Transcorneal Electrostimulation for Therapy of Retinitis Pigmentosa

Not Applicable

Completed

Brief Summary: The purpose of this study is to determine the long-term effects of transcorneal electrostimulation (TcES) in patients with retinitis pigmentosa (RP). In a prior study (NCT00804102) the results of short-term stimulation showed a positive effect on the visual field and other parameters. In this study, the patients will be stimulated with either 0%, 150% or 200% of the individually determined phosphene threshold.

Detailed Description: The study was performed at the Centre for Ophthalmology, University of Tübingen, Germany. The protocol was approved by the local ethics committee. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008. Informed consent was obtained from all patients for being included in the study. The study was conducted according to the standards of GCP, the European Union Directive for Medical Devices, and the German Medical Product Law.

Patients were seen at 14 visits over a period of 78 weeks: one baseline visit (screening), followed by 12 visits (in week 1-4 weekly, then in weeks 10, 16, 22, 28, 34, 40, 46 and 52; dates varied a maximum of ± 1 week) including application of TcES for 52 weeks and one follow-up visit (in week 78, dates varied a maximum of ± 1 week).

After inclusion patients were randomly assigned to TcES with 0 mA (sham), 150% or 200% of their individual electrical phosphene threshold (EPT) current at 20 Hz.

Patients and technicians who performed kinetic perimetry, as well as full-field electrophysiology (ERG), multifocal ERG (mfERG) and dark adaptation, were blinded to the treatment group for the entire study period. The physicians who performed all other examinations and TcES were not blinded to study treatment because they were responsible for setting the stimulation parameters.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Diabetic retinopathy
Neovascularisation of any origin
After arterial or venous occlusion
After retinal detachment
Silicone oil tamponade
Dry or exudative age-related macular degeneration
Macular edema
All forms of glaucoma
Any form of corneal degeneration that reduces visual acuity
Systemic diseases that are difficult to control or manage, that could endanger the normal study schedule
Patients in a permanently poor general condition, which could hinder the regular attendance at control examinations in the clinic
Forms of mental illness related to the bipolar affective and schizoid-affective disorders, and all forms of dementia
Simultaneous participation in another interventional study or history of interventions whose effect may still persist

Arm && Interventions

Group	Intervention	Description
Sham	Transcorneal electrostimulation	OkuStim is used to determine the phosphene threshold, device is turned on but no stimulation is performed.
150%	Transcorneal electrostimulation	OkuStim is used to determine the phosphene threshold, and then to administer transcorneal electrostimulation with a stimulation strength corresponding to 150% of the patient's phosphene threshold.
200%	Transcorneal electrostimulation	OkuStim is used to determine the phosphene threshold, and then to administer transcorneal electrostimulation with a stimulation strength corresponding to 200% of the patient's phosphene threshold.

Primary Outcome Measures

Name	Time	Method
Visual Field, III4e	one year	Change in the area measured by kinetic visual field measurement
Visual Field, V4e	one year	Change in the area measured by kinetic visual field measurement

Secondary Outcome Measures

Name	Time	Method
ERG A-wave	one year
ERG B-wave	one year
VFQ-25	one year	Visual Function Questionnaire (VFQ-25)
Dark Adaptation	one year	Adaptation time, changes in pupil diameter, threshold to fullfield blue and red light is measured with a fullfield stimulus threshold test (FST) on the ESPION ERG machine (Diagnosys).
BCVA	one year	Best corrected visual acuity