Gaze Scanning on Mid-Block Sidewalks by Pedestrians With Homonymous Hemianopia With or Without Spatial Neglect.

Purpose: The purpose of this study was to investigate gaze-scanning by pedestrians with homonymous hemianopia (HH) when walking on mid-block sidewalks. Methods: Pedestrians with right homonymous hemianopia (RHH), and left homonymous hemianopia (LHH) without and with left spatial neglect (LHSN) walked on city streets wearing a gaze-tracking system. Gaze points were obtained by combining head movement and eye-in-head movement. Mixed-effects regression models were used to compare horizontal gaze scan magnitudes and rates between the side of the hemi-field loss (BlindSide) and the seeing side (SeeingSide), among the three subject groups, and between mid-block walking and street crossing segments. Results: A total of 7021 gaze scans were obtained from 341 minutes of mid-block walking videos by 19 participants (6 with LHH, 7 with RHH, and 6 with LHSN). The average gaze magnitude and scanning rate in mid-block segments were significantly higher towards the BlindSide than the SeeingSide in LHH (magnitude larger by 1.9° (degrees), P = 0.006; scan rate higher by 4.2 scans/minute, P < 0.001) and RHH subjects (magnitude larger by 3.3°, P < 0.001; scan rate higher by 3.2 scans/minute, P = 0.002), but they were not significantly different in LHSN subjects. The scanning rate, in terms of scans/minute (mean, 95% confidence interval [CI]) was significantly lower in LHSN subjects (mean = 6.9, 95% CI = 5.6-8.7) than LHH (mean = 10.2, 95% CI = 8.0-13.1; P = 0.03) and RHH (mean = 11.1, 95% CI = 9.0-13.7; P = 0.007) subjects. Compared to street-crossings, the scan rate during the mid-block segments was lower by 3.5 scans/minute (P < 0.001) and the gaze magnitude was smaller by 3.8° (P < 0.001) over the 3 groups. Conclusions: Evidence of compensatory scanning suggests a proactive, top-down mechanism driving gaze in HH. The presence of spatial neglect (SN) appeared to negatively impact the top-down process.

Pilot study of a pedestrian collision detection test for a multisite trial of field expansion devices for hemianopia.

SIGNIFICANCE: Performance-based outcome measures are crucial for clinical trials of field expansion devices. We implemented a test simulating a real-world mobility situation, focusing on detection of a colliding pedestrian among multiple noncolliding pedestrians, suitable for measuring the effects of homonymous hemianopia and assistive devices in clinical trials. PURPOSE: In preparation for deploying the test in a multisite clinical trial, we conducted a pilot study to gather preliminary data on blind-side collision detection performance with multiperiscopic peripheral prisms compared with Fresnel peripheral prisms. We tested the hypothesis that detection rates for colliding pedestrians approaching on a 40° bearing angle (close to the highest collision risk when walking) would be higher with 100Δ oblique multiperiscopic (≈42° expansion) than 65Δ oblique Fresnel peripheral prisms (≈32° expansion). METHODS: Six participants with homonymous hemianopia completed the test with and without each type of prism glasses, after using them in daily mobility for a minimum of 4 weeks. The test, presented as a video on a large screen, simulated walking through a busy shopping mall. Colliding pedestrians approached from the left or the right on a bearing angle of 20 or 40°. RESULTS: Overall, blind-side detection was only 23% without prisms but improved to 73% with prisms. For multiperiscopic prisms, blind-side detection was significantly higher with than without prisms at 40° (88 vs. 0%) and 20° (75 vs. 0%). For Fresnel peripheral prisms, blind-side detection rates were not significantly higher with than without prisms at 40° (38 vs. 0%) but were significantly higher with prisms at 20° (94 vs. 56%). At 40°, detection rates were significantly higher with multiperiscopic than Fresnel prisms (88 vs. 38%). CONCLUSIONS: The collision detection test is suitable for evaluating the effects of hemianopia and prism glasses on collision detection, confirming its readiness to serve as the primary outcome measure in the upcoming clinical trial.

Undoubtedly unaware of homonymous hemianopia: The contribution of overconfidence to anosognosia of hemianopia.

A new functional deficit caused by a stroke can be understood as a situation of uncertainty that has to prompt deficit discovery and subsequent incorporation into an altered self-perception. Anosognosia for visual field deficits is frequent after stroke. For hemiplegia, patients' performance in a riddle test provided evidence that the inability to generate and adjust beliefs in face of uncertainty contributes to anosognosia for hemiplegia. In this prospective study, the same riddles are used in patients with homonymous hemianopia due to a first-ever stroke in the posterior cerebral artery territory and in an age-matched control cohort. The riddles create a situation of uncertainty that is resolved with five successive clues which progressively delimit the target word. After each clue, patients have to guess the target word and rate their confidence in the answer's correctness. Patients were tested once during the hospital stay. According to the Bisiach score for anosognosia, 12 out of 29 patients were unaware of their visual field deficits. All patients with anosognosia for hemianopia had right hemisphere lesions. Patients with and without anosognosia did not differ significantly in global cognitive impairment, mental flexibility or memory function. Importantly, patients with anosognosia showed higher confidence ratings than patients without anosognosia and controls in the first two clues (situations of uncertainty). This was demonstrated by a significant interaction effect in a mixed ANOVA with the factors group (anosognosia, nosognosia, controls) and riddle clues. An exploratory lesion subtraction analysis showed a high proportion of deficit unawareness in patients with lesions in the right fusiform and (para)hippocampal gyri. Our findings suggest that overconfidence in situations of uncertainty might contribute to the appearance of anosognosia for hemianopia. Because this has been demonstrated before in anosognosia for hemiplegia, we suggest that overconfidence is a supra-modal contributor to deficit unawareness.

Vertical infantile nystagmus: Explanation of why the direction of nystagmus is vertical.

This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.

Measurement of Cerebral Glucose Metabolism in the Visual Cortex Predicts the Prognosis of Hemianopia.

BACKGROUND AND OBJECTIVE: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction. METHODS: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio. RESULTS: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices. CONCLUSION: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.

Neurophysiological Alterations of the Visual Pathway in Posterior Cortical Atrophy: Systematic Review and a Case Series.

Background: The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates. Objective: To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients. Methods: Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic. Results: The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings. Conclusions: Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.

Disrupted resting-state EEG alpha-band interactions as a novel marker for the severity of visual field deficits after brain lesion.

OBJECTIVE: Homonymous visual field deficits (HFVDs) are frequent following brain lesions. Current restoration treatments aim at activating areas of residual vision through numerous stimuli, but show limited effect. Recent findings suggest that spontaneous neural α-band coupling is more efficient for enabling visual perception in healthy humans than task-induced activations. Here, we evaluated whether it is also associated with the severity of HFVD. METHODS: Ten patients with HFVDs after brain damage in the subacute to chronic stage and ten matched healthy controls underwent visual stimulation with alternating checkerboards and electroencephalography recordings of stimulation-induced power changes and of spontaneous neural interactions during rest. RESULTS: Visual areas of the affected hemisphere showed reduced event-related power decrease in α and ß frequency bands, but also reduced spontaneous α-band interactions during rest, as compared to contralesional areas and healthy controls. A multivariate stepwise regression retained the degree of disruption of spontaneous interactions, but not the reduced task-induced power changes as predictor for the severity of the visual deficit. CONCLUSIONS: Spontaneous α-band interactions of visual areas appear as a better marker for the severity of HFVDs than task-induced activations. SIGNIFICANCE: Treatment attempts of HFVDs should try to enhance spontaneous α-band coupling of structurally intact ipsilesional areas.

Prognostic Factors for Long-Term Recovery of Homonymous Visual Field Defects After Posterior Circulation Ischemic Stroke.

OBJECTIVES: Ischemic stroke (IS) is the main cause of homonymous visual field defects (HVFDs) in adults. Some reports suggest recovery even in late-phase strokes, but data is sparse. This study examines the frequency of long-term recovery from HVFDs in patients with posterior circulation infarction (POCI) and evaluates whether demographic or clinical characteristics are prognostic factors of perimetric recovery. MATERIALS AND METHODS: Our study included patients with HVFDS due to POCI who had undergone 2 or more kinetic perimetric evaluations at least 6 months after the index IS. Clinical and imaging data were systematically reviewed and we performed univariate and multivariate logistic regression analyses to determine whether demographic, stroke etiology (TOAST classification), and initial perimetric patterns were prognostic factors of visual recovery occurring 6 months and beyond from POCI. RESULTS: One hundred one patients with POCI were included. Median subject age was 60 years and 54.4% were female. After a median perimetric follow-up time of 13.5 months, spontaneous visual improvement was observed in 15.8% of patients. Prognostic factors for visual improvement were age < 50 years (OR 4.6; P = 0.093), POCI associated with hypercoagulable states (OR 12.3; P = 0.048), and vertebral artery dissection (OR 12.6; P = 0.048), while the presence of complete homonymous hemianopia was a negative predictor of recovery (OR 0.2; P = 0.048). CONCLUSION: Partial visual recovery in HVFDs is observed even 6 months and beyond POCI. Age < 50 years and stroke etiology were predictors of recovery.

Retinal blood flow reduction in normal-tension glaucoma with single-hemifield damage by Doppler optical coherence tomography.

AIMS: To evaluate the associations between retinal blood flow (RBF) and optical coherence tomography (OCT) structural measurements in normal-tension glaucoma (NTG) eyes with single-hemifield visual field (VF) damage by the Doppler OCT. METHODS: The Doppler OCT was used to measure temporal artery (TA) RBF and temporal vein (TV) RBF. Retinal nerve fibre layer thickness (RNFLT) was measured by spectral-domain OCT. RESULTS: Forty-three consecutive eyes of 43 patients with NTG with VF defect confined to a single hemifield and 24 eyes of 24 age-matched healthy subjects were studied. TA and TV RBF and RNFLT were reduced in the damaged hemisphere compared with the normal hemisphere (mean (SD), 3.61 (1.68) vs 5.86 (2.59) µL/min, p<0.001; 5.61 (2.51) vs 6.94 (2.83) µL/min, p=0.010; 69.0 (19.7) vs 99.7 (22.8) µm, p<0.001). Those values in the normal hemisphere of NTG eyes also decreased compared with the healthy hemisphere of the healthy eyes (8.40 (3.36) µL/min, p<0.001; 9.28 (4.47) µL/min, p<0.002; 122.8 (20.2) µm, p<0.001). Multivariate model showed that normal and damaged hemispheres and RNFLT were associated with RBF reduction. In addition, the RBF in the normal hemisphere was lower than that in the healthy hemisphere even after adjusting for RNFLT. CONCLUSION: In NTG eyes with single-hemifield damage, the RBF was significantly reduced in the damaged hemisphere compared with the normal one. The RBF decreased in the normal and damaged hemispheres of NTG eyes compared with the healthy hemisphere independent from RNFLT.

Pituitary Macroadenoma Presenting With Monocular Temporal Hemianopia.

ABSTRACT: A 35-year-old primigravida woman presented to the eye emergency department with reduced visual acuity in the right eye. Humphrey visual field testing showed a monocular right eye temporal hemianopia before delivery. An MRI after delivery revealed a largely symmetrical pituitary macroadenoma with chiasmal compression. This is a rare presentation of a pituitary macroadenoma especially when the tumor is largely symmetrical.

Hemorrhagic Intracranial Cavernoma Presenting as a Homonymous Horizontal Sectoranopia.

ABSTRACT: Hemorrhagic lateral geniculate nucleus (LGN) insults are rare but have been reported in association with tumors, vascular malformations, and trauma. The localization of LGN lesions is facilitated by recognition of pathognomonic visual field defects. A 21-year old woman developed a sudden onset painless left homonymous horizontal sectoranopia. Magnetic resonance imaging revealed a hemorrhagic cavernous malformation of the right temporal lobe. Optical coherence tomography (OCT) and Humphrey perimetry findings localized the lesion to the right LGN. Specifically, OCT testing revealed a right homonymous sectoranopia pattern of hemi-retinal macular ganglion layer-inner plexiform layer (mGCIPL) thinning contralateral to the left sided visual field defect. The OCT pattern reflected retrograde neuroaxonal degeneration from the right LGN lesion. This case highlights a unique pattern of mGCIPL thinning characteristic for a posterior lateral choroidal artery injury, affecting the LGN. These findings illustrate how functional eloquence correlates with topographical elegance in the afferent visual pathway.

Efficacy of Visual Retraining in the Hemianopic Field after Stroke: Results of a Randomized Clinical Trial.

PURPOSE: To evaluate the efficacy of motion discrimination training as a potential therapy for stroke-induced hemianopic visual field defects. DESIGN: Clinical trial. PARTICIPANTS: Forty-eight patients with stroke-induced homonymous hemianopia (HH) were randomized into 2 training arms: intervention and control. Patients were between 21 and 75 years of age and showed no ocular issues at presentation. METHODS: Patients were trained on a motion discrimination task previously evidenced to reduce visual field deficits, but not in a randomized clinical trial. Patients were randomized with equal allocation to receive training in either their sighted or deficit visual fields. Training was performed at home for 6 months, consisting of repeated visual discriminations at a single location for 20 to 30 minutes daily. Study staff and patients were masked to training type. Testing before and after training was identical, consisting of Humphrey visual fields (Carl Zeiss Meditech), macular integrity assessment perimetry, OCT, motion discrimination performance, and visual quality-of-life questionnaires. MAIN OUTCOME MEASURES: Primary outcome measures were changes in perimetric mean deviation (PMD) on Humphrey Visual Field Analyzer in both eyes. RESULTS: Mean PMDs improved over 6 months in deficit-trained patients (mean change in the right eye, 0.58 dB; 95% confidence interval, 0.07-1.08 dB; mean change in the left eye 0.84 dB; 95% confidence interval, 0.22-1.47 dB). No improvement was observed in sighted-trained patients (mean change in the right eye, 0.12 dB; 95% confidence interval, -0.38 to 0.62 dB; mean change in the left eye, 0.10 dB; 95% confidence interval, -0.52 to 0.72 dB). However, no significant differences were found between the alternative training methods (right eye, P = 0.19; left eye, P = 0.10). CONCLUSIONS: To date, no widely accepted therapy is available to treat HH. This study evaluated the efficacy of a promising potential treatment, visual perceptual training. We failed to find a difference between treatment training within the deficit field and control training within the sighted field when performed in a home environment.

2017 Charles F. Prentice Award Lecture: Peripheral Prisms for Visual Field Expansion: A Translational Journey.

On the occasion of being awarded the Prentice Medal, I was asked to summarize my translational journey. Here I describe the process of becoming a low-vision rehabilitation clinician and researcher, frustrated by the unavailability of effective treatments for some conditions. This led to decades of working to understand patients' needs and the complexities and subtleties of their visual systems and conditions. It was followed by many iterations of developing vision aids and the techniques needed to objectively evaluate their benefit. I specifically address one path: the invention and development of peripheral prisms to expand the visual fields of patients with homonymous hemianopia, leading to our latest multiperiscopic prism (mirror-based design) with its clear 45° field-of-view image shift.

Diagnosis of Transient Ischemic Attack: Sex-Specific Differences From a Retrospective Cohort Study.

BACKGROUND AND PURPOSE: Research suggests that women and men may present with different transient ischemic attack (TIA) and stroke symptoms. We aimed to explore symptoms and features associated with a definite TIA/stroke diagnosis and whether those associations differed by sex. METHODS: We completed a retrospective cohort study of patients referred to The Ottawa Hospital Stroke Prevention Clinic in 2015. Exploratory multinomial logistic regression was used to evaluate candidate variables associated with diagnosis and patient sex. Backwards elimination of the interaction terms with a significance level for staying in the model of 0.25 was used to arrive at a more parsimonious model. RESULTS: Based on 1770 complete patient records, sex-specific differences were noted in TIA/stroke diagnosis based on features such as duration of event, suddenness of symptom onset, unilateral sensory loss, and pain. CONCLUSIONS: This preliminary work identified sex-specific differences in the final diagnosis of TIA/stroke based on common presenting symptoms/features. More research is needed to understand if there are biases or sex-based differences in TIA/stroke manifestations and diagnosis.

Ocular Hypertension, Glaucoma or Compressive Neuropathy in Patient with Active TED.

INTRODUCTION: Severe cases of thyroid eye disease with high intraocular pressure and visual field defects are a real diagnostic challenge requiring the exclusion of dysthyroid optic neuropathy and differential diagnosis with glaucoma. AIM: To report а case of a patient with active thyroid eye disease (TED), decreased visual acuity and elevated intraocular pressure. MATERIALS AND METHODS: We present a 52-year-old woman with TED in both eyes, class 2c3c4a6a (NOSPECS), with 6 points (by CAS) activity, who received corticosteroid therapy to a maximum cumulative dose of 5750 mg, with non-insulin-dependent diabetes mellitus and topical antihypertensive treatment with tapticom, brizadopt, and luxfen. The patient received full ophthalmological exam, tonometry, exophthalmometry, computer perimetry, optical coherence tomography (OCT) and computed tomography (CT) scan of orbits. RESULTS: The following results were obtained: BCVA of right eye = 0.6, BCVA of left eye = 0.3; TOD = 26 mm Hg and ТОS = 21 mm Hg; exophthalmometry: 30 mm for the right eye and 31 mm for the left one; diplopia in all directions, edema and hyperemia of the eyelids and conjunctiva, eyelids retraction, sluggish pupil reactions, normal color vision, transparent ocular media, indistinct borders of the optic nerve disc, without glaucomatous excavation, tortuosity and dilation of the venules, retina - without diabetic changes, maculas - with normal reflex; CP datа for a localized inferotemporal visual field defect, CT data for thickening of all extraocular muscles, soft tissue orbital edema, and optic nerves compression. CONCLUSION: Our results confirmed the presence of dysthyroid optic neuropathy based on the decreased visual acuity, ophthalmo-scopic evaluation of the optic nerve head, lack of glaucomatous OCT changes, atypical perimetric changes and the CT data. The optic neuropathy is the most severe complication in patients with TED which develops due to the compression of the optic nerve and/or its blood supply from the enlarged extraocular muscles and soft tissues in the orbital apex and due to the mechanical tension of the optic nerve in cases moderate or severe proptosis is present.

Functional connectivity of the Precuneus reflects effectiveness of visual restitution training in chronic hemianopia.

Visual field defects in chronic hemianopia can improve through visual restitution training, yet not all patients benefit equally from this long and exhaustive procedure. Here, we asked if resting-state functional connectivity prior to visual restitution could predict training success. In two training sessions of eight weeks each, 20 patients with chronic hemianopia performed a visual discrimination task by directing spatial selective attention towards stimuli presented in either hemifield, while suppressing eye movements. We examined two effects: a sensitivity change in the attended (trained) minus the unattended (control) hemifield (i.e., a training-specific improvement), and an overall improvement (i.e., a total change in sensitivity after both sessions). We then identified five visual resting-state networks and evaluated their functional connectivity in relation to both training effects. We found that the functional connectivity strength between the anterior Precuneus and the Occipital Pole Network was positively related to the attention modulated (i.e., training-specific) improvement. No such relationship was found for the overall improvement or for the other visual networks of interest. Our finding suggests that the anterior Precuneus plays a role in attention-modulated visual field improvements. The resting-state functional connectivity between the anterior Precuneus and the Occipital Pole Network may thus serve as an imaging-based biomarker that quantifies a patient's potential capacity to direct spatial attention. This may help to identify hemianopia patients that are most likely to benefit from visual restitution training.