Guinea Pig’s Vision - How Guinea Pigs See

The eyes of guinea pigs are not very different from those of other rodents. More precisely, they consist of three superimposed layers:

• The fibrous tunic: it is the outermost layer. It is formed by the cornea (transparent) and the sclera (white). This layer is made of dense connective tissue, which protects the eyeball and maintains its shape.
  
  
• The vascular tunica or uvea: It is the middle layer. It is composed of the iris, ciliary bodies and choroid.
  Most guinea pigs have a black or brown iris. Less commonly, there are guinea pigs with red/pink or blue eyes.
  
  
• The nerve tunic or retina: It is the innermost layer connected to the optic nerve by the optic disk. The retina is traversed by a series of blood vessels that originate from the optic disk. In most mammals, the pattern of these retinal vessels is of the "holangiotic" type. In guinea pigs, however, this pattern is of the "paurangiotic" type. This means that the retinal vessels are barely visible on examination of the back of the eye, which can lead to the incorrect diagnosis of retinal atrophy, when in fact it is the normal image of a guinea pig's retina.

Normally, guinea pigs produce a milky, whitish ocular discharge that they use to clean themselves. Sometimes a small drop of this milky fluid can be seen in the tear area. However, this secretion often goes unnoticed by caregivers because guinea pigs tend to spread it quickly with their legs.

As a curiosity, it is worth noting that guinea pigs have developed the ability to sleep with their eyes open. Although they have movable eyelids that allow them to close their eyes, some guinea pigs always sleep with their eyes open, while others do so only sporadically. In essence, it is a defensive mechanism that gives them a quick reaction time to dangerous situations, even when they are asleep.

If you are interested in more facts about guinea pigs, do not miss this other article, where we will tell you the importance of vitamin C in guinea pigs.

You may know that the position of an animal's eyes is an indication of whether it is a predator or prey. Predators, such as dogs or cats, have their eyes in the front of their face, which limits their field of vision somewhat, but they have very good binocular vision. Therefore, predators generally have high visual acuity. Prey animals, on the other hand, have their eyes located more to the side, giving them a wider field of view and allowing them to cover a wider angle of control.

Guinea pigs, as prey animals, have lateral eyes that provide a 340º angle of vision. This means that they can cover almost the entire width of the field of view. They have only two blind spots: one in front, just in front of their nose, and one behind.

Due to the lateral arrangement of their eyes, they have poor visual acuity and their depth perception is much worse than that of predators. Their vision is limited to what is within a meter or meter and a half of them. They also cannot see what is below their nose. Because of these characteristics, guinea pigs cannot properly judge distances and heights. Therefore, it is not advisable to have guinea pigs live in high places or in an enclosure with many levels, as they can easily fall down.

Guinea pigs perceive about 33 frames per second, as opposed to the 22 frames per second that the human eye is capable of processing. This allows them to significantly shorten their reaction time to danger while preventing blurred vision when they turn their heads quickly.

Can guinea pigs see in the dark?

Whether guinea pigs can see in the dark or not is debatable. While it is true that some rodents can see relatively well at night, guinea pigs do not seem to belong to this group. In fact, they are not nocturnal animals, but crepuscular animals. That is, they are active mainly in the morning and afternoon, while the remaining hours of the day are usually devoted to rest.

In spite of the fact that they lack good night vision, they can still navigate effectively at night because of the following three features:

• Very good memory: guinea pigs are good at memorizing the environment they are in and mapping it out in their heads. This is the main reason why guinea pigs are able to find their way back to safety even at night.
  
  
• Well-developed senses: A guinea pig can hear better than a human and has a highly developed sense of smell, which helps them move around in low light conditions.
  
  
• Tactile hairs: A guinea pig's muzzle has tactile hairs that help it navigate in the dark and determine the size of an opening.

If you are interested in more facts about guinea pigs, do not miss this other article, where we will tell you how you can tell if a guinea pig is pregnant.

Humans have naturally trichromatic vision, which means they can distinguish between the three primary colors (yellow, cyan, blue, and magenta). However, the retina of guinea pigs is only capable of perceiving two of the three primary colors.

So we can say that guinea pigs have color vision, even though their vision is slightly worse than ours. In their case, they perceive mainly blue, violet and slightly greenish tones. It should be noted, however, that guinea pigs, like horses and sheep, have better color vision than cats, dogs, and most other animals.

If you are interested in more facts about guinea pigs, do not miss this other article where we will tell you how long do guinea pigs live.

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