Lopes de Faria J M, Katsumi O, Arai M, Hirose T
Schepens Eye Research Institute, Boston, MA 02114, USA.
Br J Ophthalmol. 1998 Feb;82(2):168-73. doi: 10.1136/bjo.82.2.168.
AIM/BACKGROUND: The contrast sensitivity function (CSF) measurement provides information that is not accessible by standard visual acuity determinations. The contrast sweep pattern reversal visual evoked responses (CSVER) technique was used to objectively measure the CSF in clinical practice.
The contrast thresholds were measured at five spatial frequencies in 10 normal subjects. The CSVER were recorded with sinusoidally modulated vertical gratings at 10 contrast levels (96, 64, 48, 32, 16, 8, 4, 2, 1, and 0.5%) presented in five spatial frequencies (0.5, 1.0, 2.0, 4.0, and 8.0 cycles per degree). Each of 10 contrast levels was displayed for 2 seconds at the desired spatial frequency. The CSVER amplitudes at the second harmonic were calculated by discrete Fourier transform. The results were compared with those obtained using a psychophysical method.
An inverted U-shaped CSF which peaked at 2.0 cycles per degree with a contrast sensitivity of 34.5 (contrast, 2.9%) was observed. The CSF assessed electrophysiologically was 0.62 to 0.79 log units lower than the sensitivity measured using the psychophysical method. However, the overall shapes were highly correlated.
One can objectively measure CSF with CSVER and this may be useful in patients in whom the psychophysical method is limited.
目的/背景：对比敏感度函数（CSF）测量可提供标准视力测定无法获取的信息。在临床实践中，采用对比扫描模式翻转视觉诱发电位（CSVER）技术客观测量CSF。
对10名正常受试者在五个空间频率下测量对比阈值。使用正弦调制的垂直光栅在五个空间频率（0.5、1.0、2.0、4.0和8.0周/度）下呈现10个对比度水平（96%、64%、48%、32%、16%、8%、4%、2%、1%和0.5%）来记录CSVER。每个10个对比度水平在所需空间频率下显示2秒。通过离散傅里叶变换计算二次谐波处的CSVER振幅。将结果与使用心理物理学方法获得的结果进行比较。
观察到一个倒U形的CSF，在2.0周/度时达到峰值，对比敏感度为34.5（对比度，2.9%）。通过电生理评估的CSF比使用心理物理学方法测量的敏感度低0.62至0.79对数单位。然而，总体形状高度相关。
可以使用CSVER客观测量CSF，这对于心理物理学方法受限的患者可能有用。
