title: The Groningen Longitudinal Glaucoma Study. II. A prospective comparison of frequency doubling perimetry, the GDx nerve fibre analyser and standard automated perimetry in glaucoma suspect patients.
abstract: OBJECTIVE
  We aimed to determine prospectively the incidence of abnormal test results on frequency doubling perimetry (FDT), the nerve fibre analyser (GDx) and standard automated perimetry (SAP) in a cohort of glaucoma suspect patients with normal findings for all these tests at baseline.
  
  
  METHODS
  Seventy glaucoma suspect patients were followed prospectively for 4 years with SAP (Humphrey field analyser 30-2 SITA Fast), FDT (C-20 full-threshold) and GDx (Version 2.010) in a clinical setting. All patients had normal baseline test results on SAP, FDT and GDx. After the follow-up period, the number of patients who converted (whose test results changed from normal at baseline to reproducibly abnormal during follow-up) were counted for each technique and then compared. The cut-off point for FDT was > 1 depressed test-point p < 0.01 in the total deviation probability plot; the cut-off point for GDx was the Number > 29.
  
  
  RESULTS
  Of the 70 glaucoma suspect patients, three converted on FDT, 14 on GDx and six on SAP. These proportions are significantly different for GDx versus SAP (p = 0.033) and GDx versus FDT (p = 0.002), but not for FDT versus SAP (p = 0.256).
  
  
  CONCLUSIONS
  The most frequent finding after a 4-year follow-up was conversion on GDx.
authors.affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. n.m.jansonius@ohk.umcg.nl
authors.forename: Nomdo M
authors.initials: NM
authors.lastname: Jansonius
authors.forename: Govert P
authors.initials: GP
authors.lastname: Heeg
mesh_terms: D000368:Aged; D001331:Automation; D015331:Cohort Studies; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009798:Ocular Hypertension / Q000175:diagnosis*; D011446:Prospective Studies; D058609:Visual Field Tests / Q000379:methods*