title: Noncontact Screening Methods for the Detection of Narrow Anterior Chamber Angles.
abstract: OBJECTIVE
  Comparing diagnostic accuracy of biomicroscope techniques (van Herick and Smith's tests, evaluating limbal and central anterior chamber depth, respectively) and advanced imaging (Visante OCT and Pentacam) for detection of gonioscopically narrow anterior chamber angles (ACAs).
  
  
  METHODS
  A total of 78 subjects with narrow or open ACAs underwent four index tests, performed on both eyes by examiners masked to other test results. Diagnostic performance was compared with gonioscopy, using International Society of Geographical and Epidemiological Ophthalmology (ISGEO) definition of primary angle closure and a classification based on clinical opinion of occludability. Data were analyzed using both the eye and the individual as unit of analysis. Sensitivity, specificity, and partial area under the receiver operating characteristic curve (AUROC) were generated.
  
  
  RESULTS
  Using the eye as the unit of analysis, the van Herick grading cutoff of 25% or less and ISGEO gonioscopic classification achieved 80% (confidence interval [CI] 65 to 89) sensitivity and 92% specificity (CI 80 to 97) for narrow angle detection, with specificity reaching 97% (CI 87 to 100) for a cutoff of less than or equal to 15%. Notably, with a gonioscopic classification based on clinical opinion of occludability, van Herick (≤25%) together with Smith's test (≤2.50 mm) detected 100% of narrow angle subjects. Of the three Pentacam parameters, anterior chamber volume achieved highest test sensitivity of 85% (CI 70 to 94) using the ISGEO definition. Visante OCT ACA had greatest partial AUROC at 90% specificity, also yielding sensitivity and specificity greater than 85% using the Youden-derived cutoff of less than or equal to 20.7°and ISGEO definition.
  
  
  CONCLUSIONS
  Van Herick test and Visante OCT ACA exhibited best discrimination between narrow and open angles both alone, and in combination. Van Herick test affords advantages over Visante OCT, showing potential for identifying individuals who may benefit from further gonioscopic assessment in a case-finding or screening setting.
authors.affiliation: City University London London, United Kingdom.
authors.forename: Priya L
authors.initials: PL
authors.lastname: Dabasia
authors.affiliation: City University London London, United Kingdom.
authors.forename: David F
authors.initials: DF
authors.lastname: Edgar
authors.affiliation: UCL Institute of Ophthalmology, London, United Kingdom.
authors.forename: Ian E
authors.initials: IE
authors.lastname: Murdoch
authors.affiliation: City University London London, United Kingdom.
authors.forename: John G
authors.initials: JG
authors.lastname: Lawrenson
mesh_terms: D000867:Anterior Chamber / Q000473:pathology*; D019540:Area Under Curve; D003430:Cross-Sectional Studies; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation* / Q000592:standards; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D006068:Gonioscopy; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D010781:Photography / Q000379:methods; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods