Homonymous hemianopia: challenges and solutions

Reading eye movements among homonymous hemianopia

PURPOSE

To measure the reading eye movement's parameters and quantify the oculomotor dysfunction among subjects with homonymous hemianopia compared to age-matched controls using ReadAlyzer.

METHODS

This was a prospective study carried out in the neuro-optometry clinic of a tertiary eye care hospital in South India, from October 2018 to Janurary 2019. Fifty consecutive patients diagnosed with homonymous hemianopia were enrolled in the study after obtaining their written informed consent. Reading eye movements were measured using ReadAlyzer in patients with homonymous hemianopia and age-matched controls. Reading eye movement parameters were represented in median [interquartile range (IQR)].

RESULTS

Subjects with homonymous hemianopia showed increased number of fixations/100 words- median (IQR) [175 (80-270)] compared to controls [91 (52.5-127.5)]; increased number of regressions/100 words [33 (-13-79)] compared to controls [18 (-10-46)]; and reduced reading rate [93 (46-140) words/min] compared to controls [186 (144-228) words/min] (Mann-Whitney U test, P ≤ 0.05). Similar trend was observed for grade level equivalent 2 (0-4) and regression to fixation ratio 15 (1-29) compared to controls [grade equivalent 7 (3-11) and regression to fixation ratio 11 (-2-24)] (Mann-Whitney U test, P ≤ 0.005).

CONCLUSION

Reading eye movements assessed using ReadAlyzer are found to be significantly impaired among homonymous hemianopias compared to age-matched controls (Mann-Whitney U test, P ≤ 0.05).

Precision Surgery for Glioblastomas

Glioblastomas are the most common primary malignant brain tumor. Most of the recent improvements their treatment are due to improvements in surgery. Although many would consider surgery as the most personalized treatment, the variation in resection between surgeons suggests there remains a need for objective measures to determine the best surgical treatment for individualizing therapy for glioblastoma. We propose applying a personalized medicine approach to improve outcomes for patients. We suggest looking at personalizing preoperative preparation, improving the resection target by understanding what needs removing and what ca not be removed, and better patient selection with personalized rehabilitation plans for all patients.

Telerehabilitation for visual field defects with a multisensory training: a feasibility study

BACKGROUND

Acquired homonymous visual field defects (HVFDs) result in significant disability, reducing quality of life. Spontaneous recovery occurs within the first months, then the likelihood of vision recovery decreases, making rehabilitation necessary. HVFDs rehabilitation is typically lengthy and intensive, done on an outpatient basis, hardly compatible with the return to everyday life. Telerehabilitation represents an option for continuing the therapy in the chronic phase of the disease, offering long-term support after hospital discharge. It also allows individuals with HVFDs to exercise independently, intensively, and actively at home, in a familiar environment, under remote supervision. However, the efficacy of telerehabilitation for chronic HVFDs in adults still requires empirical support.

METHODS

This single-arm clinical trial assesses the efficacy of a home-based, remote-supervised, compensatory audio-visual training (AVT) in 26 adults with chronic HVFDs following a brain lesion. Immediate and long-term (up to 6 months) effects on visual field scanning, reading, activities of daily living and mood were assessed. Predictors of treatment-induced gains were also investigated considering behavioral, neuro-ophthalmological (visual field perimetry and visual evoked potentials) and neuroradiological variables (structural imaging of grey- and white-matter damages). Finally, the efficacy of the home-based AVT was compared to that of its in-person version (16 new participants with chronic HVFDs).

RESULTS

Home-based AVT improves accuracy and speed of visual search, reading, mood, and disability in the activities of daily living, with improvements persisting up to 6 months after the end of the training (baseline vs. post-training assessments, all ps < 0.04). Post-treatment gains correlate with the severity of visual search deficit and the efficiency of multisensory integration (rs = -0.7/-0.5, all ps < 0.04). Neuro-ophthalmological and neuroradiological (structural connectivity) parameters are unaffected by the AVT, in line with its compensatory nature, although being associated to its efficacy (all ps < 0.03). Finally, the telerehabilitation version of the AVT produces effects comparable to the in-person AVT.

CONCLUSION

Multisensory training delivered in telerehabilitation is feasible and effective for ameliorating oculomotor compensation of visual field loss, improving mood and reducing functional disabilities in adults with chronic HVFDs. Trial registration This study was retrospectively registered at clinicaltrials.gov (NCT06341777; 26/03/2024).

Engaging with discursive complexities in mental health accessibility: Implications for acquired brain injury

The psychosocial needs of people with acquired brain injury (ABI) have been neglected based on ableist assumptions of incapability to participate in mental health treatment. Although people without disabilities benefit from evidence-based mental health supports, these treatments remain inaccessible for those with disabilities after ABI. Discursive simplifications used in dominant conceptualisations of health and disability may maintain this inaccessibility. This paper examines the role of discursive constraints in concealing the complexities of ABI recovery, undermining the gradients of mental health exclusion among different ABI subpopulations, and muddying possibilities for enhancing mental health accessibility. An alternate discourse that challenges disabling societies in service of centring the whole person is proposed. Discursive opportunities are thus created by conceptualising the objective and subjective dimensions of disability as intermeshed, providing both the motivation to incentivise mental health inclusion, as well as a method to achieve it. By recognising the unavoidable impact of bodily impairments on social participation, participatory ideals can be actualised by accommodating ABI-related disabilities in mental health treatments. The possibilities for transformative research and practice are illuminated through examples of mental health treatments that have been preliminarily adapted using accommodations, and a research agenda for realising these possibilities is proposed.

Self-reported health status of patients with acute retinal ischemia and stroke related hemianopia

BACKGROUND

We aimed to assess impairments on health-related quality of life, and mental health resulting from Retinal artery occlusion (RAO) with monocular visual field loss and posterior circulation ischemic stroke (PCIS) with full or partial hemianopia using patient-reported outcome measures (PROMs).

METHODS

In a prospective study, consecutive patients with acute RAO on fundoscopy and PCIS on imaging were recruited during their surveillance on a stroke unit over a period of 15 months. Baseline characteristics were determined from medical records and interviews. Health-related quality of life (PROM Information System 10-Question-Short-Form, PROMIS-10), and mental health symptoms (Patient-Health-Questionnaire-4, PHQ-4) were assessed 3 and 12 months after admission postally and via phone.

RESULTS

Ffity-seven patients with RAO and 19 with isolated full or partial hemianopia determined by the NIHSS (median = 2; IQR:0/2) according to PCIS were included. Characteristics of cardiovascular risk factors, and functional status pre-stroke were comparable between the groups. At 3 months, mean ± standard deviation T-scores of PROMIS physical and mental health were 47.1 ± 8.8 and 46.7 ± 8.8 for patients with RAO, and 43.4 ± 9.8 and 43.2 ± 6.2 for PCIS. Compared to 50 ± 10 in the general population, scores after RAO (p = 0.04; p = 0.02) and PCIS (p = 0.01; p < 0.001) were lower in both domains after 3 months. Concerning PCIS, scores in the mental health domain remained decreased at 12 months (p = 0.04). On the PHQ-4, 25% of patients with RAO, and 62% with PCIS scored indicative for anxious and/or depressive syndromes at 3 months.

CONCLUSIONS

RAO led only to partial and to less persistent mental impairments than PCIS. This suggests that a different approach involving complex visual and neuropsychological treatment over a longer period of time needs to be considered for post-stroke care of PCIS.

TRIAL REGISTRATION INFORMATION

The trial was submitted at http://www.clinicaltrials.gov, under NCT03795948.

Measuring residual visual function after cerebral damage - a potential path for optimising rehabilitation approaches

The integrity of the visual field can be assessed using clinical techniques such as perimetry that rely on subjective report, or can be quantified objectively using functional magnetic resonance imaging (fMRI). In the case of central lesions (e.g. following strokes), fMRI visual field maps can reveal spared regions of cortex that may be missed if patient assessment relies on perimetry and anatomy of lesions alone. Even when perimetry results look stereotypical and can be categorised into hemianopia or quadrantanopia, the areas of spared cortex can be highly variable. FMRI field maps could serve as an important guide for selecting and optimising training and rehabilitation programmes for patients with damage to central visual pathway structures. Alongside a standardised battery of visual function tests, anatomical scans, and tractography data on connections between brain areas, this would provide a much richer clinical picture. Importantly, this approach may also offer useful information for a personalised approach to visual developmental disorders such as cerebral visual impairment (CVI). Here, we survey some recent results from the neuroimaging literature on measuring residual visual function, anatomy, and structural connectivity in stroke survivors, discuss recent results from rehabilitation approaches, and put forward a potential approach for characterising visual function using brain imaging in individuals with CVI.

A telerehabilitation program to improve visual perception in children and adolescents with hemianopia consecutive to a brain tumor: a single-arm feasibility and proof-of-concept trial

Background

Brain tumor in children can induce hemianopia, a loss of conscious vision, profoundly impacting their development and quality of life, yet no effective intervention exists for this pediatric population. This study aimed to explore the feasibility, safety, and potential effectiveness of a home-based audiovisual stimulation in immersive virtual-reality (3D-MOT-IVR) to improve visual function and functional vision.

Methods

In a phase 2a, open-labeled, nonrandomized, single-arm study, conducted from July 2022 to October 2023 (NCT05065268), 10 children and adolescents with stable hemianopia were enrolled to perform 20-min sessions of 3D-MOT-IVR every other day for six weeks from home. We assessed feasibility by monitoring adoption, adherence and completion rates, remote data transfer and qualitative feedback. Safety was evaluated using validated cybersickness questionnaires. Comprehensive vision assessments following standardized low-vision evaluation procedures were conducted pre- and post-intervention, with follow-ups at 1- and 6 months.

Findings

The home-based 3D-MOT-IVR intervention proved both feasible and safe, with no reported adverse events. All participants completed the prescribed stimulations and the pre- and post-intervention assessment points, 90% completed the follow-ups. Nine out of ten participants showed clinically meaningful enhancement in visual function and/or functional vision, namely binocular visual field restoration and increased reading speed, but two showed concomitant deterioration in monocular visual field. These positive effects were sustained at the 6-month follow-up. Exploratory outcomes revealed a significant positive correlation between the performance at the 3D-MOT-IVR intervention and the visual perception at the binocular visual field test.

Interpretation

Our findings underscore the feasibility and safety of home-based audiovisual stimulation in immersive virtual-reality as a potential intervention for improving visual perception in children/adolescents with hemianopia consecutive to a pediatric brain tumor. These promising results lay a strong foundation for a larger randomized controlled trial, offering hope for a meaningful breakthrough in visual rehabilitation for this vulnerable population.

Funding

Meagan Bebenek Foundation and University Health Network Foundation.

Analysis of Intraoperative Visual Evoked Potentials for Inclusion of Unstable Electroretinograms

PURPOSE

The objectives of the study were to evaluate the validity of intraoperative flash visual evoked potentials (VEPs) when electroretinograms (ERGs) were unstable, to compare white versus red light-emitting diodes, and to assess the impact of luminance on ERG variability.

METHODS

Thirty patients were included (Inomed system; pre- and postoperative visual fields). Possible changes in visual fields were assessed with mean defects in perimetry. The receiver operating characteristic (ROC) curves of normalized VEPs and of normalized and corrected VEPs with ERGs were compared.

RESULTS

Thirty-two eyes could be analyzed in 20 patients (mainly gliomas and meningiomas): 2 had a severe defect in their visual field, and 6 had a mild defect. The receiver operating characteristic curve indicated (1) normalized and corrected VEPs with ERGs were more reliable than normalized VEPs only (P < 0.03) and (2) an alarm threshold of 80% of normalized and corrected VEPs. No significant difference in variability of ERGs was found with white or red light-emitting diodes with this system. Increased luminance improved stability of ERGs (P < 0.05).

CONCLUSIONS

Normalization and correction of VEPs with ERGs improved the validity of VEPs and indicated a 20% decrease as alarm criterion. This normalization and correction with peripheral excitation could be generalized to improve the reliability of neuromonitoring.

Bayesian networks for Risk Assessment and postoperative deficit prediction in intraoperative neurophysiology for brain surgery

PURPOSE

To this day there is no consensus regarding evidence of usefulness of Intraoperative Neurophysiological Monitoring (IONM). Randomized controlled trials have not been performed in the past mainly because of difficulties in recruitment control subjects. In this study, we propose the use of Bayesian Networks to assess evidence in IONM.

METHODS

Single center retrospective study from January 2020 to January 2022. Patients admitted for cranial neurosurgery with intraoperative neuromonitoring were enrolled. We built a Bayesian Network with utility calculation using expert domain knowledge based on logistic regression as potential causal inference between events in surgery that could lead to central nervous system injury and postoperative neurological function.

RESULTS

A total of 267 patients were included in the study: 198 (73.9%) underwent neuro-oncology surgery and 69 (26.1%) neurovascular surgery. 50.7% of patients were female while 49.3% were male. Using the Bayesian Network´s original state probabilities, we found that among patients who presented with a reversible signal change that was acted upon, 59% of patients would wake up with no new neurological deficits, 33% with a transitory deficit and 8% with a permanent deficit. If the signal change was permanent, in 16% of the patients the deficit would be transitory and in 51% it would be permanent. 33% of patients would wake up with no new postoperative deficit. Our network also shows that utility increases when corrective actions are taken to revert a signal change.

CONCLUSIONS

Bayesian Networks are an effective way to audit clinical practice within IONM. We have found that IONM warnings can serve to prevent neurological deficits in patients, especially when corrective surgical action is taken to attempt to revert signals changes back to baseline properties. We show that Bayesian Networks could be used as a mathematical tool to calculate the utility of conducting IONM, which could save costs in healthcare when performed.

A Two-Step Approach Using the National Health Institutes of Health Stroke Scale Assessed by Paramedics to Enhance Prehospital Stroke Detection: A Case Report and Concept Proposal

Background: Prehospital detection and triage of stroke patients mostly rely on the use of large vessel occlusion prediction scales to decrease onsite time. These quick but simplified scores, though useful, prevent prehospital providers from detecting posterior strokes and isolated symptoms such as limb ataxia or hemianopia. Case report: In the present case, an ambulance was dispatched to a 46-year-old man known for ophthalmic migraines and high blood pressure, who presented isolated visual symptoms different from those associated with his usual migraine attacks. Although the assessment advocated by the prehospital guideline was negative for stroke, the paramedic who assessed the patient was one of the few trained in the National Institutes of Health Stroke Scale assessment. Based on this assessment, the paramedic activated the fast-track stroke alarm and an ischemic stroke in the right temporal lobe was finally confirmed by magnetic resonance imaging. Discussion and conclusions: Current prehospital practice enables paramedics to detect anterior strokes but often limits the detection of posterior events or more subtle symptoms. Failure to identify such strokes delay or even forestall the initiation of thrombolytic therapy, thereby worsening patient outcomes. We therefore advocate a two-step prehospital approach: first, to avoid unnecessary delays, the prehospital stroke assessment should be carried out using a fast large vessel occlusion prediction scale; then, if this assessment is negative but potential stroke symptoms are present, a full National Institutes of Health Stroke Scale assessment could be performed to detect neurological deficits overlooked by the fast stroke scale.

The Hemianopia Reading Questionnaire (HRQ): Development and Psychometric Qualities in a Large Community Sample

The ability to read is important for daily life functioning. Individuals with homonymous visual field defects (iwHs) after brain injury experience frequent reading difficulties. The current study presents a novel self-report questionnaire aimed at measuring the wide variety of reading difficulties iwHs can experience: the Hemianopia Reading Questionnaire (HRQ). The 24-item HRQ was developed with help from clinical experts and experts by experience and was inspired by existing reading questionnaires for adults. The three tested subscales of the HRQ assess the relationship to reading, reading skills and daily life functional reading. The factor structure, reliability, convergent validity and divergent validity were examined in a large community sample (i.e., individuals without homonymous visual field defects) with a comparable distribution of age, gender and level of education to those who have suffered a stroke (N = 998). Two competing hypothesized models were tested and a good fit was found for a three-bifactor model of the HRQ. The reliability of the three subscales was found to be good (ω range 0.93-0.99), as well as the convergent and divergent validity (9 out of 12 Spearman's correlations, according to expectations). The results support further use of the HRQ in iwHs, especially in the context of reading rehabilitation. Suggestions for clinical and scientific use and future psychometric research on the HRQ are provided.

Role of corpus callosum in unconscious vision

The existence of unconscious visually triggered behavior in patients with cortical blindness (e.g., homonymous hemianopia) has been amply demonstrated and the neural bases of this phenomenon have been thoroughly studied. However, a crosstalk between the two hemispheres as a possible mechanism of unconscious or partially conscious vision has not been so far considered. Thus, the aim of this study was to assess the relationship between structural and functional properties of the corpus callosum (CC), as shown by probabilistic tractography (PT), behavioral detection/discrimination performance and level of perceptual awareness in the blind field of patients with hemianopia. Twelve patients were tested in two tasks with black-and-white visual square-wave gratings, one task of movement and the other of orientation. The stimuli were lateralized to one hemifield either intact or blind. A PT analysis was carried out on MRI data to extract fiber properties along the CC (genu, body, and splenium). Compared with a control group of participants without brain damage, patients showed lower FA values in all three CC sections studied. For the intact hemifield we found a significant correlation between PT values and visual detection/discrimination accuracy. For the blind hemifield the level of perceptual awareness correlated with PT values for all three CC sections in the movement task. Importantly, significant differences in all three CC sections were found also between patients with above-vs. chance detection/discrimination performance while differences in the genu were found between patients with and without perceptual awareness. Overall, our study provides evidence that the properties of CC fibers are related to the presence of unconscious stimulus detection/discrimination and to hints of perceptual awareness for stimulus presentation to the blind hemifield. These results underline the importance of information exchange between the damaged and the healthy hemisphere for possible partial or full recovery from hemianopia.

Assessing REALTER simulator: analysis of ocular movements in simulated low-vision conditions with extended reality technology

Immersive technology, such as extended reality, holds promise as a tool for educating ophthalmologists about the effects of low vision and for enhancing visual rehabilitation protocols. However, immersive simulators have not been evaluated for their ability to induce changes in the oculomotor system, which is crucial for understanding the visual experiences of visually impaired individuals. This study aimed to assess the REALTER (Wearable Egocentric Altered Reality Simulator) system's capacity to induce specific alterations in healthy individuals' oculomotor systems under simulated low-vision conditions. We examined task performance, eye movements, and head movements in healthy participants across various simulated scenarios. Our findings suggest that REALTER can effectively elicit behaviors in healthy individuals resembling those observed in individuals with low vision. Participants with simulated binocular maculopathy demonstrated unstable fixations and a high frequency of wide saccades. Individuals with simulated homonymous hemianopsia showed a tendency to maintain a fixed head position while executing wide saccades to survey their surroundings. Simulation of tubular vision resulted in a significant reduction in saccade amplitudes. REALTER holds promise as both a training tool for ophthalmologists and a research instrument for studying low vision conditions. The simulator has the potential to enhance ophthalmologists' comprehension of the limitations imposed by visual disabilities, thereby facilitating the development of new rehabilitation protocols.

Efficacy of Neuro-Optometric visual rehabilitation in Homonymous Hemianopia

OBJECTIVES

To assess oculomotor dysfunction and the effectiveness of neuro-optometric visual rehabilitation in improving oculomotor parameters in participants with homonymous hemianopia.

MATERIALS AND METHODS

Fifty subjects diagnosed with homonymous hemianopia (HH), referred through the neuro-ophthalmology department, were recruited for the study. All the subjects underwent a detailed neuro-optometric evaluation that included testing for sensory, visuo-motor and oculomotor functions. Subjects with homonymous hemianopia were then prescribed with yoked prisms and were randomized to two treatments at one month, namely group 1: yoked prisms (n = 15) and group 2: yoked prisms with in-office visual search training (n = 15).

RESULTS

The mean ± SD age of the subjects was 46 ± 12 years. Subjects with HH exhibited a significant delay in the completion time, response and accuracy of tasks on proactive, saccadic and visual search parameters using the SVI compared to age-matched controls (Independent t-test, p < 0.05). A significant improvement in the reading speed and visual search parameters (RM ANOVA, p < 0.001) was seen post neuro-optometric visual rehabilitation with both yoked prisms and SVI. Statistically significant differences were observed in the reaction time of the visual search paradigms between the two rehabilitative modalities yoked (group1), yoked and SVI (group2) (Mann-Whitney U test, p < 0.001), with the group 2 showing better visual search performance outcomes compared to group 1 (yoked).

CONCLUSION

Visual search parameters among participants with homonymous hemianopia improved following combined rehabilitation (yoked prisms and visual search trainng).

Homonymous hemianopia due to cerebral venous thrombosis: A case report

RATIONALE

Diagnosing cerebral venous thrombosis (CVT) can be difficult because of nonspecific symptoms, such as headache and homonymous hemianopia (HH). Herein, we present a case of delayed CVT diagnosis due to nonspecific neurological symptoms and nonprominent lesions in a patient with HH.

PATIENT CONCERN

A 65-year-old woman presented with a sudden onset headache accompanied by right HH that lasted for 1 day. Brain computed tomography and magnetic resonance imaging were initially performed due to suspicion of ischemic lesions or hemorrhage in the left postchiasmal visual pathway; however, no remarkable acute brain lesions were detected. Ophthalmological examinations revealed no notable findings, except for a definite field defect in the Humphrey visual field test. The headaches then waxed and waned but recurred 3 days after the initial symptom.A repeat brain magnetic resonance imaging was performed, which revealed left sectoral gyral swelling and vascular enhancement in the occipital lobe. To further evaluate venous drainage, additional 3-dimensional cerebral computed tomography angiography and 4-vessel angiography were conducted, revealing a partial filling defect in the left transverse sinus and superior venous drainage impairment. These findings suggested the presence of venous thrombosis in the left transverse sinus.

DIAGNOSIS

The patient was diagnosed with thrombosis of the left transverse sinus, which subsequently caused the right HH.

INTERVENTION

Anticoagulation therapy with parenteral heparin was started as soon as the diagnosis of CVT was confirmed. Eventually, the patient was solely managed with oral warfarin administration.

OUTCOMES

Following 3 days of treatment, her headache resolved, and a subsequent visual field testing conducted 2 weeks later revealed a definite improvement in the field defect.

LESSONS

Despite its favorable prognosis, CVT can be challenging to diagnose. CVT should be considered as a differential diagnosis when diagnosing patients who present with headaches accompanied by HH without prominent brain lesions.

Cross-modal exposure restores multisensory enhancement after hemianopia

Hemianopia is a common consequence of unilateral damage to visual cortex that manifests as a profound blindness in contralesional space. A noninvasive cross-modal (visual-auditory) exposure paradigm has been developed in an animal model to ameliorate this disorder. Repeated stimulation of a visual-auditory stimulus restores overt responses to visual stimuli in the blinded hemifield. It is believed to accomplish this by enhancing the visual sensitivity of circuits remaining after a lesion of visual cortex; in particular, circuits involving the multisensory neurons of the superior colliculus. Neurons in this midbrain structure are known to integrate spatiotemporally congruent visual and auditory signals to amplify their responses, which, in turn, enhances behavioral performance. Here we evaluated the relationship between the rehabilitation of hemianopia and this process of multisensory integration. Induction of hemianopia also eliminated multisensory enhancement in the blinded hemifield. Both vision and multisensory enhancement rapidly recovered with the rehabilitative cross-modal exposures. However, although both reached pre-lesion levels at similar rates, they did so with different spatial patterns. The results suggest that the capability for multisensory integration and enhancement is not a pre-requisite for visual recovery in hemianopia, and that the underlying mechanisms for recovery may be more complex than currently appreciated.

FunctionaL Assessment Scale of Hemianopia (FLASH): A New Multidisciplinary Tool to Assess Hemianopia in Patients with Severe Acquired Brain Injury

BACKGROUND

Severe acquired brain injury (sABI) encompasses a range of neurological impairments. Visual dysfunction, particularly homonymous visual field defects (HVFDs) and homonymous hemianopia (HH), commonly afflicts sABI survivors, affecting their cognitive and motor rehabilitation. This study presents the FunctionaL Assessment Scale of Hemianopia (FLASH), developed to analyze the most common postural behaviors exhibited by sABI patients with hemianopia during activities of daily living. A comparison to traditional static automated perimetry for diagnosing visual field deficits (VFDs) to determine the sensitivity and specificity of the FLASH was used. Additionally, this study also aimed to assess its reliability.

METHODS

Fifty-six patients (25 F, 31 M, mean age 60.59 ± 14.53) with strokes in the sub-acute phase (<6 months from the onset) were assessed with both FLASH and a Humphrey Field Analyzer.

RESULTS

After removing two items found to be less reliable than others, FLASH showed high sensitivity (81%) and specificity (77%) when compared to static automated perimetry. Inter-rater reliability was also high, with an intra-class correlation coefficient of 0.954, as well as the internal consistency computed by Cronbach's alpha, equal to 0.874.

CONCLUSION

FLASH could offer a valuable and cost-effective screening tool for VFD in sABI patients during neurorehabilitation, with potential implications for healthcare cost reduction.

Placebo effect after visual restitution training: no eye-tracking controlled perimetric improvement after visual border stimulation in late subacute and chronic visual field defects after stroke

Introduction

A significant number of Restitution Training (RT) paradigms claim to ameliorate visual field loss after stroke by re-activating neuronal connections in the residual visual cortex due to repeated bright light-stimulation at the border of the blind and intact fields. However, the effectiveness of RT has been considered controversial both in science and clinical practice for years. The main points of the controversy are (1) the reliability of perimetric results which may be affected by compensatory eye movements and (2) heterogeneous samples consisting of patients with visual field defects and/or visuospatial neglect.

Methods

By means of our newly developed and validated Virtual Reality goggles Salzburg Visual Field Trainer (SVFT) 16 stroke patients performed RT on a regular basis for 5  months. By means of our newly developed and validated Eye Tracking Based Visual Field Analysis (EFA), we conducted a first-time full eye-movement-controlled perimetric pre-post intervention study. Additionally, patients subjectively rated the size of their intact visual field.

Results

Analysis showed that patients' mean self-assessment of their subjective visual field size indicated statistically significant improvement while, in contrast, objective eye tracking controlled perimetric results revealed no statistically significant effect.

Discussion

Bright-light detection RT at the blind-field border solely induced a placebo effect and did not lead to training-induced neuroplasticity in the visual cortex of the type needed to ameliorate the visual field size of stroke patients.

Effects of Stimulus Luminance, Stimulus Color and Intra-Stimulus Color Contrast on Visual Field Mapping in Neurologically Impaired Adults Using Flicker Pupil Perimetry

Purpose

We improve pupillary responses and diagnostic performance of flicker pupil perimetry through alterations in global and local color contrast and luminance contrast in adult patients suffering from visual field defects due to cerebral visual impairment (CVI).

Methods

Two experiments were conducted on patients with CVI (Experiment 1: 19 subjects, age M and SD 57.9 ± 14.0; Experiment 2: 16 subjects, age M and SD 57.3 ± 14.7) suffering from absolute homonymous visual field (VF) defects. We altered global color contrast (stimuli consisted of white, yellow, cyan and yellow-equiluminant-to-cyan colored wedges) in Experiment 1, and we manipulated luminance and local color contrast with bright and dark yellow and multicolor wedges in a 2-by-2 design in Experiment 2. Stimuli consecutively flickered across 44 stimulus locations within the inner 60 degrees of the VF and were offset to a contrasting (opponency colored) dark background. Pupil perimetry results were compared to standard automated perimetry (SAP) to assess diagnostic accuracy.

Results

A bright stimulus with global color contrast using yellow (p= 0.009) or white (p= 0.006) evoked strongest pupillary responses as opposed to stimuli containing local color contrast and lower brightness. Diagnostic accuracy, however, was similar across global color contrast conditions in Experiment 1 (p= 0.27) and decreased when local color contrast and less luminance contrast was introduced in Experiment 2 (p= 0.02). The bright yellow condition resulted in highest performance (AUC M = 0.85 ± 0.10, Mdn = 0.85).

Conclusion

Pupillary responses and pupil perimetry's diagnostic accuracy both benefit from high luminance contrast and global but not local color contrast.

Ocular retinal findings in asymptomatic patients with antiphospholipid syndrome secondary to systemic lupus erythematosus

The objective is to perform a multimodal ophthalmological evaluation, including optical coherence angiography (OCTA), asymptomatic APS secondary to SLE (APS/SLE), and compare to SLE patients and control group (CG). We performed a complete structural/functional ophthalmological evaluation using OCTA/microperimetry exam in all participants. One hundred fifty eyes/75 asymptomatic subjects [APS/SLE (n = 25), SLE (n = 25), and CG (n = 25)] were included. Ophthalmologic abnormalities occurred in 9 (36%) APS/SLE, 11 (44%) SLE, and none of CG (p < 0.001). The most common retinal finding was Drusen-like deposits (DLDs) exclusively in APS/SLE and SLE (16% vs. 24%, p = 0.75) whereas severe changes occurred solely in APS/SLE [2 paracentral acute middle maculopathy (PAMM) and 1 homonymous quadrantanopsia]. A trend of higher frequency of antiphospholipid antibody (aPL) triple positivity (100% vs. 16%, p = 0.05) and higher mean values of adjusted Global Antiphospholipid Syndrome Score (aGAPSS) (14 ± 0 vs. 9.69 ± 3.44, p = 0.09) was observed in APS/SLE with PAMM vs. those without this complication. We identified that ophthalmologic retinal abnormalities occurred in more than 1/4 of asymptomatic APS/SLE and SLE. DLDs are the most frequent with similar frequencies in both conditions whereas PAMM occurred exclusively in APS/SLE patients. The possible association of the latter condition with aPL triple positivity and high aGAPSS suggests these two conditions may underlie the retinal maculopathy. Our findings in asymptomatic patients reinforce the need for early surveillance in these patients. Key Points • Retinal abnormalities occur in more than 1/4 of asymptomatic APS/SLE and SLE patients. • The occurrence of PAMM is possibly associated with APS and DLDs with SLE. • Presence of aPL triple positivity and high aGAPSS seem to be risk factors for PAMM.

Sensory sensitivity after acquired brain injury: A systematic review

Patients with acquired brain injury frequently report experiencing sensory stimuli as abnormally under- (sensory hyposensitivity) or overwhelming (sensory hypersensitivity). Although they can negatively impact daily functioning, these symptoms are poorly understood. To provide an overview of the current evidence on atypical sensory sensitivity after acquired brain injury, we conducted a systematic literature review. The primary aim of the review was to investigate the behavioural and neural mechanisms that are associated with self-reported sensory sensitivity. Studies were included when they studied sensory sensitivity in acquired brain injury populations, and excluded when they were not written in English, consisted of non-empirical research, did not study human subjects, studied pain, related sensory sensitivity to peripheral injury or studied patients with a neurodegenerative disorder, meningitis, encephalitis or a brain tumour. The Web of Science, PubMed and Scopus databases were searched for appropriate studies. A qualitative synthesis of the results of the 81 studies that were included suggests that abnormal sensory thresholds and a reduced information processing speed are candidate behavioural mechanisms of atypical subjective sensory sensitivity after acquired brain injury. Furthermore, there was evidence for an association between subjective sensory sensitivity and structural grey or white matter abnormalities, and to functional abnormalities in sensory cortices. However, further research is needed to explore the causation of atypical sensory sensitivity. In addition, there is a need for the development of adequate diagnostic tools. This can significantly advance the quantity and quality of research on the prevalence, aetiology, prognosis and treatment of these symptoms.

The effects of simulated hemianopia on eye movements during text reading

Vision loss is a common, devastating complication of cerebral strokes. In some cases the complete contra-lesional visual field is affected, leading to problems with routine tasks and, notably, the ability to read. Although visual information crucial for reading is imaged on the foveal region, readers often extract useful parafoveal information from the next word or two in the text. In hemianopic field loss, parafoveal processing is compromised, shrinking the visual span and resulting in slower reading speeds. Recent approaches to rehabilitation using perceptual training have been able to demonstrate some recovery of useful visual capacity. As gains in visual sensitivity were most pronounced at the border of the scotoma, it may be possible to use training to restore some of the lost visual span for reading. As restitutive approaches often involve prolonged training sessions, it would be beneficial to know how much recovery is required to restore reading ability. To address this issue, we employed a gaze-contingent paradigm using a low-pass filter to blur one side of the text, functionally simulating a visual field defect. The degree of blurring acts as a proxy for visual function recovery that could arise from restitutive strategies, and allows us to evaluate and quantify the degree of visual recovery required to support normal reading fluency in patients. Because reading ability changes with age, we recruited a group of younger participants, and another with older participants who are closer in age to risk groups for ischaemic strokes. Our results show that changes in patterns of eye movement observed in hemianopic loss can be captured using this simulated reading environment. This opens up the possibility of using participants with normal visual function to help identify the most promising strategies for ameliorating hemianopic loss, before translation to patient groups.

Ameliorating Hemianopia with Multisensory Training

Hemianopia (unilateral blindness), a common consequence of stroke and trauma to visual cortex, is a debilitating disorder for which there are few treatments. Research in an animal model has suggested that visual-auditory stimulation therapy, which exploits the multisensory architecture of the brain, may be effective in restoring visual sensitivity in hemianopia. It was tested in two male human patients who were hemianopic for at least 8 months following a stroke. The patients were repeatedly exposed to congruent visual-auditory stimuli within their blinded hemifield during 2 h sessions over several weeks. The results were dramatic. Both recovered the ability to detect and describe visual stimuli throughout their formerly blind field within a few weeks. They could also localize these stimuli, identify some of their features, and perceive multiple visual stimuli simultaneously in both fields. These results indicate that the multisensory therapy is a rapid and effective method for restoring visual function in hemianopia.SIGNIFICANCE STATEMENT Hemianopia (blindness on one side of space) is widely considered to be a permanent disorder. Here, we show that a simple multisensory training paradigm can ameliorate this disorder in human patients.

Innovative vision rehabilitation method for hemianopsia: Comparing pre- and post audio-luminous biofeedback training for ocular motility improving visual functions and quality of life

Background

Homonymous hemianopsia (HH) corresponds to vision loss in one hemi-field secondary to retro-chiasmal injury. Patients with HH experience difficulties in scanning and orientation in their environment. Near vision daily activities such as reading can also be impaired. There is an unmet need for standardized vision rehabilitation protocols for HH. We investigated the effectiveness of biofeedback training (BT), used for vision rehabilitation in patients with central vision loss, in individuals with HH.

Methods

In this prospective pilot pre/post study, 12 participants, with HH consecutive to brain injury, performed 5 weekly BT sessions for 20 min each under supervision using the Macular Integrity Assessment microperimeter. BT consisted of relocation of the retinal locus 1-4° toward the blind hemi-field. Outcomes measured post-BT were paracentral retinal sensitivity, visual acuity (near vision), fixation stability, contrast sensitivity, reading speed, and visual functioning questionnaire. Statistical analysis was performed using Bayesian paired t-tests.

Results

Paracentral retinal sensitivity significantly increased by 2.7 ± 0.9 dB in the treated eye in 9/11 of the participants. Significant improvements with medium-to-large effect size were observed for fixation stability (8/12 participants), contrast sensitivity (6/12 participants) and near vision visual acuity (10/12 participants). Reading speed increased by 32.5 ± 32.4 words per minute in 10/11 participants. Quality of vision scores improved significantly with large effect size for visual ability, visual information and mobility.

Conclusion

BT led to encouraging improvements in visual functions and functional vision in individuals with HH. Further confirmation with larger trials is required.

Occipito-temporal infarction manifesting as isolated visual perceptual abnormalities: A rare case of posterior cerebral artery stroke

Ischemic stroke in the Posterior Cerebral Artery (PCA) territory is an uncommon entity. Majority present with visual field defects while isolated visual perceptual abnormalities are an exceptional manifestation. About 60 year old hypertensive patient presented with vague symptoms of blurring of vision and palinopsia. Defective color vision was recorded in superior quadrants. Perimetry revealed bilateral congruous left superior quadrantanopia. Magnetic Resonance Imaging (MRI) disclosed right PCA infarct involving occipito-temporal region. This case highlights a rare presentation of PCA stroke with palinopsia and cerebral dyschromatopsia. Perimetric examination coupled with urgent neuroimaging helps the clinician in prompt diagnosis of neurological event causing unexplained visual phenomena.

Eye Signs in Stroke

A large part of the central nervous system is involved in the normal functioning of the vision, and hence vision can be affected in a stroke patient. Transient visual symptoms can likewise be a harbinger of stroke and prompt rapid evaluation for the prevention of recurrent stroke. A carotid artery disease can manifest as transient monocular visual loss (TMVL), central retinal artery occlusion (CRAO), anterior ischemic optic neuropathy or ocular ischemic syndrome (OIS). Stroke posterior to the optic chiasm can cause sectoranopias, quadrantanopias, or hemianopias, which can be either congruous or incongruous. Any stroke involving the dorsal stream (occipito-parietal lobe), or ventral stream (occipito-temporal lobe) can manifest with visuospatial perception deficits. Similarly, different ocular motility abnormalities can result from a stroke affecting the cerebrum, cerebellum, or brainstem. Among these deficits, vision and perception disorders are more difficult to overcome. Clinical, experimental, and neuroimaging studies have helped us to understand the anatomical basis, physiological dysfunction, and the underlying mechanisms of these neuro-ophthalmic signs.

Comparison of visual requirements and regulations for obtaining a driving license in different European countries and some open questions on their adequacy

We reviewed the current state of knowledge regarding visual function and its suitability as part of medical examinations for driving licenses. We focused only on Group 1 drivers. According to previous studies, visual acuity, which is the most common test, is weakly associated with a higher risk of road accidents, with a greater role of visual field. The inclusion of the visual field test in medical examinations is therefore important, but the actual limit value is still unclear and further research in specific situations is needed. Color vision impairment was not found a threat to traffic safety. Contrast sensitivity decreases with age and is affected by abnormal eye conditions. Resulting glare can lead to an increased risk of traffic accidents during night driving in the elderly and others with conditions that impair contrast sensitivity. However, the universal cut-off limits have not been established either. The current European Union (EU) regulations therefore reflect minimum common denominator across the member states which may not entirely translate to optimal driving safety. Due to these open questions, standardized testing in simulators or on polygons that simulate real life conditions would be needed to better determine safe limits of visual function in different conditions. As there is a need to have better standardization across Europe regarding the requirements and rules regarding driving licenses in European countries, we first analyzed existing rules and compared them with each other, also in terms of deviations from the EU directive itself. We reviewed the literature in this field and prepared proposals for a more optimal regulation of the rules in the future. Particular attention is paid to the new method of examining the visual field that was created to respect the European directive. The paper can serve as a basis of information for research teams to design further protocols, as it gathers research findings to date on the importance and impact of various visual functions on driving safety, as well as a starting point for a debate on revising existing rules for obtaining and maintaining licenses, as it compares the current regulations in European countries and differences between them.

Change blindness in simulated driving in individuals with homonymous visual field loss

Individuals with homonymous visual field loss (HVFL) fail to perceive visual information that falls within the blind portions of their visual field. This places additional burden on memory to represent information in their blind visual field, which may make visual changes in the scene more difficult to detect. Failing to detect changes could have serious implications in the context of driving. A change blindness driving simulator experiment was conducted with individuals with HVFL (n = 17) and in those with normal vision (NV; n = 16) where changes (pedestrians appearing) were triggered based on the driver’s gaze location. Gaze was used to ensure that the location of the change was visible before and after the change occurred. There were wide individual differences in both vision groups, ranging from no change blindness to more than 33% of events. Those with HVFL had more change blindness than those with NV (16.7% vs. 6.3%, p < 0.001) and more change blindness to pedestrians appearing in their blind than seeing hemifield (34.6% vs. 10.4%, p < 0.001). Further, there was more change blindness for events appearing in the seeing hemifield for those with HVFL than normal vision (p = 0.023). These results suggest that individuals with HVFL may be more susceptible to failures of awareness, such as change blindness, than individuals with normal vision. Increased risk for failures of awareness may result in motor vehicle crashes where the driver fails to notice the other road user (looked-but-failed-to-see incidents).

Comparison of vision-related quality of life in patients with homonymous hemianopia and monocular blindness

To evaluate the vision-related quality of life (QoL) in patients with homonymous hemianopia (HH). The study compared the QoL in 32 patients with HH and 33 patients with monocular blindness. Best-corrected visual acuity (BCVA) and visual field test were investigated. The National Eye Institute-Visual Function Questionnaire 25 (NEI VFQ-25) and independent mobility questionnaires (IMQs) were used to assess their perceived visual and physical functioning abilities. The results of QoL questionnaires were compared in two groups. The mean deviation (MD) in the better eye was significantly lower in the HH group than in the monocular blindness group. The composite scores of NEI-VFQ and IMQs were significantly lower in the HH patients than in the monocular blindness patients. The driving-related score was significantly lower in patients with right hemianopsia than in those with left hemianopsia. The outdoor activity-related score was significantly lower in patients aged less than 55 years than in patients aged 55 years and more. Homonymous hemianopia had a negative impact on patients’ QoL by limiting their vision related activities compared to monocular blindness. The MD of the better eye in the HH patients reflects the binocular visual field and can affect the real visual function and QoL.

Audio-visual stimulation for visual compensatory functions in stroke survivors with visual field defect: a systematic review

BACKGROUND

Hemianopia is a complete or partial blindness in the visual fields of both eyes, commonly caused by cerebral infarction. It has been hypothesized that systematic audio-visual (AV) stimulation of the blind hemifield can improve accuracy and search times, probably due to the stimulation of bimodal representations in the superior colliculus (SC), an important multisensory structure involved in both the initiation and execution of saccades.

METHODS

A narrative synthesis of the findings is presented to highlight how AV rehabilitation impacts on patients with hemianopia including visual oculomotor function, functional ability in activities of daily living, hemianopic dyslexia, visual scanning and searching tasks, maintaining of functional ability post training and the effect on brain multisensory integration by using neuroimaging.

RESULTS

Sixteen studies were included (fourteen articles (188 participants) and two literature reviews). Results were grouped into AV training of hemianopia in adults and in children and then further grouped according to the AV task type: tasks measuring the training effects by comparing visual stimulation training to audio-visual training, localization abilities in homonymous hemianopia (HH) and AV integration in patients with HH.

CONCLUSION

Systematic AV training may improve the processing of visual information by recruiting subcortical pathways, and because most of the patients with visual cortex damage have an intact SC, it might be useful to use the bimodal AV training to activate retinotectal functions. Nevertheless, the underlying mechanisms supporting the reported positive effects are not currently understood. Systematic functional and/or structural imaging studies may help in understanding the underlying mechanism and inform the design of optimal training paradigms.

Linking Multi-Modal MRI to Clinical Measures of Visual Field Loss After Stroke

Loss of vision across large parts of the visual field is a common and devastating complication of cerebral strokes. In the clinic, this loss is quantified by measuring the sensitivity threshold across the field of vision using static perimetry. These methods rely on the ability of the patient to report the presence of lights in particular locations. While perimetry provides important information about the intactness of the visual field, the approach has some shortcomings. For example, it cannot distinguish where in the visual pathway the key processing deficit is located. In contrast, brain imaging can provide important information about anatomy, connectivity, and function of the visual pathway following stroke. In particular, functional magnetic resonance imaging (fMRI) and analysis of population receptive fields (pRF) can reveal mismatches between clinical perimetry and maps of cortical areas that still respond to visual stimuli after stroke. Here, we demonstrate how information from different brain imaging modalities-visual field maps derived from fMRI, lesion definitions from anatomical scans, and white matter tracts from diffusion weighted MRI data-provides a more complete picture of vision loss. For any given location in the visual field, the combination of anatomical and functional information can help identify whether vision loss is due to absence of gray matter tissue or likely due to white matter disconnection from other cortical areas. We present a combined imaging acquisition and visual stimulus protocol, together with a description of the analysis methodology, and apply it to datasets from four stroke survivors with homonymous field loss (two with hemianopia, two with quadrantanopia). For researchers trying to understand recovery of vision after stroke and clinicians seeking to stratify patients into different treatment pathways, this approach combines multiple, convergent sources of data to characterize the extent of the stroke damage. We show that such an approach gives a more comprehensive measure of residual visual capacity-in two particular respects: which locations in the visual field should be targeted and what kind of visual attributes are most suited for rehabilitation.

Rehabilitation of visual perception in cortical blindness

Blindness is a common sequela after stroke affecting the primary visual cortex, presenting as a contralesional, homonymous, visual field cut. This can occur unilaterally or, less commonly, bilaterally. While it has been widely assumed that after a brief period of spontaneous improvement, vision loss becomes stable and permanent, accumulating data show that visual training can recover some of the vision loss, even long after the stroke. Here, we review the different approaches to rehabilitation employed in adult-onset cortical blindness (CB), focusing on visual restoration methods. Most of this work was conducted in chronic stroke patients, partially restoring visual discrimination and luminance detection. However, to achieve this, patients had to train for extended periods (usually many months), and the vision restored was not entirely normal. Several adjuvants to training such as noninvasive, transcranial brain stimulation, and pharmacology are starting to be investigated for their potential to increase the efficacy of training in CB patients. However, these approaches are still exploratory and require considerably more research before being adopted. Nonetheless, having established that the adult visual system retains the capacity for restorative plasticity, attention recently turned toward the subacute poststroke period. Drawing inspiration from sensorimotor stroke rehabilitation, visual training was recently attempted for the first time in subacute poststroke patients. It improved vision faster, over larger portions of the blind field, and for a larger number of visual discrimination abilities than identical training initiated more than 6 months poststroke (i.e., in the chronic period). In conclusion, evidence now suggests that visual neuroplasticity after occipital stroke can be reliably recruited by a range of visual training approaches. In addition, it appears that poststroke visual plasticity is dynamic, with a critical window of opportunity in the early postdamage period to attain more rapid, more extensive recovery of a larger set of visual perceptual abilities.

When You Do Not Get the Whole Picture: Scene Perception After Occipital Cortex Lesions

Background: Occipital cortex lesions (OCLs) typically result in visual field defects (VFDs) contralateral to the damage. VFDs are usually mapped with perimetry involving the detection of point targets. This, however, ignores the important role of integration of visual information across locations in many tasks of everyday life. Here, we ask whether standard perimetry can fully characterize the consequences of OCLs. We compare performance on a rapid scene discrimination task of OCL participants and healthy observers with simulated VFDs. While the healthy observers will only suffer the loss of part of the visual scene, the damage in the OCL participants may further compromise global visual processing. Methods: VFDs were mapped with Humphrey perimetry, and participants performed two rapid scene discrimination tasks. In healthy participants, the VFDs were simulated with hemi- and quadrant occlusions. Additionally, the GIST model, a computational model of scene recognition, was used to make individual predictions based on the VFDs. Results: The GIST model was able to predict the performance of controls regarding the effects of the local occlusion. Using the individual predictions of the GIST model, we can determine that the variability between the OCL participants is much larger than the extent of the VFD could account for. The OCL participants can further be categorized as performing worse, the same, or better as their VFD would predict. Conclusions: While in healthy observers the extent of the simulated occlusion accounts for their performance loss, the OCL participants' performance is not fully determined by the extent or shape of their VFD as measured with Humphrey perimetry. While some OCL participants are indeed only limited by the local occlusion of the scene, for others, the lesions compromised the visual network in a more global and disruptive way. Yet one outperformed a healthy observer, suggesting a possible adaptation to the VFD. Preliminary analysis of neuroimaging data suggests that damage to the lateral geniculate nucleus and corpus callosum might be associated with the larger disruption of rapid scene discrimination. We believe our approach offers a useful behavioral tool for investigating why similar VFDs can produce widely differing limitations in everyday life.

Role of Structural, Metabolic, and Functional MRI in Monitoring Visual System Impairment and Recovery

The visual system, consisting of the eyes and the visual pathways of the brain, receives and interprets light from the environment so that we can perceive the world around us. A wide variety of disorders can affect human vision, ranging from ocular to neurologic to systemic in nature. While other noninvasive imaging techniques such as optical coherence tomography and ultrasound can image particular sections of the visual system, magnetic resonance imaging (MRI) offers high resolution without depth limitations. MRI also gives superior soft-tissue contrast throughout the entire pathway compared to computed tomography. By leveraging different imaging sequences, MRI is uniquely capable of unveiling the intricate processes of ocular anatomy, tissue physiology, and neurological function in the human visual system from the microscopic to macroscopic levels. In this review we discuss how structural, metabolic, and functional MRI can be used in the clinical assessment of normal and pathologic states in the anatomic structures of the visual system, including the eyes, optic nerves, optic chiasm, optic tracts, visual brain nuclei, optic radiations, and visual cortical areas. We detail a selection of recent clinical applications of MRI at each position along the visual pathways, including the evaluation of pathology, plasticity, and the potential for restoration, as well as its limitations and key areas of ongoing exploration. Our discussion of the current and future developments in MR ocular and neuroimaging highlights its potential impact on our ability to understand visual function in new detail and to improve our protection and treatment of anatomic structures that are integral to this fundamental sensory system. LEVEL OF EVIDENCE 3:   TECHNICAL EFFICACY STAGE 3:  .

Association Cortex Is Essential to Reverse Hemianopia by Multisensory Training

Hemianopia induced by unilateral visual cortex lesions can be resolved by repeatedly exposing the blinded hemifield to auditory-visual stimuli. This rehabilitative "training" paradigm depends on mechanisms of multisensory plasticity that restore the lost visual responsiveness of multisensory neurons in the ipsilesional superior colliculus (SC) so that they can once again support vision in the blinded hemifield. These changes are thought to operate via the convergent visual and auditory signals relayed to the SC from association cortex (the anterior ectosylvian sulcus [AES], in cat). The present study tested this assumption by cryogenically deactivating ipsilesional AES in hemianopic, anesthetized cats during weekly multisensory training sessions. No signs of visual recovery were evident in this condition, even after providing animals with up to twice the number of training sessions required for effective rehabilitation. Subsequent training under the same conditions, but with AES active, reversed the hemianopia within the normal timeframe. These results indicate that the corticotectal circuit that is normally engaged in SC multisensory plasticity has to be operational for the brain to use visual-auditory experience to resolve hemianopia.

Homonymous visual field defect and retinal thinning after occipital stroke

INTRODUCTION

Stroke is the most common cause of homonymous visual field defects (VFD). About half of the stroke patients recover from VFD. However, relationship between VFD and retinal changes remains elusive.

PURPOSE

To investigate the association between occurrence of VFD, changes of macular ganglion cell and inner plexiform layer (GCIPL) and its axon retinal nerve fiber layer (RNFL) detected with optical coherence tomography (OCT).

PATIENTS AND METHODS

The study consists of retrospective review of medical records and follow-up examinations. Patients with acute occipital stroke were registered. VFD was identified with confrontation and/or perimetry tests at the onset. At follow-up, the patients were examined with visual field tests and OCT measurements.

RESULTS

Thirty-six patients met the inclusion criteria. At onset, 26 patients (72%) had VFD. At follow-up >1 year after stroke, 13 patients (36%) had remaining VFD: 5 had homonymous hemianopia, 5 had homonymous quadrantanopia, and 3 had homonymous scotomas. Average thickness of GCIPL and RNFL were significantly reduced in each eye in patients with VFD compared to non-VFD (NVFD) (p < .01 for all comparisons). Thickness of superior and inferior RNFL quadrants was significantly reduced in VFD compared to NVFD (p < .01 for both). Among these 13 patients, 4 had characteristic homonymous quadrant-GCIPL thinning, 2 had characteristic homonymous hemi-GCIPL thinning, and 7 had diffuse GCIPL thinning.

CONCLUSION

GCIPL and RNFL thinning were observed in the patients with VFD. GCIPL thinning appears in two forms: atypical diffuse thinning, or homonymous hemi-GCIPL thinning. Examining GCIPL and RNFL provides easy and reliable objective measures and is therefore proposed to be of predictive value on visual function.

Case Report: Visual Rehabilitation in Hemianopia Patients. Home-Based Visual Rehabilitation in Patients With Hemianopia Consecutive to Brain Tumor Treatment: Feasibility and Potential Effectiveness

Background/Objectives: Visual field loss is frequent in patients with brain tumors, worsening their daily life and exacerbating the burden of disease, and no supportive care strategies exist. In this case series, we sought to characterize the feasibility and potential effectiveness of a home-based visual rehabilitation program in hemianopia patients using immersive virtual-reality stimulation. Subjects/Methods: Two patients, one with homonymous hemianopia and the other with bitemporal hemianopia, consecutive to pediatric brain tumors, with no prior visual rehabilitation performed 15 min of home-based audiovisual stimulation every 2 days for 6 weeks (case 2) and 7 weeks (case 1) between February and August 2020. Patients used a virtual-reality, stand-alone, and remotely controlled device loaded with a non-commercial audiovisual stimulation program managed in real time from the laboratory. Standard visual outcomes assessed in usual care in visual rehabilitation were measured at the clinic. Following a mixed method approach in this pragmatic study of two cases, we collected quantitative and qualitative data on feasibility and potential effectiveness and compared the results pre- and post-treatment. Results: Implementation and wireless delivery of the audiovisual stimulation, remote data collection, and analysis for cases 1 and 2 who completed 19/20 and 20/20 audiovisual stimulation sessions at home, respectively, altogether indicated feasibility. Contrast sensitivity increased in both eyes for cases 1 and 2. Visual fields, measured by binocular Esterman and monocular Humphrey full-field analyses, improved in case 1. A minor increase was observed in case 2. Cases 1 and 2 enhanced reading speed. Case 2 strongly improved quality of life scores. Conclusion: This is the first report of a home-based virtual-reality visual rehabilitation program for adult patients with hemianopia consecutive to a pediatric brain tumor. We show the feasibility in real-world conditions and potential effectiveness of such technology on visual perception and quality of life.

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.

An Audiovisual 3D-Immersive Stimulation Program in Hemianopia Using a Connected Device

BACKGROUND Homonymous hemianopia is a loss of conscious vision in one hemifield, strongly affecting everyday life. Audiovisual stimulation programs improve visual perception in the blind hemifield; however, they use large equipment operated in clinical settings. Such treatments require frequent visits at the clinic, hampering the patient's adherence and compliance. In one hemianopia patient, we tested a 4-week dynamic audiovisual rehabilitation program in the stand-alone, remotely controlled, virtual-reality, head-mounted display Oculus Go and measured the effect on visual perception. CASE REPORT A 15-year-old Caucasian male was diagnosed with a right homonymous hemianopia with splitting of central fixation after a traumatic occipital contusion at age 7 months. Visual assessment showed impaired binocular contrast sensitivity and retinal sensitivity. Fixation stability and visual fields were strongly affected. After a 4-week audiovisual rehabilitation program, including 3 hours 20 minutes of stimulation, the contrast sensitivity, fixation stability, and paracentral visual perception were significantly enhanced, improving quality of life. CONCLUSIONS This pioneering work reports the use of virtual-reality in a head-mounted display to provide an audiovisual stimulation protocol for low-vision rehabilitation in a hemianopia patient. Real-time data recording and remote control of the stimulation program demonstrate that such rehabilitation treatment can be performed by the patient at home without interruption of care, decreasing the burden of disease. Beneficial effects on visual function were measured according to clinical guidelines of low-vision assessment. Improvement in visual function and quality of life challenge the prevailing belief that post-acute vision loss is both permanent and unchangeable.

Intraoperative subcortico-cortical evoked potentials of the visual pathway under general anesthesia

OBJECTIVE

To assess whether intraoperative subcortical mapping of the visual pathways during brain surgeries was feasible.

METHODS

Subcortico-cortical evoked potentials (SCEPs: 30 stimulations/site, biphasic single pulse, 1.3 Hz, 0.2 ms/phase, maximum 10 mA; bipolar probe) were measured in 12 patients for stimulation of the optic radiation, Meyer's loop or optic nerve. Recorded sites were bilateral central, parietal, parieto-occipital, occipital (subdermal scalp electrodes, 5-4000 Hz). The minimum distances from the stimulation locations, i.e. the closest border of the resection cavity to the diffusion tensor imaging based visual pathways, were evaluated postoperatively (smallest distance across coronal, sagittal and axial planes).

RESULTS

Stimulation elicited SCEPs when the visual tracts were close (≤4.5 mm). The responses consisted of a short (P1, 3.0-5.6 ms; 8/8 patients) and of a middle (P2, 15-21.6 ms; 3/8 patients) latency waveforms. In agreement with the neuroanatomy, ipsilateral occipital responses were obtained for temporal or parietal stimulations, and bi-occipital responses for optic nerve stimulations.

CONCLUSIONS

For the first time to our knowledge, intraoperative SCEPs were observed for stimulations of the optic radiation and of Meyer's loop. Short latency responses were found in agreement with fast conduction of the visual pathway's connecting myelinated fibers.

SIGNIFICANCE

The mapping of the visual pathways was found feasible for neurosurgeries under general anesthesia.

Motor Vehicle Accident Due to Homonymous Hemianopia: An Unusual Presentation of Vertebrobasilar Stroke

Acute ischemic stroke may present with various symptoms, including weakness, altered speech, and sensory and visual impairment. We present a case of a 57-year-old man who was brought to the emergency department after he sustained three minor motor vehicle accidents on the same day. After clinical assessment and detailed workup, we concluded that our patient had an acute ischemic infarct involving the left posterior cerebral artery territories causing right homonymous hemianopia resulting in motor vehicle accidents.

A Rare Presentation of Posterior Cerebral Artery Stroke With Monocular Hemianopia After Diesel Exposure

Acute ischemic stroke of the posterior cerebral artery (PCA) presents with variable symptoms that may initially make it challenging to diagnose. Common etiologies of PCA stroke include large and small artery disease, atherosclerosis, and cardioembolism. We present a 69-year-old male, initially diagnosed with sinusitis at an urgent care facility, who presented with worsening headache and peripheral vision loss following exposure to diesel vapor and exhaust. Physical examination revealed a right monocular temporal hemianopia and subsequent imaging showed infarction of the left occipital lobe. Due to the length of time between the onset of the infarct and medical treatment, angiography and physical intervention were not indicated and management was done medically. This case presents a unique exposure prior to the development of a PCA stroke, as well as an atypical visual defect and suggests that physicians should consider neuroimaging in patients with nonspecific neurological findings such as new-onset headache and vision changes.

Rehabilitation of cortically induced visual field loss

PURPOSE OF REVIEW

Homonymous visual field defects are a common sequela of stroke, and are assumed to be permanent within a few weeks of the event. Because consensus about the efficacy of rehabilitation is lacking, visual therapy is rarely prescribed. Here, we review current rehabilitation options and strategies in the translational pipeline that could change these perspectives.

RECENT FINDINGS

The mainstays of available therapy for homonymous visual defects are compensation training and substitution, which allow patients to better use their spared vision. However, early clinical studies suggest that vision can partially recover following intensive training inside the blind field. Research into the relative efficacy of different restorative approaches continues, providing insights into neurophysiologic substrates of recovery and its limitations. This, in turn, has led to new work examining the possible benefits of earlier intervention, advanced training procedures, noninvasive brain stimulation, and pharmacological adjuvants, all of which remain to be vetted through properly powered, randomized, clinical trials.

SUMMARY

Research has uncovered substantial visual plasticity after occipital strokes, suggesting that rehabilitative strategies for this condition should be more aggressive. For maximal benefit, poststroke vision-restorative interventions should begin early, and in parallel with strategies that optimize everyday use of an expanding field of view.

What cortical areas are responsible for blindsight in hemianopic patients?

The presence of above-chance unconscious behavioral responses following stimulus presentation to the blind hemifield of hemianopic patients (blindsight) is a well-known phenomenon. What is still lacking is a systematic study of the neuroanatomical bases of two distinct aspects of blindsight: the unconscious above chance performance and the phenomenological aspects that may be associated. Here, we tested 17 hemianopic patients in two tasks i.e. movement and orientation discrimination of a visual grating presented to the sighted or blind hemifield. We classified patients in four groups on the basis of the presence of above chance unconscious discrimination without or with perceptual awareness reports for stimulus presentation to the blind hemifield. A fifth group was represented by patients with interruption of the Optic Radiation. In the various groups we carried out analyses of lesion extent of various cortical areas, probabilistic tractography as well as assessment of the cortical thickness of the intact hemisphere. All patients had lesions mainly, but not only, in the occipital lobe and the statistical comparison of their extent provided clues as to the critical anatomical substrate of unconscious above-chance performance and of perceptual awareness reports, respectively. In fact, the two areas that turned out to be critical for above-chance performance in the discrimination of moving versus non-moving visual stimuli were the Precuneus and the Posterior Cingulate Gyrus while for perceptual awareness reports the crucial areas were Intracalcarine, Supracalcarine, Cuneus, and the Posterior Cingulate Gyrus. Interestingly, the proportion of perceptual awareness reports was higher in patients with a spared right hemisphere. As to probabilistic tractography, all pathways examined yielded higher positive values for patients with perceptual awareness reports. Finally, the cortical thickness of the intact hemisphere was greater in patients showing above-chance performance than in those at chance. This effect is likely to be a result of neuroplastic compensatory mechanisms.

Useful Field of View Performance in the Intact Visual Field of Hemianopia Patients

Purpose

Postchiasmatic brain damage commonly results in an area of reduced visual sensitivity or blindness in the contralesional hemifield. Previous studies have shown that the ipsilesional visual field can be impaired too. Here, we examine whether assessing visual functioning of the “intact” ipsilesional visual field can be useful to understand difficulties experienced by patients with visual field defects.

Methods

We compared the performance of 14 patients on a customized version of the useful field of view test that presents stimuli in both hemifields but only assesses functioning of their intact visual half-field (iUFOV) with that of equivalent hemifield assessments in 17 age-matched healthy control participants. In addition, we mapped visual field sensitivity with the Humphrey Field Analyzer. Last, we used an adapted version of the National Eye Institute Visual Quality of Life-25 to measure their experienced visual quality of life.

Results

We found that patients performed worse on the second and third iUFOV subtests, but not on the first subtest. Furthermore, patients scored significantly worse on almost every subscale, except ocular pain. Summed iUFOV scores (assessing the intact hemifield only) and Humphrey field analyzer scores (assessing both hemifields combined) showed almost similar correlations with the subscale scores of the adapted National Eye Institute Visual Quality of Life-25.

Conclusions

The iUFOV test is sensitive to deficits in the visual field that are not picked up by traditional perimetry. We therefore believe this task is of interest for patients with postchiasmatic brain lesions and should be investigated further.

How Does Vertical Reading Affect Reading Speed?

PURPOSE

Vertical reading is an adaptive reading strategy sometimes used in homonymous hemianopia. This study aimed to measure horizontal and vertical reading speeds in visually normal volunteers using the Radner Reading Chart.

METHODS

Fifteen orthoptic students, mean age 19.7 years, took part in this repeated measures study. Participants read sentences aloud from the Radner Reading Chart horizontally and rotated vertically, to read up and down the line. Words read correctly and the time taken to read each sentence were recorded.

RESULTS

Reading speeds were calculated (words read correctly per second) for horizontal text (2.95 words per second) and for vertical text, reading up the line (1.73 words per second) and reading down the line (1.57 words per second). Reading horizontal text was significantly faster than reading vertical text. Reading horizontal text was 1.22 words per second faster than reading text vertically up (p < 0.0001) and 1.38 words per second faster than text vertically down (p < 0.0001). There was no statistically significant difference between reading text vertically up the line and vertically down the line (0.16 words per second, p = 0.42).

CONCLUSION

Horizontal reading speed, measured with the Radner Reading Chart, was significantly faster than both vertical reading speeds. There was no significant difference between reading vertically up the line and reading vertically down the line. The slower time taken to read the vertically orientated sentences had a greater effect on reading speed than the number of errors made.

Development and diagnostic validation of the Brisbane Evidence-Based Language Test

Purpose: To describe the development and determine the diagnostic accuracy of the Brisbane Evidence-Based Language Test in detecting aphasia.Methods: Consecutive acute stroke admissions (n = 100; mean = 66.49y) participated in a single (assessor) blinded cross-sectional study. Index assessment was the ∼45 min Brisbane Evidence-Based Language Test. The Brisbane Evidence-Based Language Test is further divided into four 15-25 min Short Tests: two Foundation Tests (severe impairment), Standard (moderate) and High Level Test (mild). Independent reference standard included the Language Screening Test, Aphasia Screening Test, Comprehensive Aphasia Test and/or Measure for Cognitive-Linguistic Abilities, treating team diagnosis and aphasia referral post-ward discharge.Results: Brisbane Evidence-Based Language Test cut-off score of ≤157 demonstrated 80.8% (LR+ =10.9) sensitivity and 92.6% (LR- =0.21) specificity. All Short Tests reported specificities of ≥92.6%. Foundation Tests I (cut-off ≤61) and II (cut-off ≤51) reported lower sensitivity (≥57.5%) given their focus on severe conditions. The Standard (cut-off ≤90) and High Level Test (cut-off ≤78) reported sensitivities of ≥72.6%.Conclusion: The Brisbane Evidence-Based Language Test is a sensitive assessment of aphasia. Diagnostically, the High Level Test recorded the highest psychometric capabilities of the Short Tests, equivalent to the full Brisbane Evidence-Based Language Test. The test is available for download from brisbanetest.org.Implications for rehabilitationAphasia is a debilitating condition and accurate identification of language disorders is important in healthcare.Language assessment is complex and the accuracy of assessment procedures is dependent upon a variety of factors.The Brisbane Evidence-Based Language Test is a new evidence-based language test specifically designed to adapt to varying patient need, clinical contexts and co-occurring conditions.In this cross-sectional validation study, the Brisbane Evidence-Based Language Test was found to be a sensitive measure for identifying aphasia in stroke.