Purpose
In order to enhance the clinical utility of 1-μm Jones-matrix multi-contrast optical coherence tomography (MC-OCT), A-scan rate has been increased to 200,000 A-lines/s, which was previously 100,000 A-lines/s. This study aims at evaluating the simultaneous 3D Doppler and polarization imaging ability at the doubled high speed.
Methods
High-speed MC-OCT is capable of full Jones matrix measurement of in vivo human eye. The system does not use active polarization components and based on commercially available 100 KHz wavelength sweeping laser, and hence it is stable. The A-line rate is doubled into 200,000 A-lines by using optical buffering technology. By analyzing the measured Jones matrix tomography, scattering OCT, polarization sensitive images (phase retardation and degree-of-polarization-uniformity (DOPU)) and high-sensitive flow image are obtained. 6 mm × 6 mm areas around macula and optic nerve head (ONH) were scanned with 512 A-scans × 256 B-scans × 4 repeated-scans/B-scan in 3.3 s. The depth resolution was 10.6 μm in tissue. 8 eyes of 4 subjects without marked posterior disorder were measured to evaluate the utility of the MC-OCT.
Results
High-speed MC-OCT gives similar contrast with the images obtained in a previous study with 100,000 A-line/s MC-OCT (Ju, Hong et al., ARVO 2013) even with a reduced measurement time. Figure 1 shows a representative case of myopic eye. In OCT intensity en face projection (a) and cross-section (c), myopic conus appeared with hyper-scattering in 4 of 4 myopic eyes. Choroidal vasculature was observed from power Doppler projection (b) in 8 of 8 eyes. In a phase retardation image (e), lamina cribrosa was identified at the ONH (8 of 8 eyes). RPE layer is identified with a DOPU image (e) as low DOPU line (8 of 8 eyes). By utilizing high-speed A-scan rate, the occurrence of eye motion during the measurement was reduced. Among 16 measurements of 4 subjects, the mean occurrence of quick motion was 1.5 times/volume as exemplified by the red arrow in Fig. 1b, while it was 4.4 times/volume with the data in the previous study with the 100,000 A-lines/s system (20 measurements of 5 subjects, ARVO 2013).
Conclusions
High-speed MC-OCT demonstrated simultaneous structure, flow and RPE-contrast imaging. The reduced measurement time might enhance the clinical utility of MC-OCT with less motion artifact.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
549 image processing