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 be expected to reduce the efficiency with which the visual system performs such analysis. The purpose of the research reported here was to test the hypothesis that patients with glaucoma would be impaired on parallel search tasks, and that this would serve to distinguish glaucoma in early cases.
Methods: Three groups of observers (Glaucoma, Suspects and Normals) 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 homogenous distractors on either left or right hand side of a computer monitor. All subjects also completed a choice (CRT) reaction time task.
Results: Independent samples T tests revealed PAVS efficiency to be significantly impaired in the glaucoma group compared to both normals and suspects. Performance was impaired in all types of glaucoma tested. Analysis between normals and suspects 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 suspects and normals across all target types.
Conclusions: A test of PAVS efficiency appears capable of differentiating early glaucoma from both normals and suspects. Analysis incorporating a PAVS/CRT index enhances the diagnostic capacity to differentiate normals from suspects.
- motion displacement
- pop out
- preattentive vision
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