Simulation of air-bag impact on post-radial keratotomy eye using finite element analysis.
OBJECTIVE
To determine the physical and mechanical conditions of an impacting air bag that causes corneal rupture in a post-radial keratotomy (RK) eye using a simulation model of the human eye.


METHODS
Numerical simulation study on a computer.


METHODS
The simulations were performed by a computer using the finite element analysis program PAM-CRASH (Nihon ESI). The air bag was set to impact the surface of a post-RK eye with 4, 6, or 8 corneal incisions at various velocities. Strain on the corneal tissue including scarred incisions exceeding 9.0% was assumed to indicate the possibility of corneal rupture.


RESULTS
At a medium velocity of 30 m/s, corneal rupture was likely to occur. At an air-bag impact velocity of 40 m/s, 3 of 4, 5 of 6, and 8 of 8 incisions were likely to rupture in the case of 4-, 6-, and 8-incision procedures, respectively, leading to likely globe rupture in all situations. Lacerations extended beyond the incisions and involved the intact cornea at a velocity of 40 m/s. If the corneal tissue strength reduction was increased to 90%, most incisions were likely to rupture at impact velocities greater than 35 m/s in all incision procedures.


CONCLUSIONS
The results could partly reflect a reported case of globe rupture after RK and suggest that severe ocular trauma can be caused in the post-RK eye by air bags at ordinary impact velocities.
Uchio
E
E
Department of Ophthalmology, Yokohama City University School of Medicine, Yokohama, Japan.
Ohno
S
S
Kudoh
K
K
Kadonosono
K
K
Andoh
K
K
Kisielewicz
L T
LT
D017278:Air Bags / Q000009:adverse effects*; D003198:Computer Simulation; D003315:Cornea / Q000601:surgery; D065306:Corneal Injuries; D005131:Eye Injuries / Q000209:etiology*; D020342:Finite Element Analysis; D006801:Humans; D007646:Keratotomy, Radial; D008954:Models, Biological; D012421:Rupture; D013529:Surgical Wound Dehiscence / Q000209:etiology*