Abstract
Purpose: :
The objective of this study was to quantify changes in retinal blood flow in vessels neighbouring a branch retinal arterial occlusion (BRAO).
Methods: :
All measurements were obtained from anesthetized adult pigmented rats. BRAO was achieved using a photosensitive dye Rose Bengal (20mg/kg) and high intensity xenon white light. Retinal blood velocity was determined by tracking 1µm yellow-green fluorescent polystyrene microspheres (505/515nm maximum absorption/emission) with a Scanning Laser Ophthalmoscope (SLO). Velocity measurements were obtained before, and in 30-minute intervals after induction of occlusion (post-occlusion) and analyzed using particle-tracking velocimetry. Vessel diameters were measured from SLO infrared reflectance (IR) images. Blood flow rate was determined from average velocity and cross-sectional area. Fluorescein angiography was performed to confirm occlusion and determine vessel types. Post-occlusion measurements were acquired for a period of ~3 hours.
Results: :
A gradual decrease in velocities in adjacent vessels was observed after induction of branch arterial occlusion. By 2 hours post-occlusion velocities in adjacent arteries (60-80µm diameters) decreased significantly by ~16%, while those in adjacent veins (50-100µm diameter) decreased significantly by ~36%. Diameters of these vessels showed no significant changes over the investigated time period. Arterial and venous blood flow rates decreased significantly by ~21% and ~30% within 2 hours post-occlusion. Systemic blood pressure and other vital signs showed no dramatic changes due to occlusion.
Keywords: vascular occlusion/vascular occlusive disease • blood supply