title: Comparison of the frequency doubling technology screening algorithm and the Humphrey 24-2 SITA-FAST in a large eye screening.
abstract: OBJECTIVE
  To compare the Frequency Doubling Technology (FDT) C20-1 screening algorithm and the Humphrey Field Analyser II (HFA) 24-2 SITA-FAST in a large eye screening.
  
  
  METHODS
  In a non-randomized, prospective, free eye screening, the FDT Screening Protocol (C20-1 Screening Algorithm) was administered to 574 attendees (422 men and 152 women, average age 64, range 17-89 years) of the 1998 Veterans of Foreign Wars (VFW) Convention in San Antonio, Texas. Individuals who failed the FDT (two or more misses out of 17 locations) immediately underwent white-on-white threshold visual field perimetry (HFA 24-2, SITA-FAST). Humphrey visual field analysis included STATPAC and masked evaluations by three glaucoma specialists.
  
  
  RESULTS
  Approximately one-tenth of the VFW conference attendees voluntarily presented themselves for screening. Among these 574 volunteers, 69 (12%) failed the FDT and underwent HFA analysis. Eighty-one per cent (56/69) of these FDT failures had abnormal HFA Glaucoma Hemifield Tests. Eighty-eight per cent (61/69) were judged to have nerve fibre type visual field loss on HFA by at least two of three masked examiners. A positive correlation existed between the number of FDT locations missed and the HFA mean deviation (r = 0.5, P = 0.0001). A similar association was observed when FDT and HFA results were analysed by quadrant (r = 0.5, P < 0.0001).
  
  
  CONCLUSIONS
  There was a low false positive rate and a good positive predictive value comparing the FDT screening algorithm to the HFA 24-2 SITA-FAST in this study. This supports the potential use of FDT as an economical screening device.
authors.affiliation: San Antonio Uniformed Services Health Education Consortium Ophthalmology Residency, Texas, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Allen
authors.forename: William E
authors.initials: WE
authors.lastname: Sponsel
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Trigo
authors.forename: Monte S
authors.initials: MS
authors.lastname: Dirks
authors.forename: William J
authors.initials: WJ
authors.lastname: Flynn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005189:False Positive Reactions; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015351:Vision Screening; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields