title: Blur-resistant perimetric stimuli.
abstract: OBJECTIVE
  To develop perimetric stimuli that are resistant to the effects of peripheral defocus.
  
  
  METHODS
  One eye each was tested on subjects free of eye disease. Experiment 1 assessed spatial frequency, testing 12 subjects at eccentricities from 2 to 7 degrees using blur levels from 0 to 3 diopters (D) for two (Gabor) stimuli (spatial SD, 0.5 degrees; spatial frequencies, 0.5 and 1.0 cycles per degree [cpd]). Experiment 2 assessed stimulus size, testing 12 subjects at eccentricities from 4 to 7 degrees using blur levels 0 to 6 D for two Gaussians with SD of 0.5 and 0.25 degrees and a 0.5-cpd Gabor with SD of 0.5 degrees. Experiment 3 tested 13 subjects at eccentricities from fixation to 27 degrees using blur levels 0 to 6 D for Gabor stimuli at 56 locations; the spatial frequency ranged from 0.14 to 0.50 cpd with location, and SD was scaled accordingly.
  
  
  RESULTS
  In experiment 1, blur by 3 D caused a small decline in log contrast sensitivity for the 0.5-cpd stimulus (mean ± SE, 0.09 ± 0.08 log units) and a larger (t = 7.7, p < 0.0001) decline for the 1.0-cpd stimulus (0.37 ± 0.13 log units). In experiment 2, blur by 6 D caused minimal decline for the larger Gaussian, by 0.17 ± 0.16 log units, and larger (t > 4.5, p < 0.001) declines for the smaller Gaussian (0.33 ± 0.16 log units) and the Gabor (0.36 ± 0.18 log units). In experiment 3, blur by 6 D caused declines by 0.27 ± 0.05 log units for eccentricities from 0 to 10 degrees, by 0.20 ± 0.04 log units for eccentricities from 10 to 20 degrees, and 0.13 ± 0.03 log units for eccentricities from 20 to 27 degrees.
  
  
  CONCLUSIONS
  Experiments 1 and 2 allowed us to design stimuli for experiment 3 that were resistant to effects of peripheral defocus.
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana 47405, USA. hornerdg@indiana.edu
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Horner
authors.forename: Mitchell W
authors.initials: MW
authors.lastname: Dul
authors.forename: William H
authors.initials: WH
authors.lastname: Swanson
authors.forename: Tiffany
authors.initials: T
authors.lastname: Liu
authors.forename: Irene
authors.initials: I
authors.lastname: Tran
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011601:Psychophysics / Q000379:methods*; D012016:Reference Values; D012684:Sensory Thresholds; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult