Abstract
Purpose: :
To determine quantitative reliability of the Retinal Function Imager.
Methods: :
A prospective clinical study was done by including 26 patients (45 eyes) who had various diagnosis of retinal vascular diseases. All patients were imaged with fundus fluorescein angiography (FA) (Topcon TRC-501X FA, Topcon Medical Systems Inc., Paramus, NJ) and Retinal Function Imager (RFI) (Optical Imaging Ltd., Rehovot, Israel). The FA and oxymetry images were overlaid using Adobe Photoshop to outline non-perfusion areas on the oxymetry images. Then we did overlaying the retinal blood flow velocity images over the outlined oxymetry images. Final images were reviewed and be calculated for the localized average blood flow velocity (average blood flow) over the interesting areas. We compared the data for correlations over the perfusion and non-perfusion areas as well as other areas of interesting pathologies. The statistical analysis was done to determine statistically significance of the correlations.
Results: :
Most common diseases were diabetic retinopathy (15 eyes) and retinal vein occlusion (5 eyes). Rosen et al assumed that red color in the oxymetry images represented well oxygen perfusion and blue color represented poor oxygen perfusion as they were well correlated with non-perfusion areas in the FA. We found that the average blood flow in the red color areas of oxymetry images were significantly higher than those of the blue color areas (p-value < 0.01). We followed up a patient with CRVO for 6 weeks. The VA had been improving during the follow up period. The non-perfusion areas demonstrated by the FA and oxymetry were improving and well correlated with the changes of the average blood flow. In a case of sickle cell retinopathy with sea-fan vascular loops, oxymetry revealed the sea-fan lesion in bright red color contrasted with the blue background tissue. Average blood flow analysis confirmed that the lesion had striking higher blood flow velocity than the non-perfusion background tissue.
Conclusions: :
Retinal Function Imager is another useful and non-invasive device (no dye injection) for demonstration of oxymetry and retinal blood flow velocity in various retinal diseases. Our study reveals that RFI is reliable in term of quantitative reliability.
Keywords: oxygen • retina • imaging/image analysis: clinical