title: Transcorneal electrical stimulation for patients with retinitis pigmentosa: a prospective, randomized, sham-controlled exploratory study.
abstract: OBJECTIVE
  To assess the safety of transcorneal electrical stimulation (TES) and explore its efficacy in various subjective and objective parameters of visual function in patients with retinitis pigmentosa (RP).
  
  
  METHODS
  Twenty-four patients in this prospective, randomized, partially blinded, good-clinical-practice study underwent TES (5-ms biphasic pulses; 20 Hz; DTL electrodes) 30 minutes per week for 6 consecutive weeks. The patients were randomly assigned to one of three groups: sham, 66%, or 150% of individual electrical phosphene threshold (EPT). Visual acuity (VA), visual field (VF; kinetic, static), electroretinography (Ganzfeld, multifocal), dark-adaptation (DA), color discrimination, and EPTs were assessed at all visits or four times, according to the study plan.
  
  
  RESULTS
  TES using DTL electrodes was tolerated well; all patients finished the study. Two adverse (foreign body sensation), but no serious adverse events were encountered. There was a tendency for most functional parameters to improve (8/18) or to remain constant (8/18) in the 150% group. VF area and scotopic b-wave amplitude reached statistical significance (P < 0.027 and P < 0.001, respectively). Only desaturated color discrimination and VF mean sensitivity decreased. There was no obvious trend in the 66% group.
  
  
  CONCLUSIONS
  TES was found to be safe in RP patients. Positive trends were discovered, but due to the small sample size of this exploratory study, statistical significance was reached only for VF area and scotopic b-wave amplitude. Further studies with larger sample sizes and longer duration are needed to confirm the findings and to define optimal stimulation parameters. (ClinicalTrials.gov number, NCT00804102.).
authors.affiliation: Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schatz
authors.forename: Tobias
authors.initials: T
authors.lastname: Röck
authors.forename: Lubka
authors.initials: L
authors.lastname: Naycheva
authors.forename: Gabriel
authors.initials: G
authors.lastname: Willmann
authors.forename: Barbara
authors.initials: B
authors.lastname: Wilhelm
authors.forename: Tobias
authors.initials: T
authors.lastname: Peters
authors.forename: Karl Ulrich
authors.initials: KU
authors.lastname: Bartz-Schmidt
authors.forename: Eberhart
authors.initials: E
authors.lastname: Zrenner
authors.forename: André
authors.initials: A
authors.lastname: Messias
authors.forename: Florian
authors.initials: F
authors.lastname: Gekeler
mesh_terms: D003118:Color Perception; D003315:Cornea; D004599:Electric Stimulation Therapy / Q000379:methods*; D004596:Electroretinography; D005500:Follow-Up Studies; D006801:Humans; D011446:Prospective Studies; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D016037:Single-Blind Method; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome; D014792:Visual Acuity; D014794:Visual Fields