Abstract
Purpose: :
Diabetic retinopathy damages retinal capillaries and therefore retinal oxygen metabolism can be affected. The purpose of this study was to test retinal vessel oxygen saturation in patients with diabetic retinopathy and normal controls.
Methods: :
The retinal oxymeter (Oxymap ehf., Reykjavik, Iceland) based on a fundus camera that was used employs two wavelengths. The optical density is sensitive to oxygen saturation at 605 nm (oxygen sensitive) but not at the reference wavelength of 586 nm (oxygen insensitive). The hemoglobin oxygen saturation was measured in the retinal arterioles and venules in 18 diabetic patients (42-69 years old) with mild non-proliferative diabetic retinopathy through proliferative diabetic retinopathy and compared with six healthy control patients’ eyes.
Results: :
The oxygen saturation difference in retinal arterioles and venules (A-V) was lower (7.6 ± 2.1) in diabetic eyes compared with normal healthy control eyes. The diabetic eyes did not remove and use as much oxygen from the blood as the normal eyes did. We did not separate the results for different stages of retinopathy in this study.
Conclusions: :
The increase of oxygen found in venules of diabetic patients results from microvascular alteration, possibly because of shunting of the blood through preferential channels, caused by capillary dropout.
Keywords: diabetic retinopathy