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Show ' ournal or Clinical Neum- ophtiullmology 9( 1): 21- 25, 1989. < 0 1989 Raven Press, Ltd., New York Embolic Anterior Ischemic Optic Neuropathy Scott L. Portnoy, M. D., Paul M. Beer, M. D., Andrew J. Packer, M. D., and * Henry J. L. Van Dyk, M. D. The presumed cause of anterior ischemic optic neuropathy is atherosclerotic vascular changes. Small- vessel occlusive vascular disease most likely causes occlusion of one or more posterior ciliary arteries, compromising blood flow to the optic nerve head and choroid. We present the case of a 59- year- old black man with cholesterol emboli within the retinal vasculature combined with a clinical picture of anterior ischemic optic neuropathy and choroidal nonperfusion demonstrated by i. v. fluorescein angiography. We believe this is evidence that, in a rare case, embolic phenomena may be the cause of anterior ischemic optic neuropathy. Key Words: Anterior ischemic optic neuropathyAtherosclerotic vascular disease- Cholesterol emboliShort posterior ciliary arteries. From the LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans, Louisiana, U. S. A. Address correspondence and reprint requests to Dr. S. L. Portnoy, LSU Eye Center, 2020 Gravier St., Suite B, New Orleans, LA, U. S. A. ' Deceased. 21 Anterior ischemic optic neuropathy is characterized by a sudden monocular loss of vision associated with optic disc edema and permanent visual field defects. It occurs most frequently in middleaged and elderly patients, but in most cases, the cause is uncertain ( 1). Giant cell arteritis may account for a small portion of cases in older individuals. Nonarteritic anterior ischemic optic neuropathy is most frequently reported as occurring secondary to atherosclerotic vascular occlusive disease ( 2- 5). This association is not, however, definite. There is now some speculation that the optic disc structure may playa role in anterior ischemic optic neuropathy ( 6,7). Emboli are a rare and difficult- to- document cause of anterior ischemic optic neuropathy. We present a case of a middle- aged man with atherosclerotic carotid artery disease in combination with anterior ischemic optic neuropathy, choroidal ischemia, and cholesterol emboli in the retinal circulation. We believe this is a case of anterior ischemic optic neuropathy caused by embolic events that compromised blood flow to the posterior ciliary arteries common to both the optic nerve and the choroid. CASE REPORT The condition of a 59- year- old black man was evaluated at Charity Hospital in New Orleans on March 12, 1987. Four days previously, an episode of " darkness over the total field of vision" in his left eye had developed. Within 10 min, the visual deficit involved only the left side of the visual field of his left eye. This defect remained, He had no other neurological symptoms. His medical history revealed borderline hypertension and type II diabetes mellitus controlled with an oral hypoglycemic agent. Visual acuity on initial examination was 20/ 25 in the right eye and 20/ 40 in the left eye, Ocular motility was normal. The right pupil reacted briskly 22 S. L. PORTNOY ET AL. from 3 to 2 mm. The left pupil was sluggishly reactive from 3 to 2.5 mm, with no definite relative afferent pupillary defect present. The fundus of the right eye was normal, with no evidence of optic disc atrophy. Examination of the left disc revealed nasal opacification of the peripapillary nerve fiber layer ( Fig. 1). Cholesterol plaques were present in the superior and inferior temporal arteriolar arcades ( Fig. 2). Physical examination revealed no focal neurologic deficits. No carotid bruits were detected. Visual field testing on a Goldmann perimeter demonstrated nonspecific field constriction on the right and a loss of the temporal field, primarily superiorly, in the left eye ( Fig. 3). The emboli seen in the retinal arterial circulation were presumed to be secondary to an ulcerated carotid artery plaque. The patient was admitted to the vascular surgery service for evaluation and was given a regimen of aspirin and Persantine. Intravenous fluorescein angiography was performed on the day after the initial evaluation. A large superonasal choroidal filling defect was seen in the left eye in the early venous phase ( Fig. 4). An adjacent area of nonperfusion was also seen on the nasal aspect of the left disc, corresponding to the area of disc edema. On March 17, 1987, bilateral carotid, left vertebral, and thoracic arch arteriograms were performed. An atherosclerotic plaque with ulceration was found at the bifurcation of the left common carotid artery, creating a 50% stenosis. No significant atherosclerosis of the right common and internal carotid arteries was found. On March 31, 1987, the patient underwent a left carotid endarterectomy without complications. Two months after the carotid endarterectomy, the patient noted a la- min loss of vision in his left FIG. 1. Left optic disc with nasal opacification of the peripapillary nerve fiber layer. FIG. 2. Cholesterol emboli in the peripheral arteriolar arcades. eye. A new cholesterol plaque was found within the retinal arteriolar circulation. DISCUSSION The pathogenesis of anterior ischemic optic neuropathy is not completely understood. It is generally believed that anterior ischemic optic neuropathy results in part from alteration in the vascular supply to the optic nerve head ( 8). Two main theories have been proposed to describe blood flow to the optic nerve head. The first theory is that the major efferent supply arises from the choroidal vessels ( 9). The second theory is that the anterior and possibly posterior parts of the optic disc are supplied directly from the short posterior ciliary arteries ( 10). Lieberman et a!. ( 11) proposed that multiple circulations, including the pial vessels, the small branches from the central retinal artery, the short posterior ciliary artery, and the choroidal capillaries, all contribute and freely anastomose to supply the anterior optic nerve head. Hayreh ( 8,10,12,13) proposed that the primary lesion in anterior ischemic optic neuropathy occurs in the region of the short posterior ciliary arteries that supply the affected optic nerve head and choroid. Hayreh's theory has been supported in part by histologic studies in cases of temporal arteritis demonstrating occlusion of short posterior ciliary arteries with infarction of the optic nerve within and behind the lamina cribrosa ( 14,15). Experimental studies by Hayreh have shown that selective occlusion of various short posterior ciliary arteries in rhesus monkeys leads to anterior ischemic optic neuropathy with disc swelling and delayed choroidal filling, demonstrated by i. v. fluorescein angiography ( 16- 18). Hayreh's theory is further supported by i. v. fluorescein angiograms of the EMBOLIC ANTERIOR ISCHEMIC OPTIC NEUROPATHY 270 LEFT RIGHT FIG. 3. Goldmann visual field at initial evaluation. 23 optic discs in patients with anterior ischemic optic neuropathy, which showed delayed filling in the optic disc and slow filling of the choroid but rarely a complete absence of filling ( 19). Hayreh ( 19) proposes that the filling defects seen on i. v. fluorescein angiograms represent a compromise in blood flow from the short posterior ciliary arteries. Occlusion of a single posterior ciliary artery may not explain the entire clinical picture of anterior ischemic optic neuropathy. Ellenberger ( 5) proposed that many cases of anterior ischemic optic neuropathy may represent generalized hypertensive arteriolar occlusions of the blood supply of the anterior part of the optic nerve. Anderson and Davis ( 20) proposed that anterior ischemic optic Fig. 4. Early venous phase i. v. fluorescein angiogram with superonasal choroidal nonperfusion and nasal disc nonperfusion. neuropathy in humans requires more than occlusion of the short posterior ciliary arteries. They occluded the posterior ciliary arteries in one eye of a squirrel monkey and found that the perfusion of the optic nerve head and peripapillary retina was affected minimally. They proposed that an anastomotic network ensures flow ( 20). We describe a patient with multiple emboli in the left carotid artery distribution secondary to an ulcerated plaque. The patient initially had an apparent ischemic disc swelling ( segmental disc infarction) and adjacent choroidal ischemia documented by i. v. fluorescein angiography. In several ways, however, the appearance of an anterior ischemic optic neuropathy was atypical. The patient lacked a definite relative afferent pupillary defect and decreased color vision ( his visual evoked response was not documented). In addition, a nasal location of disc edema is clinically unusual in anterior ischemic optic neuropathy. The presence of Hollenhorst plaques within the retinal circulation offers circumstantial evidence for the embolic nature of the disc disease. The sequence of events could have been the result of either one embolus in the ophthalmic artery, which caused transient total amaurosis and then broke up, showering the short posterior ciliary artery and retinal vessels, or several emboli traveling to the short posterior ciliary artery and central retinal artery simultaneously. With migration of the emboli, the amaurosis resolved, leaving only the visual field defect caused by infarction of the optic nerve secondary to an embolus in the short posterior ciliary artery. / Clin Neuro- ophtluzlmol. Vol. 9. No. 1. 1989 24 S. L. PORTNOY ET AL. Emboli Choroid Short Posterior Ciliary Artery Optic Nerve Tissue----_.;...; Dura ------'.........-'- 1 Arachnoid ----.;-.___ Lamina Cribrosa '-_-- Sclera :...:......,.- Central Retinal Artery ,.,..--'--~ Central Retinal Vein _-'- Pia ~....;...------ Pial Artery FIG. 5. Optic nerve head illustration depicting a single embolus in the short posterior ciliary artery ( left) and multiple emboli within branches of the short posterior ciliary artery ( right). The primary systemic condition reported in association with nonarteritic anterior ischemic optic neuropathy is systemic hypertension ( 2- 5). In 388 patients with nonarteritic anterior ischemic optic neuropathy recently prospectively studied, the prevalence of hypertension and diabetes mellitus was significantly higher than in the general population ( 4). Previous reports have observed that embolism is not a major factor in the pathogenesis of anterior ischemic optic neuropathy. Clinical profiles of patients have not shown amaurosis fugax, considered to be secondary to emboli, to precede anterior ischemic optic neuropathy ( 1- 3). Eagling et a1. ( 21) studied 40 patients ( 56 eyes) with anterior ischemic optic neuropathy and found two patients with retinal emboli ( 21). The pathologic evidence for embolic phenomena as a cause for anterior ischemic optic neuropathy is limited. Lieberman et a1. ( 22) demonstrated the presence of multiple emboli that caused small- vessel occlusion and led to retrolaminar infarction of the optic nerve. Burde et a1. ( 23) described a patient with metastatic chondrosarcoma with clinical findings of an anterior ischemic optic neuropathy and compromised ocular blood flow. Histologic sections of the optic nerve tumor revealed emboli in the short posterior ciliary arteries as well as in the choroidal vessels and central retinal artery. We conclude that our patient illustrates a case of anterior ischemic optic neuropathy caused by cholesterol emboli from an ulcerated carotid artery plaLjllt' The evidence for the embolic nature of the , fr., · "'~'-' I · '. lnly circumstantial in that pathologic ev- .. ' I:, npt available. Blood flow to the anterior lull uk the uptic nerve and choroid was com- I Olll N<? Uro · ophtha/ mo/, Vol. 9, No. 1. 1989 promised from either a single emboli in the short posterior ciliary artery or multiple emboli within branches of the short posterior ciliary artery ( Fig. 5), Additionally, the blood flow may have been further compromised by hypertensive atherosclerotic vascular changes within the short posterior ciliary arteries, ACKNOWLEDGMENT: We thank Dr. Ronald Burde, New York City, for his help in reviewing and editing this article. REFERENCES 1. Boghen DR, Glaser JS. Ischemic optic neuropathy. The clinical profile and natural history. Brain 1975; 98: 689- 708. 2. Ellenberger Jr C, Keltner JL, Burde RM. Acute optic neuropathy in older patients. Arch Neurol 1973; 28: 182- 5. 3. Repka MX, Savino PI, Schatz NJ, Sergott RC. Clinical profile and long- term implications of anterior ischemic optic neuropathy. Am I OphthalmoI1983; 96: 478- 83. 4. Beri M, Klugman MR, Kohler JA, Hayreh 55. Anterior ischemic optic neuropathy. VII. 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Anterior ischemic optic neuropathy. I. Terminology and pathogenesis. Br / Ophthalmol 1974; 58: 955- 63. 13. Hayreh 55. Blood supply of the optic nerve head and its role in optic atrophy, glaucoma, and oedema of the optic disc. Br / OphthalmoI1969; 53: 721- 48. 14. Henkind P, Charles NC Pearson J. Histopathology of ischemic optic neuropathy. Am / Ophthalmol 1970; 69: 78- 90. 15. Hinzpeter EN, Naumann G. Ischemic papilledema in giant- cell arteritis. Arch Ophthalmol 1976; 94: 624-- 8. 16. Hayreh 55, Baines JAB. Occlusion of the posterior ciliary artery. I. Effects on choroidal circulation. Br / Ophthalmol 1972; 56: 719- 35. 17. Hayreh 55, Baines JAB. Occlusion of the posterior ciliary artery. II. Chorio- retinal lesions. Br / Ophthalmol 1972; 56: 736- 53. 18. Hayreh 55, Baines JAB. Occlusion of the posterior ciliary artery. III. Effects on the optic nerve head. Br / Ophthalmol 1972; 56: 754- 69. 19. Hayreh 55. Anterior ischaemic optic neuropathy. II. Fundus on ophthalmoscopy and fluorescein angiography. Br / Ophthalmol 1974; 58: 964- 80. 20. Anderson DR, Davis EB. Retina and optic nerve after posterior ciliary artery occlusion. Arch Ophthalmol 1974; 92: 422- 6. 21. Eagling EM, Sanders MD, Miller 5JH. Ischemic papillopathy. Clinical and fluorescein angiographic review of forty cases. Br / Ophthalmol 1974; 58: 990- 1008. 22. Liebennan MF, Shahi A, Green WR. Embolic ischemic optic neuropathy. Am J OphthalmoI1978; 86: 206- 10. 23. Burde RM, 5mith ME, Black JT. Retinal artery occlusion in the absence of a cherry red spot. Surv Ophthalmol 1982; 27: 181- 6. J Gin Neuro- ophthalmol, Vol. 9, No. 1, 1989 |
