Birdshot chorioretinopathy

Overview
Birdshot chorioretinopathy, also called birdshot retinochoroidopathy, is a rare form of bilateral posterior uveitis affecting the eye. It causes severe, progressive inflammation of both the choroid and retina.

Affected individuals are usually diagnosed around age 45, a common age of onset.

Pathophysiology
Birdshot chorioretinopathy is an autoimmune disease associated with the Human leukocyte antigen haplotype (HLA)-A29 in 95 to 97.5% of the cases. When birdshot chorioretinopathy is suspected, a person is usually tested to determine if they are HLA-A29 positive. A smaller percentage of the general population is positive for this allele.

Symptoms
Symptoms of this disorder include: abundant floaters, uveitis, chorioretinitis, retinitis, papillitis, retinal vasculitis, vitreous inflammation, macular edema, "flashing" lights in eyes, nyctalopia, loss of color vision, and small light-colored spots on the retina. Complete loss of visual acuity is the common prognosis.

The name of the condition comes from the small light-colored fundus spots on the retina, scattered in a pattern like birdshot from a shotgun, but these spots might not be present in early stages.

Treatment
Birdshot chorioretinopathy is quite resistant to treatment. Immunosuppressant therapy with corticosteroid-sparing drugs has been somewhat effective in slowing down the progessive 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.

Recently, the therapeutic monoclonal antibody daclizumab has proven to be a quite effective treatment option for birdshot chorioretinopathy. Substantial reduction, and even stabilization of both vitreous inflammation and retinal vasculitis has been evident via electroretinography, during daclizumab therapy. Loss of visual acuity unrelated to the inflammation caused by the disorder, however, often remains unchanged despite usage of the drug. Contraindications and adverse side-effects are always a factor, as well.