All patients will undergo a complete diurnal workup including IOP, as well as 10am Confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomography-3) of ONH topography. Optic nerve head, nasal and temporal peripapillary retinal blood flow are measured with scanning laser Doppler flowmetry (SLDF; Heidelberg Retinal Flowmeter/Tomograph, SLDF analysis software v3.3, Heidelberg Engineering, Germany Goldmann IOP will be measured at 8am, 10am 2pm and 4pm. Pulse amplitude, similar to Pulsatility Ocular Blood Flow (POBF) will be measured using the Pascal Dynamic Contour Tonometer (DCT) at 8am, 10am, 2pm, and 4 pm.