title: Determination and Validation of Thresholds of Anterior Chamber Parameters by Dedicated Anterior Segment Optical Coherence Tomography.
abstract: OBJECTIVE
  To determine and validate thresholds of anterior chamber angle (ACA) parameters in discriminating open- vs narrow-angle eyes using images from dedicated anterior segment optical coherence tomography (DASOCT).
  
  
  METHODS
  Reliability analysis.
  
  
  METHODS
  Eyes imaged by DASOCT and examined with gonioscopy were reviewed. By gonioscopy, eyes were classified as narrow if posterior trabecular meshwork was not visible and open if the angle was open to scleral spur and beyond. Imaging was performed in the dark with the CASIA SS-1000 (Tomey, Nagoya, Japan). ACA parameters angle opening distance (AOD), trabecular-iris space area (TISA), trabecular-iris circumference volume (TICV), length of iridotrabecular contact (ITC), and extent and area of ITC were calculated. AOD, TISA, and TICV were measured at both 500 μm and 750 μm from the scleral spur landmark. Study eyes were randomly divided into training and testing sets. Thresholds were calculated from the training set. Sensitivity, specificity, and agreement were then calculated against the clinical classification using the testing set.
  
  
  RESULTS
  One hundred and eighty-nine eyes (111 open, 78 narrow, including 8 borderline angles) were included. Using the threshold determined in the training set on the testing set, 9 of 24 ACA parameters had no misclassification of narrow-angle eyes as open (sensitivity = 1.0). Of 9 parameters, the specificity was >0.79. The highest kappa values (kappa = 0.91) was AOD750 inferiorly at 0.31 mm threshold, followed by both TICV500 at 1.92 μL and TICV750 at 4.00 μL with kappa = 0.86.
  
  
  CONCLUSIONS
  The parameters with the best discriminative ability for detecting narrow angles were AOD750 inferiorly, TICV500, and TICV750.
authors.affiliation: Robert Cizik Eye Clinic, Houston, Texas.
authors.forename: Ephrem K
authors.initials: EK
authors.lastname: Melese
authors.affiliation: Department of Electrical Engineering and Computer Science, College of Engineering, University of California at Berkeley, Berkeley, California.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Chan
authors.affiliation: Robert Cizik Eye Clinic, Houston, Texas; Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Blieden
authors.affiliation: Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas.
authors.forename: Alice Z
authors.initials: AZ
authors.lastname: Chuang
authors.affiliation: Robert Cizik Eye Clinic, Houston, Texas.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Baker
authors.affiliation: Robert Cizik Eye Clinic, Houston, Texas; Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Bell
authors.affiliation: Robert Cizik Eye Clinic, Houston, Texas; Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas. Electronic address: rfeldman@cizikeye.org.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Feldman
mesh_terms: D000867:Anterior Chamber / Q000000981:diagnostic imaging / Q000473:pathology*; D019540:Area Under Curve; D003937:Diagnosis, Differential; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods; D014129:Trabecular Meshwork / Q000000981:diagnostic imaging / Q000473:pathology*