Choice of Grating Orientation for Evaluation of Peripheral Vision

[jinglescode]

Paper

Link: https://pubmed.ncbi.nlm.nih.gov/26889822/
Year: 2016

Summary

• evaluate peripheral resolution and detection for different orientations in different visual field meridians

Learnings

• for accurate visual evaluation, 3 factors should be taken into considerations:
  • acuity (resolution or detection)
  • field loci (enncentricity and meridian)
  • stimulus properties (orientation of stimulus)
• peripheral resolution acuity is dependent on the orientation of visual stimuli (the meridional effect)
  • stimuli oriented radially along a meridian are better resolved
• high contract resolution is relatively unaffected by optical errors because it is neurally limited, whereas detection is affected by optical errors
  • stimulus with spatial frequency above neural sampling limit cannot be resolved
  • undersampled stimulus undergoes aliasing and can be perceived through moire patterns with a low spatial frequency, lower contrast, and different orientation
• meridional preference for detection tasks may be a combination of optical and neural orientation sensitivities
• sinusoidal gratings are common stimulus choice for research on peripheral vision, suitable for evaluating detection and resolution acuity and contrast sensitivity

Methods

• sinusoidal grating stimuli presented for 500 ms

Results

• acuity is better for gratings oriented along the meridian
• sinusoidal gratings's Gaussian window reduce the contrast of the stimuli, at radius of 1 standard deviation, the Gaussian window reduces the contrast, this means that the contrast in the center of the stimulus has been reduced to about 55% at 1 standard deviation away from the center
• studies that uses sinusoidal gratings in circular window have reported better detections, caused by well known edge effect
• grating parallel to visual field meridian will produce better acuity than perpendicular grating