Updated: Sep 25, 2008
Birdshot retinochoroidopathy (BSRC) is an uncommon chronic posterior uveitis characterized by vitritis and multiple ovoid spots, which are orange to cream in color and hypopigmented. These spots are mainly distributed in the posterior pole and in the mid periphery of the retina. The classic presentation is described to "resemble the pattern seen with birdshot in the scatter from a shotgun."
Birdshot retinochoroidopathy was first described by Franceschetti and Bable in 1949. In 1980, Ryan and Maumenee coined the term birdshot.1 Gass described birdshot retinochoroidopathy as vitiliginous choroiditis because of the similarities of the fundus lesion to cutaneous vitiligo.
Birdshot retinochoroidopathy may indeed represent a clinical disease that has only recently come into existence, and one may wonder what factors from recent times have allowed it to emerge, such as a new strain of virus, an environmental factor, or some yet unrecognized participant in the development of this disease.
The cause for birdshot retinochoroidopathy is unknown. A strong link to the presence of the human leukocyte antigen A29 (HLA-A29) molecule exists, suggesting that the disease may result from an inherited immune dysregulation. Multiple case series report 80-93.1% HLA-A29 positivity for patients with birdshot retinochoroidopathy, with a relative risk ratio from 50 to 224. This is the strongest HLA association with any known disease.
LeHoang and coauthors reported a series of European patients in which all patients who were HLA-A29 positive with birdshot retinochoroidopathy expressed the HLA-A29 type 2 subtype.2 Both the HLA-A29 type 1 subtype and the HLA-A29 type 2 subtype respond to serologic tests but migrate differently on 1-dimensional electrofocusing gel electrophoresis. Their results suggested that the HLA-A29 type 2 subtype is the risk factor for birdshot retinochoroidopathy and that the HLA-A29 type 1 subtype actually may be protective against developing the disease. However, Levinson and coauthors found that both subtypes were associated with disease in patients in the United States.3
Nussenblatt and colleagues also found a link with human leukocyte antigen B12 (HLA-B12), which has been confirmed by several other authors.4 The link to HLA-B12 is less strong, with a relative risk ratio from 2.7 to 7. Most individuals who are HLA-A29 or HLA-B12 positive do not have birdshot retinochoroidopathy, which obviously implies that other factors are required to provoke the onset of the disease.
Pathogenesis
Class I major histocompatibility (MHC) molecules play an important regulatory role in the immune response. Retinal autoimmunity may play an important role in the pathogenesis of the development of the intraocular inflammation activity for individuals who are HLA-A29 positive because of a genetic immune regulation.Birdshot retinochoroidopathy is a rare disease. There are few reports that address the incidence of birdshot retinochoroidopathy. In the United States, one uveitis clinic reported 7 out of 600 patients (1.2%) with this diagnosis. Since and including 1980, 59 cases have presented to the National Eye Institute (NEI).
In Europe, at 14 eye clinics, only 102 cases of birdshot retinochoroidopathy were diagnosed from 1980-1986.
Birdshot retinochoroidopathy is a potentially blinding disease. Although some ophthalmologists describe patients with birdshot retinochoroidopathy in whom the disease process runs a relatively benign course, where good visual acuity is preserved with minimal therapy, many patients experience a severe course with loss of functional vision, with permanent macular pathology secondary to uncontrolled inflammation and undertreated macular edema. The author strongly believes that if the disease process of a patient with birdshot retinochoroidopathy demonstrates the ability to cause significant inflammation (particularly if significant vasculitis is present) or vision-affecting macular edema, then it is imperative that treatment options be pursued aggressively to control the disease process.
Most patients are of Caucasian background.
Gender preference is not clear, as some studies showed predilection for women, but other studies showed no significant sexual predilection.
Birdshot retinochoroidopathy typically occurs during the middle age, presenting at an average age of 50 years, with an age range of 35-70 years.
The course of birdshot retinochoroidopathy, like other autoimmune diseases, is characterized by exacerbations and remissions. The principle-presenting symptom is gradual, painless vision loss, frequently complicating of floaters that may initially involve one eye but later affect the fellow eye.
A study was conducted on NEI population with birdshot retinochoroidopathy (n=59). This study showed that the most common complain of NEI population was decreased vision (68%), floaters (29%), nyctalopia (25%), dyschromatopsia (20%), glare (19%), and photopsia (17%).
Other less frequent symptoms are listed below.
Decreased visual acuity in the initial stages of birdshot retinochoroidopathy is often mild; in many cases, visual acuity is not worse than 20/40 and rarely below 20/80. Significant impairment most often is related to the presence of macular edema, but macular involvement by an active lesion, atrophic scar, severe vitritis, and choroidal neovascular membrane are other potential causes of more significant visual acuity loss.
Slit lamp biomicroscopy usually reveals a quiet eye, with anterior chamber cells only in instances in which significant vitreal reaction is present, and, rarely, one may see nongranulomatous keratic precipitates on the corneal endothelium and iridocapsular synechiae.
The cause for birdshot retinochoroidopathy is unknown.
Intermediate uveitis
Multifocal choroiditis
Multiple evanescent white dot syndrome
Reticulum cell sarcoma
Panuveitis
Only two histopathology studies have been obtained on the eyes of patients affected by birdshot retinochoroidopathy.
Nussenblatt and coauthors described the histopathological findings of a single, phthisical eye enucleated from a patient with birdshot retinochoroidopathy who exhibited a positive in vitro lymphocyte proliferative response to retinal S-Ag.4 The histopathology revealed a mild lymphocytic response, whereas the retina was involved with a diffuse, chronic granulomatous inflammation.
Gaudio and coauthors described the histopathology of a blind, phthisical eye of a patient positive for the HLA-A29 gene and diagnosed with birdshot retinochoroidopathy.6 This study found aggregation of the lymphocytes with their foci in the deep choroid, with additional foci in the optic nerve head and along the retinal vasculature. These histopathological findings were noted to have a vasotropic distribution.
The appropriate level of treatment is determined by the severity of the inflammation. Conflicting reports exist regarding the efficacy of steroids. Some patients with mild inflammation may respond well to regional injection of steroids. Other patients require the use of systemic prednisone for control of the inflammation. Some patients may be controlled on less than 10 mg/d, while other patients require higher doses. Long-term treatment, even 10 mg/d of steroids, is undesirable, considering the high risk of significant morbidity and mortality of such treatment. Many patients show no significant response to steroid therapy.
Cyclosporine has been shown to have a beneficial effect on birdshot retinochoroidopathy inflammation in retrospective case series. Initial reports demonstrated improved visual acuity, decreased vitritis, and stabilization of eyes with cyclosporine dosages of 10 mg/kg/d. However, this dose also was associated with a high incidence of nephrotoxicity and hypertension. Vitale and colleagues reported a series of 19 cases of birdshot retinochoroidopathy, which demonstrated that cyclosporine treatment with lower dosages, from 2.5-5 mg/kg, can be effective.7 This series showed control of vitreal inflammation in 88.5% of eyes and improved or stable visual acuity in 83.3% of eyes. However, the low incidence of drug toxicity was most striking; there were only 2 cases of hypertension and no cases of nephrotoxicity.
One suggestion is to initially start cyclosporine dosages at 2.5 mg/kg and then to increase to the level necessary to control the inflammation, while ensuring avoidance of drug adverse effects. The maximum dosage is 5 mg/kg according to this author. Monitoring for blood counts and renal function is performed every 4-6 weeks, along with blood pressure monitoring. Cyclosporine serum levels are not followed at these dosing regimens. Other potential adverse effects, such as hirsutism, paresthesias, tremor, and gingival hyperplasia, are not risks for morbidity, but are mentioned, since lowering of drug dosage or discontinuation of the medication may be indicated if such adverse effects occur to a point of affecting the quality of the patient's life.
One study reports the use of ketoconazole as adjunct therapy to cyclosporine. Ketoconazole delays metabolism of cyclosporine; hence, it may lower the dose of cyclosporine required to maintain control of inflammation. Silverstein and Wong demonstrated that cyclosporine trough levels could be maintained in a patient when the cyclosporine dosage was dropped from 200 mg/d (3 mg/kg) to 50 mg/d (0.75 mg/kg) with the addition of ketoconazole at 200 mg/d. This amounts to an 80% reduction of cyclosporine consumption. While this may be cost-saving, one cannot necessarily equate stabilization of cyclosporine serum levels with adequate control of inflammation nor with reduced potential toxicity. After all, the serum cyclosporine levels are still in the therapeutic range, and one might expect cyclosporine toxicity prevalence to be unchanged. Additionally, ketoconazole is not without potential adverse effects, especially the risk of hepatitis.
Other immunomodulatory therapies have been described. Kiss and colleagues reported the use of mycophenolate mofetil, azathioprine, methotrexate, and daclizumab in a series of 28 patients with birdshot retinochoroidopathy; however, the small size of the study precludes any comment on the efficacy of any single drug.8 LeHoang and colleagues reported the use of intravenous immunoglobulin in a series of 18 patients as initial therapy for active birdshot retinochoroidopathy, and they noted stable vision in 33 of 36 eyes over a mean follow-up period of 39 months.9
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
May have a beneficial effect on birdshot retinochoroidopathy inflammation.
Cyclic polypeptide that suppresses some humoral immunity and, to a greater extent, cell-mediated immune reactions, such as delayed hypersensitivity, allograft rejection, experimental allergic encephalomyelitis, and graft-versus-host disease for a variety of organs. For children and adults, base dosing on ideal body weight. The dose of 10 mg/kg/d is associated with a high incidence of nephrotoxicity and hypertension.
2.5-5 mg/kg IV divided q8-12h
Not established
Carbamazepine, phenytoin, isoniazid, rifampin, and phenobarbital may decrease cyclosporine concentrations; azithromycin, itraconazole, nicardipine, ketoconazole, fluconazole, erythromycin, verapamil, grapefruit juice, diltiazem, aminoglycosides, acyclovir, amphotericin B, and clarithromycin may increase cyclosporine toxicity; acute renal failure, rhabdomyolysis, myositis, and myalgias increase when taken concurrently with lovastatin
Documented hypersensitivity; uncontrolled hypertension or malignancies; do not administer concomitantly with PUVA or UVB radiation in psoriasis since it may increase risk of cancer
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Evaluate renal and liver functions often by measuring BUN, serum creatinine, serum bilirubin, and liver enzymes; may increase risk of infection and lymphoma; reserve IV use only for those who cannot take PO
Have both anti-inflammatory (glucocorticoid) and salt-retaining (mineralocorticoid) properties. Glucocorticoids have profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli.
Immunosuppressant for treatment of autoimmune disorders; may decrease inflammation by reversing increased capillary permeability and suppressing PMN activity. Stabilizes lysosomal membranes and suppresses lymphocytes and antibody production.
10 mg PO qd or divided bid/qid; taper over 2 wk as symptoms resolve
Not established
Coadministration with estrogens may decrease prednisone clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Documented hypersensitivity; viral infection; peptic ulcer disease; hepatic dysfunction; connective tissue infections; fungal or tubercular skin infections; GI disease
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Do not use long term; abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use
Their mechanism of action may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell. They also may inhibit P450 enzymes involved in drug metabolism.
For use concomitantly with cyclosporine. Imidazole broad-spectrum antifungal agent that acts on several of the P450 enzymes, including the first step in cortisol synthesis, cholesterol side-chain cleavage, and conversion of 11-deoxycortisol to cortisol. Also increases levels of drugs metabolized by P450 enzymes, such as cyclosporine.
200 mg PO qd
Not established
Isoniazid may decrease bioavailability of ketoconazole; coadministration decreases effects of either rifampin or ketoconazole; may increase effect of anticoagulants; may increase toxicity of corticosteroids and cyclosporine (cyclosporine dosage can be adjusted); may decrease theophylline levels
Documented hypersensitivity; fungal meningitis
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Hepatotoxicity may occur; may reversibly decrease corticosteroid serum levels (adverse effects avoided with dose of 200-400 mg/d); administer antacid, anticholinergics, or H2-blockers at least 2 h after taking ketoconazole
Ryan SJ, Maumenee AE. Birdshot retinochoroidopathy. Am J Ophthalmol. Jan 1980;89(1):31-45. [Medline].
LeHoang P, Ozdemir N, Benhamou A, et al. HLA-A29.2 subtype associated with birdshot retinochoroidopathy. Am J Ophthalmol. Jan 15 1992;113(1):33-5. [Medline].
Levinson RD, Rajalingam R, Park MS, et al. Human leukocyte antigen A29 subtypes associated with birdshot retinochoroidopathy. Am J Ophthalmol. Oct 2004;138(4):631-4. [Medline].
Nussenblatt RB, Mittal KK, Ryan S, et al. Birdshot retinochoroidopathy associated with HLA-A29 antigen and immune responsiveness to retinal S-antigen. Am J Ophthalmol. Aug 1982;94(2):147-58. [Medline].
Fuerst DJ, Tessler HH, Fishman GA, et al. Birdshot retinochoroidopathy. Arch Ophthalmol. Feb 1984;102(2):214-9. [Medline].
Gaudio PA, Kaye DB, Crawford JB. Histopathology of birdshot retinochoroidopathy. Br J Ophthalmol. Dec 2002;86(12):1439-41. [Medline].
Vitale AT, Rodriguez A, Foster CS. Low-dose cyclosporine therapy in the treatment of birdshot retinochoroidopathy. Ophthalmology. May 1994;101(5):822-31. [Medline].
Kiss S, Ahmed M, Letko E, et al. Long-term follow-up of patients with birdshot retinochoroidopathy treated with corticosteroid-sparing systemic immunomodulatory therapy. Ophthalmology. Jun 2005;112(6):1066-71. [Medline].
LeHoang P, Cassoux N, George F, et al. Intravenous immunoglobulin (IVIg) for the treatment of birdshot retinochoroidopathy. Ocul Immunol Inflamm. Mar 2000;8(1):49-57. [Medline].
Bloch-Michel E, Frau E. Birdshot retinochoroidopathy and HLA-A29+ and HLA-A29- idiopathic retinal vasculitis: comparative study of 56 cases. Can J Ophthalmol. Dec 1991;26(7):361-6. [Medline].
Brucker AJ, Deglin EA, Bene C, et al. Subretinal choroidal neovascularization in birdshot retinochoroidopathy. Am J Ophthalmol. Jan 15 1985;99(1):40-4. [Medline].
Caballero-Presencia A, Diaz-Guia E, Lopez-Lopez JM. Acute anterior ischemic optic neuropathy in birdshot retinochoroidopathy. Ophthalmologica. 1988;196(2):87-91. [Medline].
de Smet MD, Yamamoto JH, Mochizuki M, et al. Cellular immune responses of patients with uveitis to retinal antigens and their fragments. Am J Ophthalmol. Aug 15 1990;110(2):135-42. [Medline].
Godel V, Baruch E, Lazar M. Late development of chorioretinal lesions in birdshot retinochoroidopathy. Ann Ophthalmol. Feb 1989;21(2):49-52. [Medline].
Hirose T, Katsumi O, Pruett RC, et al. Retinal function in birdshot retinochoroidopathy. Acta Ophthalmol (Copenh). Jun 1991;69(3):327-37. [Medline].
Kaplan HJ, Aaberg TM. Birdshot retinochoroidopathy. Am J Ophthalmol. Dec 1980;90(6):773-82. [Medline].
Kiss S, Anzaar F, Stephen Foster C. Birdshot retinochoroidopathy. Int Ophthalmol Clin. Spring 2006;46(2):39-55. [Medline].
Levinson RD, Gonzales CR. Birdshot retinochoroidopathy: immunopathogenesis, evaluation, and treatment. Ophthalmol Clin North Am. Sep 2002;15(3):343-50, vii. [Medline].
Noble KG, Greenberg J. Appearance of birdshot retinochoroidopathy in a patient with myelodysplasia syndrome. Am J Ophthalmol. Jan 1998;125(1):108-9. [Medline].
Oh KT, Christmas NJ, Folk JC. Birdshot retinochoroiditis: long term follow-up of a chronically progressive disease. Am J Ophthalmol. May 2002;133(5):622-9. [Medline].
Rosenberg PR, Noble KG, Walsh JB, et al. Birdshot retinochoroidopathy. Ophthalmology. Mar 1984;91(3):304-6. [Medline].
Soubrane G, Bokobza R, Coscas G. Late developing lesions in birdshot retinochoroidopathy. Am J Ophthalmol. Feb 15 1990;109(2):204-10. [Medline].
Soubrane G, Coscas G, Binaghi M, et al. Birdshot retinochoroidopathy and subretinal new vessels. Br J Ophthalmol. Jul 1983;67(7):461-7. [Medline].
birdshot retinopathy, birdshot retinochoroidopathy, BSRC, vitiliginous chorioretinitis
C Michael Samson, MD, Associate Professor, Department of Ophthalmology, New York Medical College; Consulting Staff, Co-director of Uveitis Service, Faculty in Residency Training Program, Director of Uveitis Fellowship Training Program, Department of Ophthalmology, New York Eye and Ear Infirmary; Private Practice, Vitreous Retina Macula Consultants of New York
C Michael Samson, MD is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, American Uveitis Society, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.
Amro Mohamed Mohamoud Ali, MB, ChB, Consulting Staff, New York Eye and Ear Infirmary
Amro Mohamed Mohamoud Ali, MB, ChB is a member of the following medical societies: American Academy of Ophthalmology
Disclosure: Nothing to disclose.
C Stephen Foster, MD, FACS, FACR, FAAO, Clinical Professor of Ophthalmology, Harvard Medical School; Consulting Staff, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary; Founder and President, Ocular Immunology and Uveitis Foundation, Massachusetts Eye Research and Surgery Institution
C Stephen Foster, MD, FACS, FACR, FAAO is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American Association of Immunologists, American College of Rheumatology, American College of Surgeons, American Federation for Clinical Research, American Medical Association, American Society for Microbiology, American Uveitis Society, Association for Research in Vision and Ophthalmology, Massachusetts Medical Society, Royal Society of Medicine, and Sigma Xi
Disclosure: Nothing to disclose.
Russell P Jayne, MD, Consulting Vitreoretinal Surgeon, The Retina Center at Las Vegas
Russell P Jayne, MD is a member of the following medical societies: American Medical Association, American Society of Cataract and Refractive Surgery, and American Society of Retina Specialists
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Steve Charles, MD, Director of Charles Retina Institute; Clinical Professor, Department of Ophthalmology, University of Tennessee College of Medicine
Steve Charles, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Retina Specialists, Club Jules Gonin, Macula Society, and Retina Society
Disclosure: Alcon Laboratories Consulting fee Consulting; OptiMedica Ownership interest Consulting
Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.
Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.
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