Results of Clinical Investigations

Transcorneal Electrical Stimulation: A Therapy Option for Retinitis Pigmentosa

There is no therapy for retinitis pigmentosa (RP) that can halt or even reverse the progressive reduction in visual field [1]. In Germany alone there are about 20,000 patients with the diagnosis RP. Transcorneal electrical stimulation (TES) can help to slow down the progression of RP. The safety of the TES therapy with the OkuStim System has been demonstrated in extensive clinical trials involving more than 200 patients (see chart).

 

Basis of the therapy
Electrical stimulation with weak currents can activate signalling pathways and the release of substances in the diseased retina that have a protective effect on retinal cells [2]. This neuroprotective effect can maintain physiological functions in the retina for longer and slow down the retinal degeneration.

Application
In TES therapy, retinal stimulation is achieved by transcorneal applicationof a weak current (< 1mA) to the surface of the eye, which spreads in towards the retina. The current is applied by a thread electrode. The OkuStim application is designed for independent home-use by the patient, after introduction by trained medical staff. The treatment is performed once a week for 30 minutes. Six-monthly follow-ups at the ophthalmologist are expressly recommended.

Clinical investigations
A recent study conducted in Basel has shown that TES triggers physiological processes in the retina of RP patients [3]. After stimulation, an increased oxygen consumption in the retina was measured, which proves an increased cell activity. This supports the results of the studies carried out at the University Eye Hospital in Tübingen. In the pilot study EST I it was shown that TES can slow down the reduction in visual field loss [4]. The follow-up study EST II showed significantly increased retinal cell activity [5]. The safety of the application of the OkuStim system was clearly demonstrated in all clinical trials, including a multicentre observational study in 11 European clinics (TESOLA) [6, 7].
The highest decision-making body in the German health care system, the Federal Joint Committee (Gemeinsamer Bundesausschuss, G-BA), has attributed to TES therapy a potential for relevant benefit for patients with RP and issued a guideline for conducting a clinical trial [8].
The investigation is expected to start at the end of 2020.

 

 

A diagram with an overview of run-times and participants in clinical investigations
Clinical investigations into the use of transcorneal electrical stimulation (TES) with the OkuStim System in retinitis pigmentosa (RP). Left axis: name and duration of the studies, lower axis: duration of the studies (stimulation followed by observation period); right: number of patients participating in the studies.

Patient care and support
On the basis of the data obtained so far, the TES therapy is classified as safe by the Arbeitskreis Klinische Fragen (AKF) of PRO RETINA e.V., so that it can also be used outside the context of studies in RP patients. Furthermore, there are no objections to the use of the treatment in other generalised hereditary retinal dystrophies (cone and rod dystrophies, choroideremia, Usher syndrome, etc.) [9]. The OkuStim system is only available on prescription.
Detailed informationen on the international availabiliy of the therapy you can finde here.

 

You can download this information about clinical investigations in PDF format here: german / english


References

  1. Wang, A.L., et al., Retinitis Pigmentosa: Review of Current Treatment. International Ophthalmology Clinics, 2019. 59(1): p. 263-280.
  2. Pardue, M.T. and R.S. Allen, Neuroprotective strategies for retinal disease. Prog Retin Eye Res, 2018. 65: p. 50-76.
  3. Della Volpe-Waizel, M., et al., Metabolic monitoring of transcorneal electrical stimulation in retinitis pigmentosa. Graefes Arch Clin Exp Ophthalmol, 2019.
  4. Schatz, A., et al., Transcorneal electrical stimulation for patients with retinitis pigmentosa: a prospective, randomized, sham-controlled exploratory study. Invest Ophthalmol Vis Sci,2011. 52(7): p. 4485-96.
  5. Schatz, A., et al., Transcorneal Electrical Stimulation for Patients With Retinitis Pigmentosa: A Prospective, Randomized, Sham-Controlled Follow-up Study Over 1 Year. Invest Ophthalmol Vis Sci, 2017. 58(1): p. 257-269.
  6. Jolly, J.K., et al., Transcorneal Electrical Stimulation for the Treatment of Retinitis Pigmentosa: A Multicenter Safety Study of the OkuStim® System (TESOLA-Study). Ophthalmic Research, 2019.
  7. Wagner, S.K., et al., Transcorneal electrical stimulation for the treatment of retinitis pigmentosa: results from the TESOLAUK trial. BMJ Open Ophthalmol, 2017. 2(1): p.e000096.
  8. G-BA. Erprobungs-Richtlinie Transkorneale Elektrostimulation bei Retinopathia Pigmentosa. 2017; Available from: www.g-ba.de/richtlinien/99/
  9. PRO-RETINA e.V. Bewertung zur Elektrostimulation am Auge bei Patienten mit retinalen Dystrophien mit Hilfe des Okustim-Gerätes der Firma Okuvision GmbH. 2014 16.06.2018; Available from: https://www.pro-retina.de/forschungsfoerderung/wissenschaftliche-beratungsgremien/empfehlungen/bewertung-zur-elektrostimulation-am-auge