Table 3. Corneal biomechanical parameters obtained from finite element analysis: Elasticity modulus represents the static material properties; The difference between anterior and posterior cornea describes the differences in collagen interweaving and the resulting higher anterior corneal rigidity; The relaxation time – which must lie within the temporal scale that was analyzed – describes the point of time at which the corneal stiffness decreased by the factor of the relative modulus; The muscle spring and damping constants describe the static and dynamic displacement, respectively, due to whole the eye movement in in vivo measurements.
Human | Porcine | |
Condition | virgin | cross-linked |
Elasticity modulus (Mpa)posterior cornea | 0.40 | 0.85 |
Difference between anterior and posterior | 1.12 | 30 |
Relaxation time (ms) | 10 | 1.5 |
Relative modulus | 0.3 | 0.7 |
Muscle spring constant (Nm) | 350 | - |
Muscle damping constant (kg/s) | 100 | - |
The latter two parameters represent accumulated contributions of muscles and fatty tissue and were not further interpreted.