Caffeine Consumption in Glaucoma Patients and Healthy Subjects

Inclusion Criteria:

* age 18 to 90 years
* diagnosis of primary open angle glaucoma (Mild, Moderate and Advanced)
* healthy subjects with no eye disease

Exclusion Criteria:

* Diseases, ophthalmic or systemic, that are likely to affect OCTA results
* greater than moderate cataract
* nystagmus
* inability to look at target
* macular degeneration other than mild drusen or pigmentary changes
* diabetic retinopathy
* neovascular glaucoma or non-glaucoma optic neuropathies
* current macular edema, prior laser to retina, inflammatory retinopathy or choroidopathy
* keratoconus, corneal ectasia, central corneal scarring
* rheumatologic diseases or Raynaud's phenomena
* pregnant and lactating women
* mental illness or alcohol addiction
* pre-existing bladder symptoms, cardiac disease or sleep disorder
* refractive spherical diopter greater than 5 or cylinder greater than 3
* possible tolerance to caffeine (drinking more than 1 cup coffee per day).