Remote sensing of blood oxygenation using red-eye pupil reflection.

Objective: To develop a technique for remote sensing of systemic blood oxygenation using red-eye pupil reflection.

Approach: The ratio of the intensities of light from the bright pupil reflections at oxygen sensitive and isosbestic wavelengths is shown to be sensitive to the oxygenation of blood in the eye. A conventional retinal camera, fitted with an image-replicating imaging spectrometer, was used at standoff range to record snapshot spectral images of the face and eyes at eight different wavelengths.

A multispectral microscope for in vivo oximetry of rat dorsal spinal cord vasculature.

Quantification of blood oxygen saturation (SO) in vivo is essential for understanding the pathogenesis of diseases in which hypoxia is thought to play a role, including inflammatory disorders such as multiple sclerosis (MS) and rheumatoid arthritis (RA). We describe a low-cost multispectral microscope and oximetry technique for calibration-free absolute oximetry of surgically exposed blood vessels in vivo. We imaged the vasculature of the dorsal spinal cord in healthy rats, and varied inspired oxygen (FiO) in order to evaluate the sensitivity of the imaging system to changes in SO.

Assessment of acute mild hypoxia on retinal oxygen saturation using snapshot retinal oximetry.

Purpose: To study the effect of acute mild hypoxia on retinal oxygen saturation.

Methods: Spectral retinal images were acquired under normoxic and hypoxic conditions for 10 healthy human volunteers (six male, four female, aged 25 ± 5 years [mean ± SD]) using a modified fundus camera fitted with an image-replicating imaging spectrometer (IRIS). Acute, mild hypoxia was induced by changing the oxygen saturation of inhaled air from 21% to 15% using a hypoxia generator with subjects breathing the hypoxic gas mixture for 10 minutes.