Based on anatomical measurements of refractive structures in the eye, the positions of focused images were computed for several groups of semiaquatic mammals: rodents, a nonpinniped semiaquatic carnivore (the sea otter), and pinniped carnivores (seals, sea lions, and the walrus). In semiaquatic rodents, eye optics enable emmetropia in the air but cause substantial hypermetropia in the water. In semiaquatic carnivores, there are several mechanisms for amphibious vision that focus images on the retina in both air and water. These mechanisms include the potential for a substantial change in the lens shape of sea otters and the presence of the corneal emmetropic window in pinnipeds. The results suggest that several groups of mammals that independently adapted to aquatic environments vary in how their visual systems adapted to aquatic vision.

中文翻译：

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Semiaquatic哺乳动物的眼光学，用于空中和水上视觉。

基于眼睛中屈光结构的解剖学测量，计算了几组半水生哺乳动物的聚焦图像的位置：啮齿动物，非夹住的半水生食肉动物（海獭）和夹住的食肉动物（海豹，海狮和海象） 。在半水生啮齿动物中，眼睛光学器件可使空气中正视，但会引起水中的远视。在半水生食肉动物中，有几种用于两栖视觉的机制，可将图像聚焦在空气和水中的视网膜上。这些机制包括可能改变水獭的晶状体的形状，以及在夹缝区存在角膜正视窗口。结果表明，几组独立适应水生环境的哺乳动物的视觉系统如何适应水生视觉。