Why do we have myopia? Did you know that these 6 factors are the main reasons?

It is said that eyes are the windows to the soul and also the window through which we view this vast and prosperous world. Although eyes only occupy a small part of our body, they contain complex structures and huge mysteries.

Structure of the Eye:

The human eye is a spherical organ located in the eye socket. The eyeball is composed of the eyeball wall, intraocular cavity and contents, nerves, blood vessels and other tissues. The simple classification of the eyeball structure is mainly divided into two parts: the eyeball wall and the contents:

1. Eyeball wall: It can be divided into outer membrane, middle membrane and inner membrane.

(1) The outer membrane is composed of the colorless, transparent cornea rich in nerve endings that can transmit light, and the white, tough sclera that protects the eyeball; (2) The middle membrane is composed of the iris that can adjust the brightness of the light entering the eye, the ciliary membrane that adjusts the curvature of the lens, and the choroid that can block light to form a dark room; (3) The inner membrane is what we usually call the retina, which is the photosensitive system of the eye, with the most visually sensitive macula in the center.

2. The contents of the eye include aqueous humor, lens and vitreous body, which are transparent and serve as refractive media together with the cornea.

Now that we have a brief understanding of the structure of the eye, let's take a look at how our eyes perceive light:

Our eyes are like a sophisticated camera. The cornea on the surface of the black eyeball is like the lens on the camera, the pupil in the middle is like the aperture that controls the amount of light entering the eye, the lens at the back is like a zoom that adjusts the clarity of the image, and the inner retina is like a film that senses the light source. Finally, the object is imaged on the retina. The light signal is transmitted to the visual center of the brain through the optic nerve. After being processed by the visual center, we can see clear and beautiful things. [1]

So how does myopia develop?

Myopia is a type of refractive error. When our eyes are in a relaxed state, parallel light rays enter the eye and cannot focus on the retina to form a clear image. Myopia is formed in this way. Myopia can be divided into mild myopia (≤300 degrees), moderate myopia (300 degrees to 600 degrees) and high myopia (>600 degrees).

What are the causes of myopia?

(1) Genetic factors. Some people are born with an elongated eye axis and are myopic from birth. This may be related to the myopia of their parents. Studies have shown that if one parent has myopia greater than 600 degrees, the probability of passing it on to the next generation is about 20%; if both parents are myopic, the myopia rate of the next generation is as high as 40%. Therefore, for the eye health of the next generation and to reduce the chance of myopia, please protect your eyes.

(2) Light factors: "The dim light from the mobile phone, the densely packed small characters on the phone, staring at it for hours." "The light should be brighter, turn it to the brightest, otherwise the writing is not clear." When the light is too weak, in order to see clearly, you will hold things very close, and the ciliary muscles will enter a tense mode. If the light is too strong and shines on the pupil, it will shrink the pupil and make the ciliary muscles tense. The lens wants to change to a flat posture, but it is tightly restricted by the ciliary muscles, and myopia will come.

(3) Bad posture: Some people like to lie down or lie prone to play with their mobile phones or read books. They do whatever posture is comfortable for them, without considering the feelings of their eyes. Doing this for a long time will keep the ciliary muscles in a tense state, and myopia will not be far away from us.

(4) Insufficient eye relaxation: "Staying up late to watch TV series until midnight, with iPads, computers, and mobile phones all connected." This should be a portrayal of the daily life of modern young people. Everyone likes to relax themselves in front of electronic products at night. They watch TV series or play games all night long, leaving no time or opportunity for the eyes to relax. Such high-intensity eye use prevents the eyes from relaxing, and the final result is myopia.

(5) Vitamin deficiency: Vitamin B1 is a nutrient for the optic nerve. If vitamin B1 is deficient for a long time, it will lead to decreased vision due to insufficient nutrition of the eyeball.

(6) Calcium deficiency: Calcium is the “protector” of the eyes. If there is a calcium deficiency, the ciliary muscle will lose its elasticity, which can easily lead to myopia.

Eyes are an indispensable part of our daily life, but people do not pay attention to the protection of their eyes, resulting in an increasingly high rate of myopia. I hope everyone can pay attention to eye protection and reduce the occurrence of myopia.

References: [1] Bai Shuling, ed. Systemic Anatomy (7th edition). People's Medical Publishing House, 2010