title: Agreement between Heidelberg Retina Tomograph-I and -II in detecting glaucomatous changes using topographic change analysis.
abstract: OBJECTIVE
  To evaluate the suitability of including both Heidelberg Retina Tomograph-I (HRT-I) and HRT-II examinations in the same longitudinal series for HRT topographic change analysis (TCA) and to evaluate parabolic error correction (PEC) to improve the agreement between HRT-I and HRT-II examinations.
  
  
  METHODS
  A total of 66 eyes from the University of California San Diego Diagnostic Innovations in Glaucoma Study with baseline HRT-I and HRT-II examinations obtained on the same day and ≥ 3 HRT-II follow-up examinations were included. Two TCA analyses, HRT-I examination at baseline (HRT-I-mixed series) and HRT-II examination at baseline (HRT-II-only series) were compared. Agreement between the HRT-I-mixed and HRT-II-only series were estimated using Bland-Altman plots. Agreement was assessed: (1) using the current HRT software settings (PEC applied only to HRT-II-only series), and (2) modified HRT settings (PEC also applied to HRT-I-mixed series).
  
  
  RESULTS
  With current HRT software settings, the HRT-I-mixed series significantly overestimated change locations (ie, red pixels) compared with the HRT-II-only series as indicated by statistically significant proportional biases in the Bland-Altman analysis. By applying PEC to HRT-I-mixed series there were no statistically significant biases in the TCA parameter estimates compared with the HRT-II-only series.
  
  
  CONCLUSIONS
  In some eyes, HRT-I and HRT-II baseline examinations are not interchangeable in TCA analysis without parabolic error correction. HRT-I-mixed series detected more changes characteristic of glaucoma when there were only minimal changes in the HRT-II-only series. Our results suggest that in the majority of cases, with PEC, HRT-I examinations may be included in a longitudinal series containing HRT-II examinations.
authors.affiliation: Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: M
authors.initials: M
authors.lastname: Balasubramanian
authors.forename: C
authors.initials: C
authors.lastname: Bowd
authors.forename: R N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: L M
authors.initials: LM
authors.lastname: Zangwill
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019721:Ophthalmoscopes; D009898:Optic Disk / Q000473:pathology*