title: Comparing the Performance of Compass Perimetry With Humphrey Field Analyzer in Eyes With Glaucoma.
abstract: OBJECTIVE
  To evaluate the reliability indices [fixation losses, false negative response rates (FN) and false positive response rates] and threshold sensitivities obtained from glaucoma patients with a Compass perimeter and to compare the same with the Humphrey field analyzer (HFA).
  
  
  METHODS
  In a cross-sectional study, 97 eyes of 58 subjects (64 glaucoma and 33 glaucoma suspect eyes) underwent visual field examination with Compass and HFA. Any test with a fixation losses, FN or FP of >20% was considered unreliable. Reliability indices and threshold sensitivities between the 2 instruments were compared and the agreement evaluated using Bland and Altman analysis.
  
  
  RESULTS
  In total, 37 tests (38%) with Compass and 17 (18%) with HFA were unreliable. The number of unreliable tests due to high FN (>20%) was significantly more (P=0.005) with Compass (n=27) than HFA (n=3). The mean difference [95% limits of agreement (LoA)] in mean sensitivity between Compass and HFA in the 51 eyes with reliable Compass and HFA results was -0.7 dB (-5.6, 4.3 dB). The point-wise threshold sensitivities with Compass were lower than that with HFA in central and temporal but higher in the nasal field. The 95% LoA ranged from -8 to +5 dB at one of the central points to -20 to +20 dB at one of the peripheral points.
  
  
  CONCLUSIONS
  The numbers of unreliable tests were higher with Compass compared with HFA. The LoA between Compass and HFA for point-wise threshold sensitivities as well as the global indices were wide, implying that the instruments cannot be used interchangeably.
authors.affiliation: Narayana Nethralaya, Rajajinagar, Bangalore, India.
authors.forename: Harsha L
authors.initials: HL
authors.lastname: Rao
authors.forename: Sharanya
authors.initials: S
authors.lastname: Raveendran
authors.forename: Varsha
authors.initials: V
authors.lastname: James
authors.forename: Srilakshmi
authors.initials: S
authors.lastname: Dasari
authors.forename: Meena
authors.initials: M
authors.lastname: Palakurthy
authors.forename: Hemanth B
authors.initials: HB
authors.lastname: Reddy
authors.forename: Zia S
authors.initials: ZS
authors.lastname: Pradhan
authors.forename: Dhanaraj A S
authors.initials: DA
authors.lastname: Rao
authors.forename: Narendra K
authors.initials: NK
authors.lastname: Puttaiah
authors.forename: Sathi
authors.initials: S
authors.lastname: Devi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000502:physiology; D058609:Visual Field Tests / Q000379:methods* / Q000592:standards; D014794:Visual Fields / Q000502:physiology*