Characterizing Corneal Mechanical Response Using Ocular Pulse Elastograpy
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Date
2019-03
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Abstract
In vivo measurement of corneal biomechanics remains an important and challenging goal. We have developed a method, termed ocular pulse elastography (OPE), to evaluate the cornea’s biomechanical response to the intrinsic cyclic fluctuation of the intraocular pressure (IOP). In this study, we measured corneal deformation induced by ocular pulses in human donor eyes at different simulated ocular pulse amplitudes (OPA), heart rates (HR), and baseline IOP. Our goal was to evaluate how these physiological variations affect corneal biomechanical responses. Ocular pulses were induced via a programmable syringe pump in ten human donor globes. The baseline IOP, HR, and OPA were varied from the nominal condition (15 mmHg, 72 beats per minute (BPM), 3 mmHg, respectively) to baseline IOP= 10 or 20 mmHg, HR= 45 or 100 BPM, or OPA= 1 or 5 mmHg. The deformation of the central 5.7 mm of the cornea was imaged using a 50 MHz ultrasound system at a frame rate of 128 Hz. Through-thickness axial strains were obtained using a speckle tracking algorithm, and a stiffness measure (termed ocular pulse stiffness index, OPSI) was calculated using the IOP-strain data from five pulse cycles. Our results showed that corneal strains were highly dependent on baseline IOP and OPA (p’s<0.05, linear mixed model), but not HR (p’s>0.05, linear mixed model). In contrast, the OPSI was not different in the same eye under different OPA, HR, or baseline IOP (p=0.738, linear mixed models). These results suggest that OPE can reliably measure corneal strains induced by the ocular pulse, and the OPSI may provide a robust and sensitive method for quantifying corneal stiffness in vivo.
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Engineering: 2nd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
corneal biomechanics, corneal strains, IOP, ocular pulse, high frequency ultrasound, ultrasound elastography