Posts Tagged visual rehabilitation

[Abstract] Homonymous Hemianopia and Vision Restoration Therapy

Homonymous hemianopia from stroke causes visual disability. Although some patients experience spontaneous improvement, others have limited to no change and may be left with a severe disability. Current rehabilitation strategies are compensatory and cannot restore function. Animal studies suggest that central nervous system plasticity could allow for redirection of lost visual function into undamaged areas of cortex. A commercial therapy system was developed, from which claims of visual field expansion were disputed by independent researchers. The treatment remains controversial with seemingly contradictory data being generated. Continued research is underway to demonstrate the (non-)efficacy of this treatment method.

Source: Homonymous Hemianopia and Vision Restoration Therapy – Neurologic Clinics

Advertisements

, , , , ,

Leave a comment

[ARTICLE] Compensatory Recovery after Multisensory Stimulation in Hemianopic Patients: Behavioral and Neurophysiological Components – Full Text

Lateralized post-chiasmatic lesions of the primary visual pathway result in loss of visual perception in the field retinotopically corresponding to the damaged cortical area. However, patients with visual field defects have shown enhanced detection and localization of multisensory audio-visual pairs presented in the blind field. This preserved multisensory integrative ability (i.e., crossmodal blindsight) seems to be subserved by the spared retino-colliculo-dorsal pathway. According to this view, audio-visual integrative mechanisms could be used to increase the functionality of the spared circuit and, as a consequence, might represent an important tool for the rehabilitation of visual field defects. The present study tested this hypothesis, investigating whether exposure to systematic multisensory audio-visual stimulation could induce long-lasting improvements in the visual performance of patients with visual field defects. A group of 10 patients with chronic visual field defects were exposed to audio-visual training for 4 h daily, over a period of 2 weeks. Behavioral, oculomotor and electroencephalography (EEG) measures were recorded during several visual tasks before and after audio-visual training. After audio-visual training, improvements in visual search abilities, visual detection, self-perceived disability in daily life activities and oculomotor parameters were found, suggesting the implementation of more effective visual exploration strategies. At the electrophysiological level, after training, patients showed a significant reduction of the P3 amplitude in response to stimuli presented in the intact field, reflecting a reduction in attentional resources allocated to the intact field, which might co-occur with a shift of spatial attention towards the blind field. More interestingly, both the behavioral improvements and the electrophysiological changes observed after training were found to be stable at a follow-up session (on average, 8 months after training), suggesting long-term effects of multisensory audio-visual training. These long-lasting effects seem to be subserved by the activation of the spared retino-colliculo-dorsal pathway, which promotes orienting responses towards the blind field, able to both compensate for the visual field loss and concurrently attenuate visual attention towards the intact field. These results add to previous findings the knowledge that audio-visual multisensory stimulation promote long-term plastic changes in hemianopics, resulting in stable and long-lasting ameliorations in behavioral and electrophysiological measures.

Introduction

Visual field defects, resulting from damage to the visual structures located behind the chiasma, including primary visual cortex (V1), surrounding extrastriate cortices and optic radiations, consist of a loss of visual perception in up to one half of the visual field. Patients with visual field defects cannot see a visual stimulus presented within the blind area of the visual field. Although the ability to consciously perceive visual stimuli presented in the blind field is lost, these hemianopic patients have demonstrated the specific ability to implicitly detect or discriminate certain visual features of stimuli presented in the blind field, such as motion, color and orientation (Weiskrantz et al., 1974), as well as the emotional content of the visual signals (affective blindsight; De Gelder et al., 1999; Morris et al., 2001; Pegna et al., 2005; Bertini et al., 2013; Cecere et al., 2014). These patients can also integrate unseen visual stimuli with auditory information (crossmodal blindsight; Leo et al., 2008b). The neuronal structures and pathways sustaining implicit processing of visual signals following damage to V1 or the neural pathway feeding V1 are still under debate; this topic is very relevant for the rehabilitation of visual field defects, because the same pathways could mediate recovery of the deficit, if adequately boosted.

Continue —> Frontiers | Compensatory Recovery after Multisensory Stimulation in Hemianopic Patients: Behavioral and Neurophysiological Components | Frontiers in Systems Neuroscience

Figure 2. Axial views of CT/MRI scans of the patients. L = left, R = right.

, , , ,

Leave a comment

[ARTICLE] Vision problems in ischaemic stroke patients: effects on life quality and disability – European Journal of Neurology – Full Text HTML

Abstract

Background and purpose Vision problems after cerebral infarction are an increasingly acknowledged problem. Our aim was to investigate the effect on quality of life and post-stroke disability.

Methods Patients admitted to the Stroke Unit, Department of Neurology, Haukeland University Hospital, between February 2006 and July 2008 with acute cerebral infarction were prospectively registered in the NORSTROKE Registry. Patients received a postal questionnaire at least 6 months after stroke. The questionnaire included 15D©, EuroQol 5D (EQ-5D™), the Hospital Anxiety and Depression Scale (HADS), the Fatigue Severity Scale (FSS) and the Barthel Index (BI).

Results Of 328 responders, 83 (25.4%) reported a vision problem. Vision problems were associated with older age (71.8 years vs. 66.5 years, P = 0.001), higher National Institutes of Health Stroke Scale score on admission (5.9 vs. 3.8, P < 0.001), higher modified Rankin Scale day 7 (2.0 vs. 1.4, P < 0.001) and lower BI day 7 (85.7 vs. 93.9, P = 0.002). Patients with vision problems had lower median EQ-5D utility score (0.62 vs. 0.80, P < 0.001), lower median 15D utility score (0.73 vs. 0.89, P < 0.001), higher median HADS score (12 vs. 5, P < 0.001), higher median FSS score (5.6 vs. 4.3, P < 0.001) and lower median BI (95 vs. 100, P < 0.001) on long-term follow-up. Patients with self-reported vision problems scored lower on all sub-scores of BI on follow-up (all P < 0.001).

Conclusion One in four patients reported a vision problem on follow-up after cerebral infarction. Vision problems after cerebral infarction reduce quality of life and are associated with increased disability. Thorough diagnostic evaluation and targeted rehabilitation is important.

Continue: —>  Vision problems in ischaemic stroke patients: effects on life quality and disability – Sand – 2015 – European Journal of Neurology – Wiley Online Library

 

, , , , , ,

Leave a comment

[Editorial] Neural bases of binocular vision and coordination and their implications in visual training programs

Opening

To see or not to see? That is the question of this research topic. How do human beings see not with their eyes but with their brain, which lies in a moving body, itself evolving in a continuously changing environment? What and how do humans see in the context of a particular task at a given moment? How do humans cease to see after some damage in the brain or neurofunctional disorder? And how may the basic science of eye movements and vision help to develop efficient visual training programs?

The present research topic, entitled Neural bases of binocular vision and coordination and their implications in visual training programs, aims at putting forward our knowledge of the neural underpinnings of vision in its motor, sensory, cognitive, emotional and vegetative expressions. It does not target an exhaustive collection of what we know in the field of visual neurosciences. For that purpose, the reader may refer to the volume sets by Chalupa and Werner (2003). Rather, this research topic focuses on the latest findings on the neural aspects of eye movements and visual perception that directly help to understand and improve visual training programs in pathological conditions. Such disorders follow damages of the cerebral visual pathways (e.g., hemianopia) or refer to syndromes hitherto believed to be peripheral but in which neurophysiology and brain imaging are uncovering neural correlates or causes (e.g., amblyopia).

The research topic is divided into three parts respectively dedicated to eye movements, visual perception, and visual training programs, each having six chapters, and starts with an overview. In the introductory chapter, Coubard, Urbanski, Bourlon and Gaumet (2014) remind the reader of the importance of action in visual processing before describing the cascade of physiological mechanisms underlying eye movements, followed by a description of the five main neurovisual systems. After an overview of pathological conditions causing not eye but brain blindness – also called neurovisual disorders – the authors end by describing the disciplines of visual rehabilitation.

Continue —>  Frontiers | Editorial: Neural bases of binocular vision and coordination and their implications in visual training programs | Frontiers in Integrative Neuroscience.

, , , , , ,

Leave a comment

[ARTICLE] A study on the natural history of scanning behaviour in patients with visual field defects after stroke – Full Text PDF

Abstract

Background

A visual field defect (VFD) is a common consequence of stroke with a detrimental effect upon the survivors’ functional ability and quality of life. The identification of effective treatments for VFD is a key priority relating to life post-stroke. Understanding the natural evolution of scanning compensation over time may have important ramifications for the development of efficacious therapies. The study aims to unravel the natural history of visual scanning behaviour in patients with VFD. The assessment of scanning patterns in the acute to chronic stages of stroke will reveal who does and does not learn to compensate for vision loss.

Methods/Design

Eye-tracking glasses are used to delineate eye movements in a cohort of 100 stroke patients immediately after stroke, and additionally at 6 and 12 months post-stroke. The longitudinal study will assess eye movements in static (sitting) and dynamic (walking) conditions. The primary outcome constitutes the change of lateral eye movements from the acute to chronic stages of stroke. Secondary outcomes include changes of lateral eye movements over time as a function of subgroup characteristics, such as side of VFD, stroke location, stroke severity and cognitive functioning.

Discussion

The longitudinal comparison of patients who do and do not learn compensatory scanning techniques may reveal important prognostic markers of natural recovery. Importantly, it may also help to determine the most effective treatment window for visual rehabilitation

Continue —> Full Text PDF

, , , , , , , ,

Leave a comment

[WEB SITE] Vision Rehabilitation PPP – 2013 – American Academy of Ophthalmology – Full Text HTML/PDF

…HIGHLIGHTED RECOMMENDATIONS FOR CARE

All ophthalmologists are encouraged to provide information about rehabilitation resources for patients who have vision loss. Even early or moderate vision loss causes disability, and it can cause great anxiety and affect visual performance. When available, consider referral for multidisciplinary vision rehabilitation. There is emerging evidence that vision rehabilitation improves visual performance and, hence, quality of life…

Full Text HTML

Full TEXT PDF

via Vision Rehabilitation PPP – 2013 – American Academy of Ophthalmology.

, , , ,

Leave a comment

%d bloggers like this: