Assessment of the<i>ex vivo</i>biomechanical properties of porcine cornea with inflation test for corneal xenotransplantation

Bao, Fangjun; Jiang, Lu; Wang, X.; Zhang, D.; Wang, Q.; Zeng, Yiming

doi:10.3109/03091902.2011.629276

Cited by 16 publications

(18 citation statements)

References 17 publications

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“…; Bao et al. ). Our measurement set‐up is basically a combination of stress–strain and stress–relaxation testing.…”

Section: Discussionmentioning

confidence: 97%

“…; Bao et al. ). Overall, comparability of the different studies dealing with femtosecond laser‐assisted surgeries remains difficult due to the use of several different laser devices, different baseline IOP levels, different test models (human versus porcine; in vivo versus ex vivo ) and different measurement modalities (direct intracameral manometry versus direct intravitreal manometry versus indirect measurements; Kerr et al.…”

Section: Discussionmentioning

confidence: 97%

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Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser‐assisted cataract surgery

Mariacher

Laubichler

Wendelstein

et al. 2019

Acta Ophthalmologica

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Purpose: To evaluate the effect of preoperative intraocular pressure (IOP) and the vacuum level on IOP during femtosecond laser-assisted cataract surgery. Methods: Intraocular pressure was measured in 40 enucleated porcine eyes by intracameral manometry prior, during and after vacuum application using the VICTUS femtosecond laser platform (Bausch&Lomb, Technolas Perfect Vision GmbH, Germany). Twenty combinations of different preoperative IOP levels (12, 16, 20 and 24 mmHg) and different vacuum levels (350-550 mbar) were investigated. Results: Multivariate regression analysis indicated that both the vacuum level (beta = 0.138; p < 0.001) but much stronger the preoperative IOP (beta = 0.861; p < 0.001) were predictive factors for IOP rise during vacuum application. Mean IOP was 28.23 AE 3.86, 34.23 AE 3.92, 40.35 AE 4.41 and 46.82 AE 4.11 mmHg in groups with baseline IOP of 12, 16, 20 and 24 mmHg, respectively. In the 350, 450 and 550 mbar group, and mean IOP was 35.85 AE 7.85, 37.33 AE 7.90 and 39.00 AE 8.04 mmHg, respectively. Lowering the preoperative IOP by 2 mmHg and reducing the vacuum from maximum to minimum resulted in a similar reduction in IOP during vacuum application (À3.10 AE 0.79 mmHg versus À3.15 AE 0.88 mmHg; p = 0.015). Furthermore, decreasing the baseline IOP from 20 to 12 mmHg resulted in a 30.0% reduction in intraoperative IOP. Conclusion: Preoperative IOP was a stronger predictive factor for intraoperative IOP rise than the applied vacuum level. Measurements and critical interpretation of preoperative IOP in a preliminary examination could help estimating the individual risk of significant IOP rise during femtosecond laser-assisted cataract surgery and could help taking early countermeasures in selected cases. Due to the porcine ex vivo model, further studies are needed to verify these findings.

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“…; Bao et al. ). Our measurement set‐up is basically a combination of stress–strain and stress–relaxation testing.…”

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 97%

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser‐assisted cataract surgery

Mariacher

Laubichler

Wendelstein

et al. 2019

Acta Ophthalmologica

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“…Of note, the association between corneal biomechanical response and IOP has been previously reported in porcine and human eyes ex vivo. Examining 17 porcine eyes under inflation conditions, Bao and colleagues 14 measured the corneal deformation with a laser displacement sensor, estimated Young's modulus of the cornea, and found a linear relationship between Young's modulus and IOP. Elsheikh and colleagues 15 measured the corneal stiffness (expressed in Young's modulus) in 37 human donor corneas using inflation tests and demonstrated that there was a positive linear relationship between Young's modulus and IOP.…”

Section: Discussionmentioning

confidence: 99%

An Ultra-High-Speed Scheimpflug Camera for Evaluation of Corneal Deformation Response and Its Impact on IOP Measurement

Leung

Weinreb

2013

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To investigate the test-retest variability of and factors associated with the corneal deformation response, and evaluate its impact on IOP measurement.METHODS. Forty normal and 140 glaucoma suspect/glaucomatous eyes of 104 individuals were prospectively included for repeated measurements of corneal deformation response by an ultra-high-speed Scheimpflug camera, followed by corneal hysteresis and corneal resistance factor measurements by the ocular response analyzer, and dynamic contour tonometry (DCT) (the reference standard) and Goldmann applanation tonometry (GAT) during the same visit. The test-retest variability of corneal deformation response was evaluated. Univariate and multivariate linear mixed models were used to identify factors (age, manifest spherical refractive error, axial length, IOP, central corneal thickness [CCT], corneal curvature, corneal hysteresis, and corneal resistance factor) associated with corneal deformation response and the difference between DCT and GAT measurements. RESULTS.Corneal deformation amplitude (CDA) had an intraclass correlation coefficient of 0.86. There was no difference in CDA between the glaucoma and nonglaucoma groups. A higher IOP, a younger age, and a greater CCT were associated with a smaller CDA (P 0.002) (n ¼ 180). In the univariate analysis (n ¼ 180), the difference between DCT and GAT measurements was associated with spherical refractive error (P ¼ 0.037), CCT (P ¼ 0.004), and CDA (P < 0.001) after adjusting the effect of IOP (DCT). In the multivariate analysis, the only factor associated with the IOP difference was CDA (P ¼ 0.003).CONCLUSIONS. CDA was a reliable indicator to quantify corneal deformation response. CDA, rather than CCT, was the key source of measurement error of GAT.Keywords: ultra-high-speed Scheimpflug camera, intraocular pressure, corneal deformation response G oldmann applanation tonometry (GAT) is the reference standard for measurement of IOP in clinical practice and clinical trials.1 Although GAT overestimates IOP in healthy eyes with thick corneas and underestimates IOP in healthy eyes with thin corneas, the corneal biomechanical response has been suggested to be more influential than central corneal thickness (CCT) in measuring IOP. 2 In a mathematical simulation model, Liu and Roberts 2 examined the association between IOP and corneal parameters, including CCT, corneal curvature, and corneal elasticity. They showed that normal variation of CCT (443-629 lm) contributed to a difference of only 2.87 mm Hg of predicted GAT IOP measurements. By contrast, variation of corneal elasticity, measured in Young's modulus with an estimated normal range between 0.1 and 0.9 MPa, accounted for a difference of 17.26 mm Hg. This is supported by an experimental study by Dupps and colleagues 3 using sonic wave propagation velocity on the corneal surface as a measure of corneal stiffness. They showed that corneal stiffening after cross-linking in two human globes resulted in a dramatic increase in IOP measured by pneumatonometer (Mentor O&O, Inc., ...

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“…Furthermore, alternatives such as use of synthetic or biosynthetic corneas or use of human stem cells might not represent an alternative for all corneal graft indications . In a such context, porcine corneal xenografts appear as an possible alternative, because the anatomic and biochemical properties of porcine corneas closely resemble those of the human cornea .…”

Section: Introductionmentioning

confidence: 99%

hCTLA4‐Ig transgene expression in keratocytes modulates rejection of corneal xenografts in a pig to non‐human primate anterior lamellar keratoplasty model

Vabres

Bas‐Bernardet

Riochet

et al. 2014

Xenotransplantation

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Assessment of theex vivobiomechanical properties of porcine cornea with inflation test for corneal xenotransplantation

Cited by 16 publications

References 17 publications

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser‐assisted cataract surgery

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser‐assisted cataract surgery

An Ultra-High-Speed Scheimpflug Camera for Evaluation of Corneal Deformation Response and Its Impact on IOP Measurement

hCTLA4‐Ig transgene expression in keratocytes modulates rejection of corneal xenografts in a pig to non‐human primate anterior lamellar keratoplasty model

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