Air Puff Induced Corneal Vibrations: Theoretical Simulations and Clinical Observations

Abstract

PURPOSE: To investigate air puff induced corneal vibrations and their relationship to the intraocular pressure (IOP), viscoelasticity, mass, and elasticity of the cornea based on theoretical simulations and preliminary clinical observations. METHODS:To simulate the corneal movement during air puff deformation, a kinematic viscoelastic corneal model was developed involving the factors of corneal mass, damping coefficient, elasticity, and IOP. Different parameter values were taken to investigate how factors would affect the corneal movements. Two clinical ocular instruments, CorVis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) and the Ocular Response Analyzer (ORA; Reichert, Inc., Buffalo, NY), were employed to observe the corneal dynamical behaviors. RESULTS:Numerical results showed that during the air puff deformation, there would be vibrations along with the corneal deformation, and the damping viscoelastic response of the cornea had the potential to reduce the vibration amplitude. With consistent IOP, the overall vibration amplitude and inward motion depths were smaller with a stiffer cornea.CONCLUSIONS: A kinematic viscoelastic model of the cornea is presented to illustrate how the vibrations are associated with factors such as corneal mass, viscoelasticity, and IOP. Also, the predicted corneal vibrations during air puff deformation were confirmed by clinical observation.[J Refract Surg. 2014;30(3):208-213.]

Transient dynamics of an elastic Hele-Shaw cell due to external forces with application to impact mitigation

“…Corneal air puff tests, which examine the intraocular pressure via an air jet applied on the eye (Han et al 2014), also include a similar configuration of an external pressure applied on an elastic shell laying over a liquid film. Hosoi & Mahadevan (2004) studied the peeling and busting dynamics of a viscous liquid contained between a rigid surface and an elastic sheet.…”

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“…1 Hence, assessing corneal biomechanical properties are required for detecting the onset and monitoring progression of the ocular diseases as well as assessing the effects of therapeutic interventions. Previous studies have shown the feasibility of commercially available instruments such as the ocular response analyzer and the CorVis, 2 and emerging techniques such as Brillouin microscopy 3 for estimating corneal biomechanical properties. Although these methods can provide important measurements that can reflect some corneal biomechanical features, quantitative assessment of the corneal viscoelasticity is still a challenge.…”