Conventional transmission pulse oximetry is a noninvasive technique for the continuous monitoring of arterial oxygen saturation (SaO2) from peripheral vascular beds such as the finger tip or earlobe. In this paper we propose to exploit the unique transparency of the ocular media to make reflectance pulse oximetry measurements on the retinal fundus. This technique potentially offers significant advantages over conventional pulse oximetry, primarily the ability to monitor cerebral, as opposed to peripheral, oxygen saturation. We have developed an in vitro system to stimulate the retinal circulation and ocular optics. This system consists of a flexible cuvette located in a model eye and an extracorporeal blood circuit to stimulate arterial blood flow. The system was used to investigate the relationship between SaO2 and the R/IR ratio in reflectance pulse oximetry. To enable in vivo measurements to be made, we also modified a standard haptic contact lens to hold the pulse oximeter probe in front of the pupil. In a preliminary study, the lens was fitted to an awake volunteer and cardiac-synchronous signals were detected by the retinal pulse oximeter.

Original publication

DOI

10.1109/10.238467

Type

Journal article

Journal

IEEE Trans Biomed Eng

Publication Date

08/1993

Volume

40

Pages

817 - 823

Keywords

Contact Lenses, Equipment Design, Extracorporeal Membrane Oxygenation, Eye, Fundus Oculi, Humans, Models, Structural, Oximetry, Retinal Vessels