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