Abstract
Purpose: :
The purpose of this study was to evaluate differences in relative retinal vessel oxygen saturation between patients with proliferative diabetes and controls.
Methods: :
Oxygen saturations were obtained using the Oxymap Retinal Oximeter (Oxymap eph, Iceland) and Oxymap Analyzer Software. The system employs two different wavelengths of light at each point along the primary branches of the central retinal artery and central retinal vein to calculate the relative difference in oxygen saturation. Diabetic and control patients were selected randomly following complete ophthalmic evaluation. All diabetic patients demonstrated proliferative diabetic retinopathy (PDR). Both eyes were analyzed whenever possible; however, only one eye was randomly included in the analysis.
Results: :
28 PDR patients and 18 control patients were selected. 17/28 patients were female compared to 8/18 control patients (p=0.28). 4/28 diabetic patients were Caucasian, 12/28 were Hispanic, and 7/28 were African American. Of the control patients, 4/18 were Caucasian, 3/18 were Hispanic, and 3/18 were African American. Baseline arterial oxygen saturation was lower in control patients compared to diabetics (94.56% vs 105.11% (p<.001). Baseline venous oxygen saturation was also lower in control eyes compared to diabetic eyes (62.0% vs 70.86%, p<.001). Total oxygen saturation was similar in control and diabetic patients (32.56% vs 34.25%, p=.51). PDR patients were then sub-classified based on history of panretinal photocoagulation(PRP). 20/28 patients had previous PRP. Baseline arterial oxygen saturation was higher in eyes with PRP than those without PRP (108.20% vs 98.00%, p=.037). When compared with controls, there was a more significant difference between PRP and control eyes than non-PRP eyes and control eyes (p<.001 vs p=.149). Baseline venous oxygen saturation, however, was similar in both PRP eyes and non-PRP eyes (71.10% vs 69.29%, p=.602). When compared with controls, there was a more significant difference between PRP and control eyes than non-PRP eyes and control eyes (p<.001 versus p=.044).j Oxygen extraction was higher in PRP eyes than non-PRP eyes (37.10% vs 28.71%, p=.015).
Conclusions: :
There is an increase in baseline arterial and subsequent venous oxygen saturation in primary branches of the central retinal artery and vein in patients with PDR compared to controls, most likely due to decreased perfusion of capillary beds in diabetic patients. Further studies are warranted to evaluate the possible diagnostic and therapeutic role of Oxymap analysis.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy • imaging/image analysis: clinical