Abstract
Biomechanical properties are important for the cornea to maintain its normal shape and function. There is still a need to develop better methods for accurate measurement of corneal mechanical properties. In this study, we propose to introduce the optical coherence tomography (OCT) in inflation test for the imaging of corneal deformation in order to measure its biomechanical properties. Ten cornea-mimicking silicone phantoms with different stiffness and five fresh porcine corneas were tested using the proposed method. Intra-ocular pressure was changed from 10 to 90 mmHg using two different loading rates to observe the pressure-apex displacement relationship and calculate the apparent stiffness of the corneas. Stiffness of the corneal phantoms obtained by the inflation test ranged from 0.2 to 1 MPa, which was highly consistent with the results from the mechanical tensile test (y = 0.70x, p < 0.001). The porcine corneas showed highly viscoelastic behavior with obvious hysteresis in inflation. The apparent stiffness of the porcine corneas was 0.63 ± 0.07 and 1.05 ± 0.08 MPa with loading rates of 3.3 and 33 mmHg/min, respectively. Mapping of corneal surface displacement was also generated for both the phantom and porcine corneas. This study showed that it is feasible to incorporate the high resolution OCT imaging in inflation test to measure the biomechanical properties of the cornea.
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References
Anderson, K., A. El-Sheikh, and T. Newson. Application of structural analysis to the mechanical behaviour of the cornea. J. R. Soc. Interface 1:3–15, 2004.
Andreassen, T. T., A. H. Simonsen, and H. Oxlund. Biomechanical properties of keratoconus and normal corneas. Exp. Eye Res. 31:435–441, 1980.
Boschetti, F., V. Triacca, L. Spinelli, and A. Pandolfi. Mechanical characterization of porcine corneas. J. Biomech. Eng.-Trans. ASME 134:031003, 2012.
Boyce, B. L., J. M. Grazier, R. E. Jones, and T. D. Nguyen. Full-field deformation of bovine cornea under constrained inflation conditions. Biomaterials 29:3896–3904, 2008.
Chao, C. Y., G. Y. Ng, K. K. Cheung, Y. P. Zheng, L. K. Wang, and G. L. Cheing. In vivo and ex vivo approaches to studying the biomechanical properties of healing wounds in rat skin. J. Biomech. Eng.-Trans. ASME 135:101009, 2013.
Dorronsoro, C., D. Pascual, P. Pérez-Merino, S. Kling, and S. Marcos. Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas. Biomed. Opt. Express 3:473–487, 2012.
Dubbelman, M., H. A. Weeber, R. G. L. van der Heijde, and H. J. Volker-Dieben. Radius and asphericity of the posterior corneal surface determined by corrected Scheimpflug photography. Acta Ophthalmol. Scand. 80:379–383, 2002.
Dupps, W. J., and S. E. Wilson. Biomechanics and wound healing in the cornea. Exp. Eye Res. 83:709–720, 2006.
Elsheikh, A., D. Alhasso, and P. Rama. Biomechanical properties of human and porcine corneas. Exp. Eye Res. 86:783–790, 2008.
Elsheikh, A., B. Geraghty, P. Rama, M. Campanelli, and K. M. Meek. Characterization of age-related variation in corneal biomechanical properties. J. R. Soc. Interface 7:1475–1485, 2010.
Elsheikh, A., D. F. Wang, M. Brown, P. Rama, M. Campanelli, and D. Pye. Assessment of corneal biomechanical properties and their variation with age. Curr. Eye Res. 32:11–19, 2007.
Elsheikh, A., D. F. Wang, and D. Pye. Determination of the modulus of elasticity of the human cornea. J. Refract. Surg. 23:808–818, 2007.
Ford, M., W. J. Dupps, N. Huprikar, R. Lin, and A. M. Rollins. OCT corneal elastography by pressure-induced optical feature flow. In: Ophthalmic Technologies XVI, edited by F. Manns, P. G. Soderberg and A. Ho. Bellingham: SPIE-Int Soc Optical Engineering, 2006, pp. 1380.
Ford, M. R., W. J. Dupps, A. M. Rollins, A. S. Roy, and Z. L. Hu. Method for optical coherence elastography of the cornea. J. Biomed. Opt. 16:016005, 2011.
Gatzioufas, Z., and B. Seitz. Determination of corneal biomechanical properties in vivo: a review. Mater. Sci. Technol. 31:188–196, 2015.
Grulkowski, I., M. Gora, M. Szkulmowski, I. Gorczynska, D. Szlag, S. Marcos, A. Kowalczyk, and M. Wojtkowski. Anterior segment imaging with Spectral OCT system using a high-speed CMOS camera. Opt. Express 17:4842–4858, 2009.
Hall, T. J., M. Bilgen, M. F. Insana, and T. A. Krouskop. Phantom materials for elastography. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 44:1355–1365, 1997.
Hjortdal, J. Ø. Regional elastic performance of the human cornea. J. Biomech. 29:931–942, 1996.
Hon, Y., and A. K. C. Lam. Corneal deformation measurement using Scheimpflug noncontact tonometry. Optom. Vis. Sci. 90:E1–E8, 2013.
Huang, D., Y. Li, and S. Radhakrishnan. Optical coherence tomography of the anterior segment of the eye. Ophthalmol. Clin. North Am. 17:1–6, 2004.
Huang, Y. P., S. Z. Wang, S. Saarakkala, and Y. P. Zheng. Quantification of stiffness change in degenerated articular cartilage using optical coherence tomography-based air-jet indentation. Connect. Tissue Res. 52:433–443, 2011.
Huang, Y. P., Y. P. Zheng, S. Z. Wang, Z. P. Chen, Q. H. Huang, and Y. H. He. An optical coherence tomography (OCT)-based air jet indentation system for measuring the mechanical properties of soft tissues. Meas. Sci. Technol. 20:015805, 2009.
Kling, S., and S. Marcos. Effect of hydration state and storage media on corneal biomechanical response from in vitro inflation tests. J. Refract. Surg. 29:490–497, 2013.
Kling, S., L. Remon, A. Perez-Escudero, J. Merayo-Lloves, and S. Marcos. Corneal biomechanical changes after collagen cross-linking from porcine eye inflation experiments. Invest. Ophthalmol. Vis. Sci. 51:3961–3968, 2010.
Kotecha, A. What biomechanical properties of the cornea are relevant for the clinician? Surv. Ophthalmol. 52:S109–S114, 2007.
Kovesi, P. Symmetry and asymmetry from local phase. In: Tenth Australian Joint Conference on Artificial Intelligence, pp. 185–190, 1997.
Li, T., L. Tian, L. Wang, Y. Hon, A. K. Lam, Y. Huang, Y. Wang, and Y. Zheng. Correction on the distortion of Scheimpflug imaging for dynamic central corneal thickness. J. Biomed. Opt. 20:56006, 2015.
Lu, M. H., Y. P. Zheng, and Q. H. Huang. A novel method to obtain modulus image of soft tissues using ultrasound water jet indentation: a phantom study. IEEE Trans. Biomed. Eng. 54:114–121, 2007.
Luce, D. A. Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J. Cataract. Refract. Surg. 31:156–162, 2005.
Nguyen, T. M., B. Arnal, S. Z. Song, Z. H. Huang, R. K. Wang, and M. O’Donnell. Shear wave elastography using amplitude-modulated acoustic radiation force and phase-sensitive optical coherence tomography. J. Biomed. Opt. 20:016001, 2015.
Nguyen, T. D., and B. L. Boyce. An inverse finite element method for determining the anisotropic properties of the cornea. Biomech. Model. Mechanobiol. 10:323–337, 2011.
Osman, I. M., H. A. Helaly, M. Abdalla, and M. Abou. Shousha. Corneal biomechanical changes in eyes with small incision lenticule extraction and laser assisted in situ keratomileusis. BMC Ophthalmol. 16:123, 2016.
Pai, S., and W. R. Ledoux. The compressive mechanical properties of diabetic and non-diabetic plantar soft tissue. J. Biomech. 43:1754–1760, 2010.
Pérez-Escudero, A., C. Dorronsoro, L. Sawides, L. Remón, J. Merayo-Lloves, and S. Marcos. Minor influence of myopic laser in situ keratomileusis on the posterior corneal surface. Invest. Ophthalmol. Vis. Sci. 50:4146–4154, 2009.
Ramos, J. L. B., Y. Li, and D. Huang. Clinical and research applications of anterior segment optical coherence tomography: a review. Clin. Exp. Ophthalmol. 37:81–89, 2009.
Rosales, P., and S. Marcos. Pentacam Scheimpflug quantative imaging of the crystalline lens and intraocular lens. J. Refract. Surg. 25:421–428, 2008.
Roy, A. S., and W. J. Dupps. Effects of altered corneal stiffness on native and postoperative LASIK corneal biomechanical behavior: a whole-eye finite element analysis. J. Refract. Surg. 25:875–887, 2009.
Tanter, M., D. Touboul, J. L. Gennisson, J. Bercoff, and M. Fink. High-resolution quantitative imaging of cornea elasticity using supersonic shear imaging. IEEE Trans. Med. Imaging 28:1881–1893, 2009.
Tian, L., Y. F. Huang, L. Q. Wang, H. Bai, Q. Wang, J. J. Jiang, Y. Wu, and M. Gao. Corneal biomechanical assessment using corneal visualization Scheimpflug technology in keratoconic and normal eyes. J. Ophthalmol. 2014:147516, 2014.
Wang, L. K., Y. P. Huang, L. Tian, C. S. Kee, and Y. P. Zheng. Measurement of corneal tangent modulus using ultrasound indentation. Ultrasonics 71:20–28, 2016.
Wollensak, G., E. Spoerl, and T. Seiler. Stress-strain measurements of human and porcine corneas after riboflavin–ultraviolet-A-induced cross-linking. J. Cataract. Refract. Surg. 29:1780–1785, 2003.
Yu, J. G., F. J. Bao, Y. F. Feng, C. Whitford, T. Ye, Y. B. Huang, Q. M. Wang, and A. Elsheikh. Assessment of corneal biomechanical behavior under posterior and anterior pressure. J. Refract. Surg. 29:64–70, 2013.
Acknowledgments
This study was partly supported by grants from the National Natural Science Foundation of China (31600758), Beijing Natural Science Foundation (7174287), Beijing Nova Program (xx2018076) and Beijing Municipal Administration of Hospitals’ Youth Programme (QMS20170204). The authors would like to thank Ms. Sally Ding for editing the manuscript. No conflict of interest exists.
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Associate Editor Tingrui Pan oversaw the review of this article.
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Wang, L., Tian, L., Huang, Y. et al. Assessment of Corneal Biomechanical Properties with Inflation Test Using Optical Coherence Tomography. Ann Biomed Eng 46, 247–256 (2018). https://doi.org/10.1007/s10439-017-1973-7
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DOI: https://doi.org/10.1007/s10439-017-1973-7