Eyesight varies so much in the animal kingdom that it’s only natural to wonder if our pet rats see as we do, and to want to discover if they see things the same as us.
This article gives general guidance on a domesticated rat’s eyesight, including an albino rat’s eyesight, but just as eyesight differs in us humans, it may differ in your rats too, (interestingly, not as much as humans differ from one another).
What Colors Can Rats See, and Are They Colorblind?
Rats can see in color!
Up until the 90’s, rats were thought to be completely colorblind, but more recent studies have shown that rats can perceive ultraviolet light and visible light, and can distinguish between different colors in the blue-green range.
Humans and rats have two types of light receptors: cones and rods. Cones give us the ability to see bright light and color, while rods allow us to see in dim light.
But, humans and rats retinas differ.
Humans have trichromatic vision, meaning we have three color cones in our retinas, whereas rats have dichromatic vision, of course, meaning only two color cones.
Their retinas have two color cones; one that allows them to see green light and colors, and one that means they can see blue ultraviolet light. Around 88% of a rat’s cones consist of the green-light type, and 12% are the blue-UV cones.
Rats can’t see colors vividly. This is because 99% of their retinas are made up of rods, and only 1% consists of cones. This causes reds to appear dark to them, and they cannot distinguish blue-green hues from some shades of gray.
Our cones are made up of 5% cones, which means rats see colors in fainter tones than we do. However, a rat’s blue-UV cones are more sensitive to shower wavelengths than a human’s blue cones, meaning that a rat can see colors that we literally can’t see.
Do Rats Have Good Vision?
Rats have lifelong blurry sight. They’re born with poor sight, and after around 4-5 days, it stop improving altogether.
They are near-sighted, (although this is blurry near-sighted vision), and can only see up to three feet ahead of them. If you’re stood the other side of the room, your rat won’t be able to see you, but their great hearing and sense of smell means they still know you’re around.
Because rats see colors faintly, rats are much better at differentiating between different levels of brightness, making light much more useful than color when it comes to training rats, (although using sound such as a clicker, or smell and taste such as offering treats, works much much better).
Rats Use Their UV Vision to Mark with Their Urine
A rat’s UV-seeing abilities allows them to see urine, (we’d have to use a black light to see urine). So a rat can see urine marks in their environment, (rats also use smell to detect urine).
Using their UV vision and their smell senses is particularly useful in the wild, as it allows them to see when a predator has been nearby, and assess how recently they were there.
Would Tiny Eyeglasses Be Helpful to a Rat?
As utterly adorable as this would be, sadly, studies suggest tiny eyeglasses wouldn’t help them.
A rat has an enormous depth of focus. Depth of focus is the range of distances at which an object is in equivalent focus for an eye. Humans have a depth of focus from 2.3 meters to infinity, whereas a rat’s depth of focus is from 7 centimeters to infinity.
If a human with 20/20 vision put on 0.3 diopter glasses, they would notice a little blurriness. A 0.3 diopter is the lowest change in lens strength that can be perceived by humans, but because of a rat’s depth of focus being so big, it wouldn’t be able to perceive a 0.3 diopter difference.
They wouldn’t notice a change in sight if you put 2 diopter glasses, 7 diopter glasses, or even 10 diopter glasses on them. They would only start to see a change in sight once you put very thick, (around 2cm thick), 14 diopter glasses on them. But the difference to their sight would be so small, and it would make it blurrier.
Even really strong glasses would only make their vision more blurry because of their tiny optics, the coarse grain of their retina, and the rat’s inability to change the shape of their lens to adjust focus.
For the time being, it isn’t possible to give a rat 20/20 vision, or even close.
Do Albino Rats Have Worse Eyesight?
While everything is blurry to a pigmented rat, and they only see faint color, an albino rat’s eyesight is even worse.
Studies have shown us that albino rats are severally visually impaired, (and sometimes blind), within three weeks of opening their eyes, and that their retinas consistently degenerate throughout their lives.
Pigmented rats are good at distinguishing different levels of brightness, however, albino rats see poorly in both bright and dim light, and are easily dazzled by bright lights.
The brains of albino rats with vision also have trouble coordinating images. So, when it comes to eyesight, an albino rat really struggles!
To compensate for their poor sight, they use their other senses. Sadly, studies show albino rats also have an impaired sense of smell compared to pigmented rats, and only have normal hearing.
Does a Rat’s Eyesight Worsen with Age?
Sadly, yes.
Once a rat hits around 2 years of age, their retinas lose a lot of cells, and parts of their retinas become enlarged and thickened. The capillaries that supply their retinas with blood, oxygen, and nutrients, also become thickened, meaning less blood, oxygen and nutrients can fit through.
The changes in the retinas and capillaries mean that an old rat’s sight isn’t as good as a that of a young rat.
Your Pet Rats Will Still Live a Happy Life
It’s easy to feel sympathetic towards your pet rats for not being able to see the world clearly, but because rats are naturally nocturnal creatures, sight isn’t actually a very useful sense for them. Hearing and smell are much more useful in the dark!
Some rats go blind, and this can initially be heart-breaking for their human parents, but, rats adapt very quickly and very quickly and easily to blindness. They really aren’t reliant on sight like humans are.
