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Open angle glaucoma effects on preattentive visual search efficiency for flicker, motion displacement and orientation pop-out tasks
  1. James Loughman1,
  2. Peter Davison1,
  3. Ian Flitcroft2
  1. 1
    Optometry Department, Dublin Institute of Technology, Dublin, Republic of Ireland
  2. 2
    Department of Ophthalmology, The Children’s University Hospital, Dublin, Republic of Ireland
  1. James Loughman, Optometry Department, School of Physics, Dublin Institute of Technology, Kevin Street, Dublin 8, Republic of Ireland; james.loughman{at}


Background/aim: Preattentive visual search (PAVS) describes rapid and efficient retinal and neural processing capable of immediate target detection in the visual field. Damage to the nerve fibre layer or visual pathway might reduce the efficiency with which the visual system performs such analysis. The purpose of this study was to test the hypothesis that patients with glaucoma are impaired on parallel search tasks, and that this would serve to distinguish glaucoma in early cases.

Methods: Three groups of observers (glaucoma patients, suspect and normal individuals) were examined, using computer-generated flicker, orientation, and vertical motion displacement targets to assess PAVS efficiency. The task required rapid and accurate localisation of a singularity embedded in a field of 119 homogeneous distractors on either the left or right-hand side of a computer monitor. All subjects also completed a choice reaction time (CRT) task.

Results: Independent sample T tests revealed PAVS efficiency to be significantly impaired in the glaucoma group compared with both normal and suspect individuals. Performance was impaired in all types of glaucoma tested. Analysis between normal and suspect individuals revealed a significant difference only for motion displacement response times. Similar analysis using a PAVS/CRT index confirmed the glaucoma findings but also showed statistically significant differences between suspect and normal individuals across all target types.

Conclusions: A test of PAVS efficiency appears capable of differentiating early glaucoma from both normal and suspect cases. Analysis incorporating a PAVS/CRT index enhances the diagnostic capacity to differentiate normal from suspect cases.

Statistics from


  • Competing interests: None.

  • Funding: This study was partly supported by a research grant from Irish Fight for Sight.

  • Abbreviations:

    choice reaction time


    intraocular pressure


    low-tension glaucoma


    preattentive visual search


    primary open angle glaucoma


    perceptual search index


    pseudoexfoliative glaucoma

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