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Sepideh Hariri, Peng Li, Roberto Reif, Murray A Johnstone, Ruikang K Wang; Phase-Sensitive Optical Coherence Tomography for Quantification of Pulse-induced Trabecular Meshwork Movement in ex-vivo Human and Non-human Primate Eyes. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4240.
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© ARVO (1962-2015); The Authors (2016-present)
To use phase-sensitive optical coherence tomography (PhS-OCT) for quantitative assessment of dynamic trabecular meshwork (TM) motion in response to various pressure pulses simulating in-vivo blink and ocular saccades.
A PhS-OCT system was used for imaging the trabecular meshwork region in ex-vivo human and non-human primate eyes. The system is coupled with a broad bandwidth light source centered at 1340nm (∼7.2 μm axial resolution) and a ∼92 KHz A-line rate InGaAs array sensor. An anterior segment perfusion system and a pulse transducer were used to induce and record pressure pulses in the anterior chamber of mounted cadaver eyes. Various baseline intraocular pressure (IOP), pulse frequency and pulse amplitude values were used to investigate the possible effects of these parameters on the TM dynamic response.
Our results show that the TM displacement is increased with the increase of pulse amplitude and is decreased as the baseline IOP is increased. No significant difference was observed in the TM displacement between different pulse frequencies. The analysis of the tissue relaxation curve following the pulses showed marked changes in tissue mechanical response under different IOPs. Figure 1A shows the summarized TM displacement acquired from a non-human primate eye under different baseline IOP and pulse amplitudes, showing the limiting effect of increased IOP on TM response to transient pulses. The tissue relaxation response to 10mmHg pulse under 16 and 32 mmHg baseline IOP are shown in Fig1B, depicting the change in two decay rates (time constant 0.46 s vs. 0.35 s for 16 and 32 mmHg respectively, obtained from exponential fitting). Similar results were observed in the TM of human eyes.
We used a PhS-OCT system to quantify the TM motion in ex-vivo human and non-human primate eyes. Our results show the effectiveness of PhS-OCT for monitoring the functional TM response to changes in IOP, the only treatable glaucoma risk factor. Results from this study could potentially advance our understanding of mechanisms behind abnormal IOP and aid in decision making about management and treatment in glaucoma patients.
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