Retinal image quality in the rodent eye
Retinal image quality in the rodent eye
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DOI：
10.1017/s0952523898154020
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发表时间：
1998-07-01
影响因子：
1.9
通讯作者：
Green, DG
中科院分区：
文献类型：
--
作者：
Artal, P;de Tejada, PH;Green, DG
许多啮齿动物视力不佳。对于大鼠或小鼠要分辨的目标，它必须具有一定程度或更大的视角。人们通常认为这种较差的空间分辨能力是由于神经而不是光学限制造成的，但这些动物的视网膜图像质量尚未得到很好的表征。我们修改了最初为人眼设计的双通装置，因此可以与啮齿类动物一起使用来测量眼睛光学系统的调制传递函数（MTF）。也就是说，使用 CCD 相机对单色（λ = 632.8 nm）点源的双通视网膜图像进行数字化。根据这些双通道测量，在各种聚焦条件和不同瞳孔大小下计算单通道 MTF。即使眼睛处于最佳聚焦状态，大鼠和小鼠的图像质量也非常差。例如，对于 1 毫米的瞳孔，大鼠的 MTF 上限约为 2.5 周期/度，而不是如果眼睛是衍射极限系统，则达到 28 周期/度。这些图像比人眼中的类似视网膜图像差大约 10 倍。利用我们对大鼠光学系统的测量以及已发表的行为和电生理学对比敏感度函数 (CSF)，我们计算出了如果老鼠拥有完美而不是较差的光学系统，其将具有的 CSF。有趣的是，我们发现衍射极限光学器件总体上只会产生轻微的改进。也就是说，尽管视网膜图像的质量非常低，但啮齿类动物的视觉分辨率上限是由神经决定的。大鼠和小鼠的眼睛的光学系统和视网膜/大脑似乎非常匹配。
Many rodents do not see well. For a target to be resolved by a rat or a mouse, it must subtend a visual angle of a degree or more. It is commonly assumed that this poor spatial resolving capacity is due to neural rather than optical limitations, but the quality of the retinal image has not been well characterized in these animals. We have modified a double-pass apparatus, initially designed for the human eye, so it could be used with rodents to measure the modulation transfer function (MTF) of the eye's optics. That is, the double-pass retinal image of a monochromatic (lambda = 632.8 nm) point source was digitized with a CCD camera. From these double-pass measurements, the single-pass MTF was computed under a variety of conditions of focus and with different pupil sizes. Even with the eye in best focus, the image quality in both rats and mice is exceedingly poor. With a l-mm pupil, for example, the MTF in the rat had an upper limit of about 2.5 cycles/deg, rather than the 28 cycles/deg one would obtain if the eye were a diffraction-limited system. These images are about 10 times worse than the comparable retinal images in the human eye. Using our measurements of the optics and the published behavioral and electrophysiological contrast sensitivity functions (CSFs) of rats, we have calculated the CSF that the rat would have if it had perfect rather than poor optics. We find, interestingly, that diffraction-limited optics would produce only slight improvement overall. That is, in spite of retinal images which are of very low quality, the upper limit of visual resolution in rodents is neurally determined. Rats and mice seem to have eyes in which the optics and retina/brain are well matched.