New evidence of efficacy of transcorneal electrical stimulation (TES)

The recent analysis of an earlier clinical study has established final proof for the efficacy of the OkuStim therapy. The data show that this therapeutic approach – developed in Germany – significantly slows down visual field progression in RP.

A number of therapies have been tried in retinitis pigmentosa in the past. Currently, the focus of research is on gene therapy and stem cell therapy, although these options are not yet ripe for clinical routine management. Gene therapy in particular typically requires an invasive intervention with a high potential for adverse events.
By contrast, the non-invasive electrical stimulation therapy (OkuStim®), developed by Okuvision, a medical device company based in Reutlingen, Germany, has been used in 52 patients vs. placebo in the study. During TES, an electrode is placed on the lower lid and has contact with the eyeball at the inferior corneal limbus. Treatment with electrical impulses of max. 1 mA and 20 Hz takes 30 minutes, is performed once a week and can be applied by the patients themselves at home after a short instruction and training by their physician.

Of the patients (average age: 46 years) enrolled in the study, 32 individuals received weekly electrical stimulation between 0.1 and 1.0 mA on one eye; 20 patients received sham treatment (placebo group). Following a year of treatment, the eyes that had undergone TES displayed a visual field loss of 2.1% while their untreated contralateral eyes had an average visual field progression of 5.8%. In the placebo group, however, the annual decline was 7.5%. Thus, the decrease in visual field area measured by kinetic perimetry was a remarkable 64% less in the eyes treated with TES than in the untreated eyes (p=0.013) and 72% less than in the placebo group (p=0.103). Slowing the progression was dose-dependent on the extent of the stimulation. In 23 of the treated eyes, dry eye symptoms were noticed as the most frequent ocular adverse event.

Decelerating this progression, this is the study authors’ conclusion, offers the chance to significantly delay severe visual loss and disability. The exact mechanism of action of TES has not yet been fully understood. Experts suggest a neuroprotective effect independent of the genetic cause of RP – an effect that should be put to use in patients as early as possible and at a disease stage before visual function is compromised.

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