Traditional Culture Encyclopedia - Traditional culture - Why do people who are nearsighted when they are young get presbyopia when they are old?
Why do people who are nearsighted when they are young get presbyopia when they are old?
Presbyopia is actually a physiological phenomenon, mainly manifested in inability to see clearly. Many people may find that they can't see the words on the screen of their mobile phones clearly at first, so they need to hold their mobile phones far away.
This is because when light enters human eyes, it needs cornea and lens to focus. However, with the increase of age, the lens gradually becomes hard and its elasticity becomes worse, and its ability to control the ciliary shape of the lens becomes weak, which makes the eye's ability to adjust in the near future decline and it cannot focus clearly in the near future. You need reading glasses to help you see clearly.
Presbyopia generally appears after the age of 40. With the increase of age, the more obvious the symptoms are, the more reading glasses are needed.
If your myopia is very low when you are young, such as 50 ~ 100, and you are used to not wearing glasses, congratulations. When peers start to wear reading glasses, you need to wear reading glasses 5 ~ 10 years later than them. Because you "reserve" the refractive power of myopia to offset some of the refractive power lost by presbyopia, you may still need to wear presbyopic glasses as you get older.
The reason for presbyopia is that your eyes are "old" Usually, external light enters the eyeball and needs to be focused by the cornea and lens. In order to see objects at different distances clearly, we need lenses to change their shapes. For example, if we look closely, the lens will become more convex, which will increase the light gathering ability.
In order to avoid presbyopia, we must first ensure enough sleep and let our eyes get enough rest. Secondly, work closely for about 50 minutes and let your eyes rest 10 minutes. You can keep your eyes away from the computer screen or books, overlook, do eye exercises and exercise cervical vertebrae, all of which are good for relieving visual fatigue.
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