Paraorbital-Occipital Alternating Current Stimulation Therapy for Optic Neuropathy (MCT_optnerve)

Study Overview
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Brief Summary
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Aim is to validate that non-invasive brain stimulation can increase cortical excitability in the visual system. The investigators assess if transcranial alternating current stimulation (tACS) can improve visual field size in patients with optic nerve damage. Hypothesis: tACS would improve visual functions within the defective visual field (primary outcome measure).

Detailed Description
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In addition, the correlation between the brain-derived neurotrophic factor (BDNF) or other plasticity markers are correlated to the improvement of the visual field after stimulation.

Official Title
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Multicenter Study of Paraorbital-Occipital Alternating Current Stimulation Therapy in Patients With Optic Neuropathy

Conditions
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Optic Nerve Diseases, Optic Nerve Injuries, Optic Neuropathies

Intervention / Treatment
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* Device: tACS
* Device: Sham stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients with optic nerve lesion stable visual field defect with residual vision lesion age at least 6 months age at least 18 years no completely blindness, residual vision still existent Exclusion Criteria: electric or electronic implants, e.g. heart pacemaker any metal artefacts in head and truncus epilepsy auto-immune diseases in acute stage mental diseases, e.g. schizophrenia etc. unstable diabetes, diabetes causing diabetic retinopathy addiction high blood pressure (max. 160/100 mmHg) instable or high level of intraocular pressure (i.e. > 27 mmHg) retinitis pigmentosa pathological nystagmus presence of an un-operated tumor anywhere in the body pregnant or breast-feeding women photo sensibility Fundus hypertonicus acute conjunctivitis

Ages Eligible for Study
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Minimum Age: 18 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Verum stimulation<br>Complete treatment with transorbital alternating current stimulation (tACS) | Device: tACS<br>* Transorbital alternating current stimulation (tACS) is applied with a multi-channel device with paraorbital montage of 4 stimulation electrodes generating weak current pulses in predetermined firing bursts of 8 to 14 pulses. The amplitude of each current pulse was below 1000 microA. Current intensity was individually adjusted according to how well patients perceived phosphenes, i.e. any sensation of flickering light in response to the rtACS stimulation.<br>|
| Sham Comparator: Sham stimulation<br>Same electrode montage set-up is used during tACS- and placebo-stimulation. Sham stimulation condition consists of minimal treatment with low intensity/few impulses tACS. | Device: Sham stimulation<br>* tACS is applied with the same device with equal electrodes set-up procedures but only one of four channels actually delivers current. The current intensity of this channel is individually adjusted (preselected on the side of lesioned eye) according with patient able to clearly perceive single phosphenes or any skin irritation phenomena (like weak sense of needles or vibration) whenever a single pulse is applied. The amplitude of pulses is always below 1000 microA. Current pulses are given as 1 pulse per minute during 25-35 min of session time. Session duration is equal for verum and sham patients. The perception of the single pulses leaves sham patients at the impression that they might receive the verum intervention, but total number of pulses is less than 0,5% of verum tACS.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Detection accuracy (DA) change in percent over baseline within defective visual field | Central visual fields assessed with computer-based high-resolution perimetry (HRP). Based on such plots, areas of the visual field are characterized as intact, partially damaged or absolutely impaired (blind). Detection accuracy (DA) change in percent above baseline within defective visual field sectors is defined as the primary outcome criterion. | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| DA change in percent over baseline regarding the damage region of the tested visual field (computer-based high-resolution perimetry) | This parameter includes also intact sectors that are tested with HRP. It is hypothesized that improvements of the primary outcome criterion will outweigh the relative change in intact sectors as measured with HRP. | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 
| EEG parameters | EEG power spectra | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 
| Reaction time change in ms | Reaction time (RT) in HRP | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 
| Visual acuity (VA) |  | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 
| DA in static and kinetic conventional perimetry |  | Baseline - 8 weeks after stimulation; First follow-up 2 days after treatment course; Second follow-up 8 weeks after treatment course | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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optic neuropathy, visual field, electric stimulation, alternating current, perimetry