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K Momose, M Saito; Measurement of the Chromatic Contrast Sensitivity Using Visually Evoked Potential . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4735.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To develop a practical and rapid method to measure the chromatic contrast sensitivity and to examine whether the method is useful to test both the normal and defective color vision. Methods: The swept parameter technique (Norcia and Tyler, 1985) was modified to detect the chromatic contrast sensitivity function (CCSF). Vertical sinusoidal chromatic gratings presented on the color monitor were modulated sinusoidally in iso-luminant chromatic contrast at 12 reversals per second. The spatial frequency was 1 cpd and the period of a stimulus was 90 seconds. Two colors for the gratings were selected from colors on the dichromatic isochromatic lines. Steady-state VEP was measured during the stimulation in which the chromatic contrast continuously decreased at 1.25 % per second. The amplitude of the steady-state VEP component at 24 Hz was calculated using a discrete Fourier transform in each epoch of 1 second and normalized by the averaged amplitudes at 0-10% contrast. Their relation to the chromatic contrast were used as CCSF. VEPs were measured from 5 adults with normal color vision. Results: VEP amplitudes at 24 Hz decreased exponentially according to chromatic contrast decreasing and were almost flat at 0-65% contrast. These curves (CCSF) were reproducible within a subject (r ≷ 0.81) and similar among subjects. The result agreed with the previous psychophysical and electrophysiological results. Although the CCSF at 60-80% contrast was lower than those obtained from the individually measured VEPs to the chromatic modulation stimuli with the constant contrast (0, 20, 60, 80 and 100%), their whole curves were similar (r ≷ 0.74). The results indicated that the VEP amplitudes at 100% contrast and its decline around 60-100% contrast changes could be useful indices of chromatic sensitivity and they can be measured within short time (less than 40 seconds for one eye). Conclusion: The modified swept parameter technique derived the reproducible and stable CCSF which will be effective for measuring the defective color vision.
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