Posts Tagged homonymous hemianopia

[Abstract] Computer-Based Cognitive Rehabilitation in Patients with Visuospatial Neglect or Homonymous Hemianopia after Stroke

Abstract

Objectives: The purpose of this pilot study was to investigate the feasibility and effects of computer-based cognitive rehabilitation (CBCR) in patients with symptoms of visuospatial neglect or homonymous hemianopia in the subacute phase following stroke.

Method: A randomized, controlled, unblinded cross-over design was completed with early versus late CBCR including 7 patients in the early intervention group (EI) and 7 patients in the late intervention group (LI). EI received CBCR training immediately after inclusion (m = 19 days after stroke onset) for 3 weeks and LI waited for 3 weeks after inclusion before receiving CBCR training for 3 weeks (m = 44 days after stroke onset).

Results: CBCR improved visuospatial symptoms after stroke significantly when administered early in the subacute phase after stroke. The same significant effect was not found when CBCR was administered later in the rehabilitation. The difference in the development of the EI and LI groups during the first 3 weeks was not significant, which could be due to a lack of statistical power. CBCR did not impact mental well-being negatively in any of the groups. In the LI group, the anticipation of CBCR seemed to have a positive impact of mental well-being.

Conclusion: CBCR is feasible and has a positive effect on symptoms in patients with visuospatial symptoms in the subacute phase after stroke. The study was small and confirmation in larger samples with blinded outcome assessors is needed.

via Computer-Based Cognitive Rehabilitation in Patients with Visuospatial Neglect or Homonymous Hemianopia after Stroke – ScienceDirect

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[VIDEO] How to simulate HH – YouTube

Quick and easy simulation of homonymous hemianopia/homonymous hemianopsia. Great to show loved ones and caregivers the dramatic nature of stroke related visual field loss.

via How to simulate HH – YouTube

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[VIDEO] Optic nerve lesions (Bitemporal hemianopia, heteronymous hemianopia) Homonymous hemianopia – YouTube

Optic nerve lesions (Bitemporal hemianopia, heteronymous hemianopia)Homonymous hemianopia

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[VIDEO] Improved Mobility with the Peli Lens – YouTube

An educational video regarding homonymous hemianopia, homonymous hemianopsia, the Peli Lens, and prisms  for stroke related visual field cuts.

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[ARTICLE] Driving with Hemianopia V: Do Individuals with Hemianopia Spontaneously Adapt Their Gaze Scanning to Differing Hazard Detection Demands?

Abstract

Purpose: We investigated whether people with homonymous hemianopia (HH) were able to spontaneously (without training or instructions) adapt their blind-side scan magnitudes in response to differing scanning requirements for detection of pedestrians in a driving simulator when differing cues about pedestrian eccentricities and movement behaviors were available in the seeing hemifield.

Methods: Twelve HH participants completed two sessions in a driving simulator pressing the horn when they detected a pedestrian. Stationary pedestrians outside the driving lane were presented in one session and approaching pedestrians on a collision course in the other. Gaze data were analyzed for pedestrians initially appearing at approximately 14° in the blind hemifield. No instructions were given regarding scanning.

Results: After appearing, the stationary pedestrians’ eccentricity increased rapidly to a median of 31° after 2.5 seconds, requiring increasingly larger blind-side gaze scans for detection, while the approaching pedestrians’ eccentricity remained constant at approximately 14°, requiring a more moderate scan (∼14°) for detection. Although median scan magnitudes did not differ between the two conditions (approaching: 14° [IQR 9°–15°]; stationary: 13° [IQR 9°–20°]; P= 0.43), three participants showed evidence of adapting (increasing) their blind-side scan magnitudes in the stationary condition.

Conclusions: Three participants (25%) appeared to be able to apply voluntary cognitive control to modify their blind-side gaze scanning in response to the differing scanning requirements of the two conditions without explicit training.

Translational Relevance: Our results suggest that only a minority of people with hemianopia are likely to be able to spontaneously adapt their blind-side scanning in response to rapidly changing and unpredictable situations in on-road driving.

 

Introduction
Homonymous hemianopia (HH) is the loss of half the field of vision on the same side in both eyes. It is caused by lesions in the postchiasmal visual pathways, primarily due to strokes and, to a lesser extent, trauma and tumors.1 People with HH may compensate for their hemifield loss by scanning using eye and/or head movements toward the blind hemifield. However, there is accumulating evidence2 that many do not compensate well leading to impaired hazard detection in simulated driving,38 in on-road driving,9 and in walking tasks.10
In order to see an object in the blind hemifield, people with complete HH need to scan at least as far into the blind hemifield as the location of the object. However, they receive no visual cues from peripheral vision as to when to scan or how far to scan into the blind hemifield. People with HH are usually aware of their visual field loss (unless they have spatial neglect) and could use voluntary, cognitive control to guide their blind-side scanning. For example, patients with HH may be trained or told to scan to the blind side in order to detect potential hazards.11 However, relatively little is known about the extent to which people with HH use such strategies in real world situations (e.g., driving2) or whether they are able to adapt their scanning patterns in response to differing conditions (e.g., a busy city-center street with frequent hazards versus a quiet rural road with infrequent hazards).
Only a limited number of studies have addressed the question of whether people with HH adapt their scanning strategies. A recent study using a gaze-contingent simulation of HH concluded that efficient search strategies were not spontaneously adopted by the majority of participants; however, a minority (4/20) did modify their search strategy in response to changing task demands. In general, a strategy of searching the seeing side before the blind side was adopted both for difficult search tasks in which each item needed to be viewed in a serial fashion as well as easier tasks in which the target was clearly visible in the periphery and a large saccade toward the blind side would have been the more efficient strategy. Only four participants modified their search to start from the blind field when the task was easy. In another study, Schuett et al.12reported that normally sighted participants with simulated HH became more efficient at a dot-counting task (an irregular array of dots) and a reading task after a short period of practice (∼15 minutes) on each of the tasks. However, in follow-up studies they found no evidence of transfer of learning (modification of gaze behaviors) between the two tasks, either for simulated HH13 or real HH13 (i.e., participants who practiced the dot-couting task did not demonstrate improvements on the reading task and vice versa).
In a study involving detection of peripherally presented moving basketballs within a virtual environment, participants with HH scanned less extensively in the horizontal plane and spent more time looking toward the ground when performing the task while walking than when seated.10 Thus, when walking, it appears that they modified their gaze behaviors in favor of walking, at the expense of peripheral target detection. In a driving simulator study3 involving detection of stationary pedestrians on the blind and seeing sides, no improvement in blind-side detection rates was found between two simulator sessions, approximately 1 week apart. These results suggested that no learning had occurred, despite 60 minutes of test drives at each session. Moreover, information was available in the seeing hemifield about pedestrian eccentricity, which could have been used as a guide for the scanning behaviors that were needed for detection of blind-side pedestrians. However, gaze movements were not recorded so it was unknown whether there were any changes in gaze behaviors.
In this paper, we report an analysis of gaze behaviors from a driving simulator study5 in which we evaluated detection performance of people with HH for pedestrians that were stationary to the side of the driving lane and pedestrians that approached the driving lane, walking or running on a collision course (detection rates and reaction time results were reported previously5). The scanning requirements for successful detection of blind-side pedestrians differed for the two pedestrian conditions, providing an opportunity to examine whether participants adapted their scanning behaviors. In the stationary condition the pedestrians did not move after appearing.3,5 Thus, their eccentricity increased rapidly as the car progressed, moving them farther into the blind hemifield, requiring increasingly larger gaze movements for detection. On the other hand, in the approaching condition, the pedestrians were on a collision course,5,14 so their eccentricity remained approximately constant as the car progressed. Thus, the magnitude of the gaze scan needed for detection would also have remained approximately constant, and smaller than the gaze scan needed in the stationary condition.
Herein, we address two main questions: (1) did participants with HH adapt their blind-side scan magnitudes (without training or instructions) to match the differing scanning requirements (pedestrian eccentricities) for successful blind-side detection in the stationary and approaching conditions; and (2) were the previously reported5 differences in blind-side detection rates between the two conditions accounted for by differences in the scanning requirements? We quantified the magnitudes of scans after the appearance of pedestrians in the blind hemifield and tested the hypothesis that blind-side scans would be larger in the stationary than the approaching condition. We expected to find greater evidence of within-session learning in the stationary condition (where scanning requirements were higher) than in the approaching condition. In addition, we tested the hypothesis that more time would be available after the pedestrian appearance for a moderate-sized gaze scan to reach the pedestrian in the approaching than the stationary condition, resulting in better detection rates but longer response times.[…]

Continue —> Driving with Hemianopia V: Do Individuals with Hemianopia Spontaneously Adapt Their Gaze Scanning to Differing Hazard Detection Demands? | TVST | ARVO Journals

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[VIDEO] Homonymous hemianopia – YouTube

Published on Jul 3, 2017

This project was created with Explain Everything ™ Interactive Whiteboard for iPad.

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[Abstract] Combined tDCS and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

Abstract

Background

Visual field defects after posterior cerebral artery stroke can be improved by vision restoration training (VRT), but when combined with transcranial direct current stimulation (tDCS) which alters brain excitability, vision recovery can be potentiated in the chronic stage. To date the combination of VRT and tDCS has not been evaluated in post-acute stroke rehabilitation.

Objective

To determine whether combined tDCS and VRT can be effectively implemented in the early recovery phase following a stroke, we wished to explore the feasibility, safety and efficacy of an early intervention.

Design

Open-label pilot study including a case series of seven tDCS/VRT versus a convenience sample of seven control patients (clinicalTrials.gov ID: NCT02935413).

Setting

Rehabilitation center

Subjects

Patients with homonymous visual field defects following a posterior cerebral artery stroke.

Methods

Seven homonymous hemianopia patients were prospectively treated with 10 sessions of combined tDCS (2mA, 10 daily sessions of 20 min) and VRT at 66 (±50) days on average post-stroke. Visual field recovery was compared with retrospective data of 7 controls, whose defect sizes and age of lesions were matched to the experimental subjects and who had received standard rehabilitation with compensatory eye movement and exploration training.

Results

All seven patients of the treatment group completed the treatment protocol. Safety and acceptance were excellent, and patients reported occasional skin itching beneath the electrodes as the only minor side effect. Irrespective of their treatment, both groups (treatment and control) showed improved visual fields as documented by an increased mean sensitivity threshold in dB (decibel) in standard static perimetry. Recovery was significantly greater (p<.05) in tDCS/VRT patients (36.73 ± 37.0%) than in controls (10.74 ± 8.86).

Conclusion

In this open-label pilot study, tDCS/VRT in sub-acute stroke was safe, with excellent applicability and acceptance of the treatment. Preliminary effectiveness calculations show that tDCS/VRT may be superior to standard vision training procedures. A confirmatory, larger-sample, controlled, randomized and double-blind trial is now underway to compare real- vs. sham-tDCS supported visual field training in the early vision rehabilitation phase.

This study was supported by the ERA-net neuron network “Restoration of Vision after Stroke (REVIS)”, (BMBF grant nr: 01EW1210).
clinicalTrials.gov ID: NCT02935413

Source: Combined tDCS and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

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[Abstract] A pilot randomized controlled trial comparing effectiveness of prism glasses, visual search training and standard care in hemianopia

Abstract

Objective

Pilot trial to compare prism therapy and visual search training, for homonymous hemianopia, to standard care (information only).

Methods

Prospective, multicentre, parallel, single-blind, three-arm RCT across fifteen UK acute stroke units.

Participants

Stroke survivors with homonymous hemianopia.

Interventions

Arm a (Fresnel prisms) for minimum 2 hours, 5 days per week over 6 weeks. Arm b (visual search training) for minimum 30 minutes, 5 days per week over 6 weeks. Arm c (standard care—information only).

Inclusion criteria

Adult stroke survivors (>18 years), stable hemianopia, visual acuity better than 0.5 logMAR, refractive error within ±5 dioptres, ability to read/understand English and provide consent.

Outcomes

Primary outcomes were change in visual field area from baseline to 26 weeks and calculation of sample size for a definitive trial. Secondary measures included Rivermead Mobility Index, Visual Function Questionnaire 25/10, Nottingham Extended Activities of Daily Living, Euro Qual, Short Form-12 questionnaires and Radner reading ability. Measures were post-randomization at baseline and 6, 12 and 26 weeks.

Randomization

Randomization block lists stratified by site and partial/complete hemianopia.

Blinding

Allocations disclosed to patients. Primary outcome assessor blind to treatment allocation.

Results

Eighty-seven patients were recruited: 27—Fresnel prisms, 30—visual search training and 30—standard care; 69% male; mean age 69 years (SD 12). At 26 weeks, full results for 24, 24 and 22 patients, respectively, were compared to baseline. Sample size calculation for a definitive trial determined as 269 participants per arm for a 200 degree2 visual field area change at 90% power. Non-significant relative change in area of visual field was 5%, 8% and 3.5%, respectively, for the three groups. Visual Function Questionnaire responses improved significantly from baseline to 26 weeks with visual search training (60 [SD 19] to 68.4 [SD 20]) compared to Fresnel prisms (68.5 [SD 16.4] to 68.2 [18.4]: 7% difference) and standard care (63.7 [SD 19.4] to 59.8 [SD 22.7]: 10% difference), P=.05. Related adverse events were common with Fresnel prisms (69.2%; typically headaches).

Conclusions

No significant change occurred for area of visual field area across arms over follow-up. Visual search training had significant improvement in vision-related quality of life. Prism therapy produced adverse events in 69%. Visual search training results warrant further investigation.

Source: A pilot randomized controlled trial comparing effectiveness of prism glasses, visual search training and standard care in hemianopia – Rowe – 2016 – Acta Neurologica Scandinavica – Wiley Online Library

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[ARTICLE] Behavioural consequences and cortical reorganization in homonymous hemianopia – Full Text

Abstract

The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby, in each eye, patients are blind to the contralesional visual field. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, hemianopic patients can also present implicit residual capacities, now usually referred to collectively as blindsight. It was recently demonstrated that HH patients can also suffer from a subtle deficit in their ipsilesional visual field, called sightblindness (the reverse case of blindsight). Furthermore, the nature of the visual deficit in the contralesional and ipsilesional visual fields, as well as the pattern of functional reorganization in the occipital lobe of HH patients after stroke, all appear to depend on the lesion side. In addition to their contralesional and ipsilesional visual deficits, and to their residual capacities, HH patients can also experience visual hallucinations in their blind field, the physiopathological mechanisms of which remain poorly understood. Herein we review blindsight in terms of its better-known aspects as well as its less-studied clinical signs such as sightblindness, hemispheric specialization and visual hallucinations. We also discuss the implications of recent experimental findings for rehabilitation of visual field defects in hemianopic patients.

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Source: Frontiers | Behavioural consequences and cortical reorganization in homonymous hemianopia | Frontiers in Systems Neuroscience

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[ARTICLE] A Randomised Controlled Trial of Treatment for Post-Stroke Homonymous Hemianopia: Screening and Recruitment – Full Text

ABSTRACT

The authors report the screening process and recruitment figures for the VISION (Visual Impairment in Stroke; Intervention Or Not) trial. This is a prospective, randomised, single-blinded, three-arm controlled trial in 14 UK acute hospital stroke units. Stroke teams identified stroke survivors suspected as having homonymous hemianopia.
Interventions included Fresnel prisms versus visual search training versus standard care (information only). Primary outcome was change in visual field assessment from baseline to 26 weeks. Secondary measures included change in quality-of-life questionnaires.
Recruitment opened in May 2011. A total of 1171 patients were screened by the local principal investigators. Of 1171 patients, 178 (15.2%) were eligible for recruitment: 87 patients (7.4%) provided consent and were recruited; 91 patients (7.8%) did not provide consent, and 993 of 1171 patients (84.8%) failed to meet the eligibility criteria. Almost half were excluded due to complete/partial recovery of hemianopia (43.6%; n = 511).
The most common ineligibility reason was recovery of hemianopia. When designing future trials in this area, changes in eligibility criteria/outcome selection to allow more patients to be recruited should be considered, e.g., less stringent levels of visual acuity/refractive error. Alternative outcomes measurable in the home environment, rather than requiring hospital attendance for follow-up, could facilitate increased recruitment.

Continue —> A Randomised Controlled Trial of Treatment for Post-Stroke Homonymous Hemianopia: Screening and Recruitment – Neuro-Ophthalmology – Volume 40, Issue 1

Figure 1. Flow chart of recruitment figures.

 

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