Abstract
Purpose :
The spatiotemporal contrast sensitivity function (ST-CSF) is a thorough measure of vision. Especially in the periphery, as it also describes vision for moving objects with low spatial frequencies and contrast levels, which are often encountered in our visual field. This study presents normative data on the monocular resolution ST-CSF in the 10° nasal visual field of the right eye of three normally sighted subjects.
Methods :
The refraction in the 10° field was initially determined for each subject with a COAS open field wavefront aberrometer. These refractive errors were compensated for by trial lenses during all visual evaluation. The stimuli were sinusoidal gratings, drifting within a stationary Gaussian window with a standard deviation of 1.6°. A Bayesian adaptive psychophysical procedure was implemented with two-alternative-forced-choice, in which the subject had to report whether the displayed grating was leaning 45° to the left or to the right. The gratings were shown on a calibrated CRT monitor at 2 m distance. To present low contrast stimuli, the color-look-up-table of the 10-bit gray scale was modified by sampling the central portion of the table more densely. The resolution cut-off was first determined with three repetitions for each of the temporal frequencies 0, 5, 10, and 15 cycles per second [Hz]. The resolution CS was then measured with three repetitions for the same four velocities at four spatial frequencies between 0.5 cycles per degree [cpd] and the stationary cut-off.
Results :
As shown in the figure, all subjects followed the same trend of increased sensitivity at low spatial frequencies for 5 and 10 Hz drift compared to stationary gratings (maximum increase was 0.4 logCS for 5 Hz at 0.5 cpd). The peak of the CSF shifted towards lower spatial frequencies with faster drift, but no significant change in cut-off was found. The fastest drift, 15 Hz, produced a general reduction in CSF.
Conclusions :
The 10° CSF behaves very similar to the foveal CSF, but the peak shifts towards lower spatial frequencies. This shift increases with temporal frequency. The increase in CS with drifting stimuli shows that peripheral vision can be improved with appropriate choice of stimuli, which could benefit people with central scotoma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.