title: Predictive value of frequency doubling technology perimetry for detecting glaucoma in a developing country.
abstract: OBJECTIVE
  To determine the feasibility and diagnostic precision of Frequency Doubling Technology (FDT) perimetry as a method to detect glaucoma in rural villages of a developing country.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Testing included FDT perimetry (C-20-5 screening protocol), tonometry, anterior segment biomicroscopy, and dilated ophthalmoscopy in 296 rural, non-English speaking residents of Southern India over 35 years old. Participants repeated the FDT if they had a location with reduced sensitivity or an unreliable result. We defined an abnormal FDT as one location of reduced sensitivity present on both the initial and repeat examination. We determined the diagnostic precision of FDT separately for a glaucomatous optic disc, a cup to disc ratio (C/D) > or = 0.7, and a C/D > or = 0.8.
  
  
  RESULTS
  Ninety-three percent of subjects were able to complete the test satisfactorily. With repeat FDT testing, 37% of eyes with abnormal FDT results subsequently converted to normal and 67% of eyes with unreliable results subsequently became reliable. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for a glaucomatous optic disc were 7%, 87%, 13%, 76%, and 69%, respectively; for a C/D > or = 0.7, they were 0%, 87%, 0%, 91%, and 81%, respectively; and for a C/D > or = 0.8, they were 0%, 87%, 0%, 99%, and 87%, respectively.
  
  
  CONCLUSIONS
  Clinicians can use FDT perimetry to rapidly screen for glaucoma in rural villages of a developing country. FDT testing had high specificity and negative predictive value, but low sensitivity and positive predictive value. The low sensitivity suggests that FDT has limited applicability as the sole test for glaucoma screening in this population. Repeat testing of FDT results that are unreliable or suspected of being abnormal is beneficial for this screening procedure.
authors.affiliation: Devers Eye Institute/Discoveries in Sight, Portland, Oregon 97210, USA. smansberger@discoveriesinsight.org
authors.forename: Steven L
authors.initials: SL
authors.lastname: Mansberger
authors.forename: Chris A
authors.initials: CA
authors.lastname: Johnson
authors.forename: George A
authors.initials: GA
authors.lastname: Cioffi
authors.forename: Dongseok
authors.initials: D
authors.lastname: Choi
authors.forename: S R
authors.initials: SR
authors.lastname: Krishnadas
authors.forename: M
authors.initials: M
authors.lastname: Srinivasan
authors.forename: V
authors.initials: V
authors.lastname: Balamurugan
authors.forename: Usha
authors.initials: U
authors.lastname: Kim
authors.forename: Scott D
authors.initials: SD
authors.lastname: Smith
authors.forename: John H
authors.initials: JH
authors.lastname: Wilkins
authors.forename: David C
authors.initials: DC
authors.lastname: Gritz
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003906:Developing Countries; D005189:False Positive Reactions; D005240:Feasibility Studies; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007194:India; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000175:diagnosis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012424:Rural Population; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular; D058609:Visual Field Tests / Q000379:methods* / Q000592:standards