Eye Globe Case Study

In the current study the eye globes (Figure 1a) were removed from the human cadavers and employed for further experimental measurements. After removing the eyes from the cadavers, a set of MRI/CT images were taken according to the purpose we had to have a clear image of eye components and its dimensions. The images were then used to make a FE model of the eye based on the MRI/CT data as presented in Figure 1b. Thereafter, in order to have a smoother FE model to be able to mesh its components, the model was inputted into the FE packages and, consequently, a smoother model was prepared (Figure 1c). Finally, the model was inputted into the dynamic FE solver to simulate the problem according to the materials, contacts, and boundary conditions we
The process was carried out as a screw at eight different speeds ranged from the 5 to 500 mm/min hit the cornea, which is located in the apex of the eye globe, thereafter, the amount of load as well as the displacement on that were recorded via a 50 kgf load cell and an extensometer, respectively. The results showed that by increasing the rate of load on the globe the amount of displacement before the failure is decreasing. That is, the eye globe was failed in 17 mm at the strain rate of 5 mm/min while by increasing the rate of load to 500 mm/min the amount of displacement was decreased to 5.20 mm. It implies the significant load rate dependency of the eye globe before the rupture occurs. In addition, it implies that at a higher load rate the time or in the other words the displacement that the globe bears up to the breakage is decreasing. Although there are some scattering effects due to the nature of the eye globe, the results illustrated that a higher strain can lead to a lower displacement while a higher stress failure. This mechanical behavior is common among the soft biological tissues since, for instance, the coronary arteries also showed a
The reason of doing the tests under various loading rates was that during the impact to the eye, especially the blunt one, various rates of loading may impose different amount of injuries, stresses and deformations, to the eye. Therefore, in the concurrent research the authors tried to shed light on this issue to find the correlation of load speeds and stress failure of the eye globe.
A FE study on the interaction of the goggle and the eye during the air-bag opening process as well as the FE study on the globe rupture revealed the stress of 10.8 MPa [28] and 9.40 MPa [10] on the cornea which is in good agreement with the amount of stress we observed at the strain rate of 50 mm/min with 7.4 MPa found in the current