Updated: Jun 29, 2007
The central retinal artery, a branch of the ophthalmic artery, enters the eye through the optic disc and divides into multiple branches to perfuse the inner layers of the retina. A branch retinal artery occlusion (BRAO) occurs when one of these branches of the arterial supply to the retina becomes occluded.
Most commonly, a BRAO occurs secondary to an embolus. Emboli typically originate within vessels upstream where they dislodge and travel within the circulatory system to ultimately become lodged downstream in a vessel with a smaller lumen. The most common include cholesterol emboli from aorto-carotid atheromatous plaques, platelet-fibrin emboli from thrombotic disease, and calcific emboli from cardiac valvular disease. Various other endogenous emboli as well as exogenous emboli and nonembolic causes have been reported.
Ischemia of the inner layers of the retina leads to intracellular edema as a result of cellular injury and necrosis. This intracellular edema has the ophthalmoscopic appearance of grayish whitening of the superficial retina. Primate studies have shown that complete occlusion of arterial supply to the retina results in reversible ischemic injury up to 97 minutes. This may help explain why patients may give a history of transient loss of vision prior to an episode of BRAO. Possibly, these episodes are secondary to emboli transiently becoming lodged, causing temporary occlusions and then reperfusing the retina as the emboli are released.
BRAO is most likely to occur at the bifurcation of an artery since bifurcation sites are associated with a narrowed lumen. In 90% of cases, BRAO involve the temporal retinal vessels. Whether the temporal retinal vessels are affected more often or whether the nasal retinal vessels are undetected more often is uncertain.
Patients with BRAO have a higher risk for morbidity and mortality secondary to cardiovascular and cerebrovascular disease. A thorough medical workup is indicated for all patients with BRAO, and an etiology can be identified in as many as 90% of patients.
Of acute retinal artery obstructions, 58% are central retinal artery occlusions (CRAO), 38% are BRAO, and 5% are cilioretinal artery occlusions.
One study compared retinal artery occlusions in African American and white patients and found that both groups have the same risk factors for retinal arterial occlusive disease. This study also suggested that white patients were more likely to have identifiable carotid disease than African Americans.
Among elderly patients, men are 2.5 times more likely than women to have retinal emboli. This correlates with the higher rate of stroke found in men.
Typically, BRAO presents in the seventh decade of life. BRAO due to embolic causes is rare in patients younger than 30 years. It has been estimated that less than 1 in 50,000 outpatient visits to the ophthalmologist will be a person younger than 30 years with retinal arterial obstruction. These cases are more likely to be nonembolic causes of retinal arterial occlusions.
Central Retinal Artery Occlusion
Cilioretinal artery occlusion
Retinitis
Inflammatory disease of the choroid and retinal pigment epithelium
Choroidal ischemia
Retinal contusion
Neoplasia
Opaque subretinal precipitates
Myelinated nerve fiber layer
BRAO causes ischemia to the inner layers of the retina, which causes inner and intracellular edema and a coagulative necrosis. Eventually, there is loss of the inner retinal layers, which include the nerve fiber layer to the inner nuclear layer. Since the glial cells also have been destroyed, usually there is no gliosis. Histologic evidence of emboli or other etiology may be present.
Considering the increased rate of mortality, patients with BRAO should receive a full medical workup with special attention to the cerebrovascular and cardiovascular system. Depending on the findings, carotid endarterectomy or anticoagulation may be indicated. Lab workup for coagulopathies should also be performed if no embolic source is found.
Refer to an internist for complete systemic workup.
To prevent the dreaded complication of stroke, most patients are placed on some form of antiplatelet therapy, such as aspirin, clopidogrel (Plavix), dipyridamole (Aggrenox), and ticlopidine (Ticlid).
Warfarin (Coumadin) is a blood thinner that prevents the blood from clotting. This medication is often used in patients with atrial fibrillation to decrease their risk of stroke.
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branch retinal artery obstruction, BRAO, arterial occlusive disease, central retinal artery
Janice C Law, MD, Staff Physician, Department of Ophthalmology, Wayne State University, Kresge Eye Institute
Janice C Law, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Association for Research in Vision and Ophthalmology, Michigan Society of Eye Physicians & Surgeons, and Phi Beta Kappa
Disclosure: Nothing to disclose.
Gary W Abrams, MD, Professor and Chairman, Department of Ophthalmology, Wayne State University School of Medicine; Director, Kresge Eye Institute
Gary W Abrams, MD is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, American Society of Retina Specialists, Association for Research in Vision and Ophthalmology, Club Jules Gonin, International Society for Ophthalmic Ultrasound, Macula Society, Pan-American Association of Ophthalmology, and Retina Society
Disclosure: Nothing to disclose.
Rubin W Kim, MD, Staff Physician, Department of Ophthalmology, Kresge Eye Institute
Rubin W Kim, MD is a member of the following medical societies: American Academy of Ophthalmology
Disclosure: Nothing to disclose.
Dean Eliott, MD, Associate Professor, Department of Ophthalmology, Division of Vitreoretinal Surgery, Kresge Eye Institute, Wayne State University
Dean Eliott, MD is a member of the following medical societies: American Academy of Ophthalmology and American Medical Association
Disclosure: Nothing to disclose.
Enrique Garcia-Valenzuela, MD, PhD, Clinical Assistant Professor, Department of Ophthalmology, University of Illinois Eye and Ear Infirmary; Consulting Staff, Vitreo-Retinal Surgery, Midwest Retina Consultants, SC, Parkside Center
Enrique Garcia-Valenzuela, MD, PhD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, Association for Research in Vision and Ophthalmology, and Society for Neuroscience
Disclosure: Nothing to disclose.
Vytautas A Pakainis, MD, Chief of Ophthalmology, Dorn Veterans Administration Medical Center, Professor of Ophthalmology, Ophthalmology, University of South Carolina School of Medicine
Vytautas A Pakainis, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and South Carolina Medical Association
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, Macula Society, and Retina Society
Disclosure: Alcon Laboratories Consulting fee 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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