神经对比敏感度对暗适应及佩戴微光夜视镜后视觉功能的评价

Value of neural contrast sensitivity on evaluating dark adapted and night vision goggle aided visual performance

目的应用神经对比敏感度（neural contrast sensitivity，NCS）评价暗适应及佩戴微光夜视镜后的视觉功能，并与对比敏感度（contrast sensitivity，CS）相比较，探讨NCS在视觉功能鉴定中的应用价值。方法招募8名健康男性（8只眼）志愿者作为受试，以右眼为测试眼。利用视觉监视系统测量微光环境（亮度为10^-1-10^-4cd／m^2）下，明适应、暗适应及佩戴微光夜视镜时受试者的CS。利用视觉质量分析仪测量调制传递函数（modulation transfer function，MTF）值。根据CS与MTF的比值求得NCS。结果在中低频区[空间频率为0．6-3．4周／度（cycle／degree，c／d）]，暗适应能显著提高暗视觉环境下受试者的NCS及CS，在中间视觉环境下所起的作用较小；微光夜视镜能显著提高暗视觉及中间视觉环境下（空间频率为1．1-7．1c／d）受试者的NCS及CS，效果好于暗适应。在高频区，暗适应和夜视镜对提高受试者的NCS及CS均没有明显作用。结论暗适应和微光夜视镜均能够提高暗视觉环境下的视觉功能，夜视镜提升的效果更好。CS曲线反映整体视觉功能，NCS反映视觉神经系统功能。对于Cs不佳的飞行员，NCS和MTF有助于判断导致CS下降的原因。建议用NCS、MTF和CS综合检测来评价飞行员的视觉功能。

Objective To apply neural contrast sensitivity （NCS） on evaluating the dark adapted and night vision goggle （NVG） aided visual performance upon the comparison with contrast sensitivity （CS） and to investigate the value of NCS in the assessment of visual performance. Methods Eight healthy male volunteers （8 eyes） were recruited for this study, and the right eye was tested in this experiment. CS curves of volunteers in light adaptation, dark adaptation and with NVG were measured by Vision Monitor System in different environment luminance levels （10-1-10-4 cd/m^2）. Modulation transfer function （MTF） curves were measured by optical quality analysis system. NCS was defined as the ratio of CS and MTF. Results In lower and medium frequency range （spatial frequency was 0.6-3.4 cycle/degree）, dark adaptation made subjectt s NCS and CS mount up considerably in the seotopic vision environment, but less effect in mesopie vision environment. NVG considerably improved subject% NCS and CS both in scotopic and mesopic vision environments （spatial frequency was 1. 1-7. 1 cycle/degree） and more effective than in dark adaptation. In high spatial frequency range, neither dark adaptation nor NVG had obvious effect on improving subject＇s NCS and CS. Conclusions Both dark adaptation and snooper scopes can improve visual performance in the scotopic vision environment, but snooper scopes is better. CS curves can represent the comprehensive visual performance, NCS reflects the function of the retina-brain neural system. But NCS and MTF would be helpful to find the reasons in case of poor CS measured. The examination combined NCS and MTF with CS is suggested.