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Jonathan Mamou, Kazuyo Ito, Sally A McFadden, Quan V. Hoang; Quantitative ultrasound-based assessment of microstructural change in guinea pig sclera after crosslinking. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3411.
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© ARVO (1962-2015); The Authors (2016-present)
High myopia and glaucoma are leading causes of blindness worldwide, with biomechanical changes likely playing a key role in both diseases. Scleral collagen crosslinking (CXL) has been proposed as potential therapy to alter scleral biomechanics in these diseases. Novel quantitative ultrasound (QUS) methods permit obtaining biomechanical QUS parameters associated with changes in tissue microstructure. Radio-frequency echo data were acquired from the posterior sclera of guinea pigs (GPs) using an 80-MHz US system. QUS parameters were evaluated for their ability at quantifying microstructural changes occurring in the sclera during CXL.
Sixteen intact, normotensive eyes of 13 GPs (2 weeks old) were immersed ex-vivo in either 26mM CXL for 3 hours (G1, n = 6), 26mM CXL for 1 day (G2, n = 5), or 208mM CXL for 1 day (G3, n = 5). Eleven of these eyes (G0) were scanned with QUS prior to CXL to serve as controls. Eyes were placed in PBS and suspended to match their in vivo anatomical position. 3D RF data were collected by scanning the transducer and processed to yield two QUS parameters (Homodyned-K (HK) k and HK μ). ANOVA and Kruskal-Wallis analyses were performed to assess statistical significance between groups.
The average and standard deviation of HK k values were 0.04 ± 0.005 (G1), 0.10 ± 0.06 (G2), and 0.15 ± 0.007 (G3), which means this parameter tends to increase with the strength of cross-linking process. Indeed, the Kruskal-Wallis test demonstrated statistically significant difference between G1 and G3 (p = 0.02). G2 values are in between those of G1 and G3 but were not found to be statistically significant. The values of HK μ did not differ between G0, G1, G2 and G3 (all p > 0.05).
The results indicate that QUS is highly sensitive to the changes occurring the posterior sclera during crosslinking treatment. In the future, QUS methods could be used to monitor and manage myopia patients undergoing CXL treatment to limit the likelihood of developing vision-threatening staphylomas.
This is a 2020 ARVO Annual Meeting abstract.
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