How to know if you need glasses? these signs!
If you have any of the following signs, it's a warning showing that something may be wrong with your eyes and you need glasses now:
1. Your eyes are often dry and sore, and sometimes you even have the feeling of dizziness and nausea.
Using your eyes for a little longer, there are some symptoms of asthenopia (eye fatigue), such as sore or irritated eyes. Symptoms like double vision and watery eyes may also happen. Most of them can be gradually relieved after relaxation.
2. Sometimes you have blurred vision, and after a rest you may feel better.
The main feature is that your visual acuity declines clearly after using eyes for a short time, and eye fatigue is easy to be caused. To some extent, adequate rest can relieve these symptoms.
3. You may squint to see things far away or near.
You have to squint when you see things in a distance. If you have myopia, you will gradually appear to see distant things blurred, but it often doesn't affect you to see near objects.
4. The sign can also be exophthalmos or enophthalmos, which may affect your appearance.
The first two signs are generally considered to be the symptoms of ametropia. If you don't pay attention to them, you will have myopia or hyperopia; for the latter two signs, it can almost be concluded that it is ametropia. Thus, you should go to eye hospital as soon as possible.
What is ametropia?
Ametropia refers to refractive errors that the eyes are not able to focus light directly to form a clear image onto the retina without adjustment, and the image will be formed in front of or behind the retina. It includes myopia, hyperopia, and astigmatism.
There are many reasons for refractive errors, among which genetic factors are important. Of course, unreasonable use of the eye should not be ignored. Paying little attention to eye care is the same, such as reading or writing with improper postures, close distance between the eye and the book, reading for a long time, reading while walking or in a moving car, which may cause eye fatigue and refractive errors.
Ametropia can be divided into the following types based on different symptoms:
1. Hyperopia
When the refractive system of the eye is at ease, the focus of the parallel light in front of the eye is behind the retina. This is due to anterior-posterior diameter shortening of the eyeball or the insufficient refraction of the eye. This type of refraction is called 'hyperopia'.
2. Axial hyperopia
The short anterior-posterior axial shortening of the eyeball causes hyperopia. For example, newborns are almost hyperopia. The eyeballs of highly hyperopia are usually smaller than those of emmetropia or myopia.
3. Curvature hyperopia
Hyperopia can be caused by the flattening of any refractive surface of the eye, and most mainly caused by the flattening of the cornea.
4. Index hyperopia
It it possible to be caused by decreased refractive index of all refractive media in the eye, but this type is rare.
5. Myopia
When the refractive system of the eye is at ease, parallel light focuses in front of the retina, which is due to the anterior-posterior diameter lengthening of the eyeball or the strong refraction of the refractive system of the eye. This type is called 'myopia'.
6. Simple myopia
Most cases happen on students, which develop slowly and is basically stable after the age of 20 with diopters below -6D. For most people, their eyes have no pathological changes and can be corrected to normal vision with appropriate lenses.
7. Degenerative myopia
Also known as pathological myopia, congenital myopia, high myopia, progressive myopia, malignant myopia, etc. It is usually caused by genetic factors. The disease is progressive. As the eyeball gradually lengthens and myopia diopter increases (generally above -6D), the pathological changes of the eyeball also gradually aggravated.
With the myopia diopter below -10D, the degeneration of eyeball is not obvious, and can be corrected to normal vision by lens; while with that above -10D, the ocular degeneration is obvious, and vision is not easy to correct to normal even with ordinary glasses or contact lenses. If there are complications, such cases may turn into low vision. Severer cases may even cause blindness.
8. Astigmatism
The refractive system of the eye is not completely positive spherical refraction, for example, under the pressure of the eyelid, the parallel light from the front of the eye cannot converge into a single focal point on the retina but a focal line. This type of refraction is called 'astigmatism'.
9. Irregular astigmatism
As a result of the meridians or the same meridian of the corneal curvature is not consistent, it is not easy to correct with lenses.
10. Regular astigmatism
The two main meridians (i.e. the meridians with the greatest and least refractive power) are perpendicular to each other and can be corrected with lenses.
Of ametropia, there are several misunderstandings:
1. Child's blurred vision equals myopia
Our eyeballs is like a sophisticated camera, and the dioptric system is like a lens, which can focus parallel light rays from a distance onto the retina, so that we can see distant objects clearly. When the length of the axis of the eye and the refractive power of the eye don't match up well without regulating, it is called 'ametropia'.
If light rays still form a focus, but it is in front of the retina, it is called 'myopia'; while the focus is behind the retina, it is called 'hyperopia'.
The condition that light rays don't form a focal point but a focal line is called 'astigmatism'. A focal line in front of the retina is 'myopic astigmatism', and a focal line behind the retina is 'hypermetropic astigmatism'. With either type of ametropia, light doesn't focus properly on the retina, but forms diffused spots on the retina, resulting in blurred vision. With suitable eyeglasses, you can improve your vision by refocusing light properly on the retina and getting a clear image.
2. Wearing glasses will aggravate myopia
In fact, early in 1966, Shanghai Cooperative Group on Myopia Wearing glasses conducted a 14-25 month comparative observation of middle school students with and without glasses. Then they found that whether wearing glasses or not did not affect the degree of myopia.
Wearing glasses is to correct vision and make work, study and life more convenient. Appropriate eyeglasses correction can improve vision, relieve visual fatigue, rebalance the adjustment and correction, prevent or correct strabismus and amblyopia, reduce anisometropia, and develop binocular vision. Wearing glasses to correct myopic astigmatism may also prevent the deepening of diopter.
Ophthalmology studies have found that most newborns are farsighted, with an average diopter of +2 ~ +3D (that is, 200 ~ 300 degrees of hyperopia as most people say). Later, with the growth of children, the refractive state gradually changes into myopia, and the degree of hyperopia decreased step by step. Children and teenagers are in the period of physical growth, physically their eyeballs is also on the process of myopia. If it has been confirmed by myoptic optometry to be myopia rather than pseudomyopia, then the child's dioptric state is only to be deepening myopia in varying degrees.
3. Relying on instruments to treat myopia
Can a variety of instruments for treating myopia slow down the visual development and even reduce myopia degree?
After a period of using instruments to treat myopia, perhaps children's vision has improved to some extent, but such improvement is only for the skills to recognize the visual testing chart, rather than a clearer image on retina.
As for pseudomyopia, it is caused by the spasm of accommodation, and is not a real myopia. Even if you don't do special treatment, you can also relieve the spasm, reduce the symptoms of myopia, and improve vision, as long as you reduce the time to see things near and do more outdoor exercise.
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