Journal of Neuro-Ophthalmology, September 1989, Volume 9, Issue 3

Venous stasis retinopathy of stenotic or occlusive carotid origin.

Venous stasis retinopathy is an uncommon sign of carotid artery obstruction. It is found in those patients who have very severe stenosis, or complete occlusion, of the arterial lumen. Affected patients usually have advanced multivessel disease with compromise of both carotid arteries. The retinopathy is ipsilateral to the more severely compromised artery; it is caused by progressive, chronic hypoxic injury to retinal tissues, which causes an ophthalmoscopic picture of venous dilation and tortuosity, retinal hemorrhages, macular edema, and eventual neovascular proliferation. The retinal findings are quite similar to those found in diabetic retinopathy, except for unilaterality corresponding to the more obstructed artery and early onset in the retinal midzone rather than the posterior pole. The primary treatment is panretinal photocoagulation to ischemic areas, followed by either medical or surgical management of obstructive carotid disease or carotid endarterectomy alone.

lounUlI of Clinical Neuro- ophthalmology 9( 3): 195- 199. 1989. Venous Stasis Retinopathy of Stenotic or Occlusive Carotid Origin John A. McCrary III, M. D. < 9 1989 Raven Press, Ltd., New York Venous stasis retinopathy is an uncommon sign of ca­rotid artery obstruction. It is found in those patients who have very severe stenosis, or complete occlusion, of the arterial lumen. Affected patients usually have advanced multivessel disease with compromise of both carotid ar­teries. The retinopathy is ipsilateral to the more severely compromised artery; it is caused by progressive, chronic hypoxic injury to retinal tissues, which causes an oph­thalmoscopic picture of venous dilation and tortuosity, retinal hemorrhages, macular edema, and eventual ne­ovascular proliferation. The retinal findings are quite similar to those found in diabetic retinopathy, except for unilaterality corresponding to the more obstructed ar­tery and early onset in the retinal midzone rather than the posterior pole. The primary treatment is panretinal photocoagulation to ischemic areas, followed by either medical or surgical management of obstructive carotid disease or carotid endarterectomy alone. Key Words: Capillary nonperfusion- Carotid artery­Carotid stenosis- Central retinal vein occlusion­Diabetes mellitus- Panretinal photocoagulation­Retinal ischemia- Venous stasis retinopathy. From the Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Presented at the American Academy of Ophthalmology an­nual meeting, Dallas, Texas, November 1987. Address correspondence and reprint requests to Dr. J. A. McCrary, Cullen Eye Institute, 6501 Fanmn, Houston, TX 77030, U. S. A. 195 Venous stasis retinopathy is one of the clinical manifestations of obstructive carotid artery disease ( 1). It is usually unilateral and corresponds to com­plete, or nearly complete, chronic obstruction of the ipsilateral carotid artery. The circulation in the opposite carotid artery is also often affected, but not to the degree found in the eye with retinopa­thy. The hemorrhagic retinopathy must be distin­guished from the following conditions: diabetic retinopathy, incomplete central retinal vein occlu­sion, benign optic disc vasculitis ( papillophlebitis), and vascular complications of hyperviscosity syn­dromes. PATHOPHYSIOLOGY The factors that govern the onset and propaga­tion of this condition are as follows: ( a) chronically low perfusion pressure in the arterial circulation, which leads to diffuse, low- grade retinal ischemia; ( b) slowing of the circulation time, which causes secondary focal dilation and congestion of retinal veins; ( c) breakdown of capillary walls, which re­sults in superficial and deep intraretinal hemor­rhages; and, as the condition progresses, ( d) ne­ovascular proliferation, which occurs as a response to the release of angiogenic factors from ischemic tissue ( 2). CLINICAL FEATURES Both early and late phases of venous stasis reti­nopathy are recognized ( 3), depending on the se­verity and chronicity of carotid obstruction. In the early phase ( Fig. 1), the key findings are evolution of microaneurysm and hemorrhages distributed along the major vascular arcades and usually lo­cated first in the retinal midperiphery. The hem­orrhages are nerve fiber layer ( superficial, flame- 196 f. A. McCRARY III FIG. 1. Venous stasis retinopathy, early phase. Note the dilated veins and the arteriolar narrowing. Mi­croaneurysms, hemorrhages, and microinfarcts are seen in the retinal midperiphery. Photo courtesy of Dr. Ronald Burde. shaped) and intraretinal ( dot- blot) types similar to those found in diabetic retinopathy. The venous circulation of the retina appears to be congested. As the veins become overfilled, they begin to ex­hibit irregularity of caliber. In carotid occlusive ret­inopathy, there is a midperipheral retinal distribu­tion of the early changes, whereas the early retinal vascular manifestations of diabetes- incomplete central retinal vein occlusion, papillophlebitis, hy­perviscosity syndromes- are said to first affect the macular region of the posterior pole. In the late phase ( Fig. 2), there is extreme arte­riolar narrowing, considerable venous dilatation, multiple hemorrhages ( dot- blot, flame- shaped), and microaneurysms. Optic disc hemorrhages and neovasularization may occur, but disc edema is minimal or nonexistent. This relative lack of optic FIG. 2. Venous stasis retinopathy, late phase. Note the extreme dilation of the veins and the narrowing of the arteries. Hemorrhages ( flame- shaped, dot- blot) are in the ;:. rc'~ r, f thp ,-, · -, e'-.; ~ c · ' r) n! e Disc edema is absent. ":'" ] t c~ e I Cli" Neuro- ophthalmol, Vol. 9, No. 3, 1989 disc swelling is important, as it also helps to dis­tinguish carotid ischemic retinopathy from that caused by incomplete central retinal vein occlu­sion, which tends to cause disc edema early in its onset. Also, in central vein occlusion, the hemor­rhages can extend to the equator. By contrast, in venous stasis retinopathy, the hemorrhages stop at the equator. Macular edema may arise, as may focal infarc­tion of the retina or choroid, in severe examples of carotid occlusive retinopathy. Platelet and choles­terol emboli can be found at any stage of the dis­ease, but are more common prior to complete oc­clusion of the carotid artery. DIAGNOSIS If the retinal findings of carotid occlusive disease are observed without being familiar with the clin­ical history, an incorrect diagnosis will often result. It is strongly advised that the clinical history should be carefully reviewed for symptoms that suggest prior embolic events. A clinical history compatible with transient ischemic attacks of ca­rotid origin, chronic unilateral headache ( 4), with or without associated anterior neck pain ( caroti­dynia) ( 5), transient contralateral hemiparesis or hemisensory deficit, or bouts of apparent slowing of mentation might suggest severe carotid occlu­sive disease as the cause of fundus changes. The patient may complain of chronic ocular injection or aching pain ( 6). A history of chronic headache in an individual over 55 years of age demands a Westergren sedimentation rate to rule out giant cell arteritis. Although it is unlikely that giant cell arteritis could be confused with the chronic ocular hypoxic state, there are enough overlapping fea­tures to warrant obtaining a sedimentation rate. Office diagnostic studies that are most useful in­clude carotid auscultation, measurement of blood pressure in each arm, and a complete visual exam­ination to look for signs of anterior segment pa­thology or visual field, pupillary, or intraocular pressure abnormalities that might correlate with fundus changes of carotid obstruction. Ophthal­modynamometry was formerly useful as a simple office screening test to decide whether or not the retinal signs are associated with ipsilateral severe reduction of central retinal artery pressure. The test is useful only if the examiner is experienced and knows proper technique. If not, carotid dop­pler and ultrasound should be used as the primary screening tools. The suspected diagnosis can usually be obtained quickly and safely by carotid doppler and ultra- VENOUS STASIS RETINOPATHY 197 sound measurement of carotid artery blood flow and lumen caliber ( 7,8). These tests are especially useful for laboratory screening purposes. The re­sults of these noninvasive studies usually compare closely with those obtained by direct radiographic visualization of arterial circulation via digital sub­traction angiography ( DSA) ( 9) or retrograde cere­bral angiography/ arch aortography, if a hemody­namically significant extracranial carotid obstruc­tion is present ( Fig. 3). Final confirmation is best obtained by retrograde femoral or brachial cerebral angiography, which permits quality evaluation of extracranial and intracranial circulation, if surgery is being seriously considered as the best treatment. A complete cardiac evaluation by echocardiogra­phy and electrocardiography should be included in the work- up of all suspect patients, given their predilection for cardiac ischemic disease. Addi­tional studies, such as thallium cardiac scans or coronary arteriography, should be used at the dis­cretion of a cardiologist to confirm additional pre­ischemic pathology. Magnetic resonance imaging FIG. 3. Digital subtraction angiogram showing a to­tally occluded carotid artery. of the brain may disclose evidence of multiinfarct cerebral injury. DIFFERENTIAL DIAGNOSIS The differential diagnosis ( Table 1) of venous stasis retinopathy ( carotid ischemic retinopathy) ( 10) includes diabetic retinopathy, incomplete cen­tral retinal vein occlusion, benign optic disc vascu­litis ( papillophlebitis), and hyperviscosity syn­dromes such as polycythemia, Waldenstrom's macroglobulinemia, hemoglobinopathies, myelo­matosis, and lymphoma. Diabetic retinopathy usually is detected in a pa­tient known to have the disease for many years, and, like hyperviscosity syndromes, tends to affect both eyes equally. Appropriate laboratory studies, such as a complete blood count with differential, serum protein, and hemoglobin electrophoresis, and blood sugar profile should differentiate either of these possibilities from venous stasis retinopa­thy. Another differential point is that both diabetic retinopathy and hyperviscosity syndromes affect the posterior pole before the midzonal retina, and neither is expected to produce abnormal reduction of ophthalmodynamometry measurements. How­ever, it should be recognized that there is an in­creased incidence of carotid stenosis in the diabetic population. Very asymmetric retinopathy in a di­abetic patient should prompt screening tests for carotid obstruction. The clinical features that are to distinguish in­complete central retinal vein occlusion from the retinopathy of carotid artery disease are disc edema, mainly posterior pole location of early vas­cular abnormalities and no evidence of severe ca­rotid obstruction. Fully developed central retinal vein occlusion should be easy to differentiate from venous stasis by the florid ophthalmoscopic pic­ture of hemorrhage, severe venous congestion, and marked optic disc edema. Benign optic disc vasculitis is most often found in young, healthy adult patients who have no symptoms or signs of carotid artery disease and who are not diabetic. It is typically unilateral and self- limited, with venous engorgement, retinal hemorrhage, and disc edema. Retinal hemor­rhages are usually less numerous than in central vein occlusion, and the usual risk factors for vein occlusion are absent. TREATMENT The pathogenesis of carotid obstructive retinop­athy is founded on chronic slowing of retinal arte- , Clin Neuro- ophthalmoI. Vol. 9, No. 3, 1989 198 J. A. McCRARY III TABLE 1. Differential diagnosis Venous stasis retinopathy Diabetic retinopathy Incomplete retinal vein occlusion Benign optic disc vasculitis Hyperviscosity syndromes · Signs and symptoms of Yes carotid artery disease History of radiation No treatment Blood studies Normal Laterality Unilateral Area of retina Midzonal region Optic disc edema No Ophthalmodynamometry Abnormal No No Elevated blood sugar Bilateral Macular region No Normal No No Normal Usually unilateral Periphery Yes Normal No No No No Normal Possible abnormalitiesb Unilateral Bilateral Macula. disc. and Macular region peripapillary retina Yes ~ Normal Normal • These include polycythemia. macroglobulinemia, hemoglobinopathies. mylematosis. lymphoma. b The possible abnormalities involve the complete blood count. the differential count. the serum protein. and the hemoglobin electrophoresis. rial perfusion that causes tissue hypoxia and ne­ovascular proliferation similar to that encountered in diabetic retinopathy. The treatment is best started by panretinal photocoagulation of ischemic retina ( 11) and neovascular proliferation ( detected with fluorescein angiography). Photocoagulation should always be done, unless there is an absence of ischemic retina. The decision to proceed to carotid endarterec­tomy should be based on detailed angiographic studies that show the extent and surgical accessi­bility of obstruction. The vertebrobasilar circula­tion should be included in the preoperative angio­graphic evaluation. All decisions for surgery must be made on an individual basis ( 12- 14); a cookbook approach is not desirable. Most patients with ve­nous stasis retinopathy should be considered to be candidates for endarterectomy, as the extent of the disease is severe if stasis change is detected. How­ever, all risk factors for surgery must be carefully weighed. Accentuation of neovascular prolifera­tion by improvement of carotid flow after endar­terectomy cannot be disregarded as a possible con­sequence of surgical correction of a flow deficit ( 15). Thus, venous stasis retinopathy, with or with­out cerebral transient ischemia, should be treated first by panretinal ablative therapy. This is fol­lowed by endarterectomy if the obstruction is not complete, the lesion is surgically accessible, the surgical team is experienced, and documented fail­ure of medical treatment is clear. On the other hand, ischemic retinopathy of carotid origin should be treated exclusively with pametinal abla­tive therapy if acute stroke has already occurred, total occlusion of the ipsilateral carotid artery is ~ J ' r .'. " I j •. d "' lor surgical risk. Plain J Clin Nl'Uro- ophthalmol, Vol. 9, No. 3. 1989 or enteric coated aspmn ( acetylsalicylic acid), 350 mg, should be prescribed at least once daily after a meal. Aspirin is the safest and most effec­tive platelet antiaggregant medication ( 16), Major anticoagulation with coumadin anticoagulants may be required if the patient continues to mani­fest recurrent neurologic deficits. These agents should be given only when more conservative management is failing to control symptoms and signs, the patient is reliable in keeping follow- up appointments for laboratory studies, and no con­traindications otherwise exist. CONCLUSION Venous stasis retinopathy is an uncommon oc­ular sign of carotid artery obstruction. It is found in those patients who have very severe stenosis, or complete occlusion, of the artery lumen. Affected patients usually have advanced multivessel dis­ease with compromise of carotid arteries. The ret­inopathy is ipsilateral to the more severely com­promised artery; it is caused by progressive, chronic hypoxic injury to the retinal tissues that causes reactive neovascular proliferation. The vi­sual outcome of treatment is not predictable, no matter what method is chosen. Carotid endarterec­tomy, combined with panretinal ablative laser treatment to those retinal areas shown to be isch­emic via quality fluorescein photography, is of benefit in most patients. Carotid endarterectomy should be done only if the patient is a good surgi­cal risk and the lesion is accessible. Even if the carotid obstruction can be relieved by successful endarterectomy, there is no guarantee that retinal neovascularization will stop. Indeed, there are some patients who will continue to have progres- VENOUS STASIS RETINOPATHY 199 sive retinopathy, and even secondary neovascular proliferation in the anterior segment of the eye, despite relief of obstruction. Others may develop new neurologic complications caused by failure of autoregulation of cerebral vasculature after suc­cessful relief of carotid obstruction. 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