Our eyes are like a camera. The optical processing components are mainly the refractive complex of cornea and crystal in the front of the eye, which is composed of fundus retinal photoreceptors. I sorted out why people's eyes are short-sighted_ The causes of myopia are welcome for reference.
Why does the person's eye meet myopia
In fact, our eyes mainly rely on the retina and lens to see things. The external light enters the eyes and converges on a point through the lens. This point is called the focus. The focus of normal people is just on the retina, so it is clear to see things. In case of myopia, the focus of the lens will be in the front, and if the focus is not on the retina, things will be blurred. When the focus of the lens is in the back, If you fall behind the retina, you become hyperopia, and things that are close to you will be blurred. Many elderly grandparents are hyperopia. Teenagers like you are mostly myopia. As for why do you have myopia? It has something to do with your usual habits. Bad habits will cause myopia. For example, when you write, you tilt your head and read on your stomach. These are bad habits.
Causes of myopia
Our eyes are like a camera. The optical processing components are mainly the refractive complex of cornea and crystal in the front of the eye, which is composed of fundus retinal photoreceptors. The two match well. The object light image focused by the cornea and crystal happens to fall on the retina and presents a clear image, which is called normal vision or emmetropia.
Among them, under the action of ciliary muscle contraction and relaxation, the diopter of the eye lens can change in a certain range, which can accurately project objects near or far from a certain range to the retina for clear imaging.
When we stare at an object in the same axial range, we can not only see the object clearly, but also keep the same diopter as the object in the front and back of the crystal. Objects beyond this range will become blurred, just as the background in the picture becomes blurred.
The range of front and back or far and short distance that can be seen clearly is called depth of field. That is, when we focus on an object, we can see clearly everything within the depth of field of the object. Beyond this range, it will become blurred.
When the diopter of our eyes changes, whether hyperopia or myopia, when we look at near or far objects beyond the adjustment range of the eye lens, the image cannot be accurately projected on the retina, but focused in front of or behind the retina, and it will look blurred.
At this time, if we narrow our eyes, the eye crack will become smaller, just like turning down the aperture of the camera, the depth of field will become larger.
Increasing the depth of field means that the range of front and rear distance that can be seen clearly will be slightly larger. Because, whether it is hyperopia or myopia, what we can see but can't see clearly is between the critical distance between seeing clearly and not clearly. At this time, when we narrow our eyes and slightly increase the depth of field of eye imaging, the originally blurred image at the critical distance will be clearer than before, although the distance range is not limited.
This point is quite clear to photography majors or photography enthusiasts.
This is the reason why myopia often squints and looks smaller if it is not corrected.
Moreover, not only myopia, hyperopia, presbyopia and other people with poor eyesight will narrow their eyes consciously or unconsciously if they do not have eyesight correction.
Although narrowing your eyes to see things only involves the muscles outside the eyes that dominate the movement of the eyes and eyelids, the long-term vision will also increase the fatigue of these muscles, which is also a condition of visual fatigue. Therefore, even in order to avoid this visual fatigue, or even make your eyes look bigger from the appearance, you should have visual correction in time.
Therefore, it is not that "people with myopia will have smaller eyes", but that they often narrow their eyes to see things, and their eyes look smaller.