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

University of Magdeburg32 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Enrollment

Conditions

Complete Hemianopia Incomplete Hemianopia Scotoma Quadrantanopia Stroke

Interventions

Verum stimulationDEVICE

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.

Placebo stimulationDEVICE

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 75 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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)