title: Agreement among 3 optical imaging methods for the assessment of optic disc topography.
abstract: OBJECTIVE
  To assess the agreement of disc topography measurements between the Heidelberg Retina Tomograph (HRT II), Retinal Thickness Analyzer (RTA), and Optical Coherence Tomograph (StratusOCT).
  
  
  METHODS
  Observational cross-sectional study.
  
  
  METHODS
  Forty-two randomly chosen eyes of 42 subjects.
  
  
  METHODS
  Each subject underwent HRT II, RTA, and StratusOCT examination. Two experienced examiners drew the contour lines for the HRT II and RTA. Bland and Altman plots were used to evaluate agreement for each topographic parameter among the instruments. The Spearman coefficient of rank correlation was evaluated for each topographic parameter.
  
  
  METHODS
  Agreement in the measurement of optic disc topography among 3 imaging instruments, as evaluated by regression-based 95% limits of agreement.
  
  
  RESULTS
  For optic disc area, the agreement between HRT II-RTA and StratusOCT-RTA revealed the existence of proportional bias, indicated by significant slopes of the regression lines (P = 0.01 and P = 0.02, respectively). The 95% limits of agreement between instruments varied with the actual optic disc size measurement. Heidelberg Retina Tomograph disc area measurements tended to be consistently lower than StratusOCT disc area measurements (fixed bias). The Spearman correlation coefficient between the instruments ranged from r = 0.35 (rim area, HRT II-StratusOCT) to r = 0.91 (cup area, HRT II-RTA).
  
  
  CONCLUSIONS
  Moderate to high correlation was found in measurements of optic disc topography among different instruments. However, the analysis of agreement indicated important discrepancies among instruments. Therefore, these instruments should not be used interchangeably to obtain measurements of the optic disc for glaucoma diagnosis.
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, La Jolla, California, USA.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Hoffmann
authors.forename: Christopher
authors.initials: C
authors.lastname: Bowd
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
authors.forename: Catherine
authors.initials: C
authors.lastname: Boden
authors.forename: Franz H
authors.initials: FH
authors.lastname: Grus
authors.forename: Rupert R
authors.initials: RR
authors.lastname: Bourne
authors.forename: Linda M
authors.initials: LM
authors.lastname: Zangwill
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology; D012189:Retrospective Studies