title: The methodology of visual field testing with frequency doubling technology in the National Health and Nutrition Examination Survey, 2005-2006.
abstract: OBJECTIVE
  To describe the frequency doubling technology (FDT) methodology to measure visual field loss in the National Health and Nutrition Examination Survey and to evaluate data reliability.
  
  
  METHODS
  Participants aged 40 years and older were eligible (n = 2,529) for 2 visual field tests per eye performed with the Humphrey Matrix N-30-5 screening test. Visual field loss was determined using a 2-2-1 algorithm requiring 2 complete tests per eye, with at least 2 abnormal field results in each test, and 1 common abnormal field.
  
  
  RESULTS
  Response rate was 86.2%. Time constraints were the main reason for no exam (55.6%). Median times were: single test, 37 seconds; entire exam, 9.1 minutes. When defining reliability based on ≤ 1/3 blind spots, ≤ 1/3 false positive tests, and technician noted proper fixation, 80.1% of examined adults had 2 reliable tests for both eyes; an additional 13.4% had 2 reliable tests for 1 eye. Increasing age, decreasing visual acuity, and the presence of self-reported glaucoma resulted in decreased examination rates, increased test times, and decreased data reliability. Sensitivity and specificity to detect persons with glaucoma was 54.8% and 91.9%, respectively.
  
  
  CONCLUSIONS
  FDT is a feasible, fast, and reliable method for visual field loss screening in a population-based U.S. study, with an 86.2% response rate, median exam time ~9 minutes, and nearly 95% of examined participants having complete, reliable results in 1 or both eyes.
authors.affiliation: Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, USA.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Terry
authors.forename: Ryne
authors.initials: R
authors.lastname: Paulose-Ram
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Tilert
authors.forename: Chris A
authors.initials: CA
authors.lastname: Johnson
authors.forename: Xinzhi
authors.initials: X
authors.lastname: Zhang
authors.forename: Paul P
authors.initials: PP
authors.lastname: Lee
authors.forename: Jinan B
authors.initials: JB
authors.lastname: Saaddine
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D010781:Photography; D011785:Quality Assurance, Health Care; D015203:Reproducibility of Results; D014481:United States / Q000453:epidemiology; D014786:Vision Disorders / Q000175:diagnosis*; D015351:Vision Screening / Q000379:methods*; D014792:Visual Acuity; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields