June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Measuring Micron-Scale Collagen Fiber Orientation in the Lamina Cribrosa and Peripapillary Sclera
Author Affiliations & Notes
  • Ning-Jiun Jan
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
  • Jonathan Grimm
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
  • Kira Lathrop
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
  • Gadi Wollstein
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
  • Larry Kagemann
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
  • Joel Schuman
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
  • Hiroshi Ishikawa
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
  • Ian Sigal
    Ophthalmology, University of Pittsburgh, Pittsburgh, PA
    Bioengineering, University of Pittsburgh, Pittsburgh, PA
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 65. doi:
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      Ning-Jiun Jan, Jonathan Grimm, Kira Lathrop, Gadi Wollstein, Larry Kagemann, Joel Schuman, Hiroshi Ishikawa, Ian Sigal; Measuring Micron-Scale Collagen Fiber Orientation in the Lamina Cribrosa and Peripapillary Sclera. Invest. Ophthalmol. Vis. Sci. 2013;54(15):65.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Collagen fiber orientation is a critical factor in determining the local biomechanical response to loading of the lamina cribrosa (LC) and peripapillary sclera (PPS). Our goal was to evaluate the repeatability of our novel technique for measuring micron-scale collagen fiber orientation in LC and PPS.

 
Methods
 

A sheep eye (<2 yo) was obtained from a local slaughterhouse and fixed overnight in formalin (10%) within 24 hours of death. Following fixation the LC and PPS were cryosectioned coronally into 30 µm sections. One section through the LC was selected and imaged using light microscopy (Olympus BX60, 12-bit grayscale 1600x1200 pixels) three times at high resolution (0.73 µm/pixel , 10x objective, NA 0.30) and three times at low resolution (1.48 µm/pixel, 4x objective, NA 0.13). Repeatability was measured by overlying stitched image sets and calculating the angle differences between fiber orientations in each image and the mean angle over all image sets of that resolution.

 
Results
 

In both LC and PPS angle differences within resolutions were small, with 95% of the fiber orientations differing by less than 5°, independent of the resolution (Figure 1). Angle differences in the PPS were smaller than in the LC. Overlaid orientations obtained from the three high resolution image sets illustrate the small magnitude of the differences (Figure 2).

 
Conclusions
 

Our method was highly reproducible, with multiple measurements differing by only a few degrees. When the measurements are overlaid they are essentially indistinguishable. Micron-scale collagen fiber orientation data of the LC and PPS will enable better understanding of the effects of intraocular pressure on the optic nerve head.

 
 
FIGURE 1: Distributions of the differences in fiber orientation. A) Low resolution. B) High resolution. C) Composite (both tissues) low vs. high resolution.
 
FIGURE 1: Distributions of the differences in fiber orientation. A) Low resolution. B) High resolution. C) Composite (both tissues) low vs. high resolution.
 
 
FIGURE 2: A) The LC and PPS; B) Close up of a LC trabeculae (box in A) with lines illustrating collagen fiber orientation in 9x9 superpixels. Shown is an overlay of the three measurements in blue, red and green. Most pixels are white, meaning that the three measurements overlap; C) Close up of box in B.
 
FIGURE 2: A) The LC and PPS; B) Close up of a LC trabeculae (box in A) with lines illustrating collagen fiber orientation in 9x9 superpixels. Shown is an overlay of the three measurements in blue, red and green. Most pixels are white, meaning that the three measurements overlap; C) Close up of box in B.
 
Keywords: 577 lamina cribrosa • 627 optic disc • 549 image processing  
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