title: Iridotrabecular contact observed using anterior segment three-dimensional OCT in eyes with a shallow peripheral anterior chamber.
abstract: OBJECTIVE
  To evaluate the prevalence and range of iridotrabecular contact (ITC) in eyes with a shallow peripheral anterior chamber (AC) by using anterior segment swept-source optical coherence tomography (AS-SS-OCT) and to compare the results with those obtained with ultrasound biomicroscopy (UBM) and gonioscopy.
  
  
  METHODS
  Forty-three shallow peripheral AC eyes in 43 consecutive patients underwent gonioscopy. Cross-sectional images throughout the angle circumference (i.e., 360°) were obtained with AS-SS-OCT (SS-1000 noncontact, noninvasive three-dimensional imaging system) and those of the peripheral AC at the 3, 6, 9, and 12 o'clock positions were obtained with UBM (UD-1000).
  
  
  RESULTS
  ITC evaluated with AS-SS-OCT included all gonioscopically identified peripheral anterior synechia (PAS) in the area. With AS-SS-OCT, at least one ITC was found in 40 (93.0%) and 42 (97.7%) of the 43 eyes under light and dark conditions, respectively, whereas with UBM, at least one ITC was found in 22 (51.1%) and 36 (83.7%) of the 43 eyes under light and dark conditions. The prevalence of ITC in eyes with AS-SS-OCT was significantly higher than that with UBM under light conditions, but not under dark conditions (P = 0.0001, 0.07, respectively, sign test). The PAS-positive eyes had a significantly greater ITC range than the PAS-negative eyes under light conditions (P = 0.006), but not under dark conditions (P = 0.08).
  
  
  CONCLUSIONS
  AS-SS-OCT detected all PAS and the prevalence of ITC detected by AS-SS-OCT in narrow angle eyes was markedly higher than previously thought. A relationship between the ITC range under light conditions and future PAS formation was suggested.
authors.affiliation: Department of Ophthalmology, Tokyo Teishin Hospital, Tokyo, Japan. koichimishima-tky@umin.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Mishima
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tomidokoro
authors.forename: Pitipong
authors.initials: P
authors.lastname: Suramethakul
authors.forename: Naomi
authors.initials: N
authors.lastname: Mataki
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kurita
authors.forename: Chihiro
authors.initials: C
authors.lastname: Mayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
mesh_terms: D000368:Aged; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000473:pathology*; D006801:Humans; D007498:Iris / Q000002:abnormalities*; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D041623:Tomography, Optical Coherence / Q000379:methods*; D014129:Trabecular Meshwork / Q000002:abnormalities*
keywords: UBM; anterior segment OCT; iridotrabecular contact; primary angle closure glaucoma