Zusammenfassung
The purpose of this study was to measure the hemoglobin oxygenation in retinal
vessels and to evaluate the sensitivity and reproducibility of the measurement.
Using a fundus camera equipped with a special dual wavelength transmission filter
and a color charge-coupled device camera, two monochromatic fundus images at 548
and 610 nm were recorded simultaneously. The optical densities of retinal vessels
for both wavelengths and their ratio, which is known to be proportional to the
oxygen saturation, were calculated. From 50-deg images, the used semiautomatic
vessel recognition and tracking algorithm recognized and measured vessels of 100
microm or more in diameter. On average, arterial and venous oxygen saturations
were measured at 98+/-10.1\% and 65+/-11.7\%, respectively. For measurements in the
same vessel segments from the five images per subject, standard deviations of
2.52\% and 3.25\% oxygen saturation were found in arteries and veins, respectively.
Respiration of 100\% oxygen increased the mean arterial and venous oxygen
saturation by 2\% and 7\% respectively. A simple system for noninvasive optical
oximetry, consisting of a special filter in a fundus camera and software, was
introduced. It is able to measure the oxygen saturation in retinal branch vessels
with reproducibility and sensitivity suitable for clinical investigations.
Nutzer