Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

: Braaf B, Vermeer KA, Vienola KV, de Boer JF

Publisher: Optica Publishing Group

: 2012

Optics Express

: OPTICS EXPRESS

: OPT EXPRESS

: 20

: 18

: 20516

: 20534

: 19

: 1094-4087

DOI: https://doi.org/10.1364/OE.20.020516

: https://opg.optica.org/oe/fulltext.cfm?uri=oe-20-18-20516

In conventional phase-resolved OCT blood flow is detected from phase changes between successive A-scans. Especially in high-speed OCT systems this results in a short evaluation time interval. This method is therefore often unable to visualize complete vascular networks since low flow velocities cause insufficient phase changes. This problem was solved by comparing B-scans instead of successive A-scans to enlarge the time interval. In this paper a detailed phase-noise analysis of our OCT system is presented in order to calculate the optimal time intervals for visualization of the vasculature of the human retina and choroid. High-resolution images of the vasculature of a healthy volunteer taken with various time intervals are presented to confirm this analysis. The imaging was performed with a backstitched B-scan in which pairs of small repeated B-scans are stitched together to independently control the time interval and the imaged lateral field size. A time interval of >= 2.5 ms was found effective to image the retinal vasculature down to the capillary level. The higher flow velocities of the choroid allowed a time interval of 0.64 ms to reveal its dense vasculature. Finally we analyzed depth-resolved histograms of volumetric phase-difference data to assess changes in amount of blood flow with depth. This analysis indicated different flow regimes in the retina and the choroid. (C) 2012 Optical Society of America

Angiography, Optical coherence tomography, Retina, retinal vascular imaging