Measured parameters included systemic blood pressure ( BP ) , blood glucose levels , static retinal vessel analysis , as measured by central retinal artery equivalent ( CRAE ) ( which relates to the diameter of the central retinal artery ) , central retinal vein equivalent ( CRVE ) ( which relates to the diameter of central retinal vein ) and the arterio-venous ratio ( AVR ) , which represents the CRAE/CRVE ratio , dynamic retinal vessel analysis as measured by the change in vessel diameter in response to flicker light stimulation .