Pardhan Shahina
Department of Optometry, Anglia Polytechnic University, East Road, Cambridge CB1 1PT, UK.
J Opt Soc Am A Opt Image Sci Vis. 2004 Feb;21(2):169-75. doi: 10.1364/josaa.21.000169.
The relative contributions of optical and neural factors to the decrease in visual function with aging were investigated by measurement of contrast detection at three different spatial frequencies, in the presence of external noise, on young and older subjects. Contrast detection in noise functions allows two parameters to be measured: sampling efficiency, which indicates neural changes, and equivalent noise, which demonstrates optical effects. Contrast thresholds were measured in the presence of four levels (including zero) of externally added visual noise. Measurements were obtained from eight young and eight older visually normal observers. Compared with young subjects, older subjects showed significantly (p < 0.05) lower sampling efficiencies at spatial frequencies of 1 and 4 cycles per degree (c/deg) and significantly higher equivalent noise levels for gratings of 10 c/deg. Neural and optical factors affect contrast sensitivity loss with aging differently, depending on the spatial frequency tested, implying the existence of different mechanisms.
通过在存在外部噪声的情况下，对年轻和老年受试者在三种不同空间频率下的对比度检测进行测量，研究了光学和神经因素对衰老导致视觉功能下降的相对贡献。噪声中的对比度检测函数允许测量两个参数：采样效率，它指示神经变化；等效噪声，它显示光学效应。在存在四个水平（包括零）的外部添加视觉噪声的情况下测量对比度阈值。从八名年轻和八名视觉正常的老年观察者那里获得了测量结果。与年轻受试者相比，老年受试者在每度1和4周（c/deg）的空间频率下表现出显著更低（p < 0.05）的采样效率，并且对于10 c/deg的光栅具有显著更高的等效噪声水平。神经和光学因素对衰老导致的对比度敏感性损失的影响因所测试的空间频率而异，这意味着存在不同的机制。
