Inclusion Criteria:  Previous visual field test with Humphrey Field Analyzer indicating normal field, early glaucomatous field damage, moderate glaucomatous field damage, or advanced glaucomatous field damage. Ability to understand and consent to the study.  Exclusion Criteria:  Diagnosis of secondary glaucoma Diagnosis of non-glaucomatous optic neuropathy or other significant ophthalmic diagnosis that could limit vision (ex. age-related macular degeneration) Significant media opacity Previous intraocular surgery other than cataract surgery Anxiety disorder Pregnancy Seizure disorder Cardiac pacemaker or other implantable devices Severe vertigo or balance disturbance Refractive error greater than +4 diopters and less than -6 diopters spherical equivalent Inability to demonstrate competence to make informed decision regarding study participation