Collagen Fibrils Appear More Closely Packed in the Prepupillary Cornea: Optical and Biomechanical Implications

Boote, Craig; Dennis, Sally; Newton, Richard; Puri, Hina; Meek, Keith Michael Andrew

doi:10.1167/iovs.03-0131

Cited by 186 publications

(173 citation statements)

References 29 publications

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“…Collagen fibril diameter in the affected infero-nasal quadrant of the failed-graft cornea did not differ significantly from that measured elsewhere within the same tissue or from those of other normal and unscarred keratoconus corneas, 15,21 suggesting that scar tissue (which has a larger fibril diameter) 22 was not present. However, it must be remembered that X-ray scattering data provide an average measurement of fibril diameters throughout the entire thickness of the cornea at the point through which the beam passes.…”

Section: Discussionmentioning

confidence: 74%

“…Although the average fibril diameter in the failed-graft button was higher than that of the normal cornea (Po0.001), they were both within the typical range for healthy human corneas. 15 The variation in fibril diameters across the cornea was consistent for both the normal and failed-graft tissue.…”

Section: Fibril Diametermentioning

confidence: 68%

“…13,14 Measurements of fibril diameter in the failed-graft corneal tissue were compared with those obtained from an 8.5-mm button excised from a normal post-mortem cornea stored for 23 days in culture medium and then de-swelled for 2 days in dextran (obtained from the Corneal Transplant Service Eye Bank, Bristol, UK). Our previously published results from five healthy corneas 15 were used to confirm the normal range of fibril diameters in the human cornea.…”

Section: Specimen Informationmentioning

confidence: 99%

“…The images, each resulting from a 60s (normal cornea) or 90s (failedgraft) X-ray exposure, were collected on a detector placed 6.25 m behind the specimen. The data were analysed as previously described 15 to produce measurements of average collagen fibril diameter.…”

Section: Specimen Informationmentioning

confidence: 99%

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A structural investigation of corneal graft failure in suspected recurrent keratoconus

Hayes

Young

Boote

et al. 2009

Eye

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Purpose Penetrating keratoplasty was performed on the right eye of a 51-year-old patient diagnosed with advanced bilateral keratoconus. Thirteen years later, an 8.5 mm regraft was required as a result of gross vascularisation, a poor epithelium, and suspected recurrent keratoconus. To learn more about the structural basis for graft failure, we examined the removed tissue for the presence of abnormalities in the stroma and limiting membranes. Methods X-ray scattering and electron microscopy were used to study the failed-graft tissue to provide information on the integrity of the limiting membranes and the diameter, dominant orientation, and distribution of collagen within the corneal stroma. The findings were compared with similar structural data from normal and keratoconus corneas. Results In contrast to the keratoconus cornea, a normal orientation and distribution of collagen was seen throughout most of the failed-graft tissue, although abnormalities were observed in the infero-nasal quadrant at the original graft/ host junction. The average diameter of collagen fibrils in the failed-graft button did not differ from that of normal corneas. Conclusions The structural abnormalities identified in this case of graft failure were not consistent with those typically seen in keratoconus. The clear demarcation of the graft/ host boundary 13 years after surgery suggests that a normal stromal collagen arrangement may never be fully achieved in corneal graft wounds.

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Section: Discussionmentioning

confidence: 74%

Section: Fibril Diametermentioning

confidence: 68%

Section: Specimen Informationmentioning

confidence: 99%

Section: Specimen Informationmentioning

confidence: 99%

See 2 more Smart Citations

A structural investigation of corneal graft failure in suspected recurrent keratoconus

Hayes

Young

Boote

et al. 2009

Eye

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show abstract

“…Kampmeier [45] found that porcine corneas were stiffer along the IS axis than the NT axis, which is consistent with the present observations where the effect was much less pronounced. Wide angle x-ray scattering experiments [13] on human corneas were unable to statistically distinguish fibril densities in the NT and IS direction, although they did show a dramatic reduction in fibril densities at 45…”

Section: Discussionmentioning

confidence: 93%

The mechanics of soft biological composites.

Nguyen

Grazier²,

Boyce³

et al. 2007

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Biological tissues are uniquely structured materials with technologically appealing properties. Soft tissues such as skin, are constructed from a composite of strong fibrils and fluid-like matrix components. This was the first coordinated experimental/modeling project at Sandia or in the open literature to consider the mechanics of micromechanically-based anisotropy and viscoelasticity of soft biological tissues. We have exploited and applied Sandia's expertise in experimentation and mechanics modeling to better elucidate the behavior of collagen fibril-reinforced soft tissues.The purpose of this project was to provide a detailed understanding of the deformation of ocular tissues, specifically the highly structured skin-like tissue in the cornea. This discovery improved our knowledge of soft/complex materials testing and modeling. It also provided insight into the way that cornea tissue is bio-engineered such that under physiologically-relevant conditions it has a unique set of properties which enhance functionality. These results also provide insight into how non-phsyiologic loading conditions, such as corrective surgeries, may push the cornea outside of its natural design window, resulting in unexpected non-linear responses. Furthermore, this project created a clearer understanding of the mechanics of soft tissues that could lead to bio-inspired materials, such as highly supple and impact resistant body armor, and improve our design of human-machine interfaces, such as micro-electricalmechanical (MEMS) based prosthetics. Through this study,

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Natural Biomaterials for Corneal Tissue Engineering, Repair, and Regeneration

Palchesko

Carrasquilla

Feinberg

2018

Adv Healthcare Materials

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Corneal blindness is a major cause of vision loss, estimated to affect over 10 million people worldwide. Once impaired through clouding or shape change, the best treatment option for restoring vision is corneal transplantation using full or partial thickness cadaveric grafts. However, donor corneas are globally limited and face rejection and graft failure, similar to other transplanted organs. Thus, there is a need for viable alternatives to donor corneas in order to increase supply, reduce rejection, and to minimize variability in tissue quality. To address this, researchers have developed new materials and strategies to tissue engineer full or partial thickness cornea grafts in order to repair, regenerate, or replace the diseased cornea. This progress report first reviews the anatomy and physiology of the cornea to frame the biological requirements and discuss the injuries and diseases that necessitate the need fortransplantation, as well as the requirements for a suitable donor tissue alternative. This is followed by recent progress using naturally derived biomaterials including silk, collagen, amniotic membranes, and decellularized corneas. Finally, remaining challenges in the field as they relate to the biomaterials discussed are identified, and the future research directions that should result in further advances in restoring corneal vision are highlighted.

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Collagen Fibrils Appear More Closely Packed in the Prepupillary Cornea: Optical and Biomechanical Implications

Cited by 186 publications

References 29 publications

A structural investigation of corneal graft failure in suspected recurrent keratoconus

A structural investigation of corneal graft failure in suspected recurrent keratoconus

The mechanics of soft biological composites.

Natural Biomaterials for Corneal Tissue Engineering, Repair, and Regeneration

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