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Ruikang Wang, lin an, Peng Li, Murray Johnstone; Pulse-induced Optic Nerve Head Axial Movement: Characterization by Phase-sensitive OCT in Humans. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1712.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate pulse-induced motion of the human optic nerve head (ONH) using high-speed phase-sensitive spectral domain OCT
A phase-sensitive OCT system was developed to image the ONH with an imaging speed of 500 kHz A-scan rate. Phase information was extracted from the OCT signals and employed as a sensitive quantitative tool for assessing pulse-induced axial ONH movement. Pulsatile blood flow from the central retinal artery (CRA) was simultaneously imaged permitting correlation with ONH movement. Normal subjects (N=5) participated in the study.
Each subject exhibited pulse-induced ONH axial movement with a mean magnitude of 3.5±0.8 µm and a fundamental frequency of 1.2±0.2 Hz. ONH movement was 100% negatively correlated with the CRA pulse peak. Figure shows typical results from one subject: (a) typical structural OCT image encompassing the ONH (temporal-nasal section) and adjacent retina. (b) Corresponding phase-sensitive image. (c) Dynamic ONH velocity map over ~5 sec: the ONH movement exhibits an obvious pulsatile pattern (right side of image). (d) Corresponding displacement map of the ONH, obtained by integrating (c) over the time t. (e) The velocity curve of pulse-induced ONH movement extracted from the position marked by the black line in (c) and the yellow line in (a). Note the y-axis required reversal. (f) Frequency analysis of (e), indicating a fundamental frequency of 1.2 Hz (in this case), and the higher order harmonics (e.g. 2nd and 3rd harmonics) also present. (g) and (h) Corresponding ONH displacement curve (max magnitude = 3.6 µm) and frequency analysis. (l) and (m) OCT structural image (superior-inferior section) and the corresponding blood flow map, indicating retinal artery measured (circled). (n) and (o) Measured pulsatile blood flow pattern from the CRA (5 sec duration) and the corresponding frequency analysis, indicating 100% correlation with ONH movement.
The high-speed, phase-sensitive OCT system successfully documented pulse-induced axial ONH movement that was 100% negatively correlated with the CRA pulse peak. Characterization of ONH movement permits assessment of mechanical compliance, an important property that may have mechanistic, diagnostic and prognostic significance in management of glaucoma.
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