Fig 1.
A. Model cornea made out of hydrophilic contact lens material. B. Model cornea mounted in artificial eye chamber.
Table 1.
Physical properties of Model Corneas (from manufacturer).
Fig 2.
Schematic of the air puff test configuration.
Fig 3.
Cross-sections of a MC (S2, A-B) and a porcine cornea (C-D). A and C. Before the air puff deformation. B and D. At highest concavity
Fig 4.
Spatial and temporal deformation profiles.
A. Spatial deformation profile of Model Cornea Saphir 1 (Solid line). Dashed line shows the initial shape of the MC. B. Temporal deformation profile for the same MC. Deformation parameters are indicated: Central Deformation Amplitude (DA, in green), Peripheral Deformation Amplitude (PDA, in red), Time to Highest Concavity (THC, in blue).
Table 2.
Air puff deformation parameters from Corvis ST.
Fig 5.
Flowchart of the inverse modeling process to retrieve the material parameters from air puff corneal deformation measurements.
Fig 6.
FE model of the model eye with the applied boundary conditions.
Fig 7.
Experimental Deformation amplitude (DA) and Central-Peripheral Deformation Ration (CPR) from Corvis ST air puff tests, for all model corneas and the two porcine corneas.
Fig 8.
Inherent material properties C10 and C01 for model corneas of three different materials (G, S, Q) and porcine corneas (P).
Error bars stand for the standard deviation of estimates from corneas of different thicknesses in the model corneas, and for the standard deviation across corneal samples.
Fig 9.
Spatial (left) and temporal (right) deformation profiles for three model corneas and three thicknesses; and the porcine corneas.
A, B: Material G; C, D: Material S; E, F: Material Q; G, H: Porcine (P1 and P2). Black lines represent the initial profile; yellow, blue and red represent the 1, 2 and 3 MC thicknesses (350, 450, 550 μm), respectively. Green and Purple lines represent the two porcine corneas. Dotted lines stand for the measured profile and solid lines stand for the simulated profile using the reconstructed material parameters.
Fig 10.
Stress-strain curves of the MC materials and porcine corneas by the inverse modeling from air-puff measurements and from uniaxial extensiometry measurements.
A: Material G; B: Material S; C: Material Q; D: Porcine corneas.
Fig 11.
Equivalent Young's moduli from stress-strain measured and simulated stress-strain curves.
Simulated curves use material properties obtained from inverse modeling from air puff data at different thicknesses. Error bars in the simulation data represent the standard deviation across the parameter values from air puff deformation based estimates on corneal samples of different thicknesses. Error bar in measurement data of the porcine cornea (P) represent the standard deviation across samples (n = 2).