Role of corneal elasticity in damping of intraocular pressure.
PURPOSE: To determine corneal elasticity and its contribution in damping acute intraocular pressure spikes. METHODS: Twenty corneas with intact scleral rims were excised from human donor eyes and mounted on an artificial anterior chamber. A watertight seal was obtained with 17 corneas. Saline was infused into the chamber at a rate of 10 mL/h, and subsequent changes in pressure were measured to generate a pressure-volume relationship. Real-time anterior segment OCT was used to measure the change in radius of curvature and corneal thickness in nine eyes. RESULTS: The pressure-versus-volume curves of all corneal-scleral buttons were concave-up asymptotes, demonstrating elasticity. The range of the slope was 0.34 to 1.6 +/- 0.29 mm Hg/microL. The mean change in the radius of curvature in the nine eyes that were visualized by optical coherence tomography (OCT) was 247 +/- 106 microm (range, 168-412 microm). The OCT image was centered on the epithelial surface. In two eyes, the entire cornea was visible by OCT throughout the course of the experiment, and corneal thickness was measured and found to decrease by 116 +/- 4 microm. CONCLUSIONS: Human eye bank corneas demonstrate elasticity ex vivo, with expansion and thinning in response to increases in anterior chamber pressure. These elastic properties may serve as a buffering mechanism for microvolumetric changes in the eye, thus protecting the eye from intraocular pressure surges in vivo.
Johnson, CS; Mian, SI; Moroi, S; Epstein, D; Izatt, J; Afshari, NA
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