title: Blur discrimination of the human eye in the near retinal periphery.
abstract: BACKGROUND
  Although blur discrimination in the foveal region has been investigated, knowledge regarding the effect of retinal eccentricity is limited.
  
  
  METHODS
  The initial blur discrimination threshold and the blur detection threshold were assessed psychophysically and compared at the fovea and in the near retinal periphery (up to 8 degrees) with accommodation paralyzed.
  
  
  RESULTS
  The blur discrimination and blur detection thresholds increased progressively with retinal eccentricity, with the latter being about twice as large and increasing twice as fast as the former. However, the group mean blur ratio between these two parameters remained relatively constant (0.56) with retinal eccentricity.
  
  
  CONCLUSIONS
  The more sensitive blur discrimination vs. blur detection findings may be attributed to variation in the optical modulation transfer function with retinal defocus and to a perceptually based blur-buffering mechanism. The reduced blur sensitivity found with increased retinal eccentricity might be attributed to cone photoreceptor/ganglion cell sampling limitations, sharpness overconstancy, reduced visual attention, and slightly degraded visual optics.
authors.affiliation: Department of Vision Sciences, SUNY/State College of Optometry, New York, New York 10036, USA. bwang@sunyopt.edu
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
mesh_terms: D000328:Adult; D004192:Discrimination, Psychological; D005584:Fovea Centralis / Q000502:physiology; D006801:Humans; D011601:Psychophysics / Q000379:methods; D012160:Retina / Q000502:physiology*; D012684:Sensory Thresholds; D014792:Visual Acuity