Purpose:
Over 1.9 million eye injuries occur annually in the U.S., resulting in 30,000 cases of blindness. In military, automotive, and sporting safety, there is concern over eye protection and the effects of facial anthropometry differences on risk of eye injury. This study’s objective was to model differing orbital anthropometries to study the biomechanical response of the eye when subjected to a blunt impact.
Methods:
Measurements of the orbital aperture, brow protrusion angle, eye protrusion, and the eye location within the orbit were used to model 27 different orbit anthropometries. Impacts were modeled using an eye model incorporating lagrangian-eulerian fluid flow for the eye, representing a full eye for evaluation of omnidirectional impact and interaction with the orbit. Computational simulations of a Little League (CD25) baseball impact at 30.1 m/s were conducted to assess the effect of orbit anthropometry on eye injury metrics. Parameters measured included stress and strain in the corneoscleral shell, internal dynamic eye pressure, and contact forces between the orbit, eye, and baseball.
Results:
Peak stresses ranged from 11-24 MPa and peak pressure ranged from 0.6-2.4 MPa. Eye response varied significantly with anthropometry. Main effects and interaction effects identified in a statistical analysis illustrate the complex relationship between the anthropometric variation and eye response.
Conclusions:
Results suggest the eye is more protected from impact with smaller orbital apertures (p=0.038), more brow protrusion (p=0.014), and less eye protrusion (p=0.002), provided that the orbital aperture is large enough to deter contact of the eye with the orbit. Results of this study are relevant to the design and regulation of motor vehicle safety systems and eye protection equipment for sports and military applications.
Keywords: trauma • computational modeling • orbit