A. Barak, Z. Burgansky-Eliash, D. Nelson, O. Pupko, M. Berkowitch, A. Lowenstein, A.Grinvald


The Retinal Function Imager (RFI) implements a new, non-invasive diagnostic approach to measure blood flow velocity. Intravitreal Bevacizumab is widely used for treatment of various retinal conditions. We used the RFI to learn about the drug’s effect on retinal vascular function.


This pilot study includes seven patients who received intravitreal injection of Avastin. RFI scans were recorded before injection and 1 and 7 days after injection. Blood flow velocity was quantified for secondary and tertiary branches of arteries and veins. Results: Clinical diagnosis was neovascular age-related macular degeneration in four subjects and vein occlusion in three. Five of seven patients were injected for the first time; one was scanned during his third Avastin injection, and one during his sixth. In all subjects except one, there was increased velocity in retinal arteries on the first day after injection (average 94.7% increase, range 29.7% to 237.5%). In all these, velocity decreased to near baseline on day 7 (average -0.6%, range -14.3% to 8.6%). In the veins, smaller and more variable changes in blood flow velocities were observed on day 1 and 7 (average 13.8%, range -19.5% to 139%, average -10.0%, and range -15.5% to 30%, respectively).

Effectiveness / Safety:

The pilot study demonstrated for the first time, that the RFI provides a non-invasive technique to assess hemodynamic responses to intravitreal injection of Avastin. These changes may represent a side effect or serve as a marker for desirable response.