|Classification and external resources|
Affected individuals are almost exclusively caucasian and usually diagnosed in the fourth to sixth decade of their lives.
Birdshot chorioretinopathy is a rare form of posterior uveitis and accounts for 1-3% of uveitis cases in general. Birdshot chorioretinopathy is thought to be an autoimmune disease. The disease has strong association with the Human leukocyte antigen haplotype (HLA)-A29, which is the strongest association between a disease and HLA class I documented (85 to 97.5% of patients are HLA-A29 positive). This indicates a role for T-lymphocytes in the pathogenesis. Birdshot chorioretinopathy is associated with IL-17, a hallmark cytokine of TH17 cells that play an important role in autoimmunity . The disease affects typically middle aged or elderly caucasians. HLA-A29 is less prevalent in Asia and no birdshot chorioretinopathy cases have been reported in Asia. When birdshot chorioretinopathy is suspected, a person is usually tested to determine if they are HLA-A29 positive. However, HLA-A29 testing is not considered necessary for definitive diagnosis because HLA-A29 is also common in the general healthy population (7%). Additional (genetic or environmental) or unknown factors may be associated with HLA-A29 in the pathogenesis.
Symptoms of this disorder include floaters, blurred vision, photopsia (flashing lights in eyes), loss of color vision and nyctalopia. In eye examination light-colored spots on the retina is seen. Complete loss of visual acuity may happen.
Birdshot chorioretinopathy may show resistance to treatment. Immunosuppressant therapy alongside with oral corticosteroid have been somewhat effective in slowing down the progressive inflammation associated with the disorder, preserving visual intregrity as much as possible. Long-term use of such medications must be closely monitored, however, due to the discomforting, and potentially debilitating and life-threatening side-effects.
Immunosuppressive drugs such as the therapeutic monoclonal antibody Daclizumab, Cyclosporine and Methotrexate have proven to be effective treatment options for birdshot chorioretinopathy. Substantial reduction, and even stabilization of both vitreous inflammation and retinal vasculitis has been evident via electroretinography, during daclizumab (IL-2 receptor blocker) therapy. This is also supported by the observation of elevated levels of IL-2 in the eyes of patients. Loss of visual acuity unrelated to the inflammation caused by the disorder, however, often remains unchanged despite usage of the drug. This is reflected by the lack of difference in visual acuity and the vision-related quality of life between various treatment categories in birdshot patients. Contraindications and adverse side-effects are always a factor, as well.
Support and advice
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