“The windows to the soul,” is a common phrase used to describe our eyes. However, most people may not truly understand the many details about the eyes. In fact, there are many unknown secrets hidden in the eyes, even in face-to-face communication, the first thing we notice is the other person's eyes. Next, let's explore these 15 little-known facts about eyes, to see if they've ever been considered "secrets" by you.

1. What is the limit of human eyesight?

Although ancient people often used the phrase "shoot an arrow through a hundred paces" to describe excellent eyesight, in fact, even those with the best eyesight can only clearly see objects 6 meters away. For most people, being able to clearly distinguish the details of objects 3 meters away is considered to have satisfactory eyesight.

2. Heterochromia iridum: A possible hereditary eye phenomenon

In the familiar characteristics of Mongoloids, yellow skin and black eyes are indispensable marks. However, sometimes when looking in the mirror, you may suddenly find that the color of one of your eyes has changed, which is usually called "heterochromia iridum." This phenomenon has a certain heritability, so once it is found, it is advisable to seek help from an ophthalmologist in time.

3. Fear of eye contact: A real psychological reaction

Have you ever felt a sudden, inexplicable fear when gazing into someone's eyes or making eye contact? This reaction is not an isolated case; in fact, some people do have a fear of eye contact.
In fact, this fear of eye contact is a temporary disorder of advanced nerve activity, which is particularly common during puberty. Because adolescents' physiological development is faster than their psychological maturity, coupled with academic pressure and the influence of the external environment, the nervous system is prone to this temporary adaptation difficulty.

4. The amazing restorative power of the eyeball:

Although the eyes look so delicate, they are among the fastest-recovering tissues in the body. Minor scratches on the eyeball often heal quickly within a day or two. However, it should be cautioned that eyeball lacerations may cause infections and even lead to serious consequences such as insomnia. Therefore, although the eyeball recovers quickly, injuries should not be taken lightly.

5. Eyes can also get sunburned:

When going out in the summer, we often apply sunscreen to our skin and take other sun protection measures, but our eyes are often neglected. In fact, eyes also need sun protection because they can also be damaged by sunlight.

5. Eyes can also get sunburned:

When the summer sun is strong, we often apply sunscreen to our skin and take other sun protection measures, but our eyes are often neglected. In fact, eyes also need sun protection because they can also be damaged by sunlight. Sunburned eyes will have symptoms such as redness, swelling, heat, pain, and peeling. If exposed to sunlight for a long time, it may even lead to damage to the internal tissues of the eyeball. In this case, the only way to recover is surgery. Therefore, it is recommended to wear sunglasses to protect your eyes when going out in strong sunlight.

6. Changes in eyesight and health:

As people age, middle-aged and elderly people often face the problem of presbyopia. However, some people's eyesight improves with age. This may not be a good thing, but rather a signal of some health problem. For example, when people with high blood sugar suddenly experience significant changes in their eyesight, they should seek medical examination in time.

7. Unveiling the size of the eyeball:

The width of an average person's eyeball is about 24 mm, and the size of the lens in the eye is similar to that of a chocolate bean.
The lens, this key structure located directly behind the pupil, is responsible for the precise focusing of light. Its size is similar to the diameter of a spherical chewing gum, just like the "small photographer" in our eyes. When we talk about vision, we have to mention the visual center of the brain. Although the eyes capture changes in light, it is the brain that truly analyzes colors and outlines. Sometimes, people experience temporary blindness when they fall backward and their head hits the ground first, which further confirms the fact that the visual center is located in the back of the head. At the same time, the occipital nerve that connects the eyes to the occipital lobe of the brain is also located in the back of the brain, providing a neural pathway for vision. In addition, vision problems are not only related to the lens but also to the length of the eyeball. Myopia and hyperopia are the result of changes in the lens, while myopic people's eyeballs are usually longer than those with normal vision, and vice versa for hyperopic people.
This means that even slight changes in the length of the eyeball will affect eyesight. The length of the eyeball changes with the growth of the human body: In newborns, the width of the eyeball is about 16 mm, and by the age of 3, this width increases to 23 mm. After entering puberty, the width of the eyeball further reaches more than 24 mm, after which it basically remains at this level.

On the other hand, the depth of eye color is determined by the number of melanocytes. Scientists have found that the color of the iris and skin are both affected by melanocytes. The more melanocytes, the darker the eye color. The number of melanocytes is largely controlled by genes.

12. Babies' eyes are lighter in color and gradually deepen as they grow:

This is because iris pigmentation takes time, and newborns have not fully developed irises, and their pigmentation is relatively less. In the first year after birth, iris pigmentation will accelerate significantly, which means that our eye color will gradually deepen with age.

13. Staring at the sun for a long time can cause blindness:

When we were young, we may have all done an experiment, focusing paper with a magnifying glass in the summer sun to make it burn. Although our retina will not "catch fire" like paper, staring at the sun for a long time can still cause serious damage to the eyes and even lead to blindness.
This is because the lens focuses sunlight on the retina, and staring at the sun for a long time may cause permanent vision loss.

14. The structure of the eye is like two rooms:

The cornea of the eye, located in the anterior chamber, contains aqueous humor, which is an important way for the eyeball to obtain nutrients and also lubricates the iris. Immediately after the iris is the lens, which is located in the vitreous chamber, like the back room of our house. This "back room" is filled with a vitreous humor similar to egg white, mainly composed of water and hyaluronic acid.

15. The causes of floaters vary from person to person.

As we age, we sometimes feel like there are black spots floating before our eyes; this is a manifestation of floaters. However, the causes of floaters vary from person to person.
If you are over 55 years old and experience floating black spots before your eyes, it may be caused by the separation of the retina and vitreous membrane, a common occurrence.