To validate a new virtual reality (VR) based visual field test against the gold standard clinical perimetry test (Humphrey Visual field test 24-2).

Perimetry (or visual field testing) is a vision test used to evaluate a patient's peripheral vision. It involves a patient fixating on a central target and pressing a button when they see a spot of light in their peripheral vision. It is an important way of deciding whether Glaucoma is progressing or not. Next generation virtual reality (VR) technologies offer an exciting new way of conducting perimetry in either a clinical or home environment, allowing more affordable and more frequent monitoring of disease progression in glaucoma, and an easier and more comfortable experience for patients. The investigators propose to create a perimetry test using a commercially available head mounted display for VR, and to assess its accuracy in glaucoma patients in relation to standard automated perimetry.

Inclusion Criteria:

- Patients with a clinical diagnosis of glaucoma with repeatable defects on standard automated perimetry.

Exclusion Criteria:

• Presence of other ocular disease which impacts vision such as age-related macular degeneration or diabetic retinopathy.
• Any physical limitation that would make the participant unable to place their head in the head-rest to perform Humphrey Perimetry (Eg some patients with arthritic or neck problems are unable to use the headrests of ophthalmic devices).
• Any cognitive impairment that would limit their ability to perform perimetry or a history of vertigo/dizziness.

Professor Azuara-Blanco will identify participants who meet the criteria from his NHS clinics at the Shankill Health and Well-being Centre. He is part of both the direct care team and also a co-investigator on this application. Opportunistic sampling will be used to ensure that different severity levels of visual field deficit will be represented within the sample. Identification of potential participants will involve reviewing their patient records.