title: The Heidelberg retina tomograph ancillary study to the European glaucoma prevention study: study design and baseline factors.
abstract: OBJECTIVE
  To describe the study design and baseline factors of the Heidelberg Retina Tomograph ancillary study within the EGPS. Furthermore, to examine the relationship between HRT optic disc topographic measurements and baseline demographic and ocular factors.
  
  
  METHODS
  Four hundred and eighty-nine ocular hypertensive participants were included. Each participant completed HRT imaging at least annually. The associations between HRT measurements and IOP, central corneal thickness (CCT), baseline photographic estimates of vertical CDR ratio (CDR), asymmetry between the two eyes in CDR ratio and baseline visual field indices were assessed using regression analysis.
  
  
  RESULTS
  Associations between HRT measurements and vertical CDR by photographs were found for almost all stereometric optic disc parameters in both univariate and multivariate analysis. The strongest association was found between vertical CDR measurements and disc, cup and rim area; cup and rim volume, CDR area, linear CDR, mean and maximum cup depth and cup shape measure (all p < 0.0001). In multivariate analysis, pattern standard deviation (PSD) and HRT disc area had significant associations with several HRT optic disc measurements. Furthermore, CCT was significantly associated with reference height and the glaucoma probability score (GPS, outside normal limits).
  
  
  CONCLUSIONS
  The EGPS is the first multicentre, placebo-controlled randomized clinical trial to use HRT for monitoring optic disc changes in participants with ocular hypertension. We found strong associations between stereophotographic vertical CDR estimates, HRT disc area, PSD and several HRT parameters. We found, furthermore, that the parameters reference height and GPS were significantly related to central corneal thickness.
authors.affiliation: Department of Ophthalmology, University Medical Center Mainz, Mainz, GermanyDepartment of Ophthalmology, University of Milan, Monza, ItalyLeuven University Hospitals, Leuven, BelgiumInstitute Mario Negri, Milan, ItalyDepartment of Ophthalmology, Coimbra University Hospital, Coimbra, Portugal.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Hoffmann
authors.forename: Stefano
authors.initials: S
authors.lastname: Miglior
authors.forename: Thierry
authors.initials: T
authors.lastname: Zeyen
authors.forename: Valter
authors.initials: V
authors.lastname: Torri
authors.forename: Eliana
authors.initials: E
authors.lastname: Rulli
authors.forename: Shakhsanam
authors.initials: S
authors.lastname: Aliyeva
authors.forename: Irene
authors.initials: I
authors.lastname: Floriani
authors.forename: José
authors.initials: J
authors.lastname: Cunha-Vaz
authors.forename: Norbert
authors.initials: N
authors.lastname: Pfeiffer
mesh_terms: D002257:Carbonic Anhydrase Inhibitors / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D005901:Glaucoma / Q000517:prevention & control*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D009887:Ophthalmoscopy / Q000379:methods*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D012107:Research Design; D013449:Sulfonamides / Q000627:therapeutic use; D013876:Thiophenes / Q000627:therapeutic use; D014054:Tomography; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D013449:Sulfonamides; D013876:Thiophenes; C062765:dorzolamide
keywords: HRT parameter; central corneal thickness; glaucoma; intraocular pressure; ocular hypertension; pattern standard deviation; scanning laser ophthalmoscopy