Birdshot retinochoroidopathy
Encyclopedia
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.
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. The disease affects typically middle aged or elderly, white 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 vital for definitive diagnosis. Since 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 of BSCR.
, 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.
therapy with corticosteroid-sparing drugs has 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.
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.
Daclizumab was discontinued by Hoffman La Roche on Sept 01, 2009, and is no longer available to the US market. Hoffman La Roche letter to healthcare professionals: http://www.fda.gov/downloads/Drugs/DrugSafety/DrugShortages/UCM194907.pdf
Uveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
affecting the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
. It causes severe, progressive inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
of both the choroid
Choroid
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye , while in the outlying areas it narrows to 0.1 mm...
and retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
.
Affected individuals are usually diagnosed around age 45, a common age of onset.
Pathophysiology
Birdshot chorioretinopathy is a rare form of posterior uveitisUveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
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
Human leukocyte antigen
The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...
haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
(HLA)-A29, which is the strongest association between a disease and HLA class I documented (85 to 97.5% of patients are HLA-A29
HLA-A29
-Allele distribution:-Haplotypes:For A29-Cw*16-B44 haplotype see Cw*16...
positive). This indicates a role for T-lymphocytes in the pathogenesis. The disease affects typically middle aged or elderly, white caucasians
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...
. 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
HLA-A29
-Allele distribution:-Haplotypes:For A29-Cw*16-B44 haplotype see Cw*16...
positive. However, HLA-A29 testing is not considered vital for definitive diagnosis. Since 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 of BSCR.
Symptoms
Symptoms of this disorder include: abundant floaters, uveitisUveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
, chorioretinitis
Chorioretinitis
Chorioretinitis is an inflammation of the choroid and retina of the eye. It is also known as choroid retinitis.-Causes:...
, retinitis, papillitis
Papillitis
Papillitis is the term for a specific type of optic neuritis. If ocular inflammation is restricted to the optic nerve head the condition is called papillitis , and if it is located in the orbital portion of the nerve it is called retrobulbar optic neuritis .Papilledema, a bulging of the optic...
, retinal vasculitis
Vasculitis
Vasculitis refers to a heterogeneous group of disorders that are characterized by inflammatory destruction of blood vessels. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis...
, vitreous inflammation
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...
, macular edema
Macular edema
Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye and causes it to thicken and swell. The swelling may distort a person's central vision, as the macula is near the center of the retina at the back of the eyeball...
, "flashing" lights in eyes, nyctalopia
Nyctalopia
Nyctalopia is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition...
, loss of color vision, and small light-colored spots on the retina. Complete loss of visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
is the common prognosis
Prognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
.
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
Shotgun
A shotgun is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug...
, but these spots might not be present in early stages.
Treatment
Birdshot chorioretinopathy is quite resistant to treatment. ImmunosuppressantImmunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...
therapy with corticosteroid-sparing drugs has 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.
Recently, the therapeutic monoclonal antibody
Monoclonal antibodies
Monoclonal antibodies are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell....
daclizumab
Daclizumab
Daclizumab is a therapeutic humanized monoclonal antibody to the alpha subunit of the IL-2 receptor of T cells. It is used to prevent rejection in organ transplantation, especially in kidney transplants....
has proven to be a quite effective treatment option for birdshot chorioretinopathy. Substantial reduction, and even stabilization of both vitreous inflammation
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...
and retinal vasculitis
Vasculitis
Vasculitis refers to a heterogeneous group of disorders that are characterized by inflammatory destruction of blood vessels. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis...
has been evident via electroretinography
Electroretinography
Electroretinography measures the electrical responses of various cell types in the retina, including the photoreceptors , inner retinal cells , and the ganglion cells. Electrodes are usually placed on the cornea and the skin near the eye, although it is possible to record the ERG from skin electrodes...
, 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.
Daclizumab was discontinued by Hoffman La Roche on Sept 01, 2009, and is no longer available to the US market. Hoffman La Roche letter to healthcare professionals: http://www.fda.gov/downloads/Drugs/DrugSafety/DrugShortages/UCM194907.pdf