Chen S A, Wu L Z, Wu D Z
Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Sciences, Guangzhou, People's Republic of China.
Doc Ophthalmol. 1990 Sep;75(2):145-53. doi: 10.1007/BF00146550.
Contrast sensitivity functions (CSFs) were determined electrophysiologically with the steady-state visual evoked potential (VEP). Psychophysical CSFs obtained by the method of increasing contrasts were also measured concurrently with the VEP trials. The VEP contrast thresholds were obtained using a rapid recording technique in which the contrast of a counterphase sinewave modulated at a temporal frequency of 7.5 Hz was swept from 0.5% to 40% over a period of 22 s in 39 equal logarithmic steps. For this pattern reversal stimulus, the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Contrast sensitivities at five spatial frequencies ranging from 0.5 to 14.9 cpd were measured. The VEP contrast thresholds were determined by a linear extrapolation to zero amplitude. The contrast threshold obtained by the two methods correlated at 0.816 for 14 subjects. For all five spatial frequencies there were no significant differences between the contrast sensitivities derived from the two methods.
采用稳态视觉诱发电位（VEP）通过电生理方法测定对比敏感度函数（CSF）。同时，在进行VEP试验的过程中，还采用对比度递增法测量了心理物理学CSF。VEP对比阈值通过一种快速记录技术获得，其中，以7.5 Hz的时间频率调制的反相正弦波的对比度在22 s内以39个相等的对数步长从0.5%扫至40%。对于这种模式反转刺激，使用离散傅里叶变换（DFT）测量二次谐波响应的幅度和相位作为对比度的函数。测量了0.5至14.9 cpd范围内五个空间频率的对比敏感度。VEP对比阈值通过线性外推至零幅度来确定。两种方法获得的对比阈值在14名受试者中的相关性为0.816。对于所有五个空间频率，两种方法得出的对比敏感度之间均无显著差异。
