title: Reproducibility and Agreement Between 2 Spectral Domain Optical Coherence Tomography Devices for Anterior Chamber Angle Measurements.
abstract: OBJECTIVE
  To compare anterior chamber angle parameters based on the location of Schwalbe line (SL) from 2 spectral domain optical coherence tomography (SD-OCT) instruments and to measure their reproducibility.
  
  
  METHODS
  Forty-two eyes from 21 normal, healthy participants underwent imaging of the inferior irido-corneal angle with the Spectralis and Cirrus SD-OCT under tightly controlled low-light conditions. SL-angle opening distance (SL-AOD) and SL-trabecular iris space area (SL-TISA) were measured by masked, certified graders at the Doheny Imaging Reading Center using customized grading software. Interinstrument and intrainstrument, as well as interobserver and intraobserver reproducibility of SL-AOD and SL-TISA measurements were evaluated by intraclass correlation coefficients (ICCs) and Bland-Altman plots with limits of agreement (LoA).
  
  
  RESULTS
  The mean SL-AOD was 0.662±0.191 mm in Spectralis and 0.677±0.213 mm in Cirrus. The mean SL-TISA was 0.250±0.073 mm in Spectralis and 0.256±0.082 mm in Cirrus. The agreement for intrainstrument (ICCs>0.979), intragrader (ICCs>0.992), and intergrader (ICCs>0.929) was excellent. Excellent agreement between the 2 devices was also documented with a mean difference of -0.016 (LoA -0.125 to 0.092) mm for SL-AOD and -0.007 (LoA -0.056 to 0.043) mm in SL-TISA.
  
  
  CONCLUSIONS
  Both SD-OCTs provided comparable measurements and permitted calculation of SL-based angle metrics. There was excellent interinstrument and intrainstrument and intraobserver and interobserver reproducibility for Spectralis and Cirrus SD-OCTs, suggesting true interchangeability between SD-OCT devices. This has the potential to lead to development of standardized grading assessments and quantification of angle parameters that would be valid across various SD-OCT devices.
authors.affiliation: *Doheny Image Reading Center, Doheny Eye Institute ‡Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA †The Affiliated Hospital of Medical College, Qingdao University Qingdao, Shandong, P.R. China.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Marion
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Maram
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Pan
authors.forename: Anna
authors.initials: A
authors.lastname: Dastiridou
authors.forename: ZhouYuan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Alex
authors.initials: A
authors.lastname: Ho
authors.forename: Brian A
authors.initials: BA
authors.lastname: Francis
authors.forename: Srinivas R
authors.initials: SR
authors.lastname: Sadda
authors.forename: Vikas
authors.initials: V
authors.lastname: Chopra
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000033:anatomy & histology*; D002924:Ciliary Body / Q000033:anatomy & histology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007498:Iris / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D014129:Trabecular Meshwork / Q000033:anatomy & histology