title: Comparing the detection and agreement of parapapillary atrophy progression using digital optic disk photographs and alternation flicker.
abstract: OBJECTIVE
  Parapapillary atrophy (PPA) progression has been associated with progressive glaucoma, but has proven to be difficult to assess clinically. We compared inter- and intra-observer agreement using a novel automated alternation flicker technology and side-by-side digital photography inspection for the evaluation of PPA progression.
  
  
  METHODS
  Consecutive patients with serial digital optic nerve photographs at least 1 year apart were included. Two graders (NR, BV) masked to image chronology assessed a set of photographs for progressive PPA using predefined criteria based on reference photographs containing mild, moderate, extensive or no PPA progression. At a separate session, the graders evaluated photographs using alternation flicker (EyeIC, Narberth, PA, USA) applying the same criteria. The order of patients and technique was randomized. Graders then assessed the same set of flickers and photographs a second time with the order of presentation reversed. The main outcome measure was the assessment of progressive PPA as identified by alternation flicker and digital photography inspection. Inter- and intra-observer agreement using each technique was assessed using the kappa statistic. A bootstrap method for comparing correlated kappa coefficients was used to assess statistical significance.
  
  
  RESULTS
  Serial photographs from 131 eyes of 68 patients were evaluated. Both graders identified significantly more cases of PPA progression using flicker compared to photography (27-34% vs 8-13%; both p< or =0.003). Inter-observer agreement using flicker was better than using photographs (kappa=0.52 vs 0.18, p=0.02). Intra-observer agreement was similar for both graders (photos: kappa=0.58 vs 0.57, p=0.97; flicker: kappa=0.61 vs 0.70, p=0.37). When progression was assessed by the number of progressive quadrants identified by each grader using a weighted kappa statistic, flicker inter-observer agreement was still moderate (kappa=0.45) and significantly better (p=0.01) than photography, which showed poor agreement (kappa=0.15). Intra-observer agreement with a weighted kappa for quadrant progression was also similar for both graders (photos: grader 1 kappa=0.53 vs grader 2 kappa=0.52, p=0.92; flickers: grader 1 kappa=0.58 vs grader 2 kappa=0.69, p=0.22). Conclusion Flicker identified more cases of progressive PPA than photographic review. Agreement between observers was significantly higher when using the automated flicker technology.
authors.affiliation: Department of Ophthalmology, Weill Cornell Medical College, Weill Greenberg Center, 1305 York Ave. at East 70th St., New York, NY 10021, USA. brian.vanderbeek@yahoo.com
authors.forename: Brian L
authors.initials: BL
authors.lastname: VanderBeek
authors.forename: Scott D
authors.initials: SD
authors.lastname: Smith
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Radcliffe
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D015588:Observer Variation; D009798:Ocular Hypertension / Q000175:diagnosis; D009896:Optic Atrophy / Q000175:diagnosis*; D009898:Optic Disk / Q000473:pathology*; D010781:Photography / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies
references.citation: Ophthalmology. 1998 Aug;105(8):1541-5
references.pmid: 9709771
references.citation: J Glaucoma. 1998 Oct;7(5):306-11
references.pmid: 9786558
references.citation: Br J Ophthalmol. 2006 Mar;90(3):262-7
references.pmid: 16488940
references.citation: Ophthalmology. 2004 Sep;111(9):1627-35
references.pmid: 15350314
references.citation: Doc Ophthalmol. 1981 Jul 15;51(3):269-76
references.pmid: 7285773
references.citation: Am J Ophthalmol. 1976 Mar;81(3):341-5
references.pmid: 943951
references.citation: Arch Ophthalmol. 2002 Jun;120(6):701-13; discussion 829-30
references.pmid: 12049574
references.citation: Ophthalmology. 1999 Nov;106(11):2144-53
references.pmid: 10571351
references.citation: Arch Ophthalmol. 2002 Oct;120(10):1268-79
references.pmid: 12365904
references.citation: Optometry. 2009 Aug;80(8):437-41
references.pmid: 19635435
references.citation: Invest Ophthalmol Vis Sci. 1989 Nov;30(11):2376-84
references.pmid: 2807794
references.citation: Am J Ophthalmol. 2009 Jan;147(1):39-44.e1
references.pmid: 18790472
references.citation: Am J Ophthalmol. 1998 Oct;126(4):487-97
references.pmid: 9780093
references.citation: Am J Ophthalmol. 1999 May;127(5):623-5
references.pmid: 10334368
references.citation: Acta Ophthalmol (Copenh). 1979 Jun;57(3):503-6
references.pmid: 474092
references.citation: Curr Opin Ophthalmol. 2005 Apr;16(2):84-8
references.pmid: 15744137
references.citation: Ophthalmology. 2002 Sep;109(9):1612-21
references.pmid: 12208707
references.citation: Ophthalmology. 2007 Nov;114(11):1965-72
references.pmid: 17628686
references.citation: Ophthalmology. 2000 Jul;107(7):1316-20
references.pmid: 10889105
references.citation: Am J Ophthalmol. 2008 Nov;146(5):735-40
references.pmid: 18723142
references.citation: Am J Ophthalmol. 2004 Apr;137(4):646-54
references.pmid: 15059703
references.citation: Ophthalmology. 1999 May;106(5):857
references.pmid: 10328376
references.citation: Klin Monbl Augenheilkd. 2002 Dec;219(12):862-5
references.pmid: 12548470
references.citation: Invest Ophthalmol Vis Sci. 1989 May;30(5):919-26
references.pmid: 2722448