title: Imaging of the iridocorneal angle with the RTVue spectral domain optical coherence tomography.
abstract: OBJECTIVE
  To determine the ability of the RTVue spectral domain optical coherence tomography (SDOCT) to image the anterior chamber angle (ACA).
  
  
  METHODS
  Consecutive subjects, recruited from glaucoma clinics, prospectively underwent ophthalmic evaluation including gonioscopy by an ophthalmologist and anterior chamber imaging with SDOCT, adapted with a corneal lens adapter (cornea anterior module-low magnification [CAM-L]) and anterior segment OCT (ASOCT), both performed by a technician. Two different ophthalmologists, masked to gonioscopy findings, assessed visualization of the scleral spur (SS), Schwalbe's line (SL), and trabecular meshwork (TM) by the two modalities. The ability to detect a closed angle was compared with gonioscopy.
  
  
  RESULTS
  The average age (SD) of the 81 subjects enrolled was 64.1 (11.4) years; the majority were Chinese (91.4%) and female (61.7%). SDOCT images revealed the SS in 26.9% (56/324) of quadrants and the SL in 44.1% (143/324) of quadrants; in ASOCT images, the SS could be visualized in 69.1% (224/324) of quadrants (P < 0.0001), but the SL was undetectable. The TM was detected equally well (17.3%, P < 0.92) using either device. The angle status was gradable in only 41.7% images with SDOCT, compared with 71.3% of ASOCT images (P < 0.0001). ACA was classified as closed in 19.3% of quadrants (26/135) with SDOCT images and in 44.2% (102/231) with ASOCT images compared with 37.7% (122/324) on gonioscopy. When analyzing the horizontal quadrants only, both modalities agreed well with gonioscopy, 0.75 and 0.74, respectively (AC1 statistics).
  
  
  CONCLUSIONS
  The RTVue SDOCT allowed visualization of SL, TM, and SS. However, these landmarks were not detected in a large percentage of images.
authors.affiliation: Singapore National Eye Centre, Singapore and Singapore Eye Research Institute, 11 Third Hospital Avenue, Singapore. shamiraperera@hotmail.com
authors.forename: Shamira A
authors.initials: SA
authors.lastname: Perera
authors.forename: Ching Lin
authors.initials: CL
authors.lastname: Ho
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
authors.forename: Mani
authors.initials: M
authors.lastname: Baskaran
authors.forename: Henrietta
authors.initials: H
authors.lastname: Ho
authors.forename: Tin A
authors.initials: TA
authors.lastname: Tun
authors.forename: Tian Loon
authors.initials: TL
authors.lastname: Lee
authors.forename: Rajesh S
authors.initials: RS
authors.lastname: Kumar
mesh_terms: D003315:Cornea / Q000473:pathology*; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D006068:Gonioscopy; D006801:Humans; D007498:Iris / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D041623:Tomography, Optical Coherence; D014129:Trabecular Meshwork / Q000473:pathology*