Finite Element Analysis of Air Gun Impact on Post-Keratoplasty Eye

Kanno Okamura; Asami Shimokawa; Rie Takahashi; Yusuke Saeki; Hiroaki Ozaki; Eiichi Uchio

doi:10.2147/OPTH.S236825

Finite Element Analysis of Air Gun Impact on Post-Keratoplasty Eye

Clin Ophthalmol. 2020 Jan 21:14:179-186. doi: 10.2147/OPTH.S236825. eCollection 2020.

Authors

Kanno Okamura¹, Asami Shimokawa¹, Rie Takahashi¹, Yusuke Saeki¹, Hiroaki Ozaki¹, Eiichi Uchio¹

Affiliation

¹ Department of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, Japan.

Abstract

Purpose: Due to the mechanical vulnerability of eyes that have undergone penetrating keratoplasty (PKP), it is clinically important to evaluate the possibility of corneal wound dehiscence by blunt impact. We have previously developed a simulation model resembling a human eye based on information obtained from cadaver eyes and applied three-dimensional finite element analysis (FEA) to determine the physical and mechanical response to an air gun impact at various velocities on the post-PKP eye.

Methods: Simulations in a human eye model were performed with a computer using a FEA program created by Nihon, ESI Group. The air gun pellet was set to impact the eye at three-different velocities in straight or 12° up-gaze positions with the addition of variation in keratoplasty suture strength of 30%, 50% and 100% of normal corneal strength.

Results: Furthermore to little damage in the case of 100% strength, in cases of lower strength in a straight-gaze position, wound rupture seemed to occur in the early phase (0.04-0.06 ms) of impact at low velocities, while regional break was observed at 0.14 ms after an impact at high velocity (75 m/s). In contrast, wound damage was observed in the lower quadrant of the suture zone and sclera in 12° up-gaze cases. Wound damage was observed 0.08 ms after an impact threatening corneoscleral laceration, and the involved area being larger in middle impact velocity (60 m/s) simulations than in lower impact velocity simulations, and larger damaged area was observed in high impact velocity cases and leading to corneoscleral laceration.

Conclusion: These results suggest that the eye is most susceptible to corneal damage around the suture area especially with a straight-gaze impact by an air gun, and that special precautionary measures should be considered in patients who undergo PKP. FEA using a human eyeball model might be a useful method to analyze and predict the mechanical features of eyes that undergo keratoplasty.

Keywords: air gun; cornea; finite element analysis; keratoplasty; rupture.