Transcorneal electrical stimulation for the treatment of visual field defects in patients with open-angle glaucoma: a monocentric, randomised, double-masked, sham-controlled pilot study: the TES-GPS study protocol.

introductionGlaucoma is one of the leading causes of irreversible blindness and is characterised by progressive loss of retinal ganglion cells. While therapies to lower intraocular pressure slow the progression of the disease in most patients, a significant subset still shows progression despite treatment. Transcorneal electrical stimulation (TES) may potentially activate neuroprotective pathways and slow the progression of visual field defects. The OkuStim 2 System is a medical device for TES which was originally developed for the treatment of retinitis pigmentosa and similar retinal dystrophies and shall now be tested for the treatment of glaucoma. Stimulation of the diseased retina with weak currents can activate signalling pathways and the release of substances that have a protective effect on the retinal cells. This neuroprotective effect might preserve physiological functions of the retina for longer and slow down its gradual degeneration. Long-term use is required to maintain this effect. The TES-GPS study is investigating the safety and efficacy of TES in open-angle glaucoma. METHODS AND ANALYSIS: TES-GPS (short title for glaucoma pilot study) is a prospective, randomised, double-blind, sham-controlled, single-centre pilot study at the University Medical Center Mainz. 50 patients with progressive visual field loss due to open-angle glaucoma will be randomised 1:1 to receive either TES with the OkuStim 2 System or sham stimulation. The primary endpoint is the change in visual field sensitivity (Humphrey mean deviation) after 18 months. Secondary endpoints include changes in visual acuity, intraocular pressure, optical coherence tomography (OCT) parameters and quality of life (National Eye Institute Visual Function Questionnaire 25, NEI-VFQ 25). The intervention consists of weekly 30 min TES sessions, which are conducted in the patient's home after initial training in the clinic. The study comprises up to 13 scheduled visits over 18 months. ETHICS AND DISSEMINATION: The study is conducted in accordance with ISO14155, Medical Device Regulation (EU) 2017/745, International Council for Harmonisation Good Clinical Practice and the Declaration of Helsinki. Approval was obtained from the Ethics Committee of the Landesaerztekammer Rheinland-Pfalz in Mainz and from Bundesinstitut fuer Arzneimittel und Medizinprodukte. Results will be published in peer-reviewed journals and presented at scientific conferences. TRIAL REGISTRATION NUMBER: NCT06682962.