Paraorbital-Occipital Alternating Current Stimulation Therapy of Patients With Post-Chiasmatic Lesions

Study Overview
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Brief Summary
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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.

Official Title
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Paraorbital-Occipital Alternating Current Stimulation Therapy of Patients With Post-Chiasmatic Lesions

Conditions
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Complete Hemianopia, Incomplete Hemianopia, Scotoma, Quadrantanopia, Stroke, Hemorrhage, Brain Trauma

Intervention / Treatment
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* Device: Verum stimulation
* Device: Placebo stimulation


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Verum stimulation<br>repetitive transorbital alternating current stimulation (rtACS) | Device: Verum stimulation<br>* 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.<br>|
| Sham Comparator: Placebo stimulation<br>compared to verum stimulation the same electrode montage set-up is used during placebo stimulation, except that placebo patients receive a minimal stimulation | Device: Placebo stimulation<br>* 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| detection accuracy (%) in visual field measures over baseline | visual stimuli detection accuracy in residual and absolutely defect visual field will be assessed using computer-based high resolution perimetry (HRP) | baseline to 8 weeks after stimulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| detection accuracy (%) in the intact visual field over baseline | visual stimuli detection accuracy in the intact visual field will be assessed using computer-based high resolution perimetry (HRP) | baseline to 8 weeks after stimulation | 
| visual acuity (LogRAD) |  | baseline to 8 weeks after stimulation | 
| EEG parameters | entrainment of stimulation frequencies (EEG power spectra) and measures of functional connectivity | baseline to 8 weeks after stimulation | 
| conventional perimetry | visual fields obtained by static and kinetic perimetry (average threshold in db, average excentricity in degrees) | baseline to 8 weeks after stimulation | 
| reaction time (ms) | average reaction time in ms, measured by computer-based high resolution perimetry (HRP) | baseline to 8 weeks after stimulation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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hemianopia, visual field defect, stroke, non-invasive brain stimulation, alternating current stimulation