Myopia and Scleral Rigidity

Castrén, J. A.; Pohjola, S.

doi:10.1111/j.1755-3768.1962.tb02349.x

Cited by 15 publications

(7 citation statements)

References 7 publications

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“…Myopic eyes were found to be less rigid on the basis of the inverse association between the rigidity coefficient and ocular volume. Inconsistent results were shown using the same method, disregarding the discrepancy of age and refractive ranges of subjects between studies . Subsequently, other clinical methods, such as direct manometry during ocular surgery and the stretching of the ocular shell using weights were used to correlate the ocular rigidity with the axial length or elongation but no consensus was reached.…”

Section: Introductionmentioning

confidence: 99%

High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

Hon

Chen

et al. 2016

Ophthalmic Physiologic Optic

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Section: Introductionmentioning

confidence: 99%

High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

Hon

Chen

et al. 2016

Ophthalmic Physiologic Optic

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“…4a). In general it was reported that smaller fiber diameters and collagen crosslinking are associated with myopic conditions [4,5]. A smaller fiber diameter might lead to a less stiff tissue at the microscopic level leading to a weaker and less load bearing sclera in myopic conditions as found in other studies.…”

Section: Discussionmentioning

confidence: 56%

“…The excessive eye elongation underlying myopia likely occurs in the sclera, a collagen-rich tissue providing form and stability to the mammalian eye. Studies showed that the sclera is a viscoelastic structure and is more flexible and less load-bearing in myopes than in normal cases [4,5]. In mammalian models, scleral thinning and tissue loss occur during development of myopia; increased collagen degradation and decreased scleral collagen synthesis are evidenced by reduced scleral dry weight and reduced glycosaminoglycan content [6,7].…”

Section: Introductionmentioning

confidence: 99%

Microstructural assessment of the guinea pig sclera using quantitative acoustic microscopy

Rohrbach

Reisner

Wen

et al. 2016

2016 IEEE International Ultrasonics Symposium (IUS)

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The objective of this initial study is to investigate acoustic microscopy as a tool to elucidate the relationship between microscopic structural properties of the sclera and its macroscopic mechanical properties in healthy and myopic conditions. Excised sclera from both eyes of one guinea pig were scanned with a custom-built scanning acoustic microscope (SAM). Prior to euthanasia and excision, the animal wore a plastic diffuser over the right eye for 7 days, resulting in-9.3 diopters of induced myopia. The left eye served as an untreated control. Upon excision, both eyes were flash-frozen, seriallysectioned at 12-µm intervals, and scanned using SAM. Maps of bulk modulus (K) and mass density (ρ) showed a distinctive layered structure in the sclera consisting of a thin outer layer with K=2.47 ± 0.09 GPa and ρ=1.06 ± 0.02g/cm 3 followed by three layers of successively decreasing K towards the vitreous body. In general, the myopic eye was less stiff at vertical distances between 1 and 4 mm from the optic nerve head. This study suggests that the guinea pig sclera has a layered structure with different values of K and ρ; these differences may be related to the specific collagen-network structure of each layer.

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“…Myopic eyes show weaker, more flexible Sc, which may be caused by decreased scleral collagen synthesis and increased collagen degradation. 1,2 Increased ocular rigidity is associated with the development of glaucoma 3 and increased scleral stiffness is correlated with the development of glaucoma and with age. 4,5 The biomechanical model of glaucoma posits that the difference between intraocular and intracranial pressure contributes to permanent excavation of optic nerve (ON) head, 6-8 which is a defining clinical feature of glaucoma.…”

Section: Introductionmentioning

confidence: 99%

Material Properties of Human Ocular Tissue at 7-µm Resolution

et al. 2017

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Quantitative assessment of the material properties of ocular tissues can provide valuable information for investigating several ophthalmic diseases. Quantitative acoustic microscopy (QAM) offers a means of obtaining such information, but few QAM investigations have been conducted on human ocular tissue. We imaged the optic nerve (ON) and iridocorneal angle in 12-µm deparaffinized sections of the human eye using a custom-built acoustic microscope with a 250-MHz transducer (7-µm lateral resolution). The two-dimensional QAM maps of ultrasound attenuation (α), speed of sound ( c), acoustic impedance ( Z), bulk modulus ( K), and mass density (ρ) were generated. Scanned samples were then stained and imaged by light microscopy for comparison with QAM maps. The spatial resolution and contrast of scanning acoustic microscopy (SAM) maps were sufficient to resolve anatomic layers of the retina (Re); anatomic features in SAM maps corresponded to those seen by light microscopy. Significant variations of the acoustic parameters were found. For example, the sclera was 220 MPa stiffer than Re, choroid, and ON tissue. To the authors' knowledge, this is the first systematic study to assess c, Z, K, ρ, and α of human ocular tissue at the high ultrasound frequencies used in this study.

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Myopia and Scleral Rigidity

Cited by 15 publications

References 7 publications

High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

High myopes have lower normalised corneal tangent moduli (less ‘stiff’ corneas) than low myopes

Microstructural assessment of the guinea pig sclera using quantitative acoustic microscopy

Material Properties of Human Ocular Tissue at 7-µm Resolution

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