Abstract
Abstract: :
Purpose: Measurements of achromatic grating resolution acuity in peripheral vision have been shown to be sampling limited and closely related to the underlying retinal midget ganglion cell density. Psychophysical measurements using these methods confirm morphological data of a prominent nasotemporal asymmetry (visual streak) along the horizontal meridian. Recent studies have shown that peripheral grating resolution acuity for short wavelength sensitive (SWS) isolating gratings is also sampling limited and closely related to the underlying small bistratified ganglion cell density. By measuring SWS resolution acuity at different locations across the visual field, we wish to see how small bistratified ganglion density changes with eccentricity and meridian. Methods: Achromatic and SWS grating resolution acuity was measured at 10 degrees eccentricity from the fovea in 8 principal meridians (meridians 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) and also at 25 degrees (meridians 0°, 45°, 135°, 180°, 225°, 315°) and 20 degrees eccentricity (meridians 90°, 270°). Results: Achromatic resolution measurements matched previous studies with a distinct nasotemporal retinal asymmetry along the horizontal meridian (3.61 c/deg nasal vs. 2.03 c/deg temporal, 25° ecc.) and with higher resolution in the superior retina compared to the inferior retina (2.17 c/deg superior vs. 1.65 c/deg inferior, 20° ecc.). SWS acuity also showed a significant asymmetry with resolution again higher in the nasal retina than the temporal retina (0.95 nasal c/deg vs. 0.46 temporal c/deg, 25° ecc.) and with higher performance in the superior retina compared to the inferior retina (0.46 c/deg superior vs. 0.43 c/deg inferior, 20° ecc.). Conclusions: As with achromatic acuity, SWS resolution and hence the underlying small bistratified ganglion cell density shows significant asymmetry at different retinal locations of equal eccentricity with the presence of a short-wavelength sensitive visual streak along the horizontal meridian.
Keywords: ganglion cells • color vision • visual acuity