Retinal oximeter for the blue-green oximetry technique.
Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO(2)) via the retinal vessels but requires a calibrated accuracy of ±3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the blue-green oximetry (BGO) technique can provide accuracy within ±3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO(2) measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ±2% SO(2). The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry.
University of Arizona, Department of Emergency Medicine and College of Optical Sciences, 1609 North Warren Avenue, Room 116, Tucson, Arizona 85724-5057, USA. kdenninghoff@aemrc.arizona.edu
Kurt R
KR
Denninghoff
Katarzyna B
KB
Sieluzycka
Jennifer K
JK
Hendryx
Tyson J
TJ
Ririe
Lawrence
L
Deluca
Russell A
RA
Chipman
D000328:Adult; D000818:Animals; D006801:Humans; D008027:Light; D019721:Ophthalmoscopes; D055096:Optical Devices; D055620:Optical Phenomena; D010092:Oximetry / Q000295:instrumentation* / Q000706:statistics & numerical data; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000378:metabolism; D012171:Retinal Vessels / Q000378:metabolism*; D012542:Scattering, Radiation; D034421:Sus scrofa
D010108:Oxyhemoglobins; D010100:Oxygen