May 2005
Volume 46, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2005
The Effect of Stimulus Size on Perimetric Variability
Author Affiliations & Notes
  • P. Taravati
    Department of Ophthalmology, University of Iowa, Iowa City, IA
  • C.F. Brito
    Psychology, Eastern Illinois University, Charleston, IL
  • K.R. Woodward
    Veterans Administration Hospital, Iowa City, IA
  • C.K. Doyle
    Veterans Administration Hospital, Iowa City, IA
  • R.H. Kardon
    Department of Ophthalmology, University of Iowa, Iowa City, IA
    Veterans Administration Hospital, Iowa City, IA
  • M. Wall
    Department of Ophthalmology, University of Iowa, Iowa City, IA
    Veterans Administration Hospital, Iowa City, IA
  • Footnotes
    Commercial Relationships  P. Taravati, None; C.F. Brito, None; K.R. Woodward, None; C.K. Doyle, None; R.H. Kardon, None; M. Wall, None.
  • Footnotes
    Support  VA Merit Review
Investigative Ophthalmology & Visual Science May 2005, Vol.46, 3718. doi:
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    • Get Citation

      P. Taravati, C.F. Brito, K.R. Woodward, C.K. Doyle, R.H. Kardon, M. Wall; The Effect of Stimulus Size on Perimetric Variability . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3718.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Abstract:
 

to evaluate the effect of stimulus size on variability of four automated perimetry methods in glaucoma patients.

 

We tested 6 glaucoma patients with SITA MD range: –0.66 to –15.2 dB and average: –8.4 ± 4.37.once a week for 5 weeks. We tested patients in random order using four perimetry tests: 1) Humphrey program 24–2 size III, 2) Humphrey program 24–2 size V, 3) Humphrey Matrix and 4) motion perimetry.

 

There was a clear rise in variability associated with lower visual field sensitivity when stimulus size was fixed using Goldmann size III and size V stimuli with Humphrey automated perimetry. Variability remained relatively constant across visual field sensitivities with the large fixed–size stimuli of the Humphrey Matrix and with motion perimetry (a method that measures threshold by changing stimulus size until the smallest size stimulus can be detected by a subject in each visual field location). After eliminating the values subject to a floor effect, we found the following correlations:

 

 

With small, fixed size stimuli, variability rises exponentially with decreasing sensitivity in glaucoma patients. Variability remains relatively constant with decreasing sensitivity when using a very large stimulus or determining threshold by changing stimulus size.

 

 
Keywords: perimetry • visual fields 
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