April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
A Feature Search Method for Mapping the Central Visual Field
Author Affiliations & Notes
  • Thomas Kuyk
    TASC, Inc, Ft Sam Houston, TX
  • Lei Liu
    University of Alabama at Birmingham, Birmingham, AL
  • Elizabeth Belleau
    Air Force Research Laboratory, Ft Sam Houston, TX
  • Peter Smith
    TASC, Inc, Ft Sam Houston, TX
  • Leon N McLin
    Air Force Research Laboratory, Ft Sam Houston, TX
  • Footnotes
    Commercial Relationships Thomas Kuyk, None; Lei Liu, None; Elizabeth Belleau, None; Peter Smith, None; Leon McLin, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4118. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Thomas Kuyk, Lei Liu, Elizabeth Belleau, Peter Smith, Leon N McLin; A Feature Search Method for Mapping the Central Visual Field. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4118.

      Download citation file:


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

      ×
  • Supplements
Abstract
 
Purpose
 

To determine if small areas of vision loss (scotoma) of approx.1-2° in the central 10-20° of the visual field could be detected using a visual feature search (FS) paradigm. The rationale was that if a scotoma (S) covered the search target or partially obscured it, response time for target detection (RTHit) would be increased compared to targets presented outside the S; either because eye movements would be needed or reduced conspicuity would lead to longer decision times.

 
Methods
 

Nine subjects completed a FS task with and without a simulated S present in central 10° or 20° search areas. Parafoveal S were simulated with a gaze-contingent display system. The FS task consisted of a black target presented in a set of grey distracters. Stimulus items were randomly distributed at the intersections of virtual square grids laid over the search areas. Distractor density was set at 20% of possible grid locations and over trials the target appeared at each test location. On 25% of trials no target was presented. S were circular with Gaussian blurred edges and centered in open areas adjacent to grid intersections. For the 10 and 20° search areas, one grid size (11 x 11; 13 x 13), three S eccentricities (2, 3 & 6°; 5, 7 & 9°) and two S sizes (1.1 & 1.6°; 1.6 & 2.2°) were tested for each search area. Each trial was subject initiated after central fixation was achieved. Subjects responded target present or target absent with button presses that also terminated trials.

 
Results
 

For the 10° search area, a 1.1° S could be detected on the basis of increased RTHit for targets presented immediately adjacent to the S compared to RTHit averaged for all grid locations. The larger 1.6° S yielded longer RTHit and larger differences compared to average RTHit. For the 20° search area, a 2.2° S was detectable at all locations using the reference versus RTHit average. Fig 1 shows RTHit (ms) for each grid location for a 10 x10° search area. A S was located adjacent to the intersection of row 2 and column 2 and RTHit are longest in this vicinity.

 
Conclusions
 

The results suggest the FS paradigm has sufficient merit as a method to detect small central S to warrant further study. Future research should focus on ways to improve the methodology, reduce noise and speed data collection.

  
Keywords: 758 visual fields • 760 visual search • 642 perimetry  
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×