June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
More peripapillary sclera (PPS) collagen fibers straighten than lamina cribrosa (LC) fibers before reaching 10% bundle stretch
Author Affiliations & Notes
  • Po-Yi Lee
    Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, Pennsylvania, United States
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
  • Gosia Fryc
    Chemistry, University of Pittsburgh Dietrich School of Arts and Sciences, Pittsburgh, Pennsylvania, United States
  • John Gnalian
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
  • Yi Hua
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
  • Susannah Waxman
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
  • Fuqiang Zhong
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
  • Bin Yang
    Engineering, Duquesne University, Pittsburgh, Pennsylvania, United States
  • Ian A Sigal
    Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
    Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Po-Yi Lee None; Gosia Fryc None; John Gnalian None; Yi Hua None; Susannah Waxman None; Fuqiang Zhong None; Bin Yang None; Ian Sigal None
  • Footnotes
    Support  National Institutes of Health R01-EY023966, R01-EY028662, P30-EY008098 and T32-EY017271 (Bethesda, MD), the Eye and Ear Foundation (Pittsburgh, PA), and Research to Prevent Blindness (unrestricted grant to UPMC ophthalmology, and Stein innovation award to Sigal IA).
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 59. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Po-Yi Lee, Gosia Fryc, John Gnalian, Yi Hua, Susannah Waxman, Fuqiang Zhong, Bin Yang, Ian A Sigal; More peripapillary sclera (PPS) collagen fibers straighten than lamina cribrosa (LC) fibers before reaching 10% bundle stretch. Invest. Ophthalmol. Vis. Sci. 2023;64(8):59.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : To characterize collagen fiber recruitment of PPS and LC under bundle stretch.

Methods : Nine 16-µm-thickness coronal sections of optic nerve heads from three sheep eyes were mounted and stretched biaxially quasi-statically while imaging with instant polarized light microscopy (IPOL, Fig 1). Collagen fiber orientations at each image pixel were quantified using color-orientation mapping. At each stretch step, we measured the bundle stretch of PPS (N=75) and LC (37) using digital image correlation and determined collagen waviness defined as the circular standard deviation of fiber orientations. When the waviness no longer decreased with stretch we considered the fiber bundle recruited and at that point defined “% stretch to recruit” and “waviness when recruited”. Linear mixed effect models were used to compare tissues.

Results : The PPS and LC stretch-recruitment curves approximated sigmoids (Fig 2a). At low stretch more PPS than LC fibers were recruited. At high stretch the situation reversed. At 10% stretch both PPS and LC had 75% fibers recruited. The PPS uncrimping rate (0.9±0.5 degree/% stretch) was significantly higher than that the LC’s (0.6±0.3) (P's < 0.001, Fig 2b). Both PPS (3.1°±0.9°) and LC (2.7°±0.7°) waviness when recruited were non-zero (Fig 2c).

Conclusions : The stretch-recruitment curves reveal both PPS and LC fibers lost crimp and were gradually recruited under stretch. The higher PPS uncrimping rate resulted in more fibers recruited at a lower level of stretch, which could be a mechanism to protect the fragile nerve fibers at the LC from vision-threatening insult. Non-zero waviness when recruited indicates the bundle structures (e.g., twisting and bending) could resist being fully uncrimped under stretch. The uncrimping rate and waviness when recruited suggest differences in collagen microstructures between PPS and LC, which helps drive fiber-based constitutive model formations for the posterior pole to understand glaucoma mechanisms.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

IPOL images in initial and stretched states. Colors correspond to local collagen fiber orientations. An example rectangle was tracked at all stretch steps to measure collagen waviness and bundle stretch.

IPOL images in initial and stretched states. Colors correspond to local collagen fiber orientations. An example rectangle was tracked at all stretch steps to measure collagen waviness and bundle stretch.

 

(A) Percentages of fiber bundles recruited at given bundle stretch in the PPS and LC. (B) Boxplot of uncrimping rates in the PPS and LC. (C) Boxplot of waviness when recruited in the PPS and LC.

(A) Percentages of fiber bundles recruited at given bundle stretch in the PPS and LC. (B) Boxplot of uncrimping rates in the PPS and LC. (C) Boxplot of waviness when recruited in the PPS and LC.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×