Figure 1.
Effect of CL aperture luminance levels on a characteristic VEP waveform.
Grand-averaged (64 epochs) monocular VEP waveforms from one subject at high (30 cd/m2, left) and low (5 cd/m2, right) photopic levels for a natural pupil (black line) and with a contact lens of 2.5 mm (dark grey line) and 1.5 mm (light grey line) aperture. P100 latency is indicated in ms.
Figure 2.
Plots of VEP latency as a function of time for the 2.5.
(upper) Monocular (open circles, dominant eye; open squares, non-dominant eye) and binocular (filled circles) mean latency of the VEP P100 component as a function of time at high (left) and low (right) photopic levels for subjects SP (fig 2a) and for TG (fig 2b). Each point is the average of two recordings. On days -1 and 8 the subject had unobstructed natural pupils. On days 0–7 inclusive the non-dominant (left) eye was wearing a contact lens with an aperture of 2.5 mm in diameter. The dominant eye had its full, unobstructed natural pupil. The legend shows the average pupil size at each condition. (lower) Plot of the interocular latency difference as a function of time. The dotted bold line forms a linear regression for Days 0 to 7.
Figure 3.
Plots of VEP latency as a function of time for the 1.5.
(upper) Plots of monocular (open circles, dominant eye; open squares, non-dominant eye) and binocular (filled circles) mean latency of the VEP P100 component as a function of time at high (left) and low (right) photopic levels for subjects SP (fig 3a) and TG (fig 3b). Each point is the average of two recordings. On days -1 and 8 the subject had unobstructed natural pupils. On days 0–7 inclusive the non-dominant (left) eye was wearing a contact lens with an aperture of 1.5 mm in diameter. The dominant eye had its full, unobstructed natural pupil. The legend shows the average pupil size at each condition. (lower) Plot of the interocular latency difference as a function of time. The dotted bold line forms a linear regression for Days 0 to 7.
Figure 4.
Values of ND filter required to null the Pulfrich effect as a function of time.
The non-dominant eye was wearing a 2.5 mm (circles) or a 1.5 mm lens (squares). Data for subject SP (left) and TG (right) at high (open symbols) and low (filled symbols) photopic levels are presented. The average values of ND filter required to null the Pulfrich effect, when placed in front of the dominant eye, for all conditions are also shown. The dotted / dashed lines form a linear regressions for Days 0 to 7.
Figure 5.
Interocular differences in VEP latency as a function of the interocular ratio of retinal illuminance.
VEP latency is averaged for recordings between Day 0 and Day 7 and is plotted for two photopic luminance levels (30 vs. 5 cd/m2). The results of an earlier study[14] using 7 subjects are shown for comparison. The bars indicate ±1 SD.
Table 1.
Νatural pupil diameter (in mm) during binocular / monocular VEP recordings and for two luminance levels.
Figure 6.
Observed vs. predicted values of ND filter required to null the Pulfrich effect.
Average data are shown for the 2 observers and the 2 luminance conditions. Predicted ND values are based simply on relative pupil areas. The non-dominant eye was wearing a small-aperture CL of 1.5 or 2.5 mm in diameter. The dotted line represents exact agreement with predictions. The dashed lines form regression fits. The bars indicate ±1 SD during the 7 days of the trial.
Table 2.
Νatural pupil diameter (in mm) of the dominant eye during Pulfrich recordings.