title: Restoration of vision after optic nerve lesions with noninvasive transorbital alternating current stimulation: a clinical observational study.
abstract: BACKGROUND
  Non-invasive current stimulation can induce neuroplastic changes in the normal brain, including visual system structures. Because it is not known if such plasticity is of clinical value, we wished to learn if vision restoration can be induced after optic nerve damage.
  
  
  METHODS
  In an open-label, clinical observational study 446 patients with optic nerve lesions were treated with non-invasive repetitive transorbital alternating current stimulation (rtACS). Current bursts (<1000 μA, 5-20 Hz) were applied to induce phosphenes for one or two 10-day stimulation periods. Efficacy was assessed by monocular measurements of visual acuity and visual field (VF) size. EEG recordings at rest (n = 68) were made before and after treatment and global power spectra changes were analyzed.
  
  
  RESULTS
  rtACS improved VF size in the right and left eye by 7.1% and 9.3% (p < 0.001), respectively. VF enlargements were present in 40.4% of right and 49.5% of left eyes. Visual acuity (VA) significantly increased in both eyes (right = 0.02, left = 0.015; p < 0.001). A second 10-day course was conducted 6 months in a subset of 62 patients and resulted in additional significant improvements of VA. Analysis of EEG power spectra revealed that VA and VF improvements were associated with increased alpha power. Increased theta power was observed in patients that had only VF enlargements but no VA change. In contrast, non-responders had increased delta power spectra in frontal and occipital areas.
  
  
  CONCLUSIONS
  rtACS leads to long-lasting improvements in VA and VF size and after-effects in EEG power spectra. Because physiological and clinical parameters are correlated we hypothesize that rtACS enhances plasticity by inducing synchronization in different cortical regions, but the precise mechanisms needs further clarification. These encouraging results require confirmation by controlled clinical trials.
authors: Polenov Russian Neurosurgical Institute, Saint-Petersburg, Russia. imp@med.ovgu.de
authors: A
authors: A
authors: Fedorov
authors: S
authors: S
authors: Jobke
authors: V
authors: V
authors: Bersnev
authors: A
authors: A
authors: Chibisova
authors: Y
authors: Y
authors: Chibisova
authors: C
authors: C
authors: Gall
authors: B A
authors: BA
authors: Sabel
mesh_terms: D000328:Adult; D000368:Aged; D004599:Electric Stimulation Therapy / Q000379:methods*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019370:Observation; D009901:Optic Nerve Diseases / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D009915:Orbit / Q000502:physiology* / Q000528:radiation effects; D012189:Retrospective Studies; D016896:Treatment Outcome; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology* / Q000528:radiation effects; D055815:Young Adult