Initial report of quantification of retinal blood flow velocity in normal human subjects using the Retinal Functional Imager (RFI)

The Retinal Functional Imager (RFI) is a novel method for assessing retinal blood flow (RBF) velocity. The purpose of this study was to evaluate RBF velocities in normal human retinas using the RFI. RBF velocity measurements were performed in normal subjects using the RFI (Optical Imaging Ltd., Rehovot, Israel) at the Retina Center of The New York Eye and Ear Infirmary, New York, USA. Using proprietary software processing, the characteristics of the RBF were visualized and measured. The study population comprised fifty-four eyes of 27 normal subjects (20 male and 34 female). The average arterial blood flow velocity was 4.6 ± 0.6 mm/s in males and 4.8 ± 0.7 mm/s in females (the difference was not statistically significant, p value = 0.27). The average venous blood flow velocity was 3.8 ± 0.5 mm/s in males and 3.6 ± 0.4 mm/s in females (the difference again was not statistically significant, p value = 0.11). The average arterial blood flow velocity was 4.8 ± 0.5 mm/s in the right eye and 4.6 ± 0.7 mm/s in the left eye. The average venous blood flow velocity was 3.7 ± 0.4 mm/s in the right eye and 3.6 ± 0.3 mm/s in the left eye. Venous and arterial blood flow velocities were found to be faster in the right eye than in the left eye in our sample, but the differences were not statistically significant (p value = 0.53 and 0.33, respectively). This is the first report of quantification of the RBF using the RFI. The RFI appears to be an effective tool in quantitative evaluations of RBF velocities. The values from the study constitute a normative database which can be used to evaluate and compare eyes with known or suspected pathology.