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26.06.2020

Which animal has very sharp eyesight? Unimaginable vision in animals. Horse color vision

Many pet owners are interested in what and how their pets see. Do they distinguish the color of their favorite toy or their master's slippers?
In some respects, the vision of animals is more perfect than that of humans, but in the difference in colors it is clearly inferior to its owners.
Visual acuity in animals is much higher than in humans. It is known that the visual acuity of raptors is 3-8 times higher than ours. An eagle can see a ground squirrel from a height of several hundred meters, a peregrine falcon can see a pigeon a kilometer away. The buzzard unerringly looks for a green grasshopper in the green grass from a height of 100 meters. Visual acuity in dogs is estimated to be 20–40% higher. Interestingly, animals, especially predatory ones, are much better at distinguishing moving objects.
Most animals see well in the dark. This occurs because the photoreceptor cells in the retina focus rather than scatter light, allowing nocturnal animals to detect streams of very weak light of just a few photons. The glow of animal eyes in the dark is explained by the presence of a special reflective layer under the retina called tapetum. It is thanks to him that we observe the brightly glowing eyes of animals at night, for example, in the bright light of a car's headlights.
The field of vision of animals depends on the location of the eyes on the face and the shape of the skull. The eyes are often located not in the frontal plane, as in a person, but as if on both sides of the head, they are convex and protrude forward. All this allows you to have a wider view (lateral vision). For example, dogs are able to cover a visual angle of 250 degrees, and humans only 150 degrees. The record holder for panoramic vision is the woodcock bird, which has almost circular vision. The pigeon has a viewing angle of 340 degrees. Chameleons and seahorses can look in two directions at once; they owe this amazing ability to the fact that their eyes move independently of each other.
Animals' color perception is inferior to that of humans. Among vertebrates, the presence of color vision has been proven in fish, frogs, turtles, lizards, and most birds. Bees, dragonflies and other insects have excellent color vision. Dogs have poor color vision - they can slightly distinguish between red and blue. The presence of color vision in ungulates has not been proven. Nocturnal animals do not have color vision.
Animal Vision Facts
  • The penguin's cornea is not spherical, like that of humans and many other animals, but flat, which allows it to see in water without distortion.
  • Snakes do not have eyelids, and their eyes are constantly closed by a transparent elastic membrane.
  • A fly's speed of changing images is 300 frames per second, 5-6 times faster than a human's.
  • A cockroach notices movement of 0.0002 mm, so it is not so easy to catch it.
Many animals with severe visual impairments can navigate quite well, both in familiar and unfamiliar environments. This is due to the high development of other senses: hearing, smell, touch.

Eye diseases in animals

The same eye diseases occur in animals as in humans, but, of course, there are certain features associated with both clinical manifestations and the difficulties of timely diagnosis and treatment.
For the correct diagnosis of eye diseases in animals, anamnesis is very important - the information provided by the owner - when the symptoms appeared, what they were associated with, how the animal behaved. If necessary, in addition to examination, all methods of ophthalmological examination are used: examination of the fundus (ophthalmoscopy), measurement of intraocular pressure (tonometry), ultrasound of the eyeball, tests with vital dyes (fluorescein test), etc.
The most common condition in dogs and cats is conjunctivitis, an inflammation of the mucous membrane of the eyeball. With conjunctivitis, animals experience discomfort in the eyes, a feeling of a foreign body, and pain. With severe inflammation, animals behave restlessly, rubbing their eyes with their paws, which can lead to injury to the cornea with their claws.
The mucous membrane of the eyes is swollen, reddened, there may be hemorrhages, in the corners of the eyes there is discharge of a different nature - mucous, purulent, foamy.
Conjunctivitis in animals, as in humans, can be of various origins - viral, bacterial, allergic, caused by exposure to physical or chemical factors. The features of the clinical course will depend on the cause of conjunctivitis - the nature of the discharge, the presence of lacrimation, etc. Therefore, it is better not to self-medicate your pets, but to consult a veterinarian. For the treatment of uncomplicated conjunctivitis, the use of certain eye drops will be sufficient. Very often there is a sluggish allergic conjunctivitis associated with the feeding habits of the animal. Often, owners do not even contact veterinarians if the dog or cat has only a small amount of discharge in the corners of the eyes or watery eyes. In such cases, you need to consult a specialist and, most likely, adjust your pet’s diet.
Keratitis and corneal ulcers in animals most often develop after eye trauma. In this case, a limited decrease in the transparency of the cornea can be seen with the naked eye, the inflammatory focus on the cornea may be covered with a gray or yellow coating (fibrin or pus), the eye itself is red, and there may be discharge of a different nature. Keratitis or ulcers are quite serious diseases; you should urgently consult a veterinarian, preferably a veterinary ophthalmologist. In addition to local treatment (drops, ointment), medications for oral use will probably be prescribed - antibiotics, anti-inflammatory drugs, and there may be a need for injections under the conjunctiva of the eyeball.
Many dog ​​breeds often suffer from a hereditary disease called corneal dystrophy. This is usually a bilateral, non-inflammatory disease in which an area of ​​cloudiness forms on the cornea in the form of a white spot or arc. At the same time, the general condition of the animal does not suffer; vision with small-sized lesions does not deteriorate significantly. Treatment of this pathology is not effective.
Quite often in dogs and cats, especially in aging ones, there is an incorrect position of the eyelids - inversion or eversion; there may be loss or growth of the lacrimal gland, the so-called third eyelid, located in the inner corner of the eye. An inversion of the eyelid is accompanied by abnormal growth of eyelashes - towards the eyeball, while the eyelashes irritate the eye and injure the surface of the cornea. As a rule, with entropion of the eyelid and hyperplasia of the gland of the third eyelid, surgical treatment is performed - correction of the position of the eyelid and fixation of the prolapsed lacrimal gland to the periosteum of the zygomatic bone or its removal in case of neoplasms.
If you notice that one of the animal’s eyes does not glow in the dark or in photographs, or glows significantly less than the other, or the pupil has “turned white,” most likely your pet has cataracts—clouding of the lens. When the lens becomes cloudy, vision gradually decreases down to the sensation of light. The only treatment for cataracts is surgical – removal of the clouded lens. If there are cataracts in both eyes, then surgery is certainly necessary. If there is a cataract in only one eye, then the owner himself makes the decision about the operation. It is necessary to take into account the age of the animal, since in most cases cataracts are an age-related pathology, the patient’s physical ability to withstand general anesthesia (anesthesia). It is also necessary to take into account the material costs of surgical treatment.
The most difficult for timely diagnosis are retinal diseases - various forms of degeneration. There are no changes to the eyes that are visible to the owner. The animal loses its vision gradually and is well oriented in familiar surroundings. As a rule, a veterinary ophthalmologist is consulted in the later stages, when vision is almost completely lost. Retinal dystrophies are hereditary diseases, often characteristic of certain breeds of dogs and cats. To diagnose the disease, it is necessary to examine the fundus of the eye - ophthalmoscopy, which reveals certain changes in the retina, blood vessels, and optic nerve head. There is no treatment as such. Healthy dogs may undergo DNA testing to check for some type of hereditary retinal degeneration. This is done when using dogs for breeding, since dogs with retinal dystrophy cannot be used for breeding due to the presence of a genetic disease.
Taurine-deficiency retinopathy in cats is degeneration of the retina in cats due to a deficiency of taurine, an essential amino acid that enters the animal's body only with food. The disease is caused by improper feeding or metabolic disorders. If a cat suffers from taurine deficiency for several months, complete blindness develops. The prevention and treatment of this disease in cats is balanced feeding of ready-made food (the taurine content in the food corresponds to the daily needs of the animal) or the addition of supplements containing Taurine to the cat’s diet.
It happens that eye pathology is just a manifestation of a systemic disease. For example, conjunctivitis with chlamydia or mycoplasmosis, cataracts with diabetes, uveitis with renal hypertension, etc. In such cases, treatment is carried out comprehensively, taking into account the specifics of the disease.

Vision is one of the five human senses. With its help, a person receives information about the world around him, recognizes objects and their location in space. The importance of a high level of vision cannot be overestimated, because with poor vision a person’s life becomes very difficult. It is especially important to have good vision for children, since a decrease in visual acuity can become a serious obstacle to the full development of the child.

Why is verification needed?

Starting from the newborn period, children need regular vision examinations by an ophthalmologist. This must be done for preventive purposes in order to prevent future vision impairment or deterioration in the child.

Eye diseases in many cases tend to progress. For example, myopia (or myopia), as a rule, can develop intensively in children during school years, when the visual load on the eyes increases. Eye hypermetropia is also a common disease in children of preschool or primary school age. Therefore, parents need to take all measures to improve their child’s visual acuity as soon as possible and prevent the development of blindness. As a rule, progressive myopia leads to irreversible changes in the central parts of the retina, which significantly reduces visual acuity.

Vision testing for newborns occurs according to the following schedule:

  • The baby's eyes are first examined by an ophthalmologist in the first hours after birth. Particular attention is paid to premature babies, children with congenital pathologies or birth injuries, newborns after a difficult birth, since it is in this category of children that hemorrhages or retinal pathologies most often occur.
  • The first examination by an ophthalmologist for this category of children is usually scheduled a month after birth, if there are indications.
  • A healthy child should be examined for the first time in an ophthalmology office 3 months after birth.
  • The next examination of a healthy child is carried out at 6 months, and then at 12 months.

At 12 months, the child’s visual acuity is determined for the first time. Normally, it is 0.3–0.6 diopters.

A table for checking vision in children was developed by Orlova. This table is used for preschool children who have not yet learned to count.

Existing vision testing charts

In modern times, many versions of tables have been created to test visual acuity in children.

The first table by which a child’s vision is checked, as a rule, is the Orlova table. This table is used to conduct vision tests for children from the age of 3, when they have not yet learned to read and write. In this table, instead of letters, pictures are used that are familiar to the child and which he can easily name.

To test visual acuity in older children, tables with printed letters are used. In the CIS countries, the Sivtsev or Golovin table is most often used. There is also a foreign analogue - the Snellen table.

In many tables, visual acuity is determined at a distance of at least 5 meters. This distance was chosen by ophthalmologists for the reason that in an eye with normal refraction (the so-called emmetropia), at this distance the point of clear vision is located, as it were, at infinity and on the retina, thus parallel rays are collected, forming a focused, clear image.

Sivtsev table

The Sivtsev table is the most common table in the former USSR, which is used to test visual acuity in children.

The table received its name in honor of the Soviet ophthalmologist D.A. Sivtseva. The Sivtsev table is actively used for examining vision in children and adult patients in modern times.

Sivtsev’s vision test table uses 12 lines with printed characters, which can be used to effectively examine the patient’s visual acuity.

7 letters are used as printed characters - Ш, Б, М, Н, К, У, И. The letters have different sizes, but the same width and height. In this case, the size of letters decreases in lines from top to bottom.

Sivtsev’s table also has two additional columns located to the left and right of the rows. The symbols on the left side indicate the distance from which the patient sees the letters of the line with a 100% level of vision. It is expressed in meters and is marked with the symbol “D=…”.

The left column shows the level of refractive error expressed in diopters. Refraction of the eye is the position of the focal point of the eye relative to the retina. With a normal focus position on the retina, refraction is usually zero. This position of the focal point is called emmetropia.

In case of visual impairment, the position of the focal point changes. For example, with myopia, the focal point is in front of the retina, and with farsightedness, the focal point moves behind the retina. Thus, the image is not fixed in the center of the retina and objects appear blurry and indistinct.

As a rule, refractive errors affect visual acuity and require correction. The more the refraction deviates from the norm, the more visual acuity decreases. However, there is no direct relationship between these values. If the refraction is normal, but the patient has poor vision, this may indicate a possible decrease in the transparency of the optical media of the eye. For example, the patient may exhibit symptoms of amblyopia, cataracts with clouding of the lens or cornea.

The right column indicates the patient’s visual acuity if he is located at a distance of 5 meters from the table. These values ​​are marked with “V=...”. Visual acuity in the professional terminology of ophthalmologists is the ability of the eye to see and distinguish two distant points with a minimum distance between them.

In ophthalmology, the accepted rule is that an eye with normal visual acuity can distinguish two distant points with an angular distance between them equal to 1 arc minute (1/60 degree).

Normal human visual acuity corresponds to V=1.0, that is, a person with 100% vision should be able to distinguish printed characters of the first 10 lines. However, some subjects may have visual acuity that is greater than normal, for example, 1.2, 1.5, or even 3.0 or more. With refractive errors (myopia, farsightedness), astigmatism, glaucoma, cataracts and other visual impairments, the visual acuity of the subject decreases below normal and acquires values ​​of 0.8, 0.5 and lower.

In Sivtsev’s table, the values ​​of visual acuity in the first ten lines differ in increments of 0.1, the last two lines - in 0.5. In some non-standard versions of the Sivtsev table, additional 3 lines are used with visual acuity values ​​from 3.0 to 5.0.

But these tables, as a rule, are not used in ophthalmology offices of modern clinics.

Visual acuity according to the Sivtsev table is checked according to the following instructions:

  • The patient should be at a distance of 5 meters from the table. Studies are carried out for each eye separately.
  • The right eye must be tightly covered with the palm of the hand so that it cannot see the letters in the table. Instead of your palm, you can use a piece of dense material (for example, cardboard or plastic). Thus, the visual acuity of the left eye is examined.
  • The lines must be read in order, left to right, top to bottom. It takes no more than 2-3 seconds to recognize the sign.

Determining visual acuity using the Sivtsev table is quite simple. The patient, as a rule, has normal visual acuity if he was able to correctly read letters in rows with V = 0.3-0.6. Only one mistake is allowed. In rows below V=0.7, no more than two errors are allowed. The numerical value of visual acuity corresponds to the numerical value of V in the last row, in which no errors were made beyond the norm.

Using this table, only myopia is determined. Farsightedness is not determined according to the Sivtsev table. That is, if the subject sees all 12 lines at a distance of 5 meters, this does not mean that he suffers from farsightedness. This indicates visual acuity above the average.

If the test result is unsatisfactory and a deviation from the norm is detected, then a possible reason for the decrease in visual acuity in the child may be a refractive error. In this case, a subsequent determination of refraction is necessary.

Snellen chart

Snellen chart

The Snellen chart is one of the popular tables for testing visual acuity in children. In modern times, this table is especially common in the United States.

The Snellen chart was developed in 1862 by Dutch ophthalmologist Hermann Snellen. The Russian analogue of this table is the Sivtsev table.

The table includes a standard set of strings consisting of Latin letters, which are called optotypes (test types). The size of the letters, just like in Sivtsev’s table, decreases with each line in the downward direction.

The top row of the Snellen chart contains the largest characters that a person with normal visual acuity can read at a distance of 6 meters (or 20 feet). A person with 100% vision is able to distinguish the subsequent lower lines at distances of 36, 24, 18, 12, 9, 6 and 5 meters, respectively. A traditional Snellen chart typically has 11 lines printed. The first line consists of the largest letter, which can be E, H, N, or A.

The subject's vision is checked using the Snellen chart as follows:

  • The subject is located at a distance of 6 meters from the table.
  • Cover one eye with the palm of your hand or some dense material, and read the letters in the table with the other.

The visual acuity of the subject is usually checked by the indicator of the smallest row, which was read without errors at a distance of 6 meters.

As a rule, if a person with normal visual acuity is able to distinguish one of the lower rows at a distance of 6 meters, then the visual acuity value is 6/6. If the subject is able to distinguish only lines located above the line that a person with normal visual acuity can read at a distance of 12 meters, then the visual acuity of such a patient is 6/12.

Orlova table

Orlova's vision test table is used to determine visual acuity in preschool children. This table contains rows with special pictures, the size of which becomes smaller with each row from top to bottom.

Orlova table

On the left side of the table, next to each line, the distance from which a child with normal visual acuity is able to distinguish symbols is indicated.

Variation of Orlova's table

The distance is marked with the symbol “D=...”. The right side of the table indicates visual acuity if the child recognizes them at a distance of 5 meters.

Vision is considered normal if a child is able to recognize pictures of the tenth line with each eye from a distance of 5 meters.

If the child’s visual acuity is reduced and he is not able to recognize the signs on the tenth line, then he is brought closer to the table at a distance of 0.5 meters and asked to name the characters in the top row. The child's visual acuity is determined by the line in which the child can correctly name all the symbols.

Before the examination, it is advisable to show the child pictures so that he understands what is required of him and ask him to say the names of the pictures out loud.

Golovin table

The Golovin table is also a fairly common table for checking visual acuity in children. Like Sivtsev’s table, it is used mainly in the CIS countries. The table got its name in honor of the famous ophthalmologist S.S. Golovin, who lived in the USSR.

Unlike Sivtsev's table, this table uses symbols - Landolt rings - instead of printed letters. There are also twelve rows in Golovin's table and the rings printed in these rows decrease in size with each row in the downward direction. These rings are of equal and equal width in each row.

Golovin's vision table

Visual acuity indicators are indicated on the right side of the table and are marked with the symbol “V=...”.

In the traditional Golovin table, it is possible to determine visual acuity in the range of 0.1-2.0. The first 10 lines, as in Sivtsev’s table, differ in increments of 0.1, the remaining two - in 0.5. In some versions of the tables, three extra rows are additionally used to determine visual acuity above the average. These lines differ in increments of 1.0.

The left side of the table indicates the distance in meters from which a person with normal visual acuity is able to recognize the symbol in a given line. It is marked with the symbol “D=...”.

Visual acuity is determined at a distance of 5 meters separately for each eye.

The causes and symptoms of retinal detachment, what kind of disease it is and what effective treatment methods you will learn in the article.

Treatment of eye blepharitis, its symptoms and common pathogens are described here.

Glasses to protect your eyes from the computer: http://eyesdocs.ru/ochki/kompyuternye/ochki-dlya-raboty-s-kompyuterom.html

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conclusions

In childhood, ophthalmological examinations should never be ignored, since it is at this age that serious eye diseases can be first detected, which over time can lead to a noticeable deterioration in vision and even blindness, which can greatly interfere with the normal development of the child. Nowadays, various eye tables have been created for testing vision, which are used to determine the quality of peripheral vision, acuity, and other indicators. Especially considering that a disease such as farsightedness in children is now actively gaining momentum.

Four-Eyes

These fish live in Mexico and Central America. They are very small, up to 32 cm in length, feed on insects, so they spend most of their time near the surface of the water. Despite their name, these fish only have 2 eyes. However, these eyes are separated by a vein, and each half has its own pupil. This strange adaptation allows the four-eyed fish to see well both above and under water.

Stalk-eyed flies


These small but unusual creatures live in the jungles of southeast Asia and Africa. They got their name from the long protrusions on either side of their heads with eyes and antennae at the end. Males have longer stems. According to observations, females prefer males with longer stems.

Tarsier


It is a small nocturnal primate native to the tropical forests of southeast Asia. This is the only predatory primate in the world; it feeds on lizards, insects and even birds. But its most interesting feature is its huge eyes, disproportionately large in relation to the entire body. If these proportions were applied to a person, then his eyes would be the size of grapefruits. The tarsier has very sharp eyesight. It was even suggested that they could see ultraviolet light. On the other hand, tarsiers have poor color vision, like many other nocturnal predators.

Chameleon


Chameleons are known for their ability to change color, which helps them communicate and express their intentions or moods (only a few species of chameleons use color change as camouflage). These lizards also have very unusual eyes. The eyelids are completely connected, there is only a small slit for the pupil. Each eye moves independently of the other, allowing the chameleon to monitor prey and possible threats at the same time.

Dragonfly


The dragonfly's eyes are so large that they cover almost the entire head, making it look like a helmet and giving it a 360-degree field of vision. These eyes are made up of 30,000 parts, each containing a lens and several light-sensitive cells. Dragonflies have excellent vision. They can detect colors and polarized light, and dragonflies are especially sensitive to movement.

Leaf-tailed gecko


The leaf-tailed gecko has very unusual eyes. He has vertical pupils, which have several “holes”. These openings widen at night, allowing these lizards to see better. A gecko's eyes contain many more light-sensitive cells than human eyes, allowing the animal to detect objects and even distinguish colors at night. While cats and sharks see 6 and 10 times better than humans, geckos see 350 times better.

Colossal squid


It is the largest invertebrate known to science. This squid also has the largest eyes in the animal kingdom. Each eye can be up to 30 cm wide. Such large eyes allow the squid to see in semi-darkness, which is very useful for an animal that spends almost all of its time hunting at a depth of 2000 m underwater.

Opisthoproct


Opisthoproctus is a deep-sea fish with one of the strangest eye structures. A characteristic sign of opisthoproctus is cylindrical eyes directed upward.

Mantis crab


These crayfish are known for their aggressiveness and unique weapons (they have a very sharp and powerful claw that can easily cut a human finger in half and break glass in an aquarium). Mantis crabs have the most complex eye in the animal kingdom. They distinguish 12 primary colors - four times more than humans, as well as different types of light polarization, that is, the direction in which the light wave oscillates. The light-sensitive cells of the eye rotate relative to the plane of polarization of light, perceiving almost the entire visible spectrum - from the ultraviolet to the infrared. Now we can only guess what the world looks like for this crustacean.

Ogre Spider


Spiders are known to have many eyes. The ogre spider has 6 of them, but it looks like 2, since the middle pair of eyes is very enlarged. All this serves to improve night vision. Ogre spiders have excellent night vision not only due to the size of their eyes, but also the large number of light-sensitive lenses covering them. This membrane is so sensitive that it breaks down every morning and grows back at night.

Man is the highest intelligent being on Earth, but some of our organs are significantly inferior to our smaller brothers, one of which is vision. At all times, people have been interested in how birds, animals, and insects see the world around them, because outwardly everyone’s eyes are so different, and today’s technologies allow us to look through their eyes, and believe me, the vision of animals is very interesting.

Animal eyes

The first thing everyone is interested in is - how do our closest friends cats and dogs see?

Cats see perfectly in pitch darkness, as their pupil can expand up to 14 mm, thereby capturing the slightest light waves. In addition, they have a reflective membrane behind the retina, which acts as a mirror, collecting all the particles of light.

Cat pupils

Due to this, a cat sees in the dark six times better than a human.

In dogs, the eye is structured in approximately the same way, but the pupil is unable to expand as much, thereby giving it a fourfold advantage over humans to see in the dark.

What about color vision? Until recently, people were sure that dogs see everything in shades of gray, not distinguishing a single color. Recent research has proven this to be a mistake.

Dog color spectrum

But you have to pay for the quality of night vision:

  1. Dogs, like cats, are dichromats; they see the world in faded blue-violet and yellow-green colors.
  2. Visual acuity is poor. In dogs it is about 4 times weaker than ours, and in cats it is 6 times weaker. Look at the Moon - do you see spots? Not a single cat in the world sees them; for her they are just a gray spot in the sky.

It is also worth noting the location of the eyes in animals and in us, due to which pets see with peripheral vision no worse than with central vision.

Central and peripheral vision

Another interesting fact is that dogs see 70 frames per second. When we watch TV, 25 frames per second for us merge into a single video stream, but for dogs it’s a quick series of pictures, which is probably why they don’t really like watching TV.

Except dogs and cats

A chameleon and a seahorse can look in different directions at the same time, each of its eyes is processed separately by the brain. Before throwing out its tongue and grabbing the victim, the chameleon still closes its eyes to determine the distance to the victim.

But an ordinary pigeon has a viewing angle of 340 degrees, which allows you to see almost everything around, which makes hunting difficult for cats.

A few dry facts:

  • Deep-sea fish have a super-dense retina, with 25 million rods concentrated on every millimeter. This exceeds ours a hundred times;
  • A falcon sees a mouse in a field from a distance of one and a half kilometers. Despite its flight speed, clarity is completely preserved;
  • The scallop has about 100 eyes on the edge of its shell;
  • The octopus has a square pupil.

The reptiles outdid everyone a bit. Pythons and boas are able to see infrared waves, that is, heat! In a sense, we also “see” it with our skin, but snakes see it with their eyes, like the predator in the film of the same name.

Mantis shrimp

But the mantis shrimp have the most unsurpassed eyes. These are not even eyes, and an organ stuffed with wave sensors. Moreover, each eye actually consists of three - two hemispheres separated by a stripe. Visible light is perceived only by the middle zone, but the hemispheres are sensitive to ultraviolet and infrared ranges.

Shrimp sees 10 colors!

This does not take into account the fact that the shrimp has trinocular vision, in contrast to the most common on the planet (and in our country) binocular vision.

Insect eyes

Insects can also surprise us a lot:

  • It is not so easy to kill an ordinary fly with a newspaper, since it sees 300 frames per second, which is 6 times faster than us. Hence the instant reaction;
  • A domestic cockroach will see movement if the object has moved only 0.0002 millimeters. This is 250 times thinner than a hair!
  • The spider has eight eyes, but in fact they are practically blind insects, capable of distinguishing only a spot; their eyes practically do not work;
  • A bee's eye consists of 5,500 microscopic lenses that do not see red;
  • The earthworm also has eyes, but atrophied ones. He can distinguish day from night, nothing more.
Bee eyes

Dragonflies have the sharpest vision among insects, but it is still about 10 times worse than ours.

How sharp of vision do humans have compared to animals?

Scientists from Duke University asked this question and conducted a study in which they compared visual acuity in humans and in various animals. At the same time, with the help of a special program, images were even created demonstrating how blurry or clear the world can be seen by some animals.

In the animal kingdom, most species "see the world in much less detail than we do," said Eleanor Caves, co-author of the new paper. Of course, scientists can't ask animals to read the letters on an optometric chart; instead, experts study the anatomy of the eyes and conduct behavioral tests to determine the visual acuity of particular animals.

This time, the researchers used a method that measures cycles per degree to determine visual acuity. This information was then processed in a special program, which then created images demonstrating how clear or blurry the world was seen by the animal being studied.

Humans distinguish approximately 60 cycles per degree—that is, 60 pairs of black and white parallel lines per degree of visual angle. At the same time, as researchers discovered, chimpanzees and other primates have approximately the same indicator as ours. Some birds are even superior to humans: for example, the wedge-tailed eagle is able to see 140 cycles/degree - such acute vision apparently helps it notice prey on the ground at an altitude of thousands of meters.

Most other animals have much less acute vision than humans, researchers have found. Thus, many fish and birds see about 30 cycles/degree, but elephants see only 10 cycles/degree. The last indicator is already the level of blindness for humans, but in many animals and insects it is even lower.

We all know how important our eyes are. We receive most of our information, experiences and memories through our eyes. And, of course, we can enjoy the exceptional creations of nature that surround us. Some animals also have incredible or even more amazing eyes than humans. Here are the Top 10 Most Amazing Eyes in the Animal Kingdom.

The frog's large eyes are remarkable from several angles. First of all, this amphibian spends a decent amount of time in the water. To swim in water filled with debris, frogs have three eyelids - two transparent and one translucent eyelid. This translucent membrane can close completely to allow the frog to protect its eyes underwater.

The position of the frog's eyes also gives it a better field of vision. The eyes are located on the sides of the head to provide a full 360 degree view. Frogs can even see what is happening outside when they are submerged in water.


is a small primate found in the forests of Southeast Asia. Its most striking feature is its large eyes, which have a diameter of up to 1.6 cm. Compared to body size, these are the largest eyes of any mammal in the world. Just like an owl, the tarsier's eyes cannot move. Because they are fixed in the skull.

Instead, tarsiers can move their heads 180 degrees left and right. This helps them to know what is going on around them. They are nocturnal animals that only become active at night. But their large eyes give them excellent night vision. In addition, they have a keen sense of hearing. Both of these qualities help tarsiers detect prey in low light conditions.


The hammerhead shark has one of the strangest but most interesting heads - in the form of a flattened hammer with wide-set eyes. But research has shown that this strange head has a good purpose. It provides the hammerhead shark with much better vision than other shark species. More precisely, such widely spaced eyes give them excellent vision and exceptional depth perception.


The cuttlefish is an incredible sea creature that can instantly change its color. This allows cuttlefish to quickly hide from predators by blending into their environment. This remarkable power of cuttlefish comes from the help of specialized skin cells and their incredible vision. They have strange "w" shaped pupils that give them a wider range of vision. Interestingly, they can even see what is behind them.

In addition, they can detect polarized light with incredible accuracy. Even the slightest change in the angle of polarized light. This gives cuttlefish a clear idea of ​​what exactly is going on around them.


Do the rectangular pupils of a goat seem strange to you? But at the same time, they provide impressive vision. For a grazing animal like a goat, this is the most sought after power.

Because, having good eyesight, a goat has a better chance of escaping from a predator. Her rectangular pupils provide detailed panoramic vision. This helps the goat detect danger from a distance. In addition, effective eye rotation also helps detect strange movements in the field, even while grazing. Thus, they have enough time to escape from the predatory animal.


There are 1,500 different species of geckos living in warm climate regions of the world. Most of them are nocturnal animals. To adapt to this lifestyle, they have impressive eyesight. To be precise, their eyes are 350 times more sensitive than human vision and color vision threshold. Geckos can even see colors in low light with amazing quality. This is a rare force in the animal kingdom.


One of the amazing things about dragonflies is their large globular eyes. Each dragonfly eye is made of 30,000 facets and is located in different directions. The result is incredible 360-degree vision. This allows them to detect even the slightest movement in their surroundings.

Dragonflies can also detect ultraviolet and polarized light, which are outside our visual spectrum. All these qualities play a huge role in dragonfly navigation.


Owls have very interesting, large front eyes. This eye positioning provides a great advantage for owls - incredible binocular vision, or the ability to see an object with both eyes with greater depth perception. Even animals and birds whose eyes are on the sides of their heads do not have such excellent vision.

Surprisingly, instead of eyeballs, the owl's eyes are shaped like tubes. Also, their eyes cannot rotate like ours. But they can move their head 270 degrees in left and right directions. This gives owls a much broader vision. To adapt to a nocturnal lifestyle, owls also have excellent night vision, which brings in millions of light-sensitive retinal rods.


Chameleons are so famous for their ability to change colors. But their visual system is just as amazing as their ability to change color. These reptiles can move their eyes independently of each other. That is, they can focus on two different objects in two different directions at the same time. This incredible power of the chameleon's eyes provides excellent 360-degree vision. Chameleons can also focus on objects with incredible speed.


The mantis crab has the most fantastic visual system in the animal kingdom. We humans have three color receptors. But this unusual crustacean has 12 different color receptors. These mantis crabs see so many colors that we can't even comprehend.

Beautiful eyes can also turn independently of each other in different directions at the same time. The eye rotation capacity is measured up to 70 degrees. This provides a broader view of this little creature. Additionally, the mantis crab, like other animals with exceptional vision, can detect infrared, ultraviolet, and polarized light.

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