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W.J. Dupps, Jr., R.R. Krueger, B.H. Jeng; Regional Stiffness of Human Donor Corneas Measured by Sonic Wave Elastometry . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1335.
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© ARVO (1962-2015); The Authors (2016-present)
To assess regional differences in the stiffness of the intact human cornea using sonic wave elastometry.
The elastometer (Sonic Eye, PriaVision, Menlo Park CA) measures ultrasonic time–of–flight across a 4.5 mm span of the corneal surface and reports wave velocity in meters per second as an indicator of corneal stiffness. Seven human donor globes were injected with and immersed in 15% dextran solution after epithelial debridement to restore physiologic thickness. A continuous intravitreal pressure of 15 mmHg was maintained by direct infusion. Ten corneal vectors were measured in replicate: central horizontal and vertical vectors, radial vectors in 4 peripheral quadrants, and circumferential vectors just anterior and parallel to the limbus of the same quadrants.
Central corneal thickness by ultrasound pachymetry was 496 ± 64 microns after epithelial debridement and deturgescence. Average regional velocities were 85 ± 7 m/s in the central cornea, 104 ± 15 m/s in the radial periphery and 125 ± 22 m/s in the circumferential periphery (mean ± sd). Central corneal sonic wave velocities were significantly lower than those measured in the radial (p = .01) and circumferential (p = .004) peripheries.
In a normo–tensive, normo–hydrated human donor cornea model, regional stiffness estimated by sonic wave propagation velocity differs between center and periphery. These differences may be referable to regional variations in collagen lamellar interweaving and preferred fibril orientation reported by others and may prove to be important predictors of the cornea’s astigmatic response to surgery and disease.
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