title: Effects of blur and repeated testing on sensitivity estimates with frequency doubling perimetry.
abstract: OBJECTIVE
  To investigate the effect of blur and repeated testing on sensitivity with frequency doubling technology (FDT) perimetry.
  
  
  METHODS
  One eye of 12 patients with glaucoma (mean deviation [MD] mean, -2.5 dB, range +0.5 to -4.3 dB) and 11 normal control subjects underwent six consecutive tests with the FDT N30 threshold program in each of two sessions. In session 1, blur was induced by trial lenses (-6.00, -3.00, 0.00, +3.00, and +6.00 D, in random order). In session 2, only the effects of repeated testing were evaluated. The MD and pattern standard deviation (PSD) indices were evaluated as functions of blur and of test order. By correcting the data of session 1 for the reduction of sensitivity with repeated testing (session 2), the effect of blur on FDT sensitivities was established, and its clinical consequences evaluated on total- and pattern-deviation probability maps.
  
  
  RESULTS
  FDT sensitivities decreased with blur (by <0.5 dB/D) and with repeated testing (by approximately 2 dB between the first and sixth tests). Blur and repeated testing independently led to larger numbers of locations with significant total and pattern deviation. Sensitivity reductions were similar in normal control subjects and patients with glaucoma, at central and peripheral test locations and at locations with high and low sensitivities. However, patients with glaucoma showed larger deterioration in the total-deviation-probability maps.
  
  
  CONCLUSIONS
  To optimize the performance of the device, refractive errors should be corrected and immediate retesting avoided. Further research is needed to establish the cause of sensitivity loss with repeated FDT testing.
authors.affiliation: Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Artes
authors.forename: Marcelo T
authors.initials: MT
authors.lastname: Nicolela
authors.forename: Terry A
authors.initials: TA
authors.lastname: McCormick
authors.forename: Raymond P
authors.initials: RP
authors.lastname: LeBlanc
authors.forename: Balwantray C
authors.initials: BC
authors.lastname: Chauhan
mesh_terms: D000328:Adult; D000368:Aged; D005189:False Positive Reactions; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D012030:Refractive Errors / Q000150:complications*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014786:Vision Disorders / Q000175:diagnosis* / Q000503:physiopathology; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields