Plain English Summary
Background and study aims
Retinitis pigmentosa (RP) is a progressive degenerative eye disease that affects the retina, which often leads to blindness. 1 in 4000 people in the UK is affected by RP yet there is no established therapy for treating or delaying its progression.Transcorneal electrical stimulation (TES) has gained attention as a possible treatment option for RP. Research has shown that TES improves retinal cell viability and visual function. An initial small study of TES on 24 participants with RP demonstrated that it was safe and improved vision. This study aims to confirm the safety of the new CE-approved Okustim device and to further study the benefits of TES on a larger scale.
Who can participate?
Patients aged 18 and over with retinitis pigmentosa (diagnosed by an ophthalmologist). Participants, or a carer, should have sufficient motor skills to attach the device themselves. As this study seeks to ascertain the impact of TES on RP, participants with other eye diseases (e.g. diabetic retinopathy) cannot be included in the study.
What does the study involve?
All 12 recruited participants undergo weekly TES of one eye for 30 minutes for a period of 6 months. This is followed by a further 6 months of observation without stimulation giving a total participation time of 1 year. Participants are assessed at 3, 6, 9 and 12 months after their first visit with clinical examinations, investigations and questionnaires.
What are the possible benefits and risks of participating?
TES has been shown to improve the visual fields. TES may improve the sharpness of vision. TES will be delivered by the CE-marked Okustim device. Previous studies have demonstrated TES to be a low risk treatment. Some patients may experience irritation of the eye or a dry eye, which can be treated with artificial tears. Some participants have reported a 'prickly' sensation when the stimulation is applied.
When is the study starting and how long is it expected to run for?
April 2013 to April 2015
Where is the study run from?
1. The Oxford Eye Hospital (UK)
2. London Moorfields Eye Hospital (UK)
Who is funding the study?
Biomedical Research Centre Oxford and Okuvision GmbH
Who is the main contact?
Prof. Robert Maclaren
Dr Siegfried Wagner
John Radcliffe Hospital
Dept of Clinical Neurology
Transcorneal electrical stimulation for the treatment of retinitis pigmentosa: a multicentre safety study of the Okustim® system
Retinitis pigmentosa (RP) is a progressive degenerative disease of the retina, which often leads to blindness. 1 in 4000 people in the UK are affected by RP yet there is no established therapy for treating or delaying its progression. Transcorneal electrical stimulation (TES) has garnered attention as a possible therapeutic option for RP. Research has shown that TES improves retinal cell viability and visual function. An initial pilot study of TES on 24 participants with RP demonstrated that it was safe and improved vision.
This study aims to confirm the safety of the new CE-approved Okustim® device and to further characterise the benefits of TES on a larger scale.
South West Research Ethics Committee, First MREC approval date 27/11/2012, ref: 12/SW/0293
Non-randomised interventional treatment trial
Primary study design
Secondary study design
Non randomised study
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
Recruited participants will undergo weekly TES of 1 eye delivered by the CE-marked Okustim® device for 30 minutes for a period of 6 months. This will be followed by a further 6 months of observation without stimulation giving a total participation time of 1 year. Participants will be assessed at 3, 6, 9 and 12 months after their initial baseline visit by clinical examination, investigations and questionnaires.
Primary outcome measure
Adverse events measured at 3, 6, 9 and 12 months after commencing the trial
Secondary outcome measures
1. Application of Device; Timepoints: Two questionnaires detailing the participant's experience and opinion of the usability of the device
2. Efficacy of Intervention; Timepoints: Best corrected visual acuity, visual field assessment, microperimetry, fundus photography, and Optical coherence tomography (OCT)
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Male or female participants of 18 years of age or more
2. Participants with retinitis pigmentosa (diagnosed by an ophthalmologist)
3. Adult participants who have capacity
4. Visual acuity greater or equal to 0.02
5. Participants, their caregiver or a family member should have adequate motor skills to apply electrodes
6. Participants must be able to give consent and undertake a medical evaluation to assess whether they can participate in the whole study according to the protocol
7. Participant willing to allow their GP and consultant, if appropriate, to be notified of participation in the study.
Target number of participants
UK Sample Size: 12
Total final enrolment
Participant exclusion criteria
1. Diabetic retinopathy
2. Neovascularisation of any origin
3. Previous arterial or venous occlusion
4. Previous retinal detachment
5. Silicone oil tamponade
6. Dry or exudative age-related macular degeneration
7. Macular oedema
8. Any form of glaucoma
9. Any form of corneal disease, which impairs visual acuity
10. Systemic disease, which may be difficult to control or manage, and may affect normal study schedule
11. Mental Illness related to bipolar affective disorders, schizoid-affective disorders and all forms of dementia
12. Simultaneous participation in another interventional study or previous interventions, where effects may still persist
13. Female participants who are pregnant, lactating or planning pregnancy during the course of the study
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Oxford Eye Hospital
Trial participating centre
London Moorfields Eye Hospital
University of Oxford (UK)
Clinical Trials and Research Governance
BioMedical Research Centre, Oxford (UK) Grant Codes: RWAC0
Funding Body Type
Funding Body Subtype
Okuvision GmbH (Germany)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Interim study results were presented at the Annual Association of Research and Vision in Ophthalmology Meeting 2014 in Orlando, USA. The final study results were presented at the Annual Association of Research and Vision in Ophthalmology Meeting 2016 in Seattle, USA. A publication is currently in the processing stage.
IPD sharing statement
The datasets generated and/or analysed during the current study will be included in the subsequent results publication.
Intention to publish date
Participant level data
Basic results (scientific)
2017 results in: https://www.ncbi.nlm.nih.gov/pubmed/29354722 (added 21/08/2019)