Biomechanics of the Human Posterior Sclera: Age- and Glaucoma-Related Changes Measured Using Inflation Testing

Coudrillier, Baptiste; Tian, Jing; Alexander, Stephen; Myers, Kristin M.; Quigley, Harry A.; Nguyen, Thao D.

doi:10.1167/iovs.11-8009

Cited by 280 publications

(373 citation statements)

References 34 publications

(42 reference statements)

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“…Ageing might change the scleral tissue, especially through the addition of non-enzymatic cross-links, in such a way that the tissue softening due to s-GAG degradation is inhibited. This might explain why the results surprisingly follow the same trend as the overall stiffer mechanical behaviour measured in human [15] and experimental [16] glaucoma. Interestingly, another study on human myopic eyes showed an increased strain at maximum pressure and a decreased GAG content compared with normal eyes [18].…”

Section: Discussionsupporting

confidence: 76%

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The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera

Murienne

Chen

Quigley

et al. 2016

J. R. Soc. Interface.

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We characterized the structural and mechanical changes after experimental digestion of sulfated glycosaminoglycans (s-GAGs) in the human posterior sclera, using ultrasound thickness measurements and an inflation test with three-dimensional digital image correlation (3D-DIC). Each scleral specimen was first incubated in a buffer solution to return to full hydration, inflation tested, treated in a buffer solution with chondroitinase ABC (ChABC), then inflation tested again. After each test series, the thickness of eight locations was measured. After enzymatic treatment, the average scleral thickness decreased by 13.3% ( p , 0.001) and there was a stiffer overall stress-strain response ( p , 0.05). The stress-strain response showed a statistically significant increase in the low-pressure stiffness, high-pressure stiffness and hysteresis. Thus, s-GAGs play a measurable role in the mechanical behaviour of the posterior human sclera.

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Section: Discussionsupporting

confidence: 76%

“…Preconditioning cycles were not performed. A previous study showed that the effects of preconditioning are negligible for repeated inflation testing of the posterior sclera [15,64]. The inflation chamber was enclosed in a clear Perspex humidity chamber with 90% humidity to prevent dehydration of the specimens during testing (figure 1a,b).…”

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confidence: 99%

The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera

Murienne

Chen

Quigley

et al. 2016

J. R. Soc. Interface.

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“…Peripapillary sclera has been extensively investigated, because it is known to play an important role in the deformation of lamina cribrosa [47]. Since the stiffness of the peripapillary sclera of glaucomatous eyes was different from that of normal eyes in the cases of experimental monkeys and postmortem humans [7][8][9][10], it is likely that the stiffness of the peripapillary sclera is related to the progression of glaucoma. In the future, it would be interesting to investigate birefringence of peripapillary sclera in normal and glaucomatous eyes using PS-OCT especially designed for posterior segment imaging [28,48,49].…”

Section: Discussionmentioning

confidence: 99%

“…Although the alignment of scleral collagen fibers in glaucomatous eyes is not known well, Pijanka et al reported that sclerae of some glaucomatous eyes had decreased fiber anisotropy of collagen fibers in two quadrant sectors around the optic nerve head [6]. The stiffness of the peripapillary sclera of glaucomatous eyes was different from that of normal eyes in the cases of experimental monkeys and postmortem humans [7][8][9][10]. Glaucomatous human eyes had lower density of collagen fibers in peripapillary sclera than that of normal human eyes [11].…”

Section: Introductionmentioning

confidence: 99%

Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo

Yamanari

Nagase

Fukuda

et al. 2014

Biomed. Opt. Express

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Abstract:The relationship between scleral birefringence and biometric parameters of human eyes in vivo is investigated. Scleral birefringence near the limbus of 21 healthy human eyes was measured using polarizationsensitive optical coherence tomography. Spherical equivalent refractive error, axial eye length, and intraocular pressure (IOP) were measured in all subjects. IOP and scleral birefringence of human eyes in vivo was found to have statistically significant correlations (r = −0.63, P = 0.002). The slope of linear regression was −2.4 × 10 −2 deg/μm/mmHg. Neither spherical equivalent refractive error nor axial eye length had significant correlations with scleral birefringence. To evaluate the direct influence of IOP to scleral birefringence, scleral birefringence of 16 ex vivo porcine eyes was measured under controlled IOP of 5−60 mmHg. In these ex vivo porcine eyes, the mean linear regression slope between controlled IOP and scleral birefringence was −9.9 × 10 −4 deg/μm/mmHg. In addition, porcine scleral collagen fibers were observed with second-harmonic-generation (SHG) microscopy. SHG images of porcine sclera, measured on the external surface at the superior side to the cornea, showed highly aligned collagen fibers parallel to the limbus. In conclusion, scleral birefringence of healthy human eyes was correlated with IOP, indicating that the ultrastructure of scleral collagen was correlated with IOP. It remains to show whether scleral collagen ultrastructure of human eyes is affected by IOP as a long-term effect. ©2014 Optical Society of America References and links1. N. A. McBrien and A. Gentle, "Role of the sclera in the development and pathological complications of myopia," Prog. Retin. Eye Res. 22(3), 307-338 (2003). 2. C. F. Burgoyne, J. C. Downs, A. J. Bellezza, J. K. Suh, and R. T. Hart, "The optic nerve head as a biomechanical structure: a new paradigm for understanding the role of IOP-related stress and strain in the pathophysiology of glaucomatous optic nerve head damage," Prog. Retin. Eye Res. 24(1), 39-73 (2005). 3. J. A. Rada, S. Shelton, and T. T. Norton, "The sclera and myopia," Exp. Eye Res. 82(2), 185-200 (2006). 4. J. T. Siegwart, Jr. and T. T. Norton, "Regulation of the mechanical properties of tree shrew sclera by the visual environment," Vision Res. 39(2), 387-407 (1999 1714-1728 (2012) C. So, and C.-Y. Dong, "Multiphoton autofluorescence and second-harmonic generation imaging of the ex vivo porcine eye," Invest.

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“…11 Coudrillier et al also reports that older age was predictive of a stiffer response for the posterior sclera. 24 Using their regression line, the stiffness increased from 500 kPa (0.5 N/m 2 Â 10 6 ) at age 45 years to 4000 kPa (4 N/m 2 Â 10 6 ) at age 90 years. Our indentation technique of the globe is similar to the tensile modulus.…”

Section: Indentationmentioning

confidence: 99%

Indentation and needle insertion properties of the human eye

Matthews

Hutnik²,

Hill

et al. 2014

Eye

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Biomechanics of the Human Posterior Sclera: Age- and Glaucoma-Related Changes Measured Using Inflation Testing

Abstract: The observed differences in the biomechanical response of normal and glaucoma sclera may represent baseline properties that contribute to axon damage, or may be characteristics that result from glaucomatous disease.

Cited by 280 publications

References 34 publications

The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera

The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera

Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo

Indentation and needle insertion properties of the human eye

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