http://www.ratbehavior.org/RatVision.htm
excerpt: What Do Rats See?
By studying rats' eyes and behavior, scientists have a pretty good idea of how a rat sees the world. In a nutshell, rats are dichromats: they perceive colors rather like a human with red-green colorblindness, but their color saturation may be quite faint, and color appears to be far less important to them than brightness. Rat vision is quite blurry, around 20/600 for normally pigmented rats. Albino rats, however, are probably blind or severely visually impaired, with about 20/1200 vision.
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