Wide field retinal microvessel blood flow velocity and microvascular network imaged with RFI

Abstract

Purpose : To quantitatively analyze retinal blood flow velocity and microvascular network in ultra-wide field using retinal functional imager (RFI Optical Imaging Ltd, Rehovot, Israel) in healthy subjects.

Methods : Retinal microvessel blood flow velocity and network centered on the fovea were acquired with a wide field (35 degrees: 7.3 x 7.3 mm²) (Fig. 1). After the large vessels (≥ 25 µm) were removed, the microvessels were analyzed by measuring the microvascular density through fractal analysis by using the box counting method (D_box representing density). The results obtained with the wide field were compared to the results obtained with the commonly used small field (20 degrees: 4.3 x 4.3 mm²). Twenty healthy subjects were imaged to measure blood flow velocity and 10 healthy subjects were imaged to analyze the microvascular network.

Results : With the 35 degrees field of view (FOV), arteriolar blood flow velocity was 4.0 ± 0.4 mm/s (mean ± SD), which was significantly faster than the arteriolar velocity obtained through the 20 degrees FOV (3.8 ± 0.4 mm/s, P = 0.001). Venular blood flow velocity with the FOV of 35 degrees was 3.2 ± 0.3 mm/s, which was faster than that determined with the 20 degrees FOV (2.9 ± 0.3, P = 0.001). The average Dbox of the microvessels in the circular region (diameter = 6 mm) centered on the fovea was 1.80 ± 0.01, which was higher than that obtained with the 20 degrees (diameter = 3.6 mm, 1.78 ± 0.02, P = 0.005). When the trimmed equivalent regions of the wide field (equivalent 20 degrees: diameter = 3.6 mm) were compared to the small field, no significant differences were found in the D_box for both annular zones (P = 0.38) and quadrantal zones (P = 0.49).

Conclusions : This is the first study to quantitatively analyze the wide field retinal blood flow velocity and microvascular network. The comparison of the different fields for the measurements reveals that specifying blood flow velocity should be linked to a report of the measurement field for crossing references.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.