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Monica Dominique Okon, B. Audrey Nguyen, Cynthia J Roberts; Factors Influencing Change in Central Corneal Thickness with Deformation in Response to an Applied Air-Puff. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4724.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the influence of intraocular pressure (IOP) and stiffness on the percent change in central corneal thickness between the pre-deformation and maximum concavity state of a cornea loaded by an air-puff
Sixteen ex-vivo human eyes from different donors were imaged using the CorVis ST (Oculus, Wetzlar, Germany) at four different IOP levels (10, 20, 30, and 40 mmHg). From each Scheimpflug image, the front and back edges tracked by the CorVis ST software were exported into Matlab. The exported posterior corneal surface is distorted due to the Scheimpflug geometry and the refraction at the anterior corneal surface. Central corneal thickness (CCT) was defined as the difference between the front and corrected back surface of the imaged cornea at the center. CCT was calculated using a ray-tracing correction method for both the pre-deformation and maximum deformation state. Dynamic Response Parameters (DCR) from the CorVis ST were exported by the software. To determine stiffness, a Neo-Hookean model was fitted to data collected from uniaxial corneal strip testing subsequent to Corvis ST measurements. A mixed model analysis was conducted to test the effect of IOP, stiffness, and their interaction on percent change in CCT. Significance threshold was set to p < 0.05.
The mixed model analysis showed that IOP had a significant effect on percent change in CCT (p = 0.045). Stiffness was not a significant predictor (p = 0 .925), nor was the interaction between IOP and stiffness (p = 0.06).
Increasing IOP resulted in a lower percent change in CCT between the undeformed and deformed states of the cornea. This relationship is expected as IOP affects the cornea’s stiffness response due to its nonlinear material properties. Percent change in CCT may reflect corneal compressive properties and might be a potential factor in future studies to detect differences in corneal pathology.
This is a 2020 ARVO Annual Meeting abstract.
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