How Good is a Rat’s Eyesight?
WouterRats have two types of cones in their eyes, one with a high density of blue-UV photopigment and the other with a higher density of middle-green cones. This combination gives them the ability to see colors we can’t. This has led researchers to study the cones’ sensitivity and signaling.
Since most rats spend most of their time in darkness, their eyesight is pretty poor. In order to compensate, they use their whiskers to help them navigate, especially at night. This allows them to see well at night. This adaptation makes them more active at night and helps them avoid predators.
Rats have a field of vision that is roughly 40 degrees wide in the horizontal plane and 60 degrees wide in the vertical plane. Rats also have opposing eye movements, which prevent the brain from fusing visual information into a single image. In contrast, humans have eyes that are set in a fixed position and must look in the same direction.
The depth of focus is another way to assess rat eyesight. Humans and rats have a similar distance range (2.3 meters) from which they can focus, but a rat’s depth of focus is seven centimeters. Regardless of the size, however, a rat’s depth of focus can’t be improved with strong glasses.
