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Ruobing Qian, Ryan P McNabb, Anthony N Kuo, Joseph A. Izatt; Anterior Chamber Blood Cell Differentiation Using Spectroscopic Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):273.
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© ARVO (1962-2015); The Authors (2016-present)
There is great clinical importance in identifying cellular responses in the anterior chamber (AC) which can be signs of injury (hyphema – red blood cells (RBCs)) or aberrant intraocular inflammation (white blood cells (WBCs)). Unfortunately, these responses are difficult to recognize, and require specialized equipment, trained specialists, and cooperative patients. In this work, we applied spectroscopic OCT to differentiate RBCs and subtypes of WBCs both in vitro and in the ACs of porcine eyes, with the potential for in vivo application.
Fresh human RBCs and cryopreserved WBCs, including neutrophils, lymphocytes and monocytes (ZenBio) were diluted and suspended in PBS. For in vitro imaging, the suspended cells were placed in glass cuvettes. For porcine eye imaging, suspended cells were injected into the AC of porcine eyes.We utilized a custom 100 kHz swept-source OCT system in this study. Single cells in the consecutive OCT volumes were located and tracked by intensity thresholding. The spectroscopic data of each cell were extracted from the detected interferograms using the Short-time Fourier Transform (STFT) with a Hamming window. The averaged spectroscopic data from the same cell was then normalized based on the laser power spectrum to calculate the final spectrum. A look-up table of Mie theory spectra was generated and used to correlate the spectroscopic data of single cells to their characteristic sizes (likely the sizes of the nucleus for WBCs).
Histogram plots of characteristic sizes and representative spectrum from each type of cell in vitro are shown in Fig. 1. The size distributions were significantly different between each type of cells using the Kruskal-Wallis ANOVA test (p<0.01). There was also no statistically significant difference found between the size distributions of neutrophils in cuvettes and neutrophils injected into porcine eyes (p =0.96, Wilcoxon rank sum test).
Spectroscopic OCT was used to differentiate single RBCs and subtypes of WBCs. Initial studies indicated that each type of blood cells had statistically different size distributions based on the Mie spectra fit, and the initial results of cells in porcine eyes suggest the possibility to differentiate these blood cells in the AC in vivo.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1. Histogram plots of characteristic sizes and representative spectrum extracted from each blood cell type
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