Abstract
Purpose:
To evaluate total retinal blood flow (TRBF) using 100k Hz Doppler swept-source OCT for healthy and diabetic eyes.<br />
Methods:
One eye of each participant was scanned with a 100k Hz prototype swept source OCT. Eye length was measured with IOL master 500 (Carl Zeiss, CA). The TRBF scan pattern contains 8 repeated volume scans (depth=2.3mm, horizontal=1.6 mm, and vertical=2mm) obtained in 4 seconds, and centered on central retinal vessels. Each eye was scanned 3 times. Phase noise was reduced using a novel algorithm that removes timing jitter from the tunable laser k-clock using information from fixed pattern artifacts. Tissue bulk-motion was removed using a histogram method. An automated algorithm was developed for TRBF measurement using multiple plane en face technique. For each retinal vein, blood flow was measured at an optimal en face plane where the calculated flow is maximized. The TRBF was calculated by summing flow in all veins. The algorithm tracks vascular branching so that either root or branch veins are summed, but never both. The TRBF in 8 repeated volumes were averaged to reduce variation due to pulsation during the cardiac cycle. Finally the TRBF is corrected by multiplying with square of the ratio between eye length and default eye length.<br />
Results:
A total of 12 eyes of 12 participants (6 healthy controls, 6 diabetic participants) were enrolled. The TRBF of healthy controls is 46.4±5.4 µl/min. The TRBF of diabetic eyes is 36.4±12.8 µl/min. The intra-visit repeatability was 6.1% for health control and 8.4% for diabetic eyes.<br />
Conclusions:
An automated algorithm was developed for TRBF measurement using 100 kHz spectral-domain OCT. Diabetic eyes had significant lower TRBF than normal subject. The repeatability of TRBF was improved compared with previous methods and this may be useful for the monitoring of glaucoma and diabetic retinopathy.<br />