Complete Hemianopia, Incomplete Hemianopia, Scotoma, Quadrantanopia, Stroke, Hemorrhage, Brain Trauma
Conditions
Keywords
hemianopia, visual field defect, stroke, non-invasive brain stimulation, alternating current stimulation
Brief summary
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.
Interventions
DEVICEVerum stimulation
10 days (2x 5 working days), daily transorbital alternating current stimulation (rtACS) is applied with a device generating weak current pulses in predetermined firing bursts of 2 to 9 pulses. The amplitude of each current pulse is below 1000 µA. Current intensity is individually adjusted according to how well patients perceived phosphenes, e.g. any sensation of flickering light in response to the rtACS stimulation. Stimulation frequencies were between the individual alpha frequency peak and below flicker fusion.
DEVICEPlacebo stimulation
10 days (2x 5 working days), daily sham-stimulation with the same electrode montage set-up that is used for verum transorbital alternating current stimulation (rtACS). Minimal sham-stimulation was performed with single bursts (approx. one per min) of electrical currents at a given frequency of 5Hz and individually adjusted current amplitude.
Sponsors
EBS Technologies GmbH
University of Magdeburg
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* lesion of the tractus opticus or of the visual cortex * lesion age \> 6 months * stable visual field defect with residual vision
Exclusion criteria
* electric or electronic implants, e.g. heart pacer * any metal artefacts in the head * Epilepsy * Auto-immune diseases in acute stage * mental diseases, e.g. schizophrenia etc. * diabetic retinopathy * addictive diseases * blood pressure above 160/100 mmHg * instable or high level of intraocular pressure above 27 mmHg * retinitis pigmentosa * pathological nystagmus * presence of an un-operated tumor or tumor relapse (patients with non-progressive tumor are eligible if study participation is recommended by medical authorities) * focal findings in EEG or photosensitivity (patients with single seizure more than 10 yrs ago may participate) * recurrent transitional ischemic attacks after stroke * arteriosclerosis of large blood vessels with stenosis \>75% * severe coronary heart disease (CHD) * unstable angina pectoris * diabetes with blood glucose level \> 9 mmol/l * myocard infarct/ cardiomyopathy * ventricular fibrillation * risk of vascular thrombosis * pregnant or breast-feeding women
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| detection accuracy (%) in visual field measures over baseline | baseline to 8 weeks after stimulation | visual stimuli detection accuracy in residual and absolutely defect visual field will be assessed using computer-based high resolution perimetry (HRP) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| detection accuracy (%) in the intact visual field over baseline | baseline to 8 weeks after stimulation | visual stimuli detection accuracy in the intact visual field will be assessed using computer-based high resolution perimetry (HRP) |
| visual acuity (LogRAD) | baseline to 8 weeks after stimulation | — |
| EEG parameters | baseline to 8 weeks after stimulation | entrainment of stimulation frequencies (EEG power spectra) and measures of functional connectivity |
| conventional perimetry | baseline to 8 weeks after stimulation | visual fields obtained by static and kinetic perimetry (average threshold in db, average excentricity in degrees) |
| reaction time (ms) | baseline to 8 weeks after stimulation | average reaction time in ms, measured by computer-based high resolution perimetry (HRP) |
Countries
Germany
Outcome results
None listed