title: Quantitative mapping of scleral fiber orientation in normal rat eyes.
abstract: OBJECTIVE
  Previous work has suggested a major role of scleral biomechanics in the pathogenesis of glaucoma. Since fiber orientation in connective tissues is a key determinant of tissue biomechanics, experimental characterization of scleral fiber orientation is needed to fully understand scleral biomechanics. This is a report of baseline experimental measurements of fiber orientation in whole normal rat scleras.
  
  
  METHODS
  Twenty ostensibly normal Norway brown rat eyes were fixed in 4% paraformaldehyde. The scleras were cleaned of intra- and extraorbital tissues and dissected into five patches, and each patch was glycerol treated to maximize its transparency. Fiber orientation was measured using small-angle light scattering (SALS). Scattering patterns were analyzed to extract two microstructural parameters at each measurement location-the preferred fiber orientation and the degree of alignment-yielding a fiber orientation map for each sclera.
  
  
  RESULTS
  Rat sclera is structurally anisotropic with several consistent features. At the limbus, fibers were highly aligned and organized primarily into a distinct ring surrounding the cornea. In the equatorial region, the fibers were primarily meridionally aligned. In the posterior and peripapillary region, the scleral fibers were mostly circumferential but less aligned than those in the anterior and equatorial regions.
  
  
  CONCLUSIONS
  Circumferential scleral fibers may act as reinforcing rings to limit corneal and optic nerve head deformations, whereas equatorial meridional fibers may either provide resistance against extraocular muscle forces or limit globe axial elongation.
authors.affiliation: Department of Bioengineering, Imperial College, London, UK.
authors.forename: Michaël J A
authors.initials: MJ
authors.lastname: Girard
authors.forename: Annegret
authors.initials: A
authors.lastname: Dahlmann-Noor
authors.forename: Sauparnika
authors.initials: S
authors.lastname: Rayapureddi
authors.forename: Jean Antoine
authors.initials: JA
authors.lastname: Bechara
authors.forename: Benedicte M E
authors.initials: BM
authors.lastname: Bertin
authors.forename: Hannah
authors.initials: H
authors.lastname: Jones
authors.forename: Julie
authors.initials: J
authors.lastname: Albon
authors.forename: Peng T
authors.initials: PT
authors.lastname: Khaw
authors.forename: C Ross
authors.initials: CR
authors.lastname: Ethier
mesh_terms: D000818:Animals; D016880:Anisotropy; D024042:Collagen Type I / Q000032:analysis / Q000737:chemistry; D003238:Connective Tissue / Q000033:anatomy & histology; D005260:Female; D024022:Fibrillar Collagens / Q000032:analysis*; D008027:Light; D008297:Male; D051381:Rats; D011914:Rats, Inbred BN; D012542:Scattering, Radiation; D012590:Sclera / Q000033:anatomy & histology* / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D024042:Collagen Type I; D024022:Fibrillar Collagens