Safety and Clinical Applicability of Transcorneal Electrical Stimulation (TES) in Geographic Atrophy (TES-GAP)

Safety and Clinical Applicability of Transcorneal Electrical Stimulation (TES) in Geographic Atrophy Under Everyday Conditions - a Multicentric, Randomized, Double-masked, Sham-controlled Pilot Study

Geographic atrophy (GA) is a progressive eye disease that causes the degeneration of the retinal cells, particularly in the macula, leading to vision loss. The goal of this pilot study is to evaluate the safety and the effectiveness of transcorneal electrical stimulation (TES) therapy with the OkuStim 2 System in patients with geographic atrophy (GA).

Researchers will compare the effects of two different electrical stimuli with a placebo to see if the stimuli are safe and can slow down the progression of the disease.

Participants will be randomly assigned to one of these three groups:

• TES-treatment with a rectangular stimulus
• TES-treatment with a repetitive ramp stimulus
• Placebo (sham) treatment

Participants will apply the therapy at home, once a week for 30 minutes each over a duration of 1 year.

Study Overview

• Status: Recruiting
• Conditions: Geographic Atrophy Secondary to Age-related Macular Degeneration
• Intervention / Treatment: Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System

Detailed Description

Geographic atrophy (GA) is a progressive eye disease that causes the degeneration of the retinal cells, particularly in the macula, leading to vision loss. Currently, there is no approved therapy specifically for GA in Europe.

The aim of this pilot study is to evaluate the safety and potential efficacy of the treatment of visual field defects in patients with GA using transcorneal electrical stimulation (TES) with the OkuStim 2 System. One of the main mechanisms for the loss of retinal cells in GA is inflammation. It is known from preclinical studies that electrical stimulation of the eye can inhibit inflammation or cellular reactions to inflammatory processes in the retina, trigger neuroprotective mechanisms and promote blood flow in the retina. The multicentric, randomized, double-masked, sham-controlled pilot study is based on the assumption that these mechanisms can maintain the functional integrity of the outer zone of the lesion area for longer.

Participants will be randomly assigned 1:1:1 to one of these three groups:

• TES-treatment with a rectangular stimulus
• TES-treatment with a repetitive ramp stimulus
• Placebo (sham) treatment

After an initial training phase, participants will apply the therapy at home, once a week for 30 minutes each over a duration of 1 year. Only one eye will be treated (study eye).

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Ruth Schippert, PhD; Phone Number: 55 +49 7121 15935; Email: studies@okuvision.de

Study Locations

• Germany
  • Hamburg, Germany, 20246
    • Not yet recruiting
    • Department of Ophthalmology, University Medical Center Hamburg-Eppendorf
  • München, Germany, 80336
    • Recruiting
    • Department of Ophthalmology, Ludwig-Maximilians-University Munich
    • Contact: Email: augenklinik.studien@med.uni-muenchen.de
    • Principal Investigator: Claudia S. Priglinger, Prof. Dr.
  • Stuttgart, Germany, 70174
    • Recruiting
    • Department of Ophthalmology, Klinikum Stuttgart
    • Principal Investigator: Florian Gekeler, Prof. Dr.
  • Tübingen, Germany, 72076
    • Recruiting
    • Centre for Ophthalmology, University Hospital Tuebingen
  • Ulm, Germany, 89075
    • Not yet recruiting
    • Department of Ophthalmology, University Hospital Ulm
    • Contact: Email: studienzentrale.augenklinik@uniklinik-ulm.de
    • Principal Investigator: Armin Wolf, Prof. Dr.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion criteria:

• Willing and able to understand the study and provide informed consent
• 60 years of age or older
• Diagnosis of geographic atrophy due to age-related macular degeneration confirmed by imaging
• The affected area in the eye must be within a defined size range and clearly visible on imaging
• Eye conditions must allow for good-quality images and reliable measurements
• Must have a minimum level of visual acuity
• Women of childbearing potential must have a negative pregnancy test, and must agree to use effective contraception during the study (women who are postmenopausal or surgically sterile are not subject to pregnancy-related requirements)

Exclusion criteria:

• History or presence of certain eye conditions (e.g. macular edema, abnormal blood vessel growth or related conditions, retinal detachment, blood vessel blockage) in the study eye
• Previous major eye surgeries (including retinal surgery or vitrectomy)
• Previous laser treatment or injections in the study eye
• Any other eye condition that could interfere with vision tests, imaging or study results
• Planned eye surgery during the study period
• Recent treatment with investigational drugs for geographic atrophy
• Presence of active medical implants
• Serious or uncontrolled systemic diseases, history of epilepsy or poor general health or conditions affecting the ability to follow study procedures
• Participation in another clinical study recently or at the same time
• Breastfeeding, relevant allergies (e.g. to silver), or heavy smoking

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: TES-treatment with a rectangular stimulus; A ramp is applied in the beginning of the stimulation to avoid that the patient is startled by the onset of stimulation: 0µA to therapy amplitude, ramping up in 30 seconds. The therapy amplitude is then maintained for 30 minutes. The stimulation parameters are: symmetric biphasic rectangular pulse (anodic at first) with a frequency of 20 Hz and a pulse duration of 10ms (5ms each phase). Stimulation will be performed once per week, for 30 minutes, for 12 months.	Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; In TES therapy with the OkuStim 2 System, retinal stimulation is achieved through transcorneal current application: using a thread electrode, the OkuEl M, a weak current (≤ 1mA) is introduced onto the surface of the eye, which spreads through the eye towards the retina.; Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; Sham-stimulation will be performed once per week, for 30 minutes, for 12 months without effective stimulation
Experimental: TES-treatment with a repetitive ramp stimulus; A ramp is applied in the beginning of the stimulation to avoid that the patient is startled by the onset of stimulation: 0µA to therapy amplitude, ramping up in 30 seconds. The therapy amplitude is then maintained for 30 minutes. The stimulation parameters are: ramp-down sawtooth current pulses (anodic first) with a frequency of 20 Hz. Stimulation will be performed once per week, for 30 minutes, for 12 months.	Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; In TES therapy with the OkuStim 2 System, retinal stimulation is achieved through transcorneal current application: using a thread electrode, the OkuEl M, a weak current (≤ 1mA) is introduced onto the surface of the eye, which spreads through the eye towards the retina.; Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; Sham-stimulation will be performed once per week, for 30 minutes, for 12 months without effective stimulation
Sham Comparator: Sham group; The stimulation in the sham-group will be carried out with 0µA. Sham-stimulation will be performed once per week, for 30 minutes, for 12 months	Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; In TES therapy with the OkuStim 2 System, retinal stimulation is achieved through transcorneal current application: using a thread electrode, the OkuEl M, a weak current (≤ 1mA) is introduced onto the surface of the eye, which spreads through the eye towards the retina.; Device: Transcorneal electrical stimulation (TES) with the OkuStim 2 System; Sham-stimulation will be performed once per week, for 30 minutes, for 12 months without effective stimulation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety of TES therapy in GA	Determined by the nature and number of device-related adverse events	From enrolment until the end of the study for the individual participant at 52 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effects of TES therapy with two different stimulus waveforms on the progression of GA lesion areas	Assessed by fundus autofluorescence (FAF) in combination with optical coherence tomography (OCT)	At 12 months and at timepoints in between (4, 17 and 34 weeks after the baseline-visit) compared to baseline
Effects of TES therapy with two different stimulus waveforms on structural changes in retinal layers	Assessed by OCT	At 12 months and at timepoints in between (4, 17 and 34 weeks after the baseline-visit) compared to baseline
Effects of TES therapy with two different stimulus waveforms on functional changes in the border zone of GA areas	Assessed by patient-tailored microperimetry (mMAIA)	At 12 months and at timepoints in between (17 and 34 weeks after the baseline-visit) compared to baseline
Effects of TES therapy with two different stimulus waveforms on visual acuity under normal luminance conditions	Assessed with ETDRS chart	At 12 months and at timepoints in between (4, 17 and 34 weeks after the baseline-visit) compared to baseline
Effects of TES therapy with two different stimulus waveforms on visual acuity under low-luminance conditions	Assessed with ETDRS chart and a neutral density filter	At 12 months and at timepoints in between (4, 17 and 34 weeks after the baseline-visit) compared to baseline
Effects of TES therapy with two different stimulus waveforms on patient-reported outcomes regarding the impact on daily life	Assessed with the Vision Impairment in Low Luminance (VILL-33) questionnaire	At 12 months compared to baseline
Effects of TES therapy with two different stimulus waveforms on patient-reported outcome regarding the applicability of the therapy under everyday conditions during home-use	Assessed with a custom-made questionnaire	At 12 months compared to baseline

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effects of TES therapy with two different stimulus waveforms on functional changes in the GA border zone, depending on position of the microperimetry stimulus points relative to the foveal center	Assessed by patient-tailored microperimetry (mMAIA)	At 12 months and at timepoints in between (17 and 34 weeks after the baseline-visit) compared to baseline

Collaborators and Investigators

• Sponsor: Okuvision GmbH
• Collaborators: Universitätsklinikum Hamburg-Eppendorf; Nubilaria Srl; CONVIDIA clinical research GmbH; TentaConsult Pharma & Med GmbH; Department of Ophthalmology, University Hospital Ulm, Germany; Department of Ophthalmology, Klinikum Stuttgart, Germany; Centre for Ophthalmology, University Hospital Tuebingen, Germany; Department of Ophthalmology, Ludwig-Maximilians-University Munich, Germany; Steinbeis-Forschungszentrum, GRADE Reading Center; Clinical Study Core Unit SZB, Studienzentrum Bonn, University Hospital Bonn, Germany
• Investigators: Principal Investigator: Florian Gekeler, Prof. Dr., Department of Ophthalmology, Klinikum Stuttgart, Germany

Study record dates

Study Major Dates

• Study Start (Actual): May 5, 2026
• Primary Completion (Estimated): June 1, 2028
• Study Completion (Estimated): June 1, 2028

Study Registration Dates

• First Submitted: March 27, 2026
• First Submitted That Met QC Criteria: April 13, 2026
• First Posted (Actual): April 15, 2026

Study Record Updates

• Last Update Posted (Actual): May 7, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: AMD; Electrical Stimulation; TES; Geographic Atrophy; Transcorneal Electrical Stimulation; TcES; OkuStim; Okuvision; OkuStim 2
• Additional Relevant MeSH Terms: Eye Diseases; Retinal Diseases; Retinal Degeneration; Macular Degeneration; Geographic Atrophy
• Other Study ID Numbers: TES-GAP

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No