An Evidence Of Blood Pressure And Respiration Originated Variations In Fluctuations Of Pupil Diameter Of The Human Eye

Abstract

This paper presents an evidence showing the presence of the blood pressure and respiration originated variability in pupil diameter of the human eye. Fluctuations in pupil diameter, blood pressure and instantaneous lung volume were continuously and simultaneously recorded for three male subjects aged 22-23. Spectral analysis were applied to the data and showed significant crm spectral amplitude between fluctuations in pupil diameter and blood pressure or instantaneous lung volume. These covariations could be utilized to investigate the autonomic control of the visual system. set to 100 luz. Subjects have wide visual field in natural binocular viewing condition. Pupil diameter waa measured by a TV pupilometer. Horizontal scanning signal was digitized and the pupil diameter was automatically measured as an interval between two pupil edges. Blood pressure was measured by a noninvasive continuous blood pressure monitor (Nippon Colin CBM-7000). Instantaneous lung volume was measured by an impedance plethysmograph (NIMSSI02). Data were recorded on FM data recorder (TEAC MR30) The rest of processing was done off-line on a digital computer (NEC PC9801VX). Fluctuations in pupil diameter, blood pressure and instantaneous lung volume were digitized at the sampling interval of 50 (ms). Then a linear phase low pass FIR filter (stop band 1-lOHz, pass band: 0-0.5Hz, maximum ripple 0.01, filter order 115) were ap plied to all data in order to focus our attention to slow variations related to autonomic control of the visual system. Standard spectral analysis[4] were applied to decimated (4:l) data.