title: Peripapillary rat sclera investigated in vivo with polarization-sensitive optical coherence tomography.
abstract: OBJECTIVE
  To demonstrate polarization-sensitive (PS) optical coherence tomography (OCT) for noninvasive, volumetric, and quantitative imaging of the birefringent properties of the peripapillary rat sclera; to compare the findings from PS-OCT images to state-of-the-art histomorphometric analysis of the same tissues.
  
  
  METHODS
  A high-speed PS-OCT prototype operating at 840 nm was modified for imaging the rat eye. Densely sampled PS-OCT raster scans covering an area of ~1.5 × 1.5 mm centered at the papilla were acquired in the eyes of anesthetized male Sprague-Dawley rats. Cross-sectional PS-OCT images were computed, and fundus maps displaying the birefringent properties of the sclera were analyzed. Postmortem histomorphologic analysis was performed.
  
  
  RESULTS
  Polarization-sensitive OCT enables visualization of the polarization properties of ocular tissues in vivo. The birefringent characteristics of the rat sclera were quantitatively assessed. Scleral birefringence formed a donut-shaped pattern around the papilla with significantly increased values of 0.703 ± 0.089°/μm (i.e., 1.64 × 10(-3) ± 0.2 × 10(-3); mean ± standard deviation) and 0.721 ± 0.084°/μm (i.e., 1.68 × 10(-3) ± 0.2 × 10(-3)) at an eccentricity of 0.4 mm for the left and right eyes, respectively. Birefringent axis orientation maps revealed a ring-shaped distribution around the optic nerve. Postmortem PS-OCT micrographs provided access to retinal and scleral microstructure and were compared to standard histomorphologic analysis.
  
  
  CONCLUSIONS
  Polarization-sensitive OCT enables quantitative imaging of tissue polarization properties in addition to conventional OCT imaging based on reflectivity. In the rat sclera, in vivo PS-OCT provides access to volumetric mapping of birefringence. Scleral birefringence is associated with microstructural tissue organization. Therefore, PS-OCT should prove a valuable tool for the in vivo investigation of peripapillary sclera in glaucoma.
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Baumann
authors.affiliation: Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria Core Facility Imaging, Medical University of Vienna, Vienna, Austria.
authors.forename: Sabine
authors.initials: S
authors.lastname: Rauscher
authors.affiliation: Core Facility for Research and Technology, University of Veterinary Medicine Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Glösmann
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Erich
authors.initials: E
authors.lastname: Götzinger
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Pircher
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria.
authors.forename: Stanislava
authors.initials: S
authors.lastname: Fialová
authors.affiliation: Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria Core Facility Imaging, Medical University of Vienna, Vienna, Austria.
authors.forename: Marion
authors.initials: M
authors.lastname: Gröger
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria.
authors.forename: Christoph K
authors.initials: CK
authors.lastname: Hitzenberger
mesh_terms: D000818:Animals; D001718:Birefringence; D004867:Equipment Design; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012590:Sclera / Q000166:cytology*; D041623:Tomography, Optical Coherence / Q000295:instrumentation*
keywords: birefringence; optical coherence tomography; sclera