97th DOG Annual Meeting 1999


J. Welzenbach, G. Michelson, J. Harazny

J. Welzenbach, G. Michelson, J. Harazny

Purpose: Distinction of arterial and venous oxygen saturation by measurement of local gradient of the concentration of oxygenated blood ((delta)CHbO2) between adjacent measurement points.

Method: A modified confocal laser-scanning system (Heidel-berg-Engineering) takes 32 images of a 10º-section of the retina with constant focus depth alternately at 670nm and 790nm. For the following calculation we make the simplifying assumption: between adjacent points only the con-centration CHbO2 or CHbR varies; other tissue components give a constant background, also the light scattering. With these prerequisits the gradient of the concentration (delta)CHbO2 between two measurement points lying next to each other can be determined. For the analysis the interesting vessel is marked by a line. Then - automatically - for each line of this section from the beginning to the end point the course of (delta)CHbO2(x) is calculated and the results are averaged. We examined 2 volunteers 5 times. For each examination 3 measurements were made breathing normal air and 100% oxygen.

Results: In this first study arteries and veins could be distinguished using the DCHbO2 at the vessel walls.

Conclusion: This completely new method for measuring the (delta)CHbO2 enables to distinguish arterial and venous oxygen saturation.

Supported by Sonderforschungsbereich 539 "Glaukome, einschließlich PEX" of the "Deutsche Forschungsgemeinschaft" (German Research Foundation)

Friedrich-Alexander-University Erlangen-Nürnberg, Department of Ophthalmology, Schwabachanlage 6, D-91058 Erlangen, Germany