Nichtinvasive Messung der Sauerstoffsättigung retinaler Gefäße bei retinalen Astarterienverschlüssen unter Therapie

Abstract

Purpose of these study was the evaluation of a new method for the measurement of haemoglobin oxygenation in retinal vessels. Patients with branch retinal artery occlusion have been measured before and after a rheological therapy. The haemoglobin oxygenation in retinal vessels was measured by the "oxygen module" (Imedos GmbH, Jena, Germany) which uses a special filter (transmission at 548 and 610 nm, band width 10 nm) in the illumination path of a fundus camera. Fundus images were acquired by a colour CCD camera and specific software was used for vessel tracking and calculation of their haemoglobin oxygen saturation. 11 patients with branch retinal artery occlusions, average age 63.4 ± 11.7 years were investigated at time of diagnosis and at the 5th day of a rheological and intraocular pressure reduction therapy. 10 out of 11 patients have shown an increase of haemoglobin oxygenation over time (on average from 73 ± 16 % to 87 ± 11 %). This increase was statistically significant (p < 0.05, Wilcoxon test). Non-affected retinal areas have also shown an increase of haemoglobin oxygenation. The visual acuity improved by one line. This increase in visual acuity was, however, not statistically significant. We observed an increase of the arterial haemoglobin oxygenation. One possible reason of the improvement of the haemoglobin oxygenation by the therapy may be an increase of the rheological properties of the blood. All patients showed an increase or at least a stabilisation of their visual acuity. Retinal vessel oximetry might be used as an additional parameter in the follow-up of retinal artery occlusion.