission.
If this first line of treatment proves unsuccessful and inflammation returns, there are several other immuno-suppressant medications available which may work better for the individual concerned.
If you are on steroids, you will also be given medication to counteract any damage to your bones that steroids may cause. These are usually alendronic acid and vitamin D and calcium tablets. These should be asked for, if not offered.
This is a summary of our factsheet, 'What is Birdshot Chorioretinopathy', which can be found at www.birdshot.org.uk.
Birdshot Uveitis Society (BUS) is part of the Uveitis Information Group and has been set up by two people with Birdshot, specifically to provide help and support for people who are diagnosed with this rare disease.