Retinal oximeter for the blue-green oximetry technique

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Noninvasive assessment of central venous oxyhemoglobin saturation (SO(2)) using retinal oximetry is clinically valuable.
• Previous retinal oximetry designs lacked the required ±3% saturation calibration accuracy for clinical use.

Purpose of the Study:

• To demonstrate the feasibility of the blue-green oximetry (BGO) technique for accurate, noninvasive retinal oximetry.
• To develop and test a noninvasive on-axis scanning retinal oximeter (ROx-3) capable of achieving clinical accuracy.

Main Methods:

• Development of a noninvasive on-axis scanning retinal oximeter (ROx-3) utilizing the blue-green oximetry (BGO) technique.
• Implementation of a field stop and anticonfocal bisecting wire to isolate multiply backscattered light and remove specular reflections.
• Testing the device on enucleated swine eye vessels and a human retinal vein.

Main Results:

• The blue-green oximetry (BGO) technique achieved accuracy within ±3% in swine.
• Retinal SO(2) measurements in human volunteers were internally consistent with a standard error of the mean of ±2% SO(2).
• Absolute saturation measures were within the expected physiological ranges.

Conclusions:

• The developed noninvasive on-axis scanning retinal oximeter (ROx-3) successfully implements the blue-green oximetry (BGO) technique.
• This study represents the first demonstration of noninvasive on-axis BGO retinal oximetry.
• The achieved accuracy meets the clinical requirement for assessing retinal oxyhemoglobin saturation.