If you are short-sighted, you may need 2 pairs of glasses when you are old

There are more and more glasses parties in this world!

Healthy eyes see the world in a variety of shapes

There is only one kind of blurry eye--hazy

Yes, it can

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It can also be

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The most tragic thing is -

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Almost every myopic person has had a soul ask:

I heard that people are old and presbyopia

Becomes farsighted and can neutralize myopia

Wouldn't it be normal to see?

To answer this question

The first thing we have to understand is how the eyes work.

At first glance, the structure of our eyes is simple: white eyeballs and black eyeballs.

(Image source: soogif)

But in fact, the inside is clean, and the eye is like a very precise camera.

To understand myopia and farsightedness, remember 3 structures:

Cornea: A transparent "lid" on the surface of a black eyeball, equivalent to a camera's fixed-focus lens.

Lens: Suspended behind the pupil, it resembles an elastic translucent structure (like the m&m beans we ate as children) that adjusts the thickness under the pull of the ciliary muscles inside the eye, the equivalent of a zoom lens for a camera.

Retina: A camera negative deep in the eyeball that is connected to the optic nerve and transmits the focused image to the brain for recognition.

Simply put, the process of the eye seeing things, behind a series of changes, the cornea and lens are the channels of this project, the retina and brain are the acceptance officer.

At the heart of this difficult maneuver is 4 words:

Right

Healthy eyes, the light is always just right to focus on the retina, giving the brain a perfect picture.

This is face to face, which means:

The cornea and lens have a normal ability to focus light

The length of the eye is normal, that is, the eye axis is normal

The ability to focus matches the length of the eyeball

(Remember these 3 normals, which will be mentioned below)

In order to see things at different distances, the ciliary muscles holding hands with the lens must exert different forces to change the shape of the zoom lens so that the light is not focused by a fraction of a second.[2]

When looking at the apple in the distance, the ciliary muscle relaxes and the lens is flatter

When looking at the apple in front of you, the ciliary muscles tighten and the lens is more convex

In this process, the cooperation of healthy lenses, strong ciliary muscles, etc., ensures that light always falls on the retina just right and is clearly received by the brain.

So here's the problem —

Myopia is when, in a relaxed state, parallel rays of light enter the eye and focus on the front of the retina, which is myopia [2].

This is a comparison chart of normal eyes with myopic eyes (axial myopia, the vast majority of myopia types) –

There are 2 conditions of myopia:

Refractive myopia: the lens and cornea are too "convex", and the eye axis is normal.

Axial myopia: the lens and cornea are normal, and the eye axis is too long. Most of the current myopia is of this type.

Good eyes, how can it be myopia?

Although my mother said this —

However, in medicine, the specific mechanism of myopia is more or less an unsolved mystery of the world.

We are surrounded by more and more myopia. At present, it is believed that the occurrence of myopia is the result of a combination of genetic + environmental action. Most scholars believe that myopia is closely related to a variety of environmental factors such as genetics, sex, age, race, height, region, close eyes, birth season, and outdoor activities [3].

For the glasses party of aging myopia, the most concerned thing is: how will myopia develop in the future?

Question 1: Do myopic eyes have farsightedness?

First of all, the conclusion -

No!

Myopia is irreversible, myopia is myopia, it is impossible to become farsighted again.

Because myopia and farsightedness are 2 opposite states:

Most of the "true myopia" is axial myopia, usually fixed around the age of 20, under normal circumstances the eye axis is no longer longer, and it is irreversible; a small part is refractive myopia, that is, the cornea / lens and other light gathering ability is too strong, the eye axis is normal, but also irreversible.

But hyperopia may become myopia.

Under normal circumstances, the eyes of infants and young children are mostly in a state of hyperopia, as they grow up, they gradually become normal (orthopedic), generally to the age of the basic to achieve positive vision, this process is called "orthodonization" As they grow up, under the influence of genetic + environmental factors, it is possible to further develop myopia.

Although children are farsighted, they do not have blurred vision. As long as the farsightedness is not too severe, with the full force of the lens and ciliary muscle, it can have enough focusing ability on the light, so that it can be imaged exactly on the retina, and the near and far apples can be clearly seen [2].

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Many people think that farsighted eyes must have blurred vision, but they are not! In general:

With a degree of farsightedness below 300 degrees, the eyes' self-regulation is healthy, and most people's vision will not be affected until the age of 40. But compared to normal eyes, people with farsightedness need to use the adjustment ability of the eyes multiple times, so it is easier to feel eye fatigue.

If it exceeds 300 degrees, looking at objects in the vicinity requires greater adjustment force, but due to the high degree, beyond the range of its own adjustment ability, vision will be affected, and eye fatigue is often felt.

Adult patients with low-grade hyperopia generally do not need to wear glasses for correction, unless as they age, the eye's ability to concentrate light decreases and blurred vision begins.

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Question 2: Do myopic eyes get old?

Myopia doesn't become farsighted, but they all... Presbyopia (medically known as presbyopia).

Presbyopia is caused by the aging of the eyes. As we get older, the elasticity of the lens weakens, the function of the ciliary muscle weakens, and the eye is difficult to focus, and the result of this effect is that it is difficult to see clear close-ups, and it is blurry to see things near, but the vision of seeing far is not limited [2].

As myopia and hyperopia grow older, there will be a coexistence of myopia and presbyopia, hyperopia and presbyopia.

Presbyopia usually occurs slowly, starting around the age of 45 and generally reaching the age of 65 to 70 years.

However, the time when premature aging occurs in myopic and hyperopia may be different. In general, in the naked eye state, the time of aging:

Hyperopia > orthopedic > myopic eyes

Myopic people are old, the performance is-

The distance is close and can't be seen clearly, the distance is far away and can't be seen clearly, you need 2 pairs of glasses, really Mrs. Mrs. is inconvenient~

Farsightedness will generally appear presbyopia symptoms earlier, and the degree of presbyopia is higher, if you can't see clearly, remember to go to the hospital for a professional eye examination.

If you or a family member of your age fits this range and finds yourself unconsciously lifting far away when you look at things, can't read clearly from normal distances, and is more severe when you are tired and dimly lit, then it may be old age.

Don't be nervous, go to the hospital in time for a professional examination, if necessary, with a pair of reading glasses.

(Source: Network)

To summarize:

Myopia is irreversible;

Myopia does not become farsighted, so don't expect to be older, myopia will be "neutralized";

Hyperopia may become myopia;

Both myopia and farsightedness may become old;

Myopic people need 2 pairs of glasses;

Hyperopia may appear presbyopia earlier and with deeper degrees.

Have you understood after reading it?

(Image source: soogif)

bibliography

[1] Nearsightedness.mayoclinic.org.https://www.mayoclinic.org/diseases-conditions/nearsightedness/symptoms-causes/syc-20375556

Ophthalmology. Human Guard Ninth Edition

Li Yuanyuan,Zhang Xiaofeng. Influencing factors and treatment progress of myopia formation in adolescents and children. International Journal of Ophthalmology Vol. 18, No. 12, December 2018, 2179~2182

[4] Presbyopia:Overview. InformedHealth.org.https://www.ncbi.nlm.nih.gov/books/NBK423833/

Author: Zhang Xiaoyi, Zhou Yamu, Xin Yuehua

Editors: Zhang Xiaoyi, Zhang Guangyou, Zhang Liang

Proofreading: Wu Yihe | Typesetting: Li Yongmin

Operation: Han Ningning | Coordinator: Zhao Yanan