This is a single center, prospective study to evaluate the efficacy and reproducibility of frequency doubling technology (FDT)-based visual field devices compared to conventional Humphrey Visual Field (HVF) perimetry. The investigators plan to enroll 500 patients in this study.

Glaucoma is a leading cause of irreversible and preventable blindness world-wide. Insufficient evidence exists to support routine screening for glaucoma in a primary care setting due to the relatively low prevalence of the disease (Guirguis-Blake, 2005 and Moyer, 2013). Frequency doubling technology (FDT)-based perimetry is a relatively inexpensive and portable visual field testing device with a short testing time that has shown reasonable efficacy, sensitivity and specificity in screening for glaucoma in clinic- and community-based settings (Mansberger, 2005 and Nomoto 2009).

The aim of our study is to compare the efficacy and reproducibility of FDT perimetry platforms compared with Humphrey Visual Field (HVF) perimetry (which is the gold clinical standard in clinics and hospitals) in detecting glaucomatous visual field defects.

Inclusion Criteria:

• Adult patients (18 and over) who speak English, Spanish or Creole, and are capable of providing informed consent and who have a Humphrey Visual Field (HVF) test within the prior the 6 months preceding enrollment are eligible for enrollment in this non-invasive study. Patients will be recruited from among patients at the Bascom Palmer Eye Institute clinics during their regularly scheduled clinic visits. No advertising will be used to recruit patients.

Exclusion Criteria:

• Adults unable to consent, individuals who are not yet adults (infants, children and teenagers), pregnant women and prisoners and other vulnerable populations will be excluded from the study.