Parallel Variable Interscan Time Analysis (VISTA) OCTA and en Face Doppler OCT of Optic Disc and Peripapillary Vasculature

Abstract

Purpose : Variable interscan time analysis (VISTA) using high-speed optical coherence tomography (OCT) has improved quantitative interpretation of OCT angiography (OCTA). En face Doppler OCT allows direct quantitative measurement of total retinal blood flow (TRBF). Using VISTA-OCTA and en face Doppler OCT images of the optic disc, we aim to investigate the relationship between radial peripapillary capillary perfusion, optic disc perfusion, and TRBF.

Methods : OCTA and Doppler scans were acquired from eyes with age-related macular degeneration, glaucoma, diabetic retinopathy, and control subjects using a 1050-nm swept-source OCT prototype at a 400 kHz axial scan rate. VISTA-OCTA was performed by acquiring 5 repeated B-scans at each position and calculating the ratio of the OCTA signals in the OCTA images with 1.5 ms and 3 ms interscan times. OCTA volumes were flattened with respect to the vitreoretinal interface and a 190-µm depth slab was projected for visualization of the peripapillary radial capillary plexus. En face Doppler OCT volumes were acquired at a 7.1 volumes/sec scan rate to resolve blood flow pulsatility.

Results : VISTA-OCTA images provided information on the blood flow speed in the large retinal vessels and peripapillary radial capillary plexus. En face Doppler OCT resolved the pulsatility of arterial TRBF and yielded accurate measurement of mean TRBF.

Conclusions : The combination of VISTA-OCTA and en face Doppler OCT may be useful for extracting information on retinal and optic disc blood flow. Different flattening references other than the vitreoretinal interface are desired in order to measure prelaminar and laminar perfusion.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

VISTA and en face Doppler images of (A-E) a glaucoma suspect eye and (F-J) an eye with primary open-angle glaucoma. (A, F) 3-ms interscan time OCTA projection from the vitreoretinal interface to 190-µm depth. (B, G) corresponding VISTA images where blue represents slow flow speeds and red represents fast flow speeds. (C, D, H, I) en face Doppler axial flow velocity image at systole and diastole overlaid on the intensitiy projection. (E, J) plots of pulsatile total retinal blood flow. Scale bars 500 µm.