Purpose: We developed a contrast sensitivity test that considers an integrative approach of spatial and temporal frequencies to evaluate the psychophysical channels in processing two-dimensional stimulus for clinical use. Our new procedure provides a more efficient isolation of the magnocellular and parvocellular visual pathways supporting spatiotemporal contrast sensitivity processing.
Methods: We evaluated 36 participants of both sexes aged 18-30 years with 20/20 or better best-corrected visual acuity. Two spatial frequencies (0.5 cycles per degree [cpd] and 10 cpd), being in one of the three temporal frequencies (0.5 cycle per second [cps], 7.5 cps, and 15 cps), were presented in a high-resolution gamma corrected monitor. A two-alternative forced-choice procedure was conducted, and the staircase method was used to calculate the contrast sensitivity. Reliability was assessed using a retest procedure within a month ( 5 days) under the same conditions.
Results: Results showed statistical significance in 0.5 cpd and 10 cpd spatial frequencies for 0.5 cps (F = 77.36; p 0.001), 7.5 cps (F = 778.37; p 0.001), and 15 cps (F = 827.23; p 0.001) with a very high (η = 0.89) effect size. No statistical differences were found between the first and second sessions for all spatial frequencies. For reliability, a significantly high correlation and high internal consistency were found in all spatiotemporal conditions. The limits were calculated for normality.
Conclusion: We developed an approach to investigate the spatiotemporal integration of contrast sensitivity designed for clinical purposes. The relative contribution of the low spatial frequencies/high temporal frequencies and the high spatial frequencies/low temporal frequencies of the psychophysical channels can also be evaluated separately.
Keywords: Drifting Grating; Dynamic Contrast Sensitivity; Primary Visual Pathway; Spatial Vision; Clinical Psychophysics.
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