Transient Monocular Vision Loss on Awakening: A Benign Amaurotic Phenomenon

Fulminant idiopathic intracranial hypertension (FIIH) is a subtype of idiopathic intracranial hypertension (IIH) characterized by rapid, severe, progressive vision loss. Surgical intervention is often performed either as a cerebrospinal fluid (CSF) shunt procedure or an optic nerve sheath fenestration or, at times, both. These surgical procedures carry a significant risk of morbidity and failure. We present 2 patients in whom a temporary lumbar drain was successfully used in the management of medically undertreated pediatric FIIH, and circumvented the need for surgical intervention.

Original Contribution Transient Monocular Vision Loss on Awakening: A Benign Amaurotic Phenomenon Marc A. Bouffard, MD, Wayne T. Cornblath, MD, Joseph F. Rizzo III, MD, Michael S. Lee, MD, Lindsey B. DeLott, MD, Eric R. Eggenberger, DO, Nurhan Torun, MD, FRCS(C) Background: Transient monocular vision loss (TMVL) is an alarming symptom owing to potentially serious etiologies such as thromboembolism or giant cell arteritis. Our objective is to describe the phenomenon of TMVL present on awakening, which may represent a distinct and benign entity. Methods: We performed a retrospective observational case series of 29 patients who experienced TMVL on awakening. Patients who described monocular dimming or blackout of vision were included, and those with blurred vision, concurrent eye pain, and binocular vision loss were excluded. Descriptive statistics were used to summarize the study population. Results: Of the 29 patients we studied, 90% (n = 26) were female and 48% had crowded discs (cup-to-disc ratio #0.2). The mean age was 45.4 years, although women were significantly younger than men (mean ages 43.4 and 62.7 years, respectively, P = 0.017). Brain magnetic resonance imaging and vascular imaging (magnetic resonance angiography, computed tomographic angiography, or carotid Doppler) were performed in 69% and 55% of cases, respectively, Department of Neurology (MAB), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts; Department of Ophthalmology and Visual Sciences (WTC, LBD), Kellogg Eye Center, University of Michigan Medical Center, Ann Arbor, Michigan; Department of Ophthalmology (JFR), Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts; Department of Ophthalmology (MSL), University of Minnesota, Minneapolis, Minnesota; Departments of Neurology and Ophthalmology (ERE), Michigan State University, East Lansing, Michigan; and Department of Surgery (NT), Division of Ophthalmology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts. One group's series (N.T., M.A.B.) was presented at the 41st Annual Meeting of the North American Neuro-Ophthalmology Society, February 21-26, 2015, San Diego, CA. The authors report no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the full text and PDF versions of this article on the journal's Web site (www. jneuro-ophthalmology.com). Address correspondence to Marc A. Bouffard, MD, Department of Neurology, Kirstein Building, 4th Floor, Beth Israel Deaconess Medical Center, Boston, MA 02215; E-mail: [e-mail] 122 and were uniformly negative. In 14 patients for whom clear follow-up data could be obtained, no medically or visually significant sequelae of this syndrome were found, and 50% experienced resolution of symptoms. Conclusions: Evaluation was uniformly negative when patients described waking with isolated vision loss in 1 eye with subsequent resolution, usually in less than 15 minutes. The natural history seems benign with symptoms frequently remitting spontaneously. This visual phenomenon may represent an autoregulatory failure resulting in a supply/demand mismatch during low-light conditions. Journal of Neuro-Ophthalmology 2017;37:122-125 doi: 10.1097/WNO.0000000000000451 © 2016 by North American Neuro-Ophthalmology Society T ransient monocular vision loss (TMVL) may indicate serious underlying disease. Diminished blood flow to the orbit, retina, or choroid is usually due to atherosclerotic or inflammatory vascular conditions. Increases in intraocular pressure or intracranial pressure from any etiology can also transiently impair the function of the optic nerve. Retinal vasospasm and transient vision loss due to optic disc drusen represent benign causes of TMVL (1,2). We report a distinct phenomenon of isolated TMVL on awakening not previously described in the literature. This phenomenon is distinguished from other syndromes of TMVL by the presence of isolated and stereotypic visual symptoms present on waking with rapid resolution, normal neuro-ophthalmologic examination, and negative work-up for potential causes. METHODS Approval was obtained from the institutional review boards at all participating medical institutions where necessary, to review the charts of 52 patients seen for transient, recurrent visual changes on awakening. All patients were evaluated by neuro-ophthalmologists at 1 of 5 institutions: the Bouffard et al: J Neuro-Ophthalmol 2017; 37: 122-125 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution Longwood Eye Clinic at the Beth Israel Deaconess Medical Center, the Kellogg Eye Center at the University of Michigan, the Massachusetts Eye and Ear Infirmary, Michigan State University, and the University of Minnesota. Patients were included if there was well documented, isolated, monocular dimming, or blackout of the entire field of vision immediately present on waking and with complete eventual resolution. Patients with monocular blurred vision (which would suggest ocular surface disease or difficulty focusing), binocular symptoms, and concurrent eye pain or redness (suggestive of anterior segment pathology) were excluded. We did not exclude patients with preexisting neurologic or ophthalmologic conditions. Descriptive statistics were used to tabulate data on our patients and a 2-tailed unpaired t test was applied to determine whether there was a significant difference in age between men and women. RESULTS Our clinical findings are summarized in Supplemental Digital Content 1 (see Table E1, http://links.lww.com/ WNO/A212). Twenty-nine patients (26 women and 3 men), aged 20-67 years, met the inclusion criteria. The mean age of our patients was 45.5 years with a significant difference between women (mean age 43.3 years, SD 12.8) and men (mean age 62.6 years, SD 4.0), P = 0.017. The left eye was involved in 9 patients (31%), the right eye in 13 patients (45%), and either eye in 7 (24%). Duration of visual symptoms was clearly described in 27 of the 29 patients. Spells were usually of sort duration with all but 3 lasting less than 15 minutes. Almost a quarter of events (22%) lasted 30 seconds or less. Episodes lasting between 30 seconds and 15 minutes comprised two-thirds (67%) of our series. Three patients (11%) had spells lasting longer than 15 minutes, reported as 45 minutes, 1 hour, and 4 hours. These longer episodes occurred in patients who had only a single spell. Spells were typically infrequent; 6 patients (21%) had only 1 spell and 23 (79%) reported fewer than 10 at the time of initial neuro-ophthalmologic evaluation. However, in the remaining 21%, spells were frequent and often occurred several times per week for months to years before our initial evaluation. Of the 23 patients who had more than 1 spell, frequency data could be obtained in 19. Of those 19 patients, 1 (5%) had daily spells, 4 (21%) had 1 or more spell per week but not daily, 8 (42%) had 1 or more per month but not weekly, and 6 (32%) had 1 or more per year but not on a monthly basis. The average time from symptom onset to initial evaluation was difficult to quantify but ranged from several weeks to 15 years. These data were obtained from 21 of the 29 patients. Data regarding the luminance-dependence of symptoms are incomplete. At least 8 of the 29 patients experienced rapid resolution on light exposure. Two patients also Bouffard et al: J Neuro-Ophthalmol 2017; 37: 122-125 reported onset of symptoms after turning the lights off. Queries as to whether or not the episodes resolved on light exposure only became part of the history taking for this group of patients after one of the patients in one examiner's series (NT) volunteered this observation. As such, a minimum of 28% of patients (8/29) were illuminationdependent and of the 11 patients in which we have clear data, 73% resolved with light exposure. This question was not asked by the other examiners although 1 patient evaluated by one of the authors (MSL) did describe illumination-dependent symptoms. Three patients reported this phenomenon only on the side on which they had slept; however, sleeping habits were not recorded for other patients. Comorbidities were infrequent. Systemic hypertension was seen in 5 patients (17%), hyperlipidemia in 4 (14%), and diabetes in 1 (3%). A history of migraine was present in 3 patients (10%), although there was no temporal association between migraine headache and the episodes of TMVL. History of idiopathic intracranial hypertension without papilledema, systemic lupus erythematosus, Raynaud phenomenon, and sarcoidosis were present in 1 patient each. One patient was in the first trimester of pregnancy. One patient was taking an oral contraceptive. Two patients were on an estrogen-based hormonal replacement regimen. All patients examined had normal intraocular pressures and normal iridocorneal angles. Crowded discs (as defined by a cup-to-disc ratio of # 0.2 or examiner notation of "crowded disc" or "obliterated cup") were present in 48% of patients where the information was available (13 of 27 patients); the fundus examination was otherwise normal. Of the 4 patients who had asymmetric cup-to-disc ratios, 1 patient had symptoms on the side of the smaller disc. In that case, the disc ipsilateral to symptoms was crowded (cup:disc 0.2). The remaining 7 eyes with asymmetric cupping had cup:disc ratios of 0.3-0.7. Given that this is a retrospective review, the diagnostic evaluation was performed at the discretion of the clinician and work-up was not uniform because there are no guidelines in the literature for this unique presentation. Brain magnetic resonance imaging was performed in 19 patients (69%). Vascular imaging of the head and/or neck was performed in 15 patients (55%, a combination of magnetic resonance angiography, computed tomographic angiography, and carotid Doppler), whereas transthoracic echocardiography was performed in 9 (31%). Elevated sedimentation rate (ESR) and C-reactive protein (CRP) were performed in 6 patients (21%). Work-up did not reveal relevant findings in any patients. Fifteen of the 29 patients were seen only once in clinic. Follow-up data were available in the remaining 14 patients. Seven patients (50%) reported resolution of episodes over a mean follow-up period of 32.4 months (median 24.8 months). Reduction in frequency was seen 123 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution in 5 of the 14 (36%) over a mean follow-up duration of 13.2 months (median 5.6 months). Persistent symptoms at their original frequency were seen in 2 patients (14%) with a mean follow-up duration of 2.4 months. None of the patients experienced stroke or persistent visual loss during follow-up. DISCUSSION Transient-isolated monocular vision loss often carries important diagnostic implications; many cases are caused by potentially life or sight-threatening etiologies. However, dimming or blackout of vision present on awakening with subsequent resolution and without other deficits seems to comprise a distinct and previously undescribed neuroophthalmologic entity. In most respects, our cohort of patients was relatively homogenous: a high proportion were women, most had only a few episodes with a short duration of symptoms, and no patient reported other symptoms that would be consistent with transient neurological events. All had a normal anterior segment examination. Most important is the apparently benign nature of our phenomenon; laboratory testing, as well as cardiovascular, and neuroimaging studies were uniformly noncontributory. The natural history seems to be generally self-limited and benign. The mechanism of TMVL on awakening may reflect an autoregulatory failure of the retrobulbar or retinal vasculature, resulting in a supply-demand mismatch. Absolute and relative changes in serum estrogen and progesterone levels alter the resistive properties of the retrobulbar vasculature, which might account, to some extent, for the female predominance in our series and the higher age in men (3-14). Altering the resistive indices of these vessels may disrupt normal neurovascular autoregulation, resulting in insufficient retinal flow as metabolic demand increases under conditions of low light (15-18). Retinal metabolic demand is higher in darkness than in light, likely accounting for the preponderance of subjects reporting the phenomenon in dimly lit rooms. In darkness, rods and cones generate "dark current," the continuous depolarization of photoreceptors, which causes neurotransmitter release (15). Ocular blood flow, retinal glucose and oxygen consumption are all higher in darkness and reduced on exposure to constant light, consistent with neurovascular coupling (16-18). The prompt resolution of symptoms on light exposure in 8 patients is consistent with this hypothesis; light exposure eliminates the supply/demand mismatch seen under low-light conditions. The occurrence of this phenomenon on awakening rather than with exposure to low-illumination at other times of the day may reflect increased retinal metabolic demands after long periods of darkness. Havelius et al (16) showed a trend toward a progressive increase in retinal blood flow the longer subjects were deprived of light. 124 The monocular nature of symptoms may be caused by a combination of anatomic factors and dynamic changes in vascular tone of the retrobulbar vessels. Many disorders of altered vascular tone can affect the vascular tree in an asymmetric manner; reversible cerebral vasoconstriction syndrome (RCVS) and migraine with aura are well-known examples. Menstruation, presumably due to hormonal fluctuations, may trigger headache in many migraineurs, and RCVS predominantly affects women. Although there are scant data on the impact of crowded discs on ocular blood flow directly, patients with optic disc drusen may present with TMVL (1). Crowded discs were present in almost half of our patients and may play a role in the pathogenesis of this disorder. In conclusion, TMVL on awakening is a novel phenomenon with important diagnostic implications. Recognizing this as a benign entity will impact clinical management and help avoid costly testing and unnecessary anxiety. The work-up in our patients was uniformly negative and no modifiable risk factors were discovered. None of our patients experienced any adverse sequelae. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: M. A. Bouffard, W. Cornblath, J. F. Rizzo, M. S. Lee, L. B. DeLott, E. Eggenberger, and N. Torun; b. Acquisition of data: W. Cornblath, J. F. Rizzo, M. S. Lee, L. B. DeLott, E. Eggenberger, and N. Torun; c. Analysis and interpretation of data: M. A. Bouffard, W. Cornblath, J. F. Rizzo, M. S. Lee, L. B. DeLott, E. Eggenberger, and N. Torun. Category 2: a. Drafting the manuscript: M. A. Bouffard; b. Revising it for intellectual content: M. A. 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