Amaurosis fugax explained

Amaurosis fugax
Symptoms:Temporary fleeting of vision in one or both eyes
Complications:Stroke
Duration:Seconds to hours

Amaurosis fugax (Greek, Ancient (to 1453);: [[wikt:ἀμαύρωσις#Ancient Greek|ἀμαύρωσις]], Greek, Ancient (to 1453);: amaurosis meaning 'darkening', 'dark', or 'obscure', Latin: [[wikt:fugax#Latin|fugax]] meaning 'fleeting') is a painless temporary loss of vision in one or both eyes.[1]

Signs and symptoms

The experience of amaurosis fugax is classically described as a temporary loss of vision in one or both eyes that appears as a "black curtain coming down vertically into the field of vision in one eye;" however, this altitudinal visual loss is not the most common form. In one study, only 23.8 percent of patients with transient monocular vision loss experienced the classic "curtain" or "shade" descending over their vision.[2] Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring.[3] Total or sectorial vision loss typically lasts only a few seconds, but may last minutes or even hours. Duration depends on the cause of the vision loss. Obscured vision due to papilledema may last only seconds, while a severely atherosclerotic carotid artery may be associated with a duration of one to ten minutes.[4] Certainly, additional symptoms may be present with the amaurosis fugax, and those findings will depend on the cause of the transient monocular vision loss.

Cause

Prior to 1990, amaurosis fugax could, "clinically, be divided into four identifiable symptom complexes, each with its underlying pathoetiology: embolic, hypoperfusion, angiospasm, and unknown".[5] In 1990, the causes of amaurosis fugax were better refined by the Amaurosis Fugax Study Group, which has defined five distinct classes of transient monocular blindness based on their supposed cause: embolic, hemodynamic, ocular, neurologic, and idiopathic (or "no cause identified").[6] Concerning the pathology underlying these causes (except idiopathic), "some of the more frequent causes include atheromatous disease of the internal carotid or ophthalmic artery, vasospasm, optic neuropathies, giant cell arteritis, angle-closure glaucoma, increased intracranial pressure, orbital compressive disease, a steal phenomenon, and blood hyperviscosity or hypercoagulability."[7]

Embolic and hemodynamic origin

With respect to embolic and hemodynamic causes, this transient monocular visual loss ultimately occurs due to a temporary reduction in retinal artery, ophthalmic artery, or ciliary artery blood flow, leading to a decrease in retinal circulation which, in turn, causes retinal hypoxia.[8] While, most commonly, emboli causing amaurosis fugax are described as coming from an atherosclerotic carotid artery, any emboli arising from vasculature preceding the retinal artery, ophthalmic artery, or ciliary arteries may cause this transient monocular blindness.

Ocular origin

Ocular causes include:

Neurologic origin

Neurological causes include:

Diagnosis

Despite the temporary nature of the vision loss, those experiencing amaurosis fugax are usually advised to consult a physician immediately as it is a symptom that may herald serious vascular events, including transient ischemic attack (TIA) or stroke.[39] [40] Restated, "because of the brief interval between the transient event and a stroke or blindness from temporal arteritis, the workup for transient monocular blindness should be undertaken without delay." If the patient has no history of giant cell arteritis, the probability of vision preservation is high; however, the chance of a stroke reaches that for a hemispheric TIA. Therefore, investigation of cardiac disease is justified.

A diagnostic evaluation should begin with the patient's history, followed by a physical exam, with particular importance being paid to the ophthalmic examination with regards to signs of ocular ischemia. When investigating amaurosis fugax, an ophthalmologic consultation is absolutely warranted if available. Several concomitant laboratory tests should also be ordered to investigate some of the more common, systemic causes listed above, including a complete blood count, erythrocyte sedimentation rate, lipid panel, and blood glucose level. If a particular cause is suspected based on the history and physical, additional relevant labs should be ordered.

If laboratory tests are abnormal, a systemic disease process is likely, and, if the ophthalmologic examination is abnormal, ocular disease is likely. However, in the event that both of these routes of investigation yield normal findings or an inadequate explanation, non-invasive duplex ultrasound studies are recommended to identify carotid artery disease. Most episodes of amaurosis fugax are the result of stenosis of the ipsilateral carotid artery.[41] With that being the case, researchers investigated how best to evaluate these episodes of vision loss, and concluded that for patients ranging from 36 to 74 years old, "...carotid artery duplex scanning should be performed...as this investigation is more likely to provide useful information than an extensive cardiac screening (ECG, Holter 24-hour monitoring, and precordial echocardiography)."[41] Additionally, concomitant head CT or MRI imaging is also recommended to investigate the presence of a "clinically silent cerebral embolism."

If the results of the ultrasound and intracranial imaging are normal, "renewed diagnostic efforts may be made," during which fluorescein angiography is an appropriate consideration. However, carotid angiography may not be necessary in the presence of a normal ultrasound and CT.[42]

Treatment

Fleeting loss of vision does not in itself require any treatment, but it may indicate an underlying condition, sometimes serious, that must be treated. If the diagnostic workup reveals a systemic disease process, directed therapies to treat the underlying cause are required. If the amaurosis fugax is caused by an atherosclerotic lesion, use of aspirin as an anticoagulant is indicated, and a carotid endarterectomy considered based on the location and grade of the stenosis. Generally, if the carotid artery is still patent, the greater the stenosis, the greater the indication for endarterectomy. "Amaurosis fugax appears to be a particularly favorable indication for carotid endarterectomy. Left untreated, this event carries a high risk of stroke; after carotid endarterectomy, which has a low operative risk, there is a very low postoperative stroke rate."[43] However, the rate of subsequent stroke after amaurosis is significantly less than after a hemispheric TIA, therefore there remains debate as to the precise indications for which a carotid endarterectomy should be performed. If the full diagnostic workup is completely normal, patient observation is recommended.

See also

Notes and References

  1. Fisher CM . 'Transient monocular blindness' versus 'amaurosis fugax' . Neurology . 39 . 12 . 1622–4 . December 1989 . 2685658 . 10.1212/wnl.39.12.1622 . 13315378 .
  2. ((North American Symptomatic Carotid Endarterectomy Trial Collaborators)), ((Barnett HJM)), Taylor DW, Haynes RB, Sackett DL, Peerless SJ, Ferguson GG, Fox AJ, Rankin RN, Hachinski VC, Wiebers DO, Eliasziw M . Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis . N Engl J Med . 325 . 7 . 445–53 . August 1991 . 1852179 . 10.1056/NEJM199108153250701 . free .
  3. Lord RS . Transient monocular blindness . Aust N Z J Ophthalmol . 18 . 3 . 299–305 . August 1990 . 2261177 . 10.1111/j.1442-9071.1990.tb00624.x . free .
  4. Donders RC, ((Dutch Tmb Study Group)). Clinical features of transient monocular blindness and the likelihood of atherosclerotic lesions of the internal carotid artery . J Neurol Neurosurg Psychiatry . 71 . 2 . 247–9 . August 2001 . 11459904 . 1737502 . 10.1136/jnnp.71.2.247 .
  5. Burde RM . Amaurosis fugax. An overview . J Clin Neuroophthalmol . 9 . 3 . 185–9 . September 1989 . 2529279 .
  6. ((The Amaurosis Fugax Study Group)). Current management of amaurosis fugax. The Amaurosis Fugax Study Group . Stroke . 21 . 2 . 201–8 . February 1990 . 2406992 . 10.1161/01.str.21.2.201 . free .
  7. Book: Newman NJ . Cerebrovascular disease . Hoyt WG, Miller N, Walsh F, Newman NJ. Walsh and Hoyt's Clinical Neuro-Ophthalmology . Williams & Wilkins . Baltimore . 1998 . 3420–6 . 0-683-30232-9 . 3 . 5th.
  8. Jehn A, Frank Dettwiler B, Fleischhauer J, Sturzenegger M, Mojon DS . Exercise-induced vasospastic amaurosis fugax . Arch. Ophthalmol. . 120 . 2 . 220–2 . February 2002 . 11831932 . 2007-03-26 . https://web.archive.org/web/20070929133329/http://archopht.ama-assn.org/cgi/content/extract/120/2/220 . 2007-09-29 . live .
  9. Braat A, Hoogland PH, DeVries AC, de Mol VanOtterloo JC . Amaurosis Fugax and Stenosis of the Ophthalmic Artery . Vasc Endovascular Surg . 35 . 2 . 141–2 . 2001 . 10.1177/153857440103500210 . 11668383 . 38943888 .
  10. Kaiboriboon K, Piriyawat P, Selhorst JB . Light-induced amaurosis fugax . Am. J. Ophthalmol. . 131 . 5 . 674–6 . May 2001 . 11336956 . 10.1016/S0002-9394(00)00874-6.
  11. Furlan AJ, Whisnant JP, Kearns TP . Unilateral visual loss in bright light. An unusual symptom of carotid artery occlusive disease . Arch. Neurol. . 36 . 11 . 675–6 . November 1979 . 508123 . 10.1001/archneur.1979.00500470045007 .
  12. Fisher M . Transient monocular blindness associated with hemiplegia . Arch. Ophthalmol. . 47 . 2 . 167–203 . 1952 . 14894017 . 10.1001/archopht.1952.01700030174005.
  13. Ellenberger C, Epstein AD . Ocular complications of atherosclerosis: what do they mean? . Semin Neurol . 6 . 2 . 185–93 . June 1986 . 3332423 . 10.1055/s-2008-1041462 .
  14. 10.1056/NEJM199109193251207 . Burger SK, Saul RF, Selhorst JB, Thurston SE . Transient monocular blindness caused by vasospasm . N. Engl. J. Med. . 325 . 12 . 870–3 . September 1991 . 1875972 . free .
  15. Imes RK, Hoyt WF . Exercise-induced transient visual events in young healthy adults . J Clin Neuroophthalmol . 9 . 178–80 . 1989 . 2529277 . 3 .
  16. Hayreh SS, Podhajsky PA, Zimmerman B . Occult giant cell arteritis: ocular manifestations . Am. J. Ophthalmol. . 125 . 4 . 521–6 . April 1998 . 9559738 . 10.1016/S0002-9394(99)80193-7 .
  17. Goodman BW . Temporal arteritis . Am. J. Med. . 67 . 5 . 839–52 . November 1979 . 389046 . 10.1016/0002-9343(79)90744-7 .
  18. Giorgi D, David V, Afeltra A, Gabrieli CB . Transient visual symptoms in systemic lupus erythematosus and antiphospholipid syndrome . Ocul. Immunol. Inflamm. . 9 . 1 . 49–57 . March 2001 . 11262668 . 10.1076/ocii.9.1.49.3980 . 35161683 .
  19. Gold D, Feiner L, Henkind P . Retinal arterial occlusive disease in systemic lupus erythematosus . Arch. Ophthalmol. . 95 . 9 . 1580–5 . September 1977 . 901267 . 10.1001/archopht.1977.04450090102008 .
  20. Newman NM, Hoyt WF, Spencer WH . Macula-sparing monocular blackouts. Clinical and pathologic investigations of intermittent choroidal vascular insufficiency in a case of periarteritis nodosa . Arch. Ophthalmol. . 91 . 5 . 367–70 . May 1974 . 4150748 . 10.1001/archopht.1974.03900060379006 .
  21. Schwartz ND, So YT, Hollander H, Allen S, Fye KH . Eosinophilic vasculitis leading to amaurosis fugax in a patient with acquired immunodeficiency syndrome . Arch. Intern. Med. . 146 . 2059–60 . 1986 . 10.1001/archinte.146.10.2059 . 3767551 . 10 .
  22. Berdel WE, Theiss W, Fink U, Rastetter J . Peripheral arterial occlusion and amaurosis fugax as the first manifestation of polycythemia vera. A case report . Blut . 48 . 3 . 177–80 . March 1984 . 6697006 . 10.1007/BF00320341 . 13588599 .
  23. Mundall J, Quintero P, Von Kaulla KN, Harmon R, Austin J . Transient monocular blindness and increased platelet aggregability treated with aspirin. A case report . Neurology . 22 . 3 . 280–5 . March 1972 . 5062262 . 10.1212/wnl.22.3.280. 552116 .
  24. Smith DB, Ens GE . Protein C deficiency: a cause of amaurosis fugax? . J. Neurol. Neurosurg. Psychiatry . 50 . 3 . 361–2 . March 1987 . 3559620 . 1031809 . 10.1136/jnnp.50.3.361.
  25. Digre KB, Durcan FJ, Branch DW, Jacobson DM, Varner MW, Baringer JR . Amaurosis fugax associated with antiphospholipid antibodies . Annals of Neurology . 25 . 3 . 228–32 . March 1989 . 2729913 . 10.1002/ana.410250304 . 28110036 .
  26. Landi G, Calloni MV, Grazia Sabbadini M, Mannuccio Mannucci P, Candelise L . Recurrent ischemic attacks in two young adults with lupus anticoagulant . Stroke . 14 . 3 . 377–9 . 1983 . 6419415 . 10.1161/01.STR.14.3.377 . free .
  27. Elias M, Eldor A . Thromboembolism in patients with the 'lupus'-type circulating anticoagulant . Arch. Intern. Med. . 144 . 3 . 510–5 . March 1984 . 6367679 . 10.1001/archinte.144.3.510 .
  28. Hayreh SS, Servais GE, Virdi PS . Fundus lesions in malignant hypertension. V. Hypertensive optic neuropathy . Ophthalmology . 93 . 1 . 74–87 . January 1986 . 3951818 . 10.1016/s0161-6420(86)33773-4.
  29. 10.1111/j.1755-3768.1983.tb04348.x . Sørensen PN . Amaurosis fugax. A unselected material . Acta Ophthalmol (Copenh) . 61 . 4 . 583–8 . August 1983 . 6637419 . 221395995 .
  30. Bacigalupi M . Amaurosis Fugax-A Clinical Review . The Internet Journal of Allied Health Sciences and Practice . 4 . 2 . 1–6 . April 2006 .
  31. Ravits J, Seybold ME . Transient monocular visual loss from narrow-angle glaucoma . Arch. Neurol. . 41 . 9 . 991–3 . September 1984 . 6477235 . 10.1001/archneur.1984.04050200097026 .
  32. Brown GC, Shields JA . Amaurosis fugax secondary to presumed cavernous hemangioma of the orbit . Ann Ophthalmol . 13 . 10 . 1205–9 . October 1981 . 7316347 .
  33. Wilkes SR, Trautmann JC, DeSanto LW, Campbell RJ . Osteoma: an unusual cause of amaurosis fugax . Mayo Clin. Proc. . 54 . 4 . 258–60 . April 1979 . 423606 .
  34. Book: Corbett JW, Digre KB . Practical viewing of the optic disc . Butterworth-Heinemann . Oxford . 2003 . 269–344 . 0-7506-7289-7 . Amaurosis Fugax and Not So Fugax—Vascular Disorders of the Eye . http://intl.elsevierhealth.com/e-books/pdf/783.pdf . 2007-03-29 . 2007-09-26 . https://web.archive.org/web/20070926225959/http://intl.elsevierhealth.com/e-books/pdf/783.pdf . dead .
  35. Sadun AA, Currie JN, Lessell S . Transient visual obscurations with elevated optic discs . Annals of Neurology . 16 . 4 . 489–94 . October 1984 . 6497356 . 10.1002/ana.410160410 . 2245543 .
  36. Smith KJ, McDonald WI . W. Ian McDonald . The pathophysiology of multiple sclerosis: the mechanisms underlying the production of symptoms and the natural history of the disease . Philosophical Transactions of the Royal Society B . 354 . 1390 . 1649–73 . October 1999 . 10603618 . 1692682 . 10.1098/rstb.1999.0510 .
  37. Mattsson P, Lundberg PO . Characteristics and prevalence of transient visual disturbances indicative of migraine visual aura . Cephalalgia . 19 . 5 . 479–84 . June 1999 . 10403062 . 10.1046/j.1468-2982.1999.019005479.x . 5961275 . free . Cologno D, Torelli P, Manzoni GC . Transient visual disturbances during migraine without aura attacks . Headache . 42 . 9 . 930–3 . October 2002 . 12390623 . 10.1046/j.1526-4610.2002.02216.x. 32304894 . Connor RC . Complicated migraine. A study of permanent neurological and visual defects caused by migraine . Lancet . 2 . 7265 . 1072–5 . November 1962 . 14022628 . 10.1016/s0140-6736(62)90782-1. Carroll D . Retinal migraine . Headache . 10 . 1 . 9–13 . April 1970 . 5444866 . 10.1111/j.1526-4610.1970.hed1001009.x . 46246035 . McDonald WI, Sanders MD . Migraine complicated by ischaemic papillopathy . Lancet . 2 . 7723 . 521–3 . September 1971 . 4105666 . 10.1016/s0140-6736(71)90440-5. Wolter JR, Burchfield WJ . Ocular migraine in a young man resulting in unilateral transient blindness and retinal edema . Pediatr Ophthalmol. . 8 . 173–6 . 1971 . Kline LB, Kelly CL . Ocular migraine in a patient with cluster headaches . Headache . 20 . 5 . 253–7 . September 1980 . 7451120 . 10.1111/j.1526-4610.1980.hed2005253.x . 29684052 . Corbett JJ. . Neuro-ophthalmologic complications of migraine and cluster headaches . Neurol. Clin. . 1 . 4 . 973–95 . 1983 . 6390159 . 10.1016/S0733-8619(18)31134-4 .
  38. Hedges TR . The terminology of transient visual loss due to vascular insufficiency . Stroke . 15 . 5 . 907–8 . 1984 . 6474546 . 10.1161/01.STR.15.5.907 . 8664120 . free .
  39. Benavente O, Eliasziw M, Streifler JY, Fox AJ, Barnett HJ, Meldrum H . Prognosis after transient monocular blindness associated with carotid-artery stenosis . N. Engl. J. Med. . 345 . 15 . 1084–90 . October 2001 . 11596587 . 10.1056/NEJMoa002994. free .
  40. Rothwell PM, Warlow CP . Timing of TIAs preceding stroke: time window for prevention is very short . Neurology . 64 . 5 . 817–20 . March 2005 . 15753415 . 10.1212/01.WNL.0000152985.32732.EE . 19550244 .
  41. Smit RL, Baarsma GS, Koudstaal PJ . The source of embolism in amaurosis fugax and retinal artery occlusion . Int Ophthalmol . 18 . 2 . 83–6 . 1994 . 7814205 . 10.1007/BF00919244. 394747 .
  42. Walsh J, Markowitz I, Kerstein MD . Carotid endarterectomy for amaurosis fugax without angiography . Am. J. Surg. . 152 . 2 . 172–4 . August 1986 . 3526933 . 10.1016/0002-9610(86)90236-9.
  43. Bernstein EF, Dilley RB . Late results after carotid endarterectomy for amaurosis fugax . J. Vasc. Surg. . 6 . 4 . 333–40 . October 1987 . 3656582 . 10.1016/0741-5214(87)90003-6 . free .