Active clinical trials for "Hemianopsia"

The purpose of this Study is to determine whether non-invasive transcranial direct current stimulation (tDCS) is effective in increasing rehabilitation effects after stroke in visual Cortex.

The purpose of this study is to evaluate the functional utility for general mobility (walking) of new high power permanent peripheral prism glasses, which provide visual field expansion device for patients with homonymous hemianopia (the complete loss of half the field of vision on the same side in both eyes). The efficacy of real peripheral prism glasses will be assessed relative to sham peripheral prism glasses.

The purpose of this Study is to determine whether non-invasive transcranial direct current stimulation (tDCS) is effective in increasing rehabilitation effects after stroke in visual Cortex.

Visual field areas, which are not absolutely blind, are hypothesized to have some residual capacities that constitute their potential for vision restoration. Vision restoration can be achieved by varies methods including behavioral training and electrical brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transorbital alternating current stimulation (rtACS) which are able to influence the excitability and activity of cortical areas. It is hypothesized that transorbital alternating current stimulation (tACS) can improve the residual field of vision in patients with post-chiasmatic lesions.

This study will assess the effectiveness of a stimulus, in the blind field of hemianopsic patients, to restore the vision of patients with homonymous hemianopsia consecutive to stroke (unilateral occipital lesion). Hemianopsia occurs in 30% of strokes regardless of the cerebral localization and in 60% of stroke interesting the territory of the posterior cerebral artery.

Homonymous hemianopia is one of the most common symptoms following a neurologic damage and has many negative effects on functional abilities and daily activities. There are two main kind of restorative rehabilitation of hemianopia: "border training", which involves exercising vision at the edge of the damaged visual field, and "blindsight training", which is based on exercising the unconscious perceptual functions in the mild of the blind hemifield. In literature only border training effects were shown to be facilitated by transcranial direct current stimulation (tDCS). The investigators treat two patients with blindsight rehabilitation associated to tDCS over parieto-occipital cortex. The two patients undergo a cycle of blindsight treatment associated to tDCS and a cycle of blindsight training alone in inverted order. Aim of the study is to investigate if the anodic stimulation of perilesional areas enhance the improvement induced by blindsight rehabilitation treatment.

Occipital stroke is associated with homonymous visual field defects (occurring on one side of the visual field). Despite spontaneous recovery, some degree of defect is often permanent. Currently, no treatment exists for such visual field defects.The purpose of this study is to test the efficacy of a type of electrical brain stimulation method, transcranial alternating current stimulation, in reducing these type of visual field defects in their chronic stage.

Background: The most common visual field deficit after retro-chiasmatic lesions is homonymous hemianopia (HH), defined as the impossibility of seeing the contralesional visual hemisphere without ocular injury. HH affects between 90000 and 120 000 new cases per year in the United States and Europe HH was reported in 30% of patients after stroke (National Audit Office) (in France, with 130,000 strokes per year, 39,000 patients with HH). Despite the 30-year decline, the rehabilitation techniques have a low level of evidence of their effectiveness and few are used in routine clinical practice in France. Transcranial Alternate Current Stimulation (tACS) is a method of Alternative Current stimulation that can modulate neural activity by imposing local oscillatory activity. An observational study of occipital tACS in patients with optic nerve lesions showed an increase in visual field size, power, and occipital alpha synchrony. Two transorbital tACS studies showed visual improvements , and compensations for abnormally weak oscillatory activity by temporal resynchronization. Our team has demonstrated a role of noninvasive brain stimulation in right hemisphere frontal eye fields on cortical beta-high (~ 30 Hz) oscillatory activity, improving the visual perception of both hemi-fields and the fronto-parietal synchrony of the right hemisphere. Objective: This project aims to compare, on the same patient population, two tACS stimulation strategies, with the aim of increasing the attentional orientation towards the blind visual hemi-field and thus the visual detection of stimuli in this hemi-field. . For this, The investigator team will evaluate on the one hand an occipital stimulation (V1-IPS) contralateral to the lesion, at a alfa frequency (10 Hz), which induces the desynchronization of the contralateral hemisphere with the aim of improving the visual perception of targets in the blind visual hemi-field. the study will compare this intervention to a stimulation of the frontal region (FEF) of the right hemisphere at a high-beta frequency (30 Hz), which showed effects of facilitation of endogenous and exogenous attentional orientation. The two previous strategies will be compared to a placebo tACS stimulation session.

This study is designed in two Phases. In phase 1, the Functional Outcome Measure will be tested to determine its validity and reliability in three populations, subjects that have not had a stroke and have no visual field defect, subjects that have had a stroke but do not have a visual field defect, and lastly subjects that have had a stroke and have a visual field defect. The second phase will employ an amended version of the functional outcome measure to be administered to two groups of subjects. The first group of subjects will be those subjects diagnosed with a visual field defect from retrochiasmatic insults and they will perform vision restoration therapy. The second group with a similar diagnosis to the first but who do not undergo vision restoration therapy.

This study evaluates a novel collision warning device to help people with severe vision impairment or blindness avoid collisions with obstacles. The main hypothesis to be tested is that the device reduces the number of collisions with obstacles in everyday activities.