Posts Tagged Hemianopia

[Abstract] Interhemispheric visual competition after multisensory reversal of hemianopia

Abstract

Unilateral lesions of visual cortex have the secondary consequence of suppressing visual circuits in the midbrain superior colliculus (SC), collectively producing blindness in contralesional space (“hemianopia”). Recent studies have demonstrated that SC visual responses and contralesional vision can be reinstated by a non‐invasive multisensory training procedure in which spatiotemporally concordant visual‐auditory pairs are repeatedly presented within the blind hemifield. Despite this recovery of visual responsiveness, the loss of visual cortex was expected to result in permanent deficits in that hemifield, especially when visual events in both hemifields compete for attention and access to the brain’s visuomotor circuitry. This was evaluated in the present study in a visual choice paradigm in which the two visual hemifields of recovered cats were simultaneously stimulated with equally‐valent visual targets. Surprisingly, the expected disparity was not found, and some animals even preferred stimuli presented in the previously blind hemifield. This preference persisted across multiple stimulus intensity levels and there was no indication that animals were less aware of cues in the previously blind hemifield than in its spared counterpart. Furthermore, when auditory cues were combined with visual cues, the enhanced performance they produced on a visual task was no greater in the normal than in the previously blind hemifield. These observations suggest that the multisensory rehabilitation paradigm revealed greater inherent visual information processing potential in the previously blind hemifield than was believed possible given the loss of visual cortex.

 

via Interhemispheric visual competition after multisensory reversal of hemianopia – Dakos – – European Journal of Neuroscience – Wiley Online Library

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[VIDEO] Fitting and Training Patients with Peripheral Prisms – YouTube

This video outlines the fitting and training process for The Peli Lens for Homonymous Hemianopsia

via Fitting and Training Patients with Peripheral Prisms – YouTube

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[VIDEO] Visual pathway lesion – YouTube

Right optic nerve lesion➡Blindness of Right eye

Left optic nerve lesion➡Blindness of  left eye

Lateral part of optic chiasma lesion➡Binasal Hemianopia

Medial Part of optic chiasma lesion➡ Bitemporal Hemianopia

Right Optic tract lesion➡Left Homonymous Hemianopia

via Visual pathway lesion – YouTube

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[Abstract] A qualitative exploration of the effect of visual field loss on daily life in home-dwelling stroke survivors

To explore the effect of visual field loss on the daily life of community-dwelling stroke survivors.

A qualitative interview study.

Adult stroke survivors with visual field loss of at least six months’ duration.

Semi-structured interviews were conducted with a non-purposive sample of 12 stroke survivors in their own homes. These were recorded, transcribed verbatim and analyzed with the framework method, using an inductive approach.

Two key analytical themes emerged. ‘Perception, experience and knowledge’ describes participant’s conflicted experience of having knowledge of their impaired vision but lacking perception of that visual field loss and operating under the assumption that they were viewing an intact visual scene when engaged in activities. Inability to recognize and deal with visual difficulties, and experiencing the consequences, contributed to their fear and loss of self-confidence. ‘Avoidance and adaptation’ were two typologies of participant response to visual field loss. Initially, all participants consciously avoided activities. Some later adapted to vision loss using self-directed head and eye scanning techniques.

Visual field loss has a marked impact on stroke survivors. Stroke survivors lack perception of their visual loss in everyday life, resulting in fear and loss of confidence. Activity avoidance is a common response, but in some, it is replaced by self-initiated adaptive techniques.

via A qualitative exploration of the effect of visual field loss on daily life in home-dwelling stroke survivors – Christine Hazelton, Alex Pollock, Anne Taylor, Bridget Davis, Glyn Walsh, Marian C Brady, 2019

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[Abstract] Using Vision to Study Poststroke Recovery and Test Hypotheses About Neurorehabilitation

Approximately one-third of stroke patients suffer visual field impairment as a result of their strokes. However, studies using the visual pathway as a paradigm for studying poststroke recovery are limited. In this article, we propose that the visual pathway has many features that make it an excellent model system for studying poststroke neuroplasticity and assessing the efficacy of therapeutic interventions. First, the functional anatomy of the visual pathway is well characterized, which makes it well suited for functional neuroimaging studies of poststroke recovery. Second, there are multiple highly standardized and clinically available diagnostic tools and outcome measures that can be used to assess visual function in stroke patients. Finally, as a sensory modality, the assessment of vision is arguably less likely to be affected by confounding factors such as functional compensation and patient motivation. Given these advantages, and the general similarities between poststroke visual field recovery and recovery in other functional domains, future neurorehabilitation studies should consider using the visual pathway to better understand the physiology of neurorecovery and test potential therapeutics.

via Using Vision to Study Poststroke Recovery and Test Hypotheses About Neurorehabilitation – Ania Busza, Colleen L. Schneider, Zoë R. Williams, Bradford Z. Mahon, Bogachan Sahin, 2019

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[VIDEO] Hemianopia – Half blind – YouTube

This is an attempt to show people how I see the world since my brain injury 8 years ago. This is what I see when I’m going shopping… I hate going shopping… I rarely go full shopping….. My left side of vision is missing, it’s not really black, it’s just not there, but I can’t explain it… and what I have left, is what you see here… My camera caught it all perfectly, sun glare as well… So if I don’t recognise you in the street, it’s really because I can’t see your face. If I need to see your face, I look for the right side edge of your face and look above you… that helps me see more of your features. But to be honest, I’ve kind of got used to not seeing people’s faces. I look at the floor a lot so I can see people’s feet, so I can sort of work out where they are if they are too close to me. Gradually, over 8 years I have adapted to doing things, walking, etc on the right. I stop in mid walking sometimes because I saw a person in front of me, then they vanished to my left and I wasn’t sure how close to me they were and I didn’t want to bump into them…. I cope better in wider spaces. Narrow corridors look even more narrow. I discreetly use my hands to touch anything that might be too close, so that I know to move myself away. I still walk into things and get hurt. If I turn my head too quickly, then I go off balance and sometimes fall over. It is very frightening when you can’t see properly, but look normal to everyone else. I’m not too bad if I’m with someone else. I constantly rely on touch… Hence doing Papiér Maché instead of drawing or painting. Also, I still get lost and wonder where I am, even sometimes going past my own house… I haven’t read a book in years, and I used to like reading… I couldn’t work out why I couldn’t see the words properly, and they kept vanishing, and the bits that I could see were double vision – then I had prisms fitted in my glasses lenses, which helped with the double vision, but I still couldn’t work out why I couldn’t see properly. I was officially diagnosed in January 2017. The Neurologist said despite all that, I had made some very good ways of trying to cope… It still is a struggle, but I do my best.

via Hemianopia – Half blind – YouTube

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[BLOG] Visual effects of stroke often undetected

Every year, nearly 800,000 Americans suffer a stroke, according to the Internet Stroke Center.

Strokes are a leading cause of death and disability, but what many people don’t realize is that two out of three stroke survivors will also experience visual impairments related to their stroke (Rowe). These can include diminished central or peripheral vision, eye movement abnormalities or visual perceptual defects.

Sadly, it is not uncommon for me to see patients who are still struggling with undiagnosed vision problems months or even years after a stroke. There are a number of reasons for this. In the immediate days and weeks after a stroke, patients and their families and doctors are often most concerned about preventing brain hemorrhages and addressing motor and language deficits. After that, patients may have difficulty articulating their symptoms or may not be aware that balance issues are connected to vision. In some cases, they may have been examined and incorrectly told that nothing can be done.

Given the prevalence of post-stroke visual impairment, anyone who suffers a stroke should be seen by an eye care specialist as soon as possible and, ideally, be referred to a neuro-optometric rehabilitation optometrist. Visual rehabilitation can lead to greater independence and improved quality of life and can accelerate the success of other therapies. In fact, most stroke survivors need more than one type of rehabilitation, so it is not unusual for me to work with a team of speech, occupational or physical therapists to help the stroke survivor learn new ways of performing tasks to circumvent or compensate for any residual disabilities.

The most common visual complication of stroke is a homonymous hemianopsia, or a visual field defect on the same side in each eye, resulting from damage to the occipital lobe, where the majority of visual processing takes place. This type of stroke-related field loss is often accompanied by a visual midline shift, which occurs when there is a mismatch between visual spatial information and the patient’s proprioceptive base of support.

A shift in the visual midline can directly affect posture, balance and spatial orientation, and it significantly increases the risk of falls. It is relatively easy to diagnose: Just ask a patient to walk down the hall and observe whether they drift to one side or tip backwards or forwards. In a study that I co-authored with Dr. William Padula, we showed that intervention with yoked prisms can restore the visual midline, thereby improving balance and reducing the risk of falls and subsequent injury.

Strokes that affect other parts of the brain may result in cranial nerve damage-associated diplopia or the rare but fascinating phenomenon of visual neglect, in which the patient completely loses awareness of one side of the body. In less severe cases, there can also be subtle effects on eye tracking and teaming, leading to impaired saccades and pursuits or convergence insufficiency. These impairments can be improved with vision rehabilitation and prism lenses.

Vision rehabilitation may not always be able to fully restore patients to the same degree of visual function they had before the stroke, but we can go a long way towards improving quality of life and helping patients maximize the vision they have.

References:

Internet Stroke Center. U.S. Stroke Statistics. http://www.strokecenter.org/patients/about-stroke/stroke-statistics/. Accessed January 16, 2019.

Padula WV, et al. NeuroRehabilitation. 2015;doi:10.3233/NRE-151263.

Rowe FJ. Brain Behav. 2017;doi:10.1002/brb3.778.

 

via BLOG: Visual effects of stroke often undetected

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[WEB SITE] Attention network plays key role in restoring vision after brain damage: New study highlights the role of attention as a component of vision restoration training in hemianopia

Date: September 4, 2018
Source: Institute for Medical Psychology, Otto-v.-Guericke University Magdeburg
Summary: About one-third of patients who have suffered a stroke end up with low vision, losing up to half of their visual field. This partial blindness was long considered irreversible, but recent studies have shown that vision training after optic nerve and brain damage can help restore or improve vision. A new study reports on key mechanisms of vision restoration: attention.

FULL STORY

About one third of patients who have suffered a stroke end up with low vision, losing up to half of their visual field. This partial blindness was long considered irreversible, but recent studies have shown that vision training after optic nerve and brain damage can help restore or improve vision. A new study published in the journal Clinical Neurophysiology reports on key mechanisms of vision restoration: attention.

Hemianopia is a decreased vision or blindness in half the visual field, usually as a consequence of stroke or trauma to the brain. It greatly reduces quality of life, affecting patients’ reading, driving and spatial navigation.

“Knowledge in this field is still rather fragmentary, but recent studies have shown that vision can be partially restored by vision training, which improves the deficient visual field sectors,” explains Prof. Bernhard Sabel, PhD, Director of the Institute of Medical Psychology at Magdeburg University, Germany, co-investigator of the study. “Neuroimaging evidence supports a possible role of attention in this vision restoration.”

The study confirmed this hypothesis by obtaining evidence from functional magnetic resonance imaging (fMRI) that visual training led to functional connectivity reorganization of the brain´s attentional network.

Seven chronic hemianopic patients with lesions of the visual cortex took part in vision rehabilitation training for five weeks. After the pre-tests all received training sessions lasting one and a half hours per day for six days per week for five weeks. Each training session, lasting about 60 minutes, was composed of six blocks with 120 training trials each, during which participants had to respond to specially designed visual stimuli on a computer monitor. The pre- and post-test included perimetry testing, contrast sensitivity testing and fMRI scanning one or two days before and after training, respectively. Each contrast sensitivity test consisted of 420 trials in six blocks. The visual rehabilitation training was performed with one eye open, which was randomly chosen, while the non-trained eye was covered with an opaque eye patch.

After training, the patients had significantly improved visual function at the training location, and fMRI showed that the training led to a strengthening of the cortical attentional network connections between the brain region of the right temporoparietal junction (rTPJ) and the insula and the anterior cingulate cortex (ACC).

“Our MRI results highlight the role of attention and the right TPJ activation as a component of vision restoration training in hemianopia,” notes lead investigator Yifeng Zhou, DSc, of the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Science, University of Science and Technology of China, Hefei, P.R. China, and State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R. China. “However, it is unclear whether the rehabilitation of attentional networks is the direct result of training or the result of the rebalancing of bottom-up sensory streams, which should be investigated in future studies.”

“This discovery that the brain´s attention network is a key mechanism in partially reversing blindness is an exciting advance in the field of restoring vision in the blind, and it opens up new avenues to design new therapies that are even more effective than current methods to help people with low vision or blindness,” concludes Prof. Sabel.

Story Source:

Materials provided by Institute for Medical Psychology, Otto-v.-Guericke University MagdeburgNote: Content may be edited for style and length.


Journal Reference:

  1. Qilin Lu, Xiaoxiao Wang, Lin Li, Bensheng Qiu, Shihui Wei, Bernhard A. Sabel, Yifeng Zhou. Visual rehabilitation training alters attentional networks in hemianopia: An fMRI studyClinical Neurophysiology, 2018; 129 (9): 1832 DOI: 10.1016/j.clinph.2018.05.027

via Attention network plays key role in restoring vision after brain damage: New study highlights the role of attention as a component of vision restoration training in hemianopia — ScienceDaily

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[VIDEO] SYMPTOMS OF HEMIANOPSIA – YouTube

 

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[WEB SITE] Attention network plays key role in restoring vision after brain damage – ScienceDaily

New study highlights the role of attention as a component of vision restoration training in hemianopia

Summary:
About one-third of patients who have suffered a stroke end up with low vision, losing up to half of their visual field. This partial blindness was long considered irreversible, but recent studies have shown that vision training after optic nerve and brain damage can help restore or improve vision. A new study reports on key mechanisms of vision restoration: attention.
 
FULL STORY

About one third of patients who have suffered a stroke end up with low vision, losing up to half of their visual field. This partial blindness was long considered irreversible, but recent studies have shown that vision training after optic nerve and brain damage can help restore or improve vision. A new study published in the journal Clinical Neurophysiology reports on key mechanisms of vision restoration: attention.

Hemianopia is a decreased vision or blindness in half the visual field, usually as a consequence of stroke or trauma to the brain. It greatly reduces quality of life, affecting patients’ reading, driving and spatial navigation.

“Knowledge in this field is still rather fragmentary, but recent studies have shown that vision can be partially restored by vision training, which improves the deficient visual field sectors,” explains Prof. Bernhard Sabel, PhD, Director of the Institute of Medical Psychology at Magdeburg University, Germany, co-investigator of the study. “Neuroimaging evidence supports a possible role of attention in this vision restoration.”

The study confirmed this hypothesis by obtaining evidence from functional magnetic resonance imaging (fMRI) that visual training led to functional connectivity reorganization of the brain´s attentional network.

Seven chronic hemianopic patients with lesions of the visual cortex took part in vision rehabilitation training for five weeks. After the pre-tests all received training sessions lasting one and a half hours per day for six days per week for five weeks. Each training session, lasting about 60 minutes, was composed of six blocks with 120 training trials each, during which participants had to respond to specially designed visual stimuli on a computer monitor. The pre- and post-test included perimetry testing, contrast sensitivity testing and fMRI scanning one or two days before and after training, respectively. Each contrast sensitivity test consisted of 420 trials in six blocks. The visual rehabilitation training was performed with one eye open, which was randomly chosen, while the non-trained eye was covered with an opaque eye patch.

After training, the patients had significantly improved visual function at the training location, and fMRI showed that the training led to a strengthening of the cortical attentional network connections between the brain region of the right temporoparietal junction (rTPJ) and the insula and the anterior cingulate cortex (ACC).

“Our MRI results highlight the role of attention and the right TPJ activation as a component of vision restoration training in hemianopia,” notes lead investigator Yifeng Zhou, DSc, of the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Science, University of Science and Technology of China, Hefei, P.R. China, and State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R. China. “However, it is unclear whether the rehabilitation of attentional networks is the direct result of training or the result of the rebalancing of bottom-up sensory streams, which should be investigated in future studies.”

“This discovery that the brain´s attention network is a key mechanism in partially reversing blindness is an exciting advance in the field of restoring vision in the blind, and it opens up new avenues to design new therapies that are even more effective than current methods to help people with low vision or blindness,” concludes Prof. Sabel.

Story Source:

Materials provided by Institute for Medical Psychology, Otto-v.-Guericke University MagdeburgNote: Content may be edited for style and length.


Journal Reference:

  1. Qilin Lu, Xiaoxiao Wang, Lin Li, Bensheng Qiu, Shihui Wei, Bernhard A. Sabel, Yifeng Zhou. Visual rehabilitation training alters attentional networks in hemianopia: An fMRI studyClinical Neurophysiology, 2018; 129 (9): 1832 DOI: 10.1016/j.clinph.2018.05.027

Cite This Page:

Institute for Medical Psychology, Otto-v.-Guericke University Magdeburg. “Attention network plays key role in restoring vision after brain damage: New study highlights the role of attention as a component of vision restoration training in hemianopia.” ScienceDaily. ScienceDaily, 4 September 2018. <www.sciencedaily.com/releases/2018/09/180904114753.htm>.
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via Attention network plays key role in restoring vision after brain damage: New study highlights the role of attention as a component of vision restoration training in hemianopia — ScienceDaily

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