Diagnostic Sensitivity/Specificity of Preattentive Vision Tests in Glaucoma

Abstract

Damage to the nerve fiber layer or visual pathway might be expected to reduce the efficiency with which the visual system performs analysis of the ever-changing field of vision. The purpose of this article is to provide a further analysis of previously reported data (Loughman J, Davison P, Flitcroft I, Br J Ophthalmol 2007;91:1493-98.) to: (i) determine the sensitivity and specificity of a test of preattentive vision for glaucoma detection and (ii) provide a cutoff performance level that would serve to distinguish glaucoma in early cases. Three groups of observers (glaucoma, suspects, and normals) were examined, using computer-generated flicker, orientation, and vertical displacement targets to assess preattentive visual search (PAVS) efficiency. The task required rapid and accurate localization 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 reaction time task. Receiver operating characteristic curve analysis demonstrates consistently high diagnostic sensitivity and specificity values (significantly above 90% for all tasks) using the raw PAVS data and also for a novel perceptual search index (which improves the diagnostic capacity of the test). Optimal performance cutoff values for each task were also computed. A test of PAVS efficiency demonstrates high sensitivity and specificity to early glaucoma. Analysis incorporating the perceptual search index confirms the high diagnostic capacity of the test.