Morrison J D, Jay J L
Institute of Physiology, University of Glasgow, UK.
Eye (Lond). 1993;7 ( Pt 1):20-5. doi: 10.1038/eye.1993.5.
We have been able to separate the neural and optical components of vision with contrast sensitivity tests employing laser interferometry and direct viewing of a cathode ray tube display. In normal ageing, neural function declined markedly while optical function remained essentially unchanged. On the other hand, even the mildest degree of cataract was shown to degrade optical function to the extent that it exceeded the age-related neural deterioration. The satisfactory optical performance of the monofocal implant lens has been confirmed, though the diffractive bifocal implant lens was shown to have optical limitations. A major cause of these was shown, by simulation experiments, to be the dilution of the contrast of the in-focus image by the superimposed defocused image, particularly under conditions of reduced retinal sensitivity as would be present in the elderly.
我们已经能够通过使用激光干涉测量法的对比敏感度测试以及直接观察阴极射线管显示器，来分离视觉的神经和光学成分。在正常衰老过程中，神经功能显著下降，而光学功能基本保持不变。另一方面，即使是最轻微程度的白内障也被证明会使光学功能退化到超过与年龄相关的神经退化程度。单焦点植入式人工晶状体的光学性能令人满意，不过衍射双焦点植入式人工晶状体被证明存在光学局限性。模拟实验表明，其主要原因是叠加的散焦图像会稀释聚焦图像的对比度，尤其是在老年人视网膜敏感度降低的情况下。
