11/11/2023
⭐视力保健很重要但你对眼睛的了解有多少❓
⭐为啥大家都这么重视视力？因为视力是指视网膜分辨影像的能力，人类的视觉、听觉、味觉、嗅觉、触觉这五官感受中，视觉对信息的获取超过其他四个总和。
⭐那么，人是怎样用眼睛和大脑产生视觉的？近视的发生发展过程是怎样的？我们应该从哪些方面着手保护视力？
⭐人类80%的知识记忆通过眼睛获得；因此，如果双眼视力丧失，它对人的生命质量，他对外界的感知、他的学习等等造成的损失是不可低估的。
⭐本期我们解读视觉的相关科学奥秘。
PART 1❗❗
A
从光线到图像
眼睛+大脑=视觉
💗利用放大镜在太阳下点燃小纸片这个小实验，其原理是放大镜对光的会聚作用——太阳光通过放大镜后会聚到一个小点，所有光线的热量会全部汇集在一起，当温度达到着火点，纸片就燃烧起来了。
💗其实，每个人身上都藏着一双“放大镜”——眼睛。事实上，我们眼睛与照相机的原理很相似，现在请你们化作一束光，以相机作类比，经历一场眼球之旅吧。
💗首先，我们进入的第一关是角膜，俗称"黑眼珠"，相当于相机镜头。它占眼球表面积的1/6，直径约为11.5毫米，中央厚0.6毫米，旁边厚1毫米，它的屈光力有42D左右，光线在这里就已经开始会聚。
💗接下来，路过的是虹膜围绕的瞳孔，相当于相机光圈，如果光照太强了太刺眼，瞳孔就会缩小，反之放大。
💗第三关是重要关卡“晶状体”，相当于相机的全自动变焦镜头，在瞳孔虹膜后面。视力正常人既能看近又能看远，全依赖于晶状体的调节。看远时，睫状肌放松，悬韧带绷紧，晶状体变扁平，折光力减少；看近时，睫状肌收缩，悬韧带放松，晶状体依靠其本身弹性变凸，折光力增加。
💗但是，如果长时间盯着近处的物体，晶状体会一直处于饱满状态，对光线的会聚能力始终较强，长此以往，当我们看远处物体时，晶状体难以恢复到扁平状态，因此，光线通过晶状体后就只能会聚在视网膜之前，就是近视眼。而如果晶状体难以从扁平状态调节到饱满状态，那么看近处物体时，光线会聚在视网膜之后，就是远视眼。
💗像上面这样，光线通过一系列的会聚作用不断向一处聚拢，最终打在视网膜进行感光作用，这与相机的胶卷很像。在视网膜上感光最敏锐的那部分，称为黄斑。虽然视网膜很薄，结构却很复杂，分为10层，感光的细胞主要是视锥细胞和视杆细胞，视锥细胞主要负责明视觉和色觉，视杆细胞主要负责暗视觉。
💗这时候，视觉图像还没有产生，这趟旅程还没有达到终点，需要我们的大脑C位登场了。
💗接收到了光信号后，视网膜会做一件很重要的事——将光信号转换成微电流信号。这个信号中包含了物体的形状、大小、颜色等，并通过视神经一路传递到视觉中枢，也就是位于后脑勺的视觉皮层，之后大脑就会开始研究信号当中包含的颜色、形状、深度以及看到的物体到底是什么等等信息了。
💗因此，我们平常所说的“用眼睛”看到物体，其实是大脑中的视觉中枢产生的视觉。如果没有大脑作为视觉信息处理器不断工作，通过眼睛接收到的视觉信息将是一团乱麻。
#视力保健
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⭐Vision care is important, but how much do you know about your eyes❓
⭐Why does everyone pay so much attention to vision? Because vision refers to the ability of the retina to distinguish images. Among the five senses of human vision, hearing, taste, smell, and touch, vision acquires more information than the other four combined.
⭐So, how do people use their eyes and brain to produce vision? What is the development process of myopia? Where should we start to protect our eyesight?
⭐80% of human knowledge and memory are obtained through the eyes; therefore, if binocular vision is lost, the damage it will cause to a person's quality of life, his perception of the outside world, his learning, etc. cannot be underestimated.
⭐In this issue, we interpret the scientific mysteries related to vision.
PART 1❗❗
A
From light to image
Eyes + brain = vision
💗Use a magnifying glass to ignite small pieces of paper under the sun. The principle is the converging effect of the magnifying glass on light - the sunlight converges to a small point after passing through the magnifying glass, and the heat of all the rays will be gathered together. When the temperature reaches the ignition point , the piece of paper burned.
💗In fact, everyone has a pair of "magnifying glasses" hidden in their body - eyes. In fact, the principles of our eyes and cameras are very similar. Now please turn into a beam of light, use the camera as an analogy, and experience an eyeball journey.
💗First of all, the first level we enter is the cornea, commonly known as the "black eyeball", which is equivalent to the camera lens. It occupies 1/6 of the surface area of the eyeball, has a diameter of about 11.5 mm, is 0.6 mm thick in the center, and 1 mm thick on the sides. Its refractive power is about 42D, and light has begun to converge here.
💗Next, what passes by is the pupil surrounded by the iris, which is equivalent to the camera aperture. If the light is too strong and dazzling, the pupil will shrink, and vice versa.
💗The third level is the important level "Lens", which is equivalent to the camera's fully automatic zoom lens, behind the iris of the pupil. People with normal vision can see both near and far, all relying on the adjustment of the lens. When looking far, the ciliary muscles relax, the zonules tighten, the lens becomes flat, and the refractive power decreases; when looking near, the ciliary muscles contract, the zonules relax, the lens becomes convex due to its own elasticity, and the refractive power increases.
💗However, if we stare at nearby objects for a long time, the lens will always be in a full state and its ability to converge light will always be strong. In the long run, when we look at distant objects, the lens will be difficult to return to a flat state. Therefore, light passes through The back of the lens can only converge in front of the retina, which is myopia. And if it is difficult for the lens to adjust from a flat state to a full state, then when looking at near objects, the light will converge behind the retina, resulting in hyperopia.
💗Like the above, the light continues to gather in one place through a series of convergence effects, and finally hits the retina for photosensitivity, which is very similar to the film of a camera. The part of the retina that is most sensitive to light is called the macula. Although the retina is very thin, its structure is very complex and is divided into 10 layers. The light-sensitive cells are mainly cones and rods. Cones are mainly responsible for light vision and color vision, and rods are mainly responsible for dark vision.
💗At this time, the visual image has not yet been generated, this journey has not yet reached the end, and our brain’s C position needs to appear.
💗After receiving the light signal, the retina will do a very important thing - convert the light signal into a microcurrent signal. This signal contains the shape, size, color, etc. of the object, and is transmitted through the optic nerve to the visual center, which is the visual cortex located at the back of the head. Then the brain will begin to study the color, shape, depth and what is seen in the signal. Information about what the object is and so on.
💗Therefore, what we usually call seeing objects “with our eyes” is actually the vision produced by the visual center in the brain. Without the brain constantly working as a visual information processor, the visual information received through the eyes would be a mess.
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