Indirect Measurement of Eye-Level Arterial Pressure by the Volume Oscillometric Method

Eye-level blood pressure was indirectly measured in human superficial temporal arteries with a newly designed sphygmomanometer using the volume oscillometric principle. This device comprises a reflected, infrared, photoelectric plethysmograph (RIPP) for detecting arterial volume variations and an artery compression cuff. Systolic and mean arterial pressures were determined from the cuff pressure corresponding respectively to the appearance and maximum point of the arterial volume variations. Diastolic pressure was calculated from these pressure values using a conventional equation. The pressures were corrected with respect to the hydrostatic pressure difference between the heart and eye, and compared with the data simultaneously obtained by (1) auscultation method in the brachial arteries; (2) volume compensation; and (3) a volume oscillometric method in the finger arteries. The eye-level pressure and its change were recorded during rest and exercises such as bicycle ergometry, weight lifting, Master's two-step test, and acceleration loading by a human centrifuge.