Reducing Spatial Uncertainty Through Attentional Cueing Improves Contrast Sensitivity in Regions of the Visual Field With Glaucomatous Defects

Abstract

PurposeCurrent clinical perimetric test paradigms present stimuli randomly to various locations across the visual field (VF), inherently introducing spatial uncertainty, which reduces contrast sensitivity. In the present study, we determined the extent to which spatial uncertainty affects contrast sensitivity in glaucoma patients by minimizing spatial uncertainty through attentional cueing.MethodsSix patients with open-angle glaucoma and six healthy subjects underwent laboratory-based psychophysical testing to measure contrast sensitivity at preselected locations at two eccentricities (9.5° and 17.5°) with two stimulus sizes (Goldmann sizes III and V) under different cueing conditions: 1, 2, 4, or 8 points verbally cued. Method of Constant Stimuli and a single-interval forced-choice procedure were used to generate frequency of seeing (FOS) curves at locations with and without VF defects.ResultsAt locations with VF defects, cueing minimizes spatial uncertainty and improves sensitivity under all conditions. The effect of cueing was maximal when one point was cued, and rapidly diminished when more points were cued (no change to baseline with 8 points cued). The slope of the FOS curve steepened with reduced spatial uncertainty. Locations with normal sensitivity in glaucomatous eyes had similar performance to that of healthy subjects. There was a systematic increase in uncertainty with the depth of VF loss.ConclusionsSensitivity measurements across the VF are negatively affected by spatial uncertainty, which increases with greater VF loss. Minimizing uncertainty can improve sensitivity at locations of deficit.Translational RelevanceCurrent perimetric techniques introduce spatial uncertainty and may therefore underestimate sensitivity in regions of VF loss.

Clinical Evaluation of Swedish Interactive Thresholding Algorithm–Faster Compared With Swedish Interactive Thresholding Algorithm–Standard in Normal Subjects, Glaucoma Suspects, and Patients With Glaucoma

“…34 Starting with an age-corrected sensitivity value (rather than 25 dB) at the 4 seeding points introduces significant uncertainty. 21,22,48 Consequently, this may alter response criterion, such that a more intense stimulus is required before the subject indicates a response. This is further complicated by having only 1 reversal for the staircase, which finally manifests as higher seeding point errors using SFR because there is no opportunity to reorient to the actual sensitivity.…”

“…[10][11][12][13] One significant problem with clinical perimetry is the variability in sensitivity measurement, 14 particularly in conditions of disease [15][16][17] that may stem from a number of causes. [18][19][20][21][22] In the face of known issues with variability within and between tests, there has been a paradigm shift towards conducting more visual field tests. [23][24][25] Specifically, the concept of frontloading visual fields has been recommended at a baseline examination and at follow-up in order to minimize variability to maximize the detection of progressive loss.…”

Differences in Static and Kinetic Perimetry Results are Eliminated in Retinal Disease when Psychophysical Procedures are Equated

“…We showed that so-called physiologic SKD 7 , 8 , 14 in normal subjects can be eliminated by equating the psychophysical procedure used to measure sensitivity to static and kinetic stimuli. 17 Physiologic SKD is due to the differences in psychophysical procedures: MoL used in kinetic perimetry (which is affected by errors such as individual criterion bias and reaction time 17 , 18 ) and staircase procedures used in static perimetry (affected by errors such as habituation, local adaptation, 19 response variability, 20 – 23 and attentional factors 24 – 26 ) result in discordance between the isopter border and the threshold point where stimulus uncertainty is highest. Instead, a forced choice procedure that reduces criterion bias results in equal sensitivities to static and kinetic stimuli, thus eliminating physiologic SKD.…”

Neutralizing Peripheral Refraction Eliminates Refractive Scotomata in Tilted Disc Syndrome

“… 8 , 9 Conversely, identifying statistically significant changes does not falsely highlight apparently large improvements or worsening in patients with true pathology, as the depth of defect is more likely to maintain the same level of statistical significance. As sensitivity loss increases, factors such as uncertainty and biases have been recently alluded to as contributors toward an increase in variability in sensitivity measurements 32 (also see Turpin A, et al IOVS 2018;59:E-Abstract 5129). Clinically, this has been shown to manifest as an increase in false-negative results.…”