Purpose:
Diabetic retinopathy is believed to involve retinal hypoxia. Our previous measurements showed elevated oxygen saturation in retinal vessels in patients with diabetic retinopathy. In this study we measure oxygen saturation in retinal vessels with a new generation of a retinal oximeter.
Methods:
The retinal oximeter (Oxymap ehf., Reykjavik, Iceland) is composed of a fundus camera, beam splitting optics and two digital cameras. The oximeter simultaneously yields two images of the same area of the fundus, one with 570nm light and one with 600nm. Calculated light absorbance is used to estimate hemoglobin oxygen saturation. Oxygen saturation was measured in major temporal retinal vessels in 17 healthy individuals and 19 patients with diabetes. ANOVA and Dunnett’s post test were used for statistical analysis.
Results:
Saturation values for subgroups are shown in the table. Overall p value was 0.051 for arterioles and 0.048 for venules (ANOVA).
Conclusions:
These preliminary data show a trend towards elevated saturation in retinal vessels in proliferative diabetic retinopathy after treatment. This is consistent with results from an earlier oximeter. Possible explanations include shunting of blood through damaged capillary network and decreased oxygen consumption due to laser treatment.
Keywords: diabetic retinopathy • imaging/image analysis: clinical • oxygen