title: The Effect of Limiting the Range of Perimetric Sensitivities on Pointwise Assessment of Visual Field Progression in Glaucoma.
abstract: OBJECTIVE
  Automated perimetry does not produce reliable estimates of true psychophysical threshold in glaucomatous visual fields when the perimetric threshold falls below 15 to 19 dB. It may be possible to truncate testing at such locations and not use stimuli with very high contrast. However, this can only be recommended if it does not harm the ability to monitor change. This study examined the effect of applying such a cutoff by censoring sensitivities in two existing longitudinal datasets.
  
  
  METHODS
  Series of six visual fields were taken from participants with glaucoma or high-risk ocular hypertension in the Portland Progression Project (P3) and Rotterdam Eye Study (RES). Pointwise linear regression was used to find "progressing" locations, defined as a slope ≤ -1 dB/y with P < 1%. An eye was labeled progressing if ≥3 locations were progressing. This was repeated after setting any sensitivities below the cutoff value C (CdB) to instead equal that value for different integer values of CdB.
  
  
  RESULTS
  In the P3 cohort tested using Swedish Interactive Testing Algorithm (SITA) Standard, censoring below 15 to 19 dB did not reduce the number of eyes flagged as progressing. For the RES cohort tested using the Full Threshold algorithm, censoring below 10 dB did not reduce the number of eyes flagged as progressing, but a modest reduction was seen for CdB between 10 dB and 15 to 19 dB.
  
  
  CONCLUSIONS
  The proportion of eyes flagged as progressing was not decreased by censoring unreliable sensitivities. Restricting the range of contrast used in clinical perimetry may be possible without hampering the ability to monitor glaucomatous visual field progression.
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Stuart K
authors.initials: SK
authors.lastname: Gardiner
authors.affiliation: School of Optometry, Indiana University, Bloomington, Indiana, United States.
authors.forename: William H
authors.initials: WH
authors.lastname: Swanson
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Shaban
authors.initials: S
authors.lastname: Demirel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*
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