Macular Ganglion Cell Analysis (GCA) of the Cirrus HD-OCT in Glaucoma

Inclusion Criteria: * Age of 40 years or older * Diagnosed to have glaucoma by the Principal Investigator or co-investigator * Able and willing to make the required study visits * Able and willing to give consent and follow study instructions Exclusion Criteria: Ophthalmic: * Best corrected visual acuity in either eye worse than 20/40 on a Snellen chart or on a Snellen equivalent acuity chart. * Refractive error outside -12.00D to +8.00D spherical range or \>-3.00D cylinder. * Previous vitreoretinal surgery in study eye. * Vitreoretinal traction or epiretinal membrane in the study eye. * Any active infection of anterior or posterior segments. * Evidence of diabetic retinopathy, diabetic macular edema, or other vitreoretinal disease in the study eye upon dilated examination, or upon evaluation of retinal photos. Systemic: * History of diabetes, leukemia, AIDS, uncontrolled systemic hypertension, dementia or multiple sclerosis. * A life threatening or debilitating disease. * Participation in any study involving a non-FDA approved investigational drug (IND) within the past month, or ongoing participation in a study with a non-FDA approved or cleared investigational device (IDE). * Current or recent (within the past 14 days) use of an agent with photosensitizing properties by any route (e.g., Visudyne®, ciprofloxacin, Bactrim®, doxycycline, etc.). * Concomitant use of hydrochloroquine and/or chloroquine.