Study of Application of Pulse Electrical Stimulation Around Eye in Glaucoma Patients

Inclusion Criteria: * Participants must be 19 to 75 years of age, at the time of screening * Patients with normal tension glaucoma or open angle glaucoma * Patients with best-corrected visual acuity of 20/40 or more * Patients whose Mean Deviation(MD) value of visual field test is -6dB or less * Patients who have stable eye pressure of less than 20mmHg over the past 2 months * If glaucoma treatment is in progress, the type, dose, and form of drug for treatment are stable for more than 2 months * A person who has no pregnancy plan during the clinical trial period and has agreed to an effective contraceptive plan for WOCBP(Women of child bearing potential) * WONCBP(Women of non-child bearing potential) must meet at least one of the following criteria: 1. Postmenopausal women who are at least 45 years old and had no menses for 24 consecutive months 2. A woman who underwent hysterectomy of bilateral ovarian resection recorded by a doctor * All other female patients will be considered WOCBP. * A person who voluntarily agreed to participate in this clinical trial Exclusion Criteria: * Ophthalmological and neurological diseases that can affect visual field test(e.g., optic neuritis, diabetic retinopathy, age-related macular degeneration, and the epiretinal membrane) * A person with a history of surgery related to eyeball excluding simple cataract surgery or orbital surgery such as orbital fracture * Those who have more than -6D of refractive errors * Those who have cataracts of ETDRS(Early Treatment Diabetic Retinopathy Study) grade 3 or higher * Those who have a history of trauma around the eyeball, such as an orbital fracture, etc., * Patients with active malignancy or history of malignancy, except completely treated in situ carcinoma of the cervix, completely treated and resected non-metastatic squamous of basal cell carcinoma of the skin. * A person who recently(within 1 month before the clinical trial medical device is applied) suffered severe trauma or underwent major surgery * Pregnant or lactating women * Any other severe acute or chronic medical or psychological conditions * Those who can't understand or read the consent form of this clinical trial(e.g. illiterate or foreigners) * Any other cases that PI considers hard to participate in this clinical trial(e.g. heart-related problems, seizure, epilepsy. Patients transplanted metal or electronic device in head \& neck. Patient suffering from unknown pain. Patients who are warned not to use out clinical trial device or is prohibited from using it.) * In the case of participating in other clinical trials within 6 months prior to the time of obtaining the consent form * Subjects who are not suitable for the clinical trial, are likely to be in danger when participate in the study or interfere with the interpretation of the trial results. * Brain and neck implant or pacemaker including deep brain stimulation device. Implantable or wearable cardioverter defibrillator. (Dental implants are accepted.)