title: Identification of Schlemm's canal and its surrounding tissues by anterior segment fourier domain optical coherence tomography.
abstract: OBJECTIVE
  To identify Schlemm's canal (SC) and trabecular meshwork (TM) by anterior segment Fourier-domain optical coherence tomography (AS-FD-OCT) with histologic confirmation in enucleated human eyes and to quantitatively evaluate SC and TM in living human eyes.
  
  
  METHODS
  In enucleated human eyes, the imaging of the anterior chamber angle by AS-FD-OCT was performed before and after surgical expansion of SC with an injection of a viscoelastic material, followed by histologic examination. In 60 living human eyes, the agreement of identification of SC between examiners was evaluated with the Cohen's κ values, and the lengths of SC and TM and the area of TM were measured on temporal and nasal sections of the AS-FD-OCT images.
  
  
  RESULTS
  In enucleated human eyes, SC was observed to be a thin, linear, lucent space in the AS-FD-OCT image obtained with the high-definition raster scan protocol, but not in those obtained with the bi-angle radial scan protocol. This space was enlarged after the SC expansion. In the histologic study, the SC was confirmed to be in the same position as in the AS-FD-OCT images. The κ values of observable SC in living human subjects were 0.92 or higher. The axial length of the SC averaged 347.2 ± 42.3 μm, TM length 466.9 ± 60.7 μm, and TM area 0.0671 ± 0.0058 mm². These measurements showed sufficient repeatability and reproducibility.
  
  
  CONCLUSIONS
  Using the high-definition images of the AS-FD-OCT, SC and its surrounding tissues were successfully observed in most of the living eyes and were quantitatively evaluated in a noninvasive manner.
authors.affiliation: Department of Ophthalmology, University of Tokyo, Graduate School of Medicine, Tokyo, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Usui
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tomidokoro
authors.forename: Koichi
authors.initials: K
authors.lastname: Mishima
authors.forename: Naomi
authors.initials: N
authors.lastname: Mataki
authors.forename: Chihiro
authors.initials: C
authors.lastname: Mayama
authors.forename: Norihiko
authors.initials: N
authors.lastname: Honda
authors.forename: Shiro
authors.initials: S
authors.lastname: Amano
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000033:anatomy & histology*; D015353:Eye Enucleation; D005583:Fourier Analysis; D006801:Humans; D016850:Limbus Corneae / Q000033:anatomy & histology*; D008875:Middle Aged; D012590:Sclera / Q000033:anatomy & histology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014129:Trabecular Meshwork / Q000033:anatomy & histology*; D055682:Viscoelastic Substances; D014792:Visual Acuity / Q000502:physiology
chemical_list: D055682:Viscoelastic Substances