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Shaozhen SONG, Murray A Johnstone, Chen Xin, Joanne C Wen, Tueng Shen, Ruikang K Wang; Tracking pulsatile motion of trabecular meshwork(TM) and collector channel entrances (CCE) in vivo in human subjects with PhS-OCT. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4682. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Tissue stiffness changes that alter aqueous outflow system (AOS) tissue motion have been implicated as factor in the IOP elevation in glaucoma. We report a technique for in vivo imaging & quantitation of AOS micro-scale motion in humans.
Human subjects (12), Mean age: (32.7±8.27), F/M: 7/5, Race: Asian (12). Both eyes of each subject imaged. Laboratory prototype spectral domain, phase-sensitive OCT (PhS-OCT) system; Scan rate: 400 frames per second. The imaging system provides high-resolution and high frame rate structural images and micro-motion videos with typical sensitivity of ~0.31 nm. A new algorithm removes background in vivo tissue motion and enhances detection of TM and CCE motion. A trigger synchronizes a digital pulsimeter with OCT images permitting synchronous analysis of the pulse and TM tissue motion. Displacement amplitudes of the TM and CCE are determined from the time sequence of PhS-OCT imaging data.
In each of 12 subjects TM motion synchronous with the pulse was apparent in color-coded displacement videos. Some typical displacement images when TM reaches maximum amplitude are seen in Fig.1 (a). TM maximum displacement was 0.37±0.05 um. In some subjects, synchrony of the pulse with not only TM, but also CCE motion was apparent on displacement maps. Tissue motion recordings indicate TM and CCE motion are synchronous with the cardiac pulse but with phase delays (Fig.1 (b)); such delays may provide information about wave propagation through the tissues and additional algorithm to analyze phase relationships are under development.
Our prototype PhS-OCT system incorporates protocols and algorithms that permit in vivo observation of TM and CCE motion in human subjects. The premise that tissue motion is essential to regulation of IOP homeostasis has support from both laboratory and clinical studies. Studies also implicate increased tissue stiffness as a factor leading to IOP elevation in glaucoma. We demonstrate that PhS-OCT permits imaging and quantifying AOS motion. As OCT imaging technologies continue to advance, in vivo monitoring of pulse-dependent AOS tissue motion may become useful in diagnosis as well as medical and surgical decisions in glaucoma management.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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