title: Long-term reproducibility of screening for glaucoma with FDT-perimetry.
abstract: OBJECTIVE
  Aim of this study was to evaluate the long-term reproducibility of frequency doubling technology (FDT) screening procedures.
  
  
  METHODS
  Longitudinal data of 433 eyes of 294 patients with no progression of glaucomatous optic disc atrophy were retrospectively analyzed: 62 control eyes, 184 ocular hypertensive eyes, 104 preperimetric, and 83 perimetric open-angle glaucoma eyes. All subjects had annual tests with the FDT perimeter and a standardized ophthalmologic examination (ie, conventional perimetry, optic disc inspection, tonometry, lens opacity measurement for exclusion of cataract). The present analysis used a published overall screening score with case-wise recalculation of missed localized probability levels. We analyzed long-term variability by correlation analysis, sign tests, and limits of agreement (LoA) as introduced by Altman and Bland. All subjects had at least 2 annual tests. Three hundred twenty-six eyes had 2 annual tests with the C-20 procedure and at least 1 test with the N-30 protocol another year later. One hundred thirty-five eyes had 1 C-20 and 2 annual tests with the N-30 protocol.
  
  
  RESULTS
  Analyses of repeated measurements revealed a significant learning effect (P<0.001, LoA: -4, 17) between the first and second examination but no significant difference between the second and following tests with the C-20 protocol (P>0.6, LoA: +/-9). In addition, there was no significant difference between second C-20 and N-30 tests (P>0.5, LoA: -12, 6).
  
  
  CONCLUSIONS
  The study demonstrates the variability of FDT tests over several years. Longitudinal FDT-results in a clinical study showed a higher reproducibility if the first test was discarded. Reproducibility of screening with the N-30 protocol is comparable to the C-20 procedure if an overall score is considered.
authors: Department of Ophthalmology and University Eye Hospital, Friedrich-Alexander University Erlangen-Nürnberg at Erlangen, Germany. folkert.horn@augen.imed.uni-erlangen.de
authors: Folkert K
authors: FK
authors: Horn
authors: Barbara
authors: B
authors: Link
authors: Christian Y
authors: CY
authors: Mardin
authors: Anselm G
authors: AG
authors: Jünemann
authors: Peter
authors: P
authors: Martus
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014065:Tonometry, Ocular; D058609:Visual Field Tests / Q000379:methods*