An In Vitro Intact Globe Expansion Method for Evaluation of Cross-linking Treatments

Mattson, M.; Huynh, J.; Wiseman, M. J.; Coassin, Marco; Kornfield, Julie; Schwartz, Daniel M.

doi:10.1167/iovs.09-4001

Cited by 23 publications

(23 citation statements)

References 33 publications

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“…They reported that both riboflavin-UVA and glyceraldehyde cross-linking treatments reduced corneal expansion, implying increased mechanical stability. 17 In contrast to these in vitro studies, in our study, we did not observe significant changes in biomechanical properties of the cornea after CXL for keratoconus as measured in vivo by ORA. We previously published similar results after 6 months of follow-up.…”

Section: Discussioncontrasting

confidence: 98%

Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus

Goldich

Marcovich

Barkana

et al. 2012

Cornea

124

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Two years after CXL, the observation of stable UCVA, improved BCVA, and reduced keratometry suggests stabilization in progression of keratoconus. Unchanged corneal thickness, endothelial cell density, and foveal thickness suggest the long-term safety of this procedure. The observed increase in axial length and stability in corneal biomechanical parameters measured with the ocular response analyzer require further study for verification and explanation.

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Section: Discussioncontrasting

confidence: 98%

Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus

Goldich

Marcovich

Barkana

et al. 2012

Cornea

124

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“…In a comparison of uniaxial testing and whole globe inflation of porcine eyes (Lari et al 2012) found smaller extensibility and larger stress-induced stiffening with whole eye preparations. For these reasons, whole globe testing is becoming increasingly common, with recently published studies investigating bovine scleral biomechanics (Myers et al 2010) and the effects of scleral cross-linking treatments on rabbit eyes (Mattson et al, 2010). This approach has also been used to study age-related changes at the optic nerve head (Girard et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Intact globe inflation testing of changes in scleral mechanics in myopia and recovery

Lewis

Garcia²,

Rani³

et al. 2014

Experimental Eye Research

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The purpose of this study was to examine the effects of myopia-inducing and myopia recovery conditions on the scleral biomechanics of enucleated eyes of young chicks. Enucleated eyes from 5-day old chicks, with fiducial markers attached at 5 locations on the external sclera, were placed in a custom-built chamber filled with phosphate-buffered saline, and subjected to controlled increments in intraocular pressure (IOP). IOP was initially ramped from 15 to 100 mmHg and then maintained at 100 mmHg for one hour, with eyes photographed at a rate of 0.1 Hz over the same period. There were two experimental groups, one in which chicks were monocularly form deprived for four days to induce myopia, and the other in which chicks were allowed two days of recovery from myopia induced by two days of form deprivation. For all chicks, the contralateral (fellow) eyes served as controls. Myopic eyes showed less initial deformation relative to their fellows, while no difference was recorded between recovering eyes and their fellows over the same time frame. With exposure to sustained elevated pressure, eyes in all groups displayed time-dependent changes in creep behavior, which included a linear region of secondary, steady creep. The creep deformation of myopic eyes was significantly higher than that of their fellows, consistent with results of previous studies using uniaxial loading of scleral strips. When allowed only 2 days to recover from induced myopia, previously myopic eyes continued to show increased creep deformation. Compared to results reported in studies involving scleral strips, our whole globe testing yielded higher values for creep rate. Whole globe inflation testing provides a viable, less anatomically disruptive and readily adaptable method for investigating scleral biomechanics than uniaxial tensile strip testing. Furthermore, our results suggest that elastic stretching does not contribute to the increased axial elongation underlying myopia in young chick eyes. They also confirm the very limited involvement of the sclera in the early recovery from myopia, reflecting the well documented lag in scleral versus choroidal recovery responses.

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“…Viscoelastic tensile creep and relaxation tests have also been conducted on these tissues [21,[23][24][25]. Inflation tests wherein whole [19,[26][27][28][29][30][31] or partial globes [32][33][34][35][36][37] are subjected to increasing levels of pressure while the scleral surface is imaged have been used to study the sclera's strain field, viscoelasticity, and the effects of various eye disease treatments. In general, these types of tests, particularly those on whole globes, are more physiologically realistic than tests on excised specimens.…”

Section: Introductionmentioning

confidence: 99%

Shear Behavior of Bovine Scleral Tissue

Argento

Kim

Rozsa

et al. 2014

Journal of Biomechanical Engineering

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Ocular tissue properties have been widely studied in tension and compression for humans and a variety of animals. However, direct shear testing of the tissues of the sclera appear to be absent from the literature even though modeling, analyses, and anatomical studies have indicated that shear may play a role in the etiology of primary open angle glaucoma (POAG). In this work, the mechanical behavior of bovine scleral tissue in shear has been studied in both out-of-plane and in-plane modes of deformation. Stress-strain and relaxation tests were conducted on tissue specimens at controlled temperature and hydration focusing on trends related to specimen location and orientation. There was generally found to be no significant effect of specimen orientation and angular location in the globe on shear stiffness in both modes. The in-plane response, which is the primary load carrying mode, was found to be substantially stiffer than the out-of-plane mode. Also, within the in-plane studies, tissue further from the optic nerve was stiffer than the near tissue. The viscosity coefficient of the tissue varied insignificantly with distance from the optic nerve, but overall was much higher in-plane than out-of-plane.

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An In Vitro Intact Globe Expansion Method for Evaluation of Cross-linking Treatments

Cited by 23 publications

References 33 publications

Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus

Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus

Intact globe inflation testing of changes in scleral mechanics in myopia and recovery

Shear Behavior of Bovine Scleral Tissue

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