Abstract

P 264

Hemoglobin oxygenation of retinal vessels in vein occlusions over time and correlation with clinical outcome

Simone Gehlert, Jens Dawczynski, Martin Hammer, Jürgen Strobel
Klinik für Augenheilkunde, Universitätsklinikum Jena, Jena

Purpose
Evaluation of a new method for the measurement of hemoglobin oxygenation in retinal vessels. Patients with retinal vein occlusion have been measured before and after a rheological therapy.
Method
We measure the haemoglobin oxygenation in retinal vessels by a modified dynamic vessel analyser (Fa. Imedos, Jena). This module uses a special filter (transmission at 548 and 610 nm, bandwidth 10nm). Fundus images were acquired by a colour CCD camera and special software was used for vessels tracking and calculation of their haemoglobin oxygen saturation.
11 patients (6 branch and 5 central retinal vein occlusions, average age 54,4±8,8 and 68,8±3,7 years) were investigated at the time of diagnosis and at the 6th day of a rheological and intra-ocular pressure reduction therapy.
Results
5 out of 11 patients have shown an increase of haemoglobin oxygenation over time. For patients with central retinal vein occlusion a considerable increase of the hemoglobin oxygenation was observed (on average from 49,8±4,8% to 54,8±19,9%.), in branch retinal vein occlusions the hemoglobin oxygenation were constant over time (59,2±17,3% vs. 59,3±23,1%). The arterial haemoglobin oxygenation increased in branch retinal vein occlusions by 8%, but remained nearly constant in central vein occlusions.
Although haemoglobin oxygenation did not increase in branch retinal vein occlusions, the visual acuity improved on average for two lines. In central vein occlusions, the visual acuity of patients improved by up to seven lines, however starting from lower baseline values.
Discussion
We observe a wide variety of hemoglobin oxygenation in occluded retinal veins. Patients with central vein occlusions have shown an increase in venous haemoglobin oxygenation. In branch retinal vein occlusions the arterial haemoglobin oxygenation did increase. One possible reason of the improvement of the hemoglobin 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 the visual acuity. The increase of haemoglobin oxygenation in venous occlusions were less than in the already analysed retinal artery occlusion. Retinal vessel oximetry might be used as an additional parameter in the follow-up of retinal vein occlusion.

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