Table 6.
Characteristics of the porcine cornea in comparison with the human.
| Breed of pig | Pig data | Pig Age (months) | Human data | Human Age (years) | ||||
|---|---|---|---|---|---|---|---|---|
| Central Thickness (μm) | Danish Landrace (WT) | 666 ± 68 | 3.5 | 527 ± 34 | 57.9 ± 10.8 | |||
| Wally Whippo (WT) | 722 ± 5 | 2–3.8 | ||||||
| 995 ± 10 | 42 | |||||||
| SNU miniature (WT) | 833 ± 66 | 41.7 ± 18.7 | ||||||
| GE (Revivicor) | 659 ± 31 | 1.5 | ||||||
| 914 ± 25 | 20–25 | |||||||
| Tensile strength (MPa) | 3.7 ± 0.2 | NA | 3.8 ± 0.4 | NA | ||||
| Median shear modulus (kPa)a | Danish Crown (WT) | 0.34 | NA | 2.0 | 53 ± 14 | |||
| Young's modulus (MPa) | WT | 0.22ζ | 4–6 | 0.29ζ | 50–64 | |||
| 0.30ζζ | 0.43ζζ | |||||||
| Stress-strain relationshipb | α | WT | 39.3 ± 11.0 | NA | 42.8 ± 11.7 | NA | ||
| β | 2.97 ± 0.2 | 2.97 ± 0.2 | ||||||
| Stress-relaxationc | P (X100) | WT | 64.6 ± 3.3 | NA | 85.6 ± 1.5 | NA | ||
| K (−) | 0.055 ± 0.007 | 0.017 ± 0.002 | ||||||
| Average stress reduction (%)d | WT | 49.2 ± 8.3 | 4–6 | 27.7 ± 5.6 | 76 ± 6 | |||
| The ratio of average creep strain (%) | WT | 42 | 4–6 | 49 | 58 ± 6 | |||
| Swell pressure (mmHg) | Danish Crown (WT) | 45e | NA | 84f | NA | |||
| Refractive Power (Diopter) | Sus scrofa domestica (WT) | 40.0 ± 2.3 | 6–8 | 43.7 ± 1.6 | 55 ± 11 | |||
| SNU miniature (WT) | 36.5 ± 1.8 | 41.7 ± 18.7 | ||||||
| GT-KO miniature (GE) | 43.2 ± 6.1 | 11.3 ± 3.4 | ||||||
| Endothelial cell density (/mm2) | Wally Whippo (WT) | 3093 ± 285 | 5–10 | 2720 ± 364g | 40–75 | |||
| GE (Revivicor) | 3022 ± 258 | 15 | ||||||
| SNU miniature (WT) | 2647 ± 32 | 32 ± 15 | ||||||
| Wally Whippo (WT) | 2130 ± 194 | 42 | ||||||
| GE (Revivicor) | 1714 ± 19 | 20–25 | ||||||
Abbreviations: GE: genetically-engineered, NA: not available, WT: wild-type.
The ratio of average creep strain at 300 and 1000 s between pig and human showed statistical significance (Elsheikh et al., 2008).
Young's modulus was measured by inflation test per 20 mm Hgζ or 40 mm Hgζζ (Elsheikh et al., 2008).
Median shear modulus (kPa) at 5% axial Compression with full-hickness porcine cornea and 0% axial compression with full-thickness human cornea (Sondergaard et al., 2013a).
α is scale factor and β is the exponent of the nonlinear relationship between stress and strain using the strip extensiometry method (Zeng et al., 2001).
P (X100) is the value of G(t) at the end of the stress-relaxation test, K is the slope of fitted G(t)-ln t line, and both data were statistically significant between pig and human (Zeng et al., 2001).
Average loss of initial stress after 400s in Stress-relaxation behavior (Elsheikh et al., 2008).
The swelling pressure in the full-thickness porcine corneas at 0% compression, at 760 μm (Sondergaard et al., 2013b).
The swelling pressure at a standard stromal thickness of 500 μm (Han et al., 2015; Olsen and Sperling, 1987).
In vivo human data with non-contact specular microscopy (Snellingen et al., 2001).