Transcorneal Electrical Stimulation for the Treatment of Visual Field Defects in Patients With Open-Angle Glaucoma

Inclusion Criteria: 1. Willingness to participate in the study, the subjects signed and dated informed consent must be submitted before the start of the screening 2. Age ≥ 40 years 3. Primary open-angle glaucoma, pseudoexfoliation glaucoma, pigment dispersion glaucoma or normal tension glaucoma (according to the EGS criteria) in the study eye 4. Current progression in perimetry of at least 1.5 dB per year in the study eye and mean defect (MD) in the study eye between ≥ 6 and ≤ 12 dB (Octopus visual field) or ≤ -6 and ≥ -12 dB (Humphrey visual field) in the screening examination as the mean value of the two visual field examinations carried out as part of the screening (permitted deviation maximum 2 dB) 5. Visual acuity ≥ 0.2 decimal in the study eye (corresponds to a visual acuity of 0.7 logMAR) 6. The patient must master home stimulation after extensive training. 7. Ability of subject to understand the scope, significance and individual consequences of participation in the study 8. Ability of subject to give consent 9. If both eyes meet the inclusion/exclusion criteria, the eye with the higher MD is selected as the study eye. If the MD is the same in both eyes, the eye with the worse visual acuity will be selected as the study eye. If there is no difference between the eyes, the right eye will be selected as the study eye 10. Negative serum or urine pregnancy test at screening in women of childbearing potential. Participants are considered to be of nonchildbearing potential if they are postmenopausal and have not menstruated for at least 12 months prior to screening or if they are surgically sterile 11. Women of childbearing potential must agree to be abstinent or to use highly effective methods of contraception that result in a failure rate of less than 1% per year. This applies consistently throughout the duration of the treatment once you have given your consent to participate in the study. Exclusion Criteria: 1. Neovascularisations of any origin in the study eye 2. Condition after arterial or venous occlusions in the study eye 3. Condition after intraocular surgery in the last 3 months before the screening examination in the study eye 4. Acute (intra)ocular inflammation in any eye 5. Non-proliferative or proliferative diabetic retinopathy in the study eye 6. Condition after retinal detachment in the study eye 7. Dry age-related macular degeneration affecting the visual field in the study eye 8. Exsudative age-related macular degeneration in the study eye 9. Macular edema of any origin in the study eye 10. Other relevant retinal diseases in the study eye 11. Any form of corneal degeneration that limits vision in the study eye 12. Any disease other than glaucoma affecting the central 30° visual field in the study eye 13. No cataract surgery or other eye surgery may be planned for the patient in the study eye during the duration of the study (except laser trabeculoplasty) 14. Patients with active implants 15. General illnesses that are difficult to control/adjust and which, in the opinion of the investigator, could jeopardize regular study routines 16. Poor general condition according to the investigators assessment 17. Mental illness or dementia, that, in the opinion of the investigator, reduces the understanding of the study procedures and use of the Okustim 2 System 18. Simultaneous participation in another interventional study or past interventions whose effect may still be ongoing (30 days) 19. Breastfeeding women 20. Patients unable to consent 21. Previous enrolment in the TES-GPS study 22. Contraindications to the use of OkuStim 2 such as allergies/hypersensitivity to silver