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Chen Xin, Murray A Johnstone, Shaozhen Song, Steven Padilla, Ruikang K Wang; High-Resolution OCT Platform to Characterize TM Stiffness Relevant to Glaucoma. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4704.
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© ARVO (1962-2015); The Authors (2016-present)
Trabecular meshwork (TM) stiffness and the nature of its change in glaucoma remain an enigma. Our study describes the capabilities of a new optical coherence tomography (OCT) platform for characterization of TM stiffness.
Four quadrants were prepared from 1 normal nemestrina primate eye (24 years) and 1 human pseudoexfoliation eye (70 years). An OCT system with spatial resolution of 7 µm and temporal resolution of 1.25 milliseconds was used to acquire 2D and 3D images with the TM surface facing the beam. The platform consists of a spectral domain OCT, a perfusion unit, a pressure sensor reading unit, and a triggered valve. (Fig. 1) A trigger signal was sent to synchronize initiation of OCT scanning and pressure sensor reading followed by triggering of the valve switching between 2 reservoirs, one with pressure at zero and the other with pressure of 5, 10, 20, 30, 40 and 50 in both ascending and descending sequences. Instantaneous volumes of Schlemm’s canal (SC) were assumed to be the mean area between frames. Steady state maximum volume vs. pressure was used to develop an elastance curve. For each pressure sequence, both the time course and the rise time of the change in SC area were recorded.
3D reconstructions showed marked changes in shape of SC and collector channel dimensions in response to static increases in pressure, observations consistent with quantitative results. Each eye’s elastance curve was determined (Fig. 2A). The slope of the time dependent change in SC area in the ascending sequence were 0.056, 0.057, 0.037, 0.032, 0.029, 0.026 in the primate eye, and 0.0906, 0.1242, 0.0946, 0.0808, 0.0689, 0.0593 in the human eye. For the descending sequence, the slopes were 0.0917, 0.0784, 0.0466, 0.0469, 0.0469, 0.0567 in the primate eye and 0.1289, 0.1006, 0.0946, 0.0763, 0.0519, 0.0807 in the human eye. All the corresponding r2 values were over 0.85. Both distention and recoil time of the change in SC area at each pressure gradient is summarized in Fig. 2B.
Our new high-resolution OCT platform is useful to characterize the TM stiffness as a tissue unit, a bulk motion behavior with properties similar to those present in vivo.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Fig. 1 Schematic diagram of the new OCT platform
Fig. 2 Elastance curve (A) and Rise time (B) for primate and human eye.
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