Abstract
Purpose: :
To evaluate the correspondence between RFI retinal oxymetry map patterns and fluorescein angiography perfusion patterns.
Methods: :
Patients with retinal vascular disease who had undergone FA were recruited after informed consent to have RFI blood velocity analysis and oymetry mapping. The RFI uses high-speed stroboscopic fundus imaging in 4 wavelengths which are subtracted to create a pseudocolor scale of relative oxygenation. Fluorescein images taken after full venous filling were examined for areas of non-perfusion which were then outlined manually. The retinal oxymetry map was superimposed using PhotoshopTM over the FA to allow visual inspection of the extent of correspondence the blue hypoxic region and the area of capillary non-perfusion. A grid overlay was used to measure the areas of overlap and areas of discrepancy. Statistical analysis of the areas of correspondence and differences were evaluated for percentage of difference.
Results: :
5 eyes from 5 patients with diabetic retinopathy or vascular occlusion were evaluated. Areas of FA non-perfusion appeared similar in shape and extent to blue areas of low oxygen tension on the RFI maps in all cases. Percentage of differences of areas ranged from 6 to 11.4% with an average of 6.63%. All FA defined areas of non-perfusion appeared blue on oxymetry maps, but oxymetry blue regions often extended beyond the FA borders.
Conclusions: :
Retinal Function imager (RFI) is a non-invasive device which provides qualitative mapping of retinal oxygenation. Areas of low oxygen tension were qualitatively and quantitatively in good agreement with areas of capillary non-perfusion demonstrated by FA.
Keywords: blood supply • retina • oxygen