Figure 1.
Testing paradigm (referenced visual localisation, Panel A; pointing, Panel B) and example data for a single observer (and for the case of Panel D, a single quadrant). Stimuli were presented for 100 ms after the button press that initiated each trial. For the visual localisation task (Panel A), the target spot appeared at one of 28 (7 MOCS steps x 4 isoeccentric locations) possible target locations. For the pointing task (Panel B), the target appeared at one of 4 possible target locations. Pointing precision was calculated as the reciprocal of the standard deviation (SD) of the population of pointing errors in the radial direction (Panel D), and visual localisation precision calculated as the reciprocal of the SD of the psychometric function fitted to the frequency of responding that the spot appeared outside the reference circle (Panel C). We also performed an unreferenced visual localisation task (not shown) wherein the reference circle (12 circularly arranged target spots, with 4 gaps) was displayed only once at the beginning of a block of trials.
Figure 2.
Visual fields and results for glaucoma participants in Experiment 2.
Greyscale age matched normal visual field plots are shown on the left and precision plots on the right for each of the eight glaucoma patients. On the greyscale plots, the eye that was used for monocular testing has a border. The location of test stimuli are illustrated by the x symbols in the top-left greyscale panel. The precision plots show monocular (left) and binocular (right) visual localisation (•) and pointing (▿) precision as a function of visual field sensitivity for each test location. The numbers in the top left corner of each panel represent the percentage of pointing data that was used in the analysis. If less than 50% of trials were to the wrong quadrant, all data for that quadrant was excluded from analysis, as seen in row 5. The locations of the numbers correspond to the appropriate quadrants.
Figure 3.
This plot shows the precision of (A) referenced visual localisation, (B) unreferenced visual localisation and (C) pointing for younger (closed symbols) and older (open symbols) observers at eccentricities of 5°, 10° and 15°. Symbols represent the group mean, with error bars showing 95% confidence intervals for the mean.
Figure 4.
Linear regression of pointing precision against 95% confidence ellipse area for pointing at 15° eccentricity.
Data of older participants is represented with open symbols and dashed regression lines, while younger participants are shown with filled symbols and unbroken regression lines. Panels A–D represent the four quadrants that were tested in Experiment 1.
Figure 5.
Pointing and visual localisation precision of glaucoma patients and older controls. Individual data has been plotted next to the mean and 95% confidence interval of the mean for both monocular and binocular conditions.
Figure 6.
Average pointing time vs. visual field global indices for glaucoma participants.
Visual field global indices provide an indication of visual field abnormality relative to an age-matched normative database. Absolute defect status (left panel) is an indication of general visual field loss, with increasingly negative numbers associated with greater levels of visual field loss. Pattern deviation (right panel) describes areas of local visual field loss, with increasingly positive numbers associated with higher levels of localised visual field loss. For both panels data points more to the left indicate greater loss of visual field sensitivity. The grey bands indicate the mean ±2 standard deviations of the older control data.