Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Filas, Benjamen A.; Shah, Nihar S.; Zhang, Qianru; Shui, Ying-Bo; Lake, Spencer P.; Beebe, David C.

doi:10.1167/iovs.14-15225

Cited by 9 publications

(8 citation statements)

References 51 publications

(69 reference statements)

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“…We theorize that the confocal system is necessary to powerfully reduce speckle noise due to inherently weak signal of vitreous fibers. The inherently weak signal likely also explains why we were unable to image vitreous with second harmonic generation microscopy, even when using an ultra-sensitive, refractiveindex-matched substage detector [22], and why Filas et al were not able to image individual fibers with quantitative polarized light microscopy [18]. They were able to extract measures of average alignment and orientation, and found poor alignment, consistent with our findings.…”

Section: Discussionsupporting

confidence: 86%

“…Based on the generally anterior-posterior orientations that Filas et al observed by quantitative polarized light microscopy [18] along the anterior-posterior axes originating at the nasal and temporal limbus, we anticipated that we would find angular means around 0 degrees, which we defined as parallel to the anterior-posterior axis. Although the angular means in the nasal-radial dataset were closer to zero, the angular means in the remaining 4 tangential datasets were widely distributed (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Based on slit-lamp images from human eyes, [15] we hypothesized that fibers would be aligned parallel to the anterior-posterior axis, regardless of the origination site. We also anticipated that overall alignment would be weak based on low retardation measured by quantitative polarized light microscopy [18]. After automated fiber segmentation, we used linear regression to obtain an angle for each fiber.…”

Section: Resultsmentioning

confidence: 99%

“…Some prior vitreous imaging methods required extracting a small sample of the vitreous gel, which resulted in loss of original position, orientation, and shape of the imaged sample. In contrast, we adopted the strategy of Filas et al of grossly sectioning the eye a single time and imaging near the surface of the open face [18,20]. This preparation strategy, combined with the large range of motion of the microscope stage, allowed us to map the images to a specific location within the eye and evaluate whether our technique was able to detect previously-established regional differences in collagen density [3,6,17].…”

Section: Discussionmentioning

confidence: 99%

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Confocal reflectance microscopy for mapping collagen fiber organization in the vitreous gel of the eye

Hwang

Morgan

Sun

et al. 2022

Preprint

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Vitreous collagen structure plays an important role in ocular mechanics, but capturing this structure with existing vitreous imaging methods is hindered by loss of sample position and orientation, low resolution, or small field of view. The objective of this study was to evaluate confocal reflectance microscopy as a solution to these limitations. The use of intrinsic reflectance avoids staining and optical sectioning eliminates the requirement for thin sectioning, minimizing processing for optimal preservation of natural structure. We developed a sample preparation and imaging strategy using ex vivo grossly sectioned porcine eyes. Imaging revealed a network of uniform diameter crossing fibers (1.1 plus/minus 0.3 micro metres for a typical image) with generally poor alignment (alignment coefficient = 0.40 plus/minus 0.21 for a typical image). To test the utility of our approach for detecting differences in fiber spatial distribution, we imaged eyes every 1 mm along an anterior-posterior axis originating at the limbus and quantified the number of fibers in each image. Fiber density was higher anteriorly near the vitreous base, regardless of imaging plane. These data demonstrate that confocal reflectance microscopy addresses the previously unmet need for a robust, micron-scale technique to map features of collagen networks in situ across the vitreous.

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Section: Discussionsupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Confocal reflectance microscopy for mapping collagen fiber organization in the vitreous gel of the eye

Hwang

Morgan

Sun

et al. 2022

Preprint

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“…(Jan et al, 2017a; Jan et al, 2015; Jan et al, 2017b) It has been shown that the PLM signal correlates with the orientation of collagen fibers. (Bromage et al, 2003; Diamant et al, 1972; Keikhosravi et al, 2017) In addition, PLM has been used extensively for quantifying crimp in other tissues, such as the vitreous, (Filas et al, 2014) tendon (Diamant et al, 1972; Franchi et al, 2007; Hansen et al, 2001) and ligament. (Boorman et al, 2006; Shah et al, 1977)…”

Section: Discussionmentioning

confidence: 99%

Crimp around the globe; patterns of collagen crimp across the corneoscleral shell

Jan

Brazile

et al. 2018

Experimental Eye Research

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Our goal was to systematically quantify the collagen crimp morphology around the corneoscleral shell, and test the hypothesis that collagen crimp is not uniform over the globe. Axial longitudinal cryosections (30 μm) of three sheep eyes, fixed at 0 mmHg IOP, were imaged using polarized light microscopy to quantify the local collagen in 8 regions: two corneal (central and peripheral) and six scleral (limbus, anterior-equatorial, equatorial, posterior-equatorial, posterior and peripapillary). Collagen crimp period (length of one wave), tortuosity (path length divided by end-to-end length), waviness (SD of orientation), amplitude (half the peak to trough distance), and conformity (width of contiguous similarly oriented bundles) were measured in each region. Measurements were obtained on 8216 collagen fiber bundles. When pooling measurements across the whole eye globe, the median crimp values were: 23.9 μm period, 13.2 μm conformity, 0.63 μm amplitude, 1.006 tortuosity, and 12.7° waviness. However, all parameters varied significantly across the globe. Median bundle periods in the central cornea, limbus, and peripapillary sclera (PPS) were 14.1 μm, 29.5 μm, and 22.9 μm, respectively. Median conformities were 20.8 μm, 14.5 μm, and 15.1 μm, respectively. Median tortuosities were 1.005, 1.007, and 1.007, respectively. Median waviness' were 11.4°, 13.2°, and 13.2°, respectively. Median amplitudes were 0.35 μm, 0.87 μm, and 0.65 μm, respectively. All parameters varied significantly across the globe. All regions differed significantly from one another on at least one parameter. Regions with small periods had large conformities, and bundles with high tortuosity had high waviness and amplitude. Waviness, tortuosity, and amplitude, associated with nonlinear biomechanical behavior, exhibited "double hump" distributions, whereas period and conformity, representing tissue organization, were substantially different between sclera and cornea. Though the biomechanical implications and origin of the patterns observed remain unclear, our findings of well-defined patterns of collagen crimp across the corneoscleral shell, consistent between eyes, support the existence of mechanisms that regulate collagen characteristics at the regional or smaller levels. These results are experimental data necessary for more realistic models of ocular biomechanics and remodeling.

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On the Spatiotemporal Material Anisotropy of the Vitreous Body in Tension and Compression

et al. 2016

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Although linked to several vitreoretinal pathologies including traumatic retinal tears, breaks, and symptomatic vitreomacular traction, the dynamic material behavior of the vitreous body in response to mechanical loads is not well understood. The purpose of this study was to evaluate spatiotemporal patterns of collagen fiber reorganization and vitreous deformation (strain) in response to tensile and compressive forces. Using thick slabs of bovine eyes we examined collagen fiber reorganization following tensile and compressive step-loading with quantitative polarized light imaging. Strains were measured from sparse marker arrays and temporal collagen behavior was estimated from creep compliance rheological tests. Results showed that under applied loads (1) collagen fibers became significantly more aligned at the vitreous base (near the pars plana and the ciliary body), (2) vitreous located directly behind the lens deformed significantly more than surrounding regions, and (3) changes in collagen fiber alignment occurred on a short (<5 s) timescale. Together these results show that, despite a homogeneous visual appearance, the vitreous body exhibits anisotropic material behavior in tension and compression. Spatiotemporal patterns of collagen rearrangement were consistent with epidemiological patterns of traumatic retinal damage and vitreoretinal topology. High strains in the vitreous corresponded with locations of lower collagen content that are prone to age-related degeneration. These data suggest that differential fiber alignment and mechanical deformation could contribute to the pathogenesis of these diseases. Computational models that incorporate these experimental data will help improve our understanding of the biomechanical mechanisms that contribute to the pathogenesis of traumatic retinal damage, vitreous degeneration, and vitreoretinal disease.

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Quantitative Imaging of Enzymatic Vitreolysis-Induced Fiber Remodeling

Cited by 9 publications

References 51 publications

Confocal reflectance microscopy for mapping collagen fiber organization in the vitreous gel of the eye

Confocal reflectance microscopy for mapping collagen fiber organization in the vitreous gel of the eye

Crimp around the globe; patterns of collagen crimp across the corneoscleral shell

On the Spatiotemporal Material Anisotropy of the Vitreous Body in Tension and Compression

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