title: Reliability of the disk damage likelihood scale.
abstract: OBJECTIVE
  To report the reliability of the glaucoma disk damage likelihood scale (DDLS) in comparison to the Armaly cup/disk ratio by determining the interobserver and intraobserver agreement for optic disk stereo photographs and the interobserver agreement for in vivo patient measurements of the optic disk.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  Optic disk photographs: 48 stereo pairs of optic nerve photographs were selected from patients with a spectrum of glaucomatous visual field loss. Two masked observers graded the optic disk photographs three times according to the DDLS and Armaly cup/disk ratio. Interobserver and intraobserver agreements were calculated using the test-retest method. Patient measurements: three observers performed in vivo patient measurements on 34 eyes of glaucoma clinic patients and made a single determination of the DDLS stage and Armaly cup/disk ratio, based on the indirect biomicroscopic examination. Level of interobserver agreement was tabulated.
  
  
  RESULTS
  Optic disk photographs: interobserver and intraobserver agreement for the vertical DDLS measurement was greater than for two determinations (clinical impression and measured) of the vertical Armaly cup/disk ratio (interobserver: 85% vs 68% and 74%, respectively; intraobserver grader 1: 97% vs 89% and 80%, grader 2: 99% vs 95% and 89%, respectively). In vivo patient measurements: the interobserver agreement for the DDLS and Armaly cup/disk ratio was similar (70.1% vs 67.6%, respectively).
  
  
  CONCLUSIONS
  For the stereo optic disk photographs, the inter- and intra-observer agreement for the DDLS is greater than the Armaly cup/disk ratio. For the in vivo patient measurements, the level of agreement for the DDLS and the Armaly cup/disk ratio is similar.
authors.affiliation: William and Anna Goldberg Glaucoma Service, Wills Eye Hospital, Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania 19107, USA. henderer@willsglaucoma.org
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Henderer
authors.forename: Connie
authors.initials: C
authors.lastname: Liu
authors.forename: Muge
authors.initials: M
authors.lastname: Kesen
authors.forename: Undraa
authors.initials: U
authors.lastname: Altangerel
authors.forename: Atilla
authors.initials: A
authors.lastname: Bayer
authors.forename: William C
authors.initials: WC
authors.lastname: Steinmann
authors.forename: George L
authors.initials: GL
authors.lastname: Spaeth
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards*; D005901:Glaucoma / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D015588:Observer Variation; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000145:classification / Q000175:diagnosis*; D010781:Photography; D015203:Reproducibility of Results; D012189:Retrospective Studies