COMPLETE VISUAL RECOVERY AFTER INCIPIENT CRAO DUE TO OCULAR HYPOPERFUSION IN A PATIENT WITH MOYAMOYA DISEASE Eleonora M. Lad, MD, PhD,* Shivanand P. Lad, MD, PhD,† Cindy Ung, BA,‡ ATul Jain, MD,§ Gary K. Steinberg, MD, PhD,¶ Michael W. Gaynon, MD**
Purpose: The purpose of this study was to report a case of an impending central retinal artery occlusion with hypoperfusion in a moyamoya patient. Methods: A young, surgically revascularized moyamoya patient experienced severe unilateral vision loss from 20/25 to hand motions because of impending central retinal artery occlusion. The patient was treated with a combination of intermittent ocular massage, intraocular pressure–lowering medications, and aspirin. Patients: A case of a moyamoya patient at Stanford University Medical Center. Results: Visual acuity was restored to baseline by improving the ocular arterial–venous gradient after prompt administration of ocular massage, intraocular pressure–lowering drops, and aspirin. Conclusion: This dramatic result suggests that, if performed in a timely manner, augmentation of ocular perfusion can result in complete restoration of vision in some cases of incipient central retinal artery occlusion. RETINAL CASES & BRIEF REPORTS 7:248–251, 2013
taking simple steps to improve the arterial–venous pressure gradient within the eye.
From the *Department of Ophthalmology, and †Division of Neurosurgery, Duke University Medical Center, Durham, North Carolina; ‡School of Medicine, Stanford University, Stanford, California; §San Diego Retinal Associates, San Diego, California; and Departments of ¶Neurosurgery, and **Palo Alto Medical Foundation, Palo Alto, California.
Case Report A 17-year-old man presented to the emergency room with the complaint of sudden loss of vision in his left eye at approximately 7 pm, 1 hour before arrival. His medical history was significant for neurofibromatosis type I and MMD, status post encephaloduroarteriosynangiosis on the left side 9 years ago. He was recently seen by his optometrist, and corrected vision was 20/20 in the right eye and 20/25 in the left eye, with an otherwise normal examination. A few days later, he experienced an episode of transient obscuration of vision in his left eye that lasted only a few seconds but he was not concerned by this at that time. He had a magnetic resonance imaging/magnetic resonance angiogram performed at an outside hospital before presentation in the emergency room (images not available), which were judged by the neuroradiology and neurosurgery services to be unchanged compared with imaging done 6 months earlier. Imaging studies revealed a small caliber left internal carotid artery, which came to an abrupt end in the distal segment, roughly near the takeoff of the ophthalmic artery. There was also occlusion of the proximal portions of the middle cerebral artery (MCA) artery on that side, and it appeared as if the MCA was being fed by collaterals through his indirect bypass surgery on the
M
oyamoya disease (MMD) is defined as an idiopathic stenosis or occlusion of the terminal internal carotid, proximal anterior or middle cerebral arteries, resulting in the development of an abnormal vascular network in the areas of the arterial occlusions. We present a case of severe unilateral vision loss because of an incipient central retinal artery occlusion (CRAO) in a young, surgically revascularized moyamoya patient, which was completely reversed by The authors declare no conflict of interest. Reprint requests: Michael W. Gaynon, MD, the Palo Alto Medical Foundation, 795 El Camino Real, Palo Alto, CA 94301; email: [email protected]
248
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VISUAL RECOVERY AFTER CRAO IN A MOYAMOYA PATIENT left side. The ophthalmology and neurosurgery services were consulted. Given the recent magnetic resonance imaging/MRA findings, neurosurgery did not think that any immediate surgical intervention would be likely to acutely improve vision. On ophthalmologic examination, just before midnight, his vision was 20/20 in the right eye and hand motions at 1 ft in the left eye. His pupillary examination was significant for a florid (4+) afferent pupillary defect in the left eye. Intraocular pressure (IOP) by tonometry was 14 mmHg in the right eye and 13 mmHg in the left eye. Extraocular movements and anterior segment examination were within normal limits bilaterally. The provisional differential diagnosis at this point included incipient or complete CRAO, ophthalmic artery occlusion, vasospasm, and, less likely, central retinal vein occlusion. Intermittent (press and release) ocular massage was initiated, just before administration of dilating drops. This was done in the hope that a thrombus, if present, might be dislodged and that, by lowering IOP, there would be less resistance to ocular blood flow. The intermittent massage was continued for 20 minutes while the patient dilated. Intraocular pressure by Tonopen (Reichert Technologies, Depew, NY) in the left eye after 20 minutes of ocular massage was 11 mmHg. Dilated fundus examination revealed a normal examination in the right eye (Figure 1A) and slight retinal pallor with possible vascular sludging in the left eye (Figure 1B). Blood flow appeared to be very slow but not completely arrested. There was no cherry red spot. The fundus examination did not show frank retinal whitening, but there was some boxcar segmentation of retinal blood flow visible in the posterior pole. No emboli were visible. The cause of the hypoperfusion could not be determined, and fluorescein angiogram was not available, but the presumption was that it was related to proximal vascular changes related to moyamoya. The hypothesis was that the patient had marginal perfusion at baseline as a result of the moyamoya vascular changes and was at a high risk of hypoperfusion before symptoms arose. The hypoperfusion, when it occurred, led to his sudden loss of vision. By lowering IOP with massage and medications, afterload was reduced and his probably suboptimal perfusion pressure was again adequate to perfuse the retina and restore vision. There was no evidence for an embolic or thrombotic event. The patient was then treated with topical brimonidine and timolol drops in the left eye, combined with 500 mg oral acetazolamide. Intraocular pressure after the initial set of drops was 9 mmHg, and the patient’s visual acuity improved to hand motions at 6 ft. Ocular massage for another 30 minutes and an additional set of drops were administered, and IOP was 7 mmHg and vision had further improved to counting fingers at 3 ft. Paracentesis was deferred at this time, because vision had improved as the IOP was lowered to 50% of the initial measurement and because the patient was opposed to having this intervention. A Goldmann visual field was performed using a size V target and was found to be normal in both eyes. The patient was discharged home on brimonidine, timolol, acetazolamide, and 325 mg of aspirin. He was asked to continue the intermittent ocular massage through the night. The following day the visual acuity in the left eye was 20/60, with a 2+ afferent pupillary defect. He denied red desaturation in the left eye but missed two Ishihara plates on color testing. Intraocular pressure was 12 mmHg in the right eye and 7 mmHg in the left eye. Confrontational visual fields were within normal limits bilaterally. Dilated fundus examination revealed a normal examination in the right eye and slight retinal pallor in the left eye. Two days after the initial presentation, the vision in the left eye was 20/30 and he reported adherence to ocular massage, acetazolamide, and the pressure-lowering eyedrops. A fluorescein angiogram of the left eye demonstrated very prompt arteriovenous filling (Figure 2A) and slightly patchy choridal filling, which normalized by 57 seconds (Figure 2B). Two weeks later, the vision in the left eye further improved to 20/25 and he did not have an afferent pupillary defect.
Discussion Moyamoya disease was first described by Takeuchi and Shimizu in 1957. Literally translated from Japanese the term moyamoya means “wavering puff of smoke” describing the appearance of the abnormal vasculature. Patients usually present with signs of ischemia or hemorrhage. Signs at presentation include motor disturbances (most common, 80%), transient ischemic attack, ischemic stroke, sensory attacks, infantile hemiplegia, headaches, choreiform movements, and convulsions.1 Moyamoya disease is a progressive disease with a devastating natural history. The main goal of revascularization surgery in MMD patients is prevention of future ischemic and hemorrhagic strokes and,
Fig. 1. Fundus photographs obtained on the second day after the initial presentation. Dilated fundus examination revealed a normal examination in the right eye (A, visual acuity 20/20) and slight retinal pallor in the left eye (B, visual acuity 20/60).
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potentially, limitation of disease progression. Direct revascularization, consisting of a superficial temporal artery–MCA bypass, although more complex, is the first choice because it provides immediate increase in blood flow to the ischemic area.1 Indirect revascularization procedures such as encephaloduroarteriosynangiosis or encephaloduromyosynangiosis are applied in patients in whom either the superficial temporal artery or MCA is too small or fragile to allow performance of a direct bypass.1 The MMD patient in the current report underwent an indirect revascularization surgery at an outside facility. After his revascularization, neuroimaging studies revealed occlusion of the proximal left MCA and a small caliber left internal carotid artery that appeared to come to an abrupt end in the distal segment, roughly near the takeoff of the ophthalmic artery. These changes in the left internal carotid artery and ophthalmic artery likely accounted for the decrease in arterial flow and retinal hypoperfusion observed during clinical examination. Visual disturbances in patients with moyamoya have been reported to occur as a result of the pathologic cerebrovascular network involving the ophthalmic or posterior cerebral artery. These include nystagmus, homonymous hemianopia, amaurosis fugax, transient diplopia, decreased visual acuity with visual–spatial agnosia, and cortical blindness.1 Only one previous report documented the occurrence of a CRAO associated with MMD.2 Ours is the only case documenting reversible visual loss secondary to incipient CRAO from hypoperfusion in a patient with MMD. Central retinal artery occlusion results in acute, painless, monocular vision loss analogous to an ischemic cerebral stroke. Treatment for CRAO is only effective if performed within 8 hours of occlusion. However, some studies reported benefit of therapeutic measures given up to 24 hours or 48 hours after onset of symptoms.3 A number of therapies for CRAO have been attempted in daily clinical practice: sublingual isosorbide dinitrate, rebreathing of carbon dioxide, ocular massage, IOP reduction via anterior chamber paracentesis,4,5 intravenous acetazolamide, intravenous mannitol or trabeculectomy,3 thrombolytic agents such as urokinase and recombinant tissue plasminogen activator,3 antiplatelet therapy with tirofiban,3 pentoxifylline, systemic steroids, and external counterpulsation.3 Some researchers and clinicians have used a combination of some of the above treatments. Despite these numerous attempts to reestablish retinal perfusion after CRAO, a Cochrane metaanalysis from 2002 found that none of these therapies improved visual outcomes beyond the natural course of the disease.6 In the current report, we present a case of a likely impending CRAO with hypoperfusion in a patient with MMD in which visual acuity was progressively restored
Fig. 2. A. Fluorescein angiogram performed on the left eye demonstrated very prompt arteriovenous filling with laminar flow present by 24 seconds. B. The choroidal filling was slightly patchy but normalized by 57 seconds. There was no macular edema or signs of retinal nonperfusion.
from hand motion at 1 ft to 20/25 over a 2-week period by the use of a combination of intermittent ocular massage, IOP-lowering medications, and aspirin. Most of this recovery was obtained over the first 2 days of treatment. This approach was aimed at improving ocular perfusion, in the face of at least a partial proximal vascular obstruction. Ocular massage was initiated 5 hours after the onset of visual loss, followed soon thereafter by topical brimonidine and timolol eyedrops, 500 mg of oral acetazolamide, and aspirin. The patient continued treatment with topical timolol and brimonidine, oral acetazolamide, and aspirin for 2 weeks. With this combination treatment, the patient’s visual acuity returned to 20/30 by the second day and to his baseline of 20/25 at the 2-week return visit. In our patient, reduction of IOP may have contributed to the
251
VISUAL RECOVERY AFTER CRAO IN A MOYAMOYA PATIENT
improvement in ocular perfusion through collateral flow distal to the patient’s left-sided ophthalmic artery stenosis, which allowed for improvement in his vision. This dramatic result suggests that, if performed in a timely manner before irreversible retinal damage occurs, augmentation of ocular perfusion can result in dramatic improvement and even complete restoration of vision in some cases of incipient CRAO. This treatment strategy has also been used successfully by us for patients with recent onset of completed CRAO and may obviate the need for paracentesis in some cases. The advantage of initially using ocular massage is that it can be carried on over an extended period, but it cannot be safely performed once a paracentesis has been performed. Paracentesis remains an option, if no improvement results from the less invasive ocular massage. It is important to remember that, to maintain adequate blood flow, there must be a gradient between arterial pressure and venous pressure across a capillary bed. When arterial pressure is abnormally low (or, in the case of venous occlusion, venous pressure is abnormally high), that gradient is lost, and blood flow declines or even stops, as it largely did in our patient. Addressing this gradient, by either increasing arterial pressure or reducing venous pressure, can lead to improved blood flow and hopefully a return of function to tissues that have not been irreparably damaged by hypoxia. In our case, we attempted to improve the arterial–venous gradient by lowering IOP, effectively lowering venous pressure. Interestingly, one of the agents we used to lower IOP, acetazolamide, may have had a secondary unanticipated benefit for ocular blood flow. In MMD, revascularized patients show improved cerebral blood flow when given acetazolamide, whereas those who have not been
revascularized do not.7 By reducing vascular afterload and facilitating blood flow through the brain, there may be reduced resistance to flow through the compromised carotid artery. This may have the effect of improving the arterial–venous gradient within the ipsilateral eye, thus bringing about improved ocular blood flow. This concept may also have benefit when applied to the other more common cause of disordered ocular blood flow ophthalmologists face: retinal venous occlusive disease. Attention to and therapeutic manipulation of the arterial–venous gradient most likely explains the progressive functional improvement in our patient’s vision. Key words: central retinal artery occlusion, intervention, Moyamoya, ocular hypoperfusion, retina. References 1. Guzman R, Lee H, Achrol A, et al. Clinical outcome after 450 revascularization procedures for moyamoya disease. Clinical article. J Neurosurg 2009;111:927–935. 2. Chace R, Hedges TR III. Retinal artery occlusion due to moyamoya disease. J Clin Neuroophthalmol 1984;4:31–34. 3. Rumelt S, Dorenboim Y, Rehany U. Aggressive systematic treatment for central retinal artery occlusion. Am J Ophthalmol 1999;128:733–738. 4. Atebara NH, Brown GC, Cater J. Efficacy of anterior chamber paracentesis and carbogen in treating acute nonarteritic central retinal artery occlusion. Ophthalmology 1995;102:2029–2034; discussion 2034–2025. 5. Ffytche TJ. A rationalization of treatment of central retinal artery occlusion. Trans Ophthalmol Soc U K 1974;94:468–479. 6. Fraser S, Siriwardena D. Interventions for acute non-arteritic central retinal artery occlusion. Cochrane Database Syst Rev 2002:CD001989. 7. Kuroda S, Houkin K, Ishikawa T, et al. Novel bypass surgery for moyamoya disease using pericranial flap: its impacts on cerebral hemodynamics and long-term outcome. Neurosurgery 2010;66:1093–1101; discussion 1101.
Purpose: The purpose of this study was to report a case of an impending central retinal artery occlusion with hypoperfusion in a moyamoya patient. Methods: A young, surgically revascularized moyamoya patient experienced severe unilateral vision loss from 20/25 to hand motions because of impending central retinal artery occlusion. The patient was treated with a combination of intermittent ocular massage, intraocular pressure–lowering medications, and aspirin. Patients: A case of a moyamoya patient at Stanford University Medical Center. Results: Visual acuity was restored to baseline by improving the ocular arterial–venous gradient after prompt administration of ocular massage, intraocular pressure–lowering drops, and aspirin. Conclusion: This dramatic result suggests that, if performed in a timely manner, augmentation of ocular perfusion can result in complete restoration of vision in some cases of incipient central retinal artery occlusion. RETINAL CASES & BRIEF REPORTS 7:248–251, 2013
taking simple steps to improve the arterial–venous pressure gradient within the eye.
From the *Department of Ophthalmology, and †Division of Neurosurgery, Duke University Medical Center, Durham, North Carolina; ‡School of Medicine, Stanford University, Stanford, California; §San Diego Retinal Associates, San Diego, California; and Departments of ¶Neurosurgery, and **Palo Alto Medical Foundation, Palo Alto, California.
Case Report A 17-year-old man presented to the emergency room with the complaint of sudden loss of vision in his left eye at approximately 7 pm, 1 hour before arrival. His medical history was significant for neurofibromatosis type I and MMD, status post encephaloduroarteriosynangiosis on the left side 9 years ago. He was recently seen by his optometrist, and corrected vision was 20/20 in the right eye and 20/25 in the left eye, with an otherwise normal examination. A few days later, he experienced an episode of transient obscuration of vision in his left eye that lasted only a few seconds but he was not concerned by this at that time. He had a magnetic resonance imaging/magnetic resonance angiogram performed at an outside hospital before presentation in the emergency room (images not available), which were judged by the neuroradiology and neurosurgery services to be unchanged compared with imaging done 6 months earlier. Imaging studies revealed a small caliber left internal carotid artery, which came to an abrupt end in the distal segment, roughly near the takeoff of the ophthalmic artery. There was also occlusion of the proximal portions of the middle cerebral artery (MCA) artery on that side, and it appeared as if the MCA was being fed by collaterals through his indirect bypass surgery on the
M
oyamoya disease (MMD) is defined as an idiopathic stenosis or occlusion of the terminal internal carotid, proximal anterior or middle cerebral arteries, resulting in the development of an abnormal vascular network in the areas of the arterial occlusions. We present a case of severe unilateral vision loss because of an incipient central retinal artery occlusion (CRAO) in a young, surgically revascularized moyamoya patient, which was completely reversed by The authors declare no conflict of interest. Reprint requests: Michael W. Gaynon, MD, the Palo Alto Medical Foundation, 795 El Camino Real, Palo Alto, CA 94301; email: [email protected]
248
249
VISUAL RECOVERY AFTER CRAO IN A MOYAMOYA PATIENT left side. The ophthalmology and neurosurgery services were consulted. Given the recent magnetic resonance imaging/MRA findings, neurosurgery did not think that any immediate surgical intervention would be likely to acutely improve vision. On ophthalmologic examination, just before midnight, his vision was 20/20 in the right eye and hand motions at 1 ft in the left eye. His pupillary examination was significant for a florid (4+) afferent pupillary defect in the left eye. Intraocular pressure (IOP) by tonometry was 14 mmHg in the right eye and 13 mmHg in the left eye. Extraocular movements and anterior segment examination were within normal limits bilaterally. The provisional differential diagnosis at this point included incipient or complete CRAO, ophthalmic artery occlusion, vasospasm, and, less likely, central retinal vein occlusion. Intermittent (press and release) ocular massage was initiated, just before administration of dilating drops. This was done in the hope that a thrombus, if present, might be dislodged and that, by lowering IOP, there would be less resistance to ocular blood flow. The intermittent massage was continued for 20 minutes while the patient dilated. Intraocular pressure by Tonopen (Reichert Technologies, Depew, NY) in the left eye after 20 minutes of ocular massage was 11 mmHg. Dilated fundus examination revealed a normal examination in the right eye (Figure 1A) and slight retinal pallor with possible vascular sludging in the left eye (Figure 1B). Blood flow appeared to be very slow but not completely arrested. There was no cherry red spot. The fundus examination did not show frank retinal whitening, but there was some boxcar segmentation of retinal blood flow visible in the posterior pole. No emboli were visible. The cause of the hypoperfusion could not be determined, and fluorescein angiogram was not available, but the presumption was that it was related to proximal vascular changes related to moyamoya. The hypothesis was that the patient had marginal perfusion at baseline as a result of the moyamoya vascular changes and was at a high risk of hypoperfusion before symptoms arose. The hypoperfusion, when it occurred, led to his sudden loss of vision. By lowering IOP with massage and medications, afterload was reduced and his probably suboptimal perfusion pressure was again adequate to perfuse the retina and restore vision. There was no evidence for an embolic or thrombotic event. The patient was then treated with topical brimonidine and timolol drops in the left eye, combined with 500 mg oral acetazolamide. Intraocular pressure after the initial set of drops was 9 mmHg, and the patient’s visual acuity improved to hand motions at 6 ft. Ocular massage for another 30 minutes and an additional set of drops were administered, and IOP was 7 mmHg and vision had further improved to counting fingers at 3 ft. Paracentesis was deferred at this time, because vision had improved as the IOP was lowered to 50% of the initial measurement and because the patient was opposed to having this intervention. A Goldmann visual field was performed using a size V target and was found to be normal in both eyes. The patient was discharged home on brimonidine, timolol, acetazolamide, and 325 mg of aspirin. He was asked to continue the intermittent ocular massage through the night. The following day the visual acuity in the left eye was 20/60, with a 2+ afferent pupillary defect. He denied red desaturation in the left eye but missed two Ishihara plates on color testing. Intraocular pressure was 12 mmHg in the right eye and 7 mmHg in the left eye. Confrontational visual fields were within normal limits bilaterally. Dilated fundus examination revealed a normal examination in the right eye and slight retinal pallor in the left eye. Two days after the initial presentation, the vision in the left eye was 20/30 and he reported adherence to ocular massage, acetazolamide, and the pressure-lowering eyedrops. A fluorescein angiogram of the left eye demonstrated very prompt arteriovenous filling (Figure 2A) and slightly patchy choridal filling, which normalized by 57 seconds (Figure 2B). Two weeks later, the vision in the left eye further improved to 20/25 and he did not have an afferent pupillary defect.
Discussion Moyamoya disease was first described by Takeuchi and Shimizu in 1957. Literally translated from Japanese the term moyamoya means “wavering puff of smoke” describing the appearance of the abnormal vasculature. Patients usually present with signs of ischemia or hemorrhage. Signs at presentation include motor disturbances (most common, 80%), transient ischemic attack, ischemic stroke, sensory attacks, infantile hemiplegia, headaches, choreiform movements, and convulsions.1 Moyamoya disease is a progressive disease with a devastating natural history. The main goal of revascularization surgery in MMD patients is prevention of future ischemic and hemorrhagic strokes and,
Fig. 1. Fundus photographs obtained on the second day after the initial presentation. Dilated fundus examination revealed a normal examination in the right eye (A, visual acuity 20/20) and slight retinal pallor in the left eye (B, visual acuity 20/60).
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RETINAL CASES & BRIEF REPORTS´ 2013 VOLUME 7 NUMBER 3
potentially, limitation of disease progression. Direct revascularization, consisting of a superficial temporal artery–MCA bypass, although more complex, is the first choice because it provides immediate increase in blood flow to the ischemic area.1 Indirect revascularization procedures such as encephaloduroarteriosynangiosis or encephaloduromyosynangiosis are applied in patients in whom either the superficial temporal artery or MCA is too small or fragile to allow performance of a direct bypass.1 The MMD patient in the current report underwent an indirect revascularization surgery at an outside facility. After his revascularization, neuroimaging studies revealed occlusion of the proximal left MCA and a small caliber left internal carotid artery that appeared to come to an abrupt end in the distal segment, roughly near the takeoff of the ophthalmic artery. These changes in the left internal carotid artery and ophthalmic artery likely accounted for the decrease in arterial flow and retinal hypoperfusion observed during clinical examination. Visual disturbances in patients with moyamoya have been reported to occur as a result of the pathologic cerebrovascular network involving the ophthalmic or posterior cerebral artery. These include nystagmus, homonymous hemianopia, amaurosis fugax, transient diplopia, decreased visual acuity with visual–spatial agnosia, and cortical blindness.1 Only one previous report documented the occurrence of a CRAO associated with MMD.2 Ours is the only case documenting reversible visual loss secondary to incipient CRAO from hypoperfusion in a patient with MMD. Central retinal artery occlusion results in acute, painless, monocular vision loss analogous to an ischemic cerebral stroke. Treatment for CRAO is only effective if performed within 8 hours of occlusion. However, some studies reported benefit of therapeutic measures given up to 24 hours or 48 hours after onset of symptoms.3 A number of therapies for CRAO have been attempted in daily clinical practice: sublingual isosorbide dinitrate, rebreathing of carbon dioxide, ocular massage, IOP reduction via anterior chamber paracentesis,4,5 intravenous acetazolamide, intravenous mannitol or trabeculectomy,3 thrombolytic agents such as urokinase and recombinant tissue plasminogen activator,3 antiplatelet therapy with tirofiban,3 pentoxifylline, systemic steroids, and external counterpulsation.3 Some researchers and clinicians have used a combination of some of the above treatments. Despite these numerous attempts to reestablish retinal perfusion after CRAO, a Cochrane metaanalysis from 2002 found that none of these therapies improved visual outcomes beyond the natural course of the disease.6 In the current report, we present a case of a likely impending CRAO with hypoperfusion in a patient with MMD in which visual acuity was progressively restored
Fig. 2. A. Fluorescein angiogram performed on the left eye demonstrated very prompt arteriovenous filling with laminar flow present by 24 seconds. B. The choroidal filling was slightly patchy but normalized by 57 seconds. There was no macular edema or signs of retinal nonperfusion.
from hand motion at 1 ft to 20/25 over a 2-week period by the use of a combination of intermittent ocular massage, IOP-lowering medications, and aspirin. Most of this recovery was obtained over the first 2 days of treatment. This approach was aimed at improving ocular perfusion, in the face of at least a partial proximal vascular obstruction. Ocular massage was initiated 5 hours after the onset of visual loss, followed soon thereafter by topical brimonidine and timolol eyedrops, 500 mg of oral acetazolamide, and aspirin. The patient continued treatment with topical timolol and brimonidine, oral acetazolamide, and aspirin for 2 weeks. With this combination treatment, the patient’s visual acuity returned to 20/30 by the second day and to his baseline of 20/25 at the 2-week return visit. In our patient, reduction of IOP may have contributed to the
251
VISUAL RECOVERY AFTER CRAO IN A MOYAMOYA PATIENT
improvement in ocular perfusion through collateral flow distal to the patient’s left-sided ophthalmic artery stenosis, which allowed for improvement in his vision. This dramatic result suggests that, if performed in a timely manner before irreversible retinal damage occurs, augmentation of ocular perfusion can result in dramatic improvement and even complete restoration of vision in some cases of incipient CRAO. This treatment strategy has also been used successfully by us for patients with recent onset of completed CRAO and may obviate the need for paracentesis in some cases. The advantage of initially using ocular massage is that it can be carried on over an extended period, but it cannot be safely performed once a paracentesis has been performed. Paracentesis remains an option, if no improvement results from the less invasive ocular massage. It is important to remember that, to maintain adequate blood flow, there must be a gradient between arterial pressure and venous pressure across a capillary bed. When arterial pressure is abnormally low (or, in the case of venous occlusion, venous pressure is abnormally high), that gradient is lost, and blood flow declines or even stops, as it largely did in our patient. Addressing this gradient, by either increasing arterial pressure or reducing venous pressure, can lead to improved blood flow and hopefully a return of function to tissues that have not been irreparably damaged by hypoxia. In our case, we attempted to improve the arterial–venous gradient by lowering IOP, effectively lowering venous pressure. Interestingly, one of the agents we used to lower IOP, acetazolamide, may have had a secondary unanticipated benefit for ocular blood flow. In MMD, revascularized patients show improved cerebral blood flow when given acetazolamide, whereas those who have not been
revascularized do not.7 By reducing vascular afterload and facilitating blood flow through the brain, there may be reduced resistance to flow through the compromised carotid artery. This may have the effect of improving the arterial–venous gradient within the ipsilateral eye, thus bringing about improved ocular blood flow. This concept may also have benefit when applied to the other more common cause of disordered ocular blood flow ophthalmologists face: retinal venous occlusive disease. Attention to and therapeutic manipulation of the arterial–venous gradient most likely explains the progressive functional improvement in our patient’s vision. Key words: central retinal artery occlusion, intervention, Moyamoya, ocular hypoperfusion, retina. References 1. Guzman R, Lee H, Achrol A, et al. Clinical outcome after 450 revascularization procedures for moyamoya disease. Clinical article. J Neurosurg 2009;111:927–935. 2. Chace R, Hedges TR III. Retinal artery occlusion due to moyamoya disease. J Clin Neuroophthalmol 1984;4:31–34. 3. Rumelt S, Dorenboim Y, Rehany U. Aggressive systematic treatment for central retinal artery occlusion. Am J Ophthalmol 1999;128:733–738. 4. Atebara NH, Brown GC, Cater J. Efficacy of anterior chamber paracentesis and carbogen in treating acute nonarteritic central retinal artery occlusion. Ophthalmology 1995;102:2029–2034; discussion 2034–2025. 5. Ffytche TJ. A rationalization of treatment of central retinal artery occlusion. Trans Ophthalmol Soc U K 1974;94:468–479. 6. Fraser S, Siriwardena D. Interventions for acute non-arteritic central retinal artery occlusion. Cochrane Database Syst Rev 2002:CD001989. 7. Kuroda S, Houkin K, Ishikawa T, et al. Novel bypass surgery for moyamoya disease using pericranial flap: its impacts on cerebral hemodynamics and long-term outcome. Neurosurgery 2010;66:1093–1101; discussion 1101.
