Evaluation of Retinal Circulation Using Segmental-Scanning Doppler Optical Coherence Tomography in Anesthetized Cats

Abstract

Citation: Nagaoka T, Tani T, Song Y-S, et al. Evaluation of retinal circulation using segmental-scanning Doppler optical coherence tomography in anesthetized cats. Invest Ophthalmol Vis Sci. 2016;57:293657: -294157: . DOI:10.1167 PURPOSE. To study retinal blood flow (RBF) measurement reproducibility using segmentalscanning Doppler optical coherence tomography (DOCT) in vitro in glass capillaries and in vivo in anesthetized cats.METHODS. As a preliminary study, the flow rates of human blood through glass capillaries were changed by using an infusion pump and measured at 13 preset velocities by DOCT. For in vivo measurement, the cats were anesthetized using sevoflurane. The flow in the parent vessel was compared with the sum of the flow values in the two daughter vessels. The RBF was measured using two different instruments: bidirectional laser Doppler velocimetry (LDV) and DOCT. The reproducibility of the measurements was assessed by calculating the coefficients of variation (CVs) for repeated measurements of RBF at the superior retinal arterioles and venules.RESULTS. In vitro, the flow velocities measured by DOCT agreed well with the preset velocities. In vivo, the flow in the parent vessel agreed with the sum of the flow values in the two daughter vessels. In addition, there were no significant differences in the mean averaged CVs of the RBF in both the arterioles and venules between LDV and DOCT.CONCLUSIONS. The newly developed segmental-scanning DOCT revealed the accuracy of the measurement in in vitro glass capillaries and reproducibility of the measurements of blood velocity in both the retinal arterioles and venules in anesthetized cats.

Repeatability and Reproducibility of Retinal Blood Flow Measurement Using a Doppler Optical Coherence Tomography Flowmeter in Healthy Subjects

“…9 Our DOCT flowmeter is based on a commercially available spectral-domain OCT system (3D OCT-1 Maestro; Topcon Corp., Tokyo, Japan) operated at an 800-nm wavelength range. 16 Only the software was modified for blood flow imaging, where extra image-processing software and quantification software were newly developed to measure blood flow.…”

“…A detailed description has been published previously. 16 In the retina, most blood vessels run nearly parallel to the retinal surface except at the area around the optic nerve head. As h approaches 908, the measured velocity becomes very sensitive to the accuracy of h. To minimize this potential velocity measurement error, our Doppler blood flow measurements were performed where the Doppler angle h is considerably less than 908, that is,~808.…”

“…In such methods, it is possible to measure the retinal venous blood flow velocity but not the arterial velocity. Another research group 15 has reported the results with the swept-source-based OCT flowmeter in which both the arterial and venous total flow are assessed by using their prototype OCT. We have previously developed a DOCT instrument with novel software, referred to as a segmental-scanning method, 16 which enables simultaneous measurement of the RBF in the retinal arterioles and adjacent venules during one cardiac cycle. We have previously reported the accuracy of the measurements in in vitro glass capillaries.…”

Dense concentric circle scanning protocol for measuring pulsatile retinal blood flow in rats with Doppler optical coherence tomography

“…4 Recent studies [1][2][3][4] indicated that metrics that characterize the pulsatility of retinal BF are sensitive to early pathophysiological changes in the retina, therefore accurate assessment of retinal BF pulsatility can aid the early diagnosis of potentially blinding diseases. Previously, different optical imaging modalities, such as scanning laser ophthalmology, 5 laser Doppler velocimetry, 6 and retinal vessel analyzer 7 have been used for assessment of the pulsatility of retinal BF. In comparison, Doppler optical coherence tomography (DOCT) offers higher sensitivity and provides simultaneously both structural and BF/blood perfusion information about the imaged object, which offers an opportunity to examine the relationship between morphological and BF changes in the retina induced by retinal diseases.…”

“…However, this method requires more complex and expensive design of the OCT system, while precise alignment of the two imaging beams at the same location in the retina can be difficult and time consuming. An alternative approach to measuring absolute retinal BF with DOCT is to utilize a dual-circle scanning pattern 6 and use the location displacement of blood vessels between the two circular OCT scans to calculate the Doppler angle. One limitation of this approach is that it is based on the assumption that the retinal blood vessel runs along a straight line between the two circular OCT scans, which is frequently not the case.…”