Efficacy of Nicotinamide on Retinal Ganglion Cell Functions in Glaucoma Patients

Inclusion Criteria: 1. Adult(Male or Female) over 19 years who were diagnosed with glaucoma. 2. In the case of participants receiving glaucoma treatment drugs, the investigator judges that the intraocular pressure remains constant for at least 1 year. 3. Intraocular pressure (IOP) \>/= 8mmHg and \< 18mmHg in each eye using Goldmann applanation tonometry prior to the screening visit 4. Adult participants diagnosed and treated for early-moderate glaucoma (VF mean deviation(MD) ≥-12 dB) 5. Have performed a reliable visual field in the last year, with \<33% fixation losses, false positives and false negatives. 6. Written consent voluntarily to participate in this clinical trial. Exclusion Criteria: 1. Patients with congenital glaucoma and secondary glaucoma caused by steroid drugs, etc. 2. BCVA (best-corrected visual acuity) Snellen equivalent of Snellen 20/80(logMar 0.25) or less. 3. Patients who have medical history of ocular inflammation 4. Patients with any ocular/systemic conditions that may affect electroretinogram parameter, or with visual field defects(Ischemic optic neuropathy, Proliferative diabetic retinopathy, Macular degeneration etc.) 5. Patients who have plans to intraocular surgery within the clinical trial period. 6. Patients with a history of significant ocular trauma within 6 months prior to the screening visit 7. Pregnant or lactating women. 8. A person who disagrees to contraception during a clinical trial period. 9. Patients with a history of malignancy within 5 years prior to the screening visit. 10. Patients that other researchers are determined inadequately.