title: Heidelberg Retina Tomograph (HRT3) in population-based epidemiology: normative values and criteria for glaucomatous optic neuropathy.
abstract: OBJECTIVE
  To establish normative values for Heidelberg Retina Tomograph (HRT3) variables and to develop HRT3-based criteria for glaucomatous optic neuropathy for epidemiological research in a white population.
  
  
  METHODS
  Consecutive participants in the Rotterdam Study were examined with HRT and simultaneous stereoscopic fundus photography (ImageNet) in addition to other ophthalmic examinations including intraocular pressure (IOP) measurements and perimetry. Normative values for all HRT3 variables were determined in participants who met all the following criteria: no glaucomatous visual field loss (GVFL), an IOP of 21mmHg or less, no IOP lowering treatment, and a negative family history of glaucoma. Sensitivity was determined in participants with glaucomatous visual field loss at a fixed high specificity of 97.5% - a value commonly used in population-based epidemiology.
  
  
  RESULTS
  A total of 2516 participants were included in this study of whom 66 had glaucomatous visual field loss in at least one eye and 1680 fulfilled the criteria for contributing to the normative values. The HRT3 linear cup-disc ratio (LCDR) variable, adjusted for disc area, showed the highest sensitivity, 35%, at the required specificity of 97.5%. The 97.5th percentile of the LCDR was 0.67 for small discs (up to 1.5 mm(2)), 0.71 [corrected] for medium-sized discs and 0.76 [corrected] for large discs (above 2.0 mm(2)).The HRT3 Glaucoma Probability Score and previously published linear discriminant functions showed a lower sensitivity than LCDR at this specificity.
  
  
  CONCLUSIONS
  At the high specificity of 97.5% as is commonly used in population-based epidemiology, the sensitivity of the HRT3 is low - albeit not lower than that of the vertical cup-disc ratio as assessed with simultaneous stereoscopic fundus photography and analyzed with the ImageNet software. The LCDR variable, stratified for disc area, seems to be the most suitable variable to develop criteria for glaucomatous optic neuropathy for epidemiological purposes.
authors.affiliation: Department of Epidemiology & Biostatistics, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Wishal D
authors.initials: WD
authors.lastname: Ramdas
authors.forename: Roger C W
authors.initials: RC
authors.lastname: Wolfs
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Paulus T V M
authors.initials: PT
authors.lastname: de Jong
authors.forename: Johannes R
authors.initials: JR
authors.lastname: Vingerling
authors.forename: Nomdo M
authors.initials: NM
authors.lastname: Jansonius
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D003941:Diagnostic Techniques, Ophthalmological; D016002:Discriminant Analysis; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D008297:Male; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014054:Tomography / Q000379:methods* / Q000592:standards; D014794:Visual Fields