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Yu-Chi Liu, Lin Ke, Ericia Teo, Gary Hin Fai Yam, Jodhbir Mehta; The use of TeraHertz scanning system as a quantitative tool in the evaluation of corneal edema. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3539. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the feasibility and accuracy of using the Terahertz scanning system as a quantitative tool in the evaluation of corneal edema
Compressed collagen sheets that contained different water concentrations ranging from 8% to 92% were first scanned with the TPS Spectra 3000 Teraview Terahertz scanning system. The peak intensity of the curve from the spectral domain was recorded and used to establish the standard curve. Porcine eyes (n = 50) with different extent of corneal edema resulting from different time duration after procurement (0 day to 4 days), were then scanned with the Terahertz and anterior segment optical coherence tomography systems, to obtain the hydration level and central corneal thickness (CCT), respectively. The correlation between the hydration level and CCT was also analyzed.
The Terahertz scanning system had the capacity to differentiate different extents of corneal stromal edema (Figure). For the corneas with the procurement time of 0, 1, 2, 3 and 4 days, the mean peak signal intensity was 159951±5122, 177338±5012, 224761±6223, 250290±5665, and 327236±6368 atomic units, and the corresponding hydration level was 75.3±7.8%, 79.2±6.2%, 84.7±8.2%, 89.7±10.9%, and 96.8±10.1%, respectively. The mean CCT was 682±45, 745±68, 836±48, 1006±66, and 1225±62 μm, respectively. The peak signal intensity was positively and significantly correlated with CCT measurements (r = 0.91, P = 0.002).
The Terahertz scanning system has the potential to provide a novel tool to quantitatively evaluate corneal hydration status. It may be helpful in monitoring the disease progression in patients with corneal edema.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure: Representative scans showing the changes in the Terahertz peak signal intensity in the corneal stroma for continuous 4 days in porcine eyes. A more edematous cornea (4th day > 3rd day > 2nd day > 1st day > 0 day) had higher signal amplitude.
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