What is myopia, hyperopia, astigmatism, presbyopia

Myopia, hyperopia and astigmatism are collectively referred to as refractive errors. Refractive errors refer to the fact that when the eye does not use adjustment, the parallel light 5 meters away cannot form a clear image on the retina after passing through the refractive system of the eye, but in front or behind the retina. imaging. Presbyopia is a normal physiological phenomenon, not a refractive error.

I. Emmetropia

What is emmetropia? When the human eye is in a state of relaxation and adjustment (when looking far away, it is in a state of adjustment and relaxation), and the parallel light 5 meters away is focused on the retina after passing through the eye refractive system. It is called emmetropia, that is, the eyes have no problems such as refractive error, and they are good eyes. Emmetropia, imaged on the retina

2. Causes, symptoms and treatment of myopia

(1) What is myopia? When the human eye is in a state of adjustment and relaxation, parallel rays of light from 5 meters away pass through the eyeball When the refractive system is back focused in front of the retina, it is called myopia. Myopia, the image is in front of the retina (2) Causes of myopia Environmental factors: long-term use of the eyes at close range, the eyes do not get a good rest, and it is easy to cause eye fatigue. Such as working in front of the computer for a long time, playing games, playing mobile phones for a long time, etc. Genetic factors: High myopia is an autosomal recessive inheritance. If both parents are highly myopic, the probability of children suffering from myopia increases. People with genetic factors have an earlier age of disease, and the degree is more than 600 degrees. Dysplasia: The eyes of children under 6 years old are in the developmental stage. If the eyes are overdeveloped and the eye axis becomes longer, myopia will be formed. The normal axial length of the eye is 24mm, and for every 1mm increase, the degree of myopia increases by 300 degrees. (3) What are the symptoms of decreased visual acuity: see near clearly, see far blurry, and need squinting to see far away. Visual fatigue: myopic eyes use more collective force, the medial rectus muscle is too tense, and vision cannot be sustained for a long time. (4) Wear frame glasses or contact lenses for the treatment of myopia: Frame glasses are the most reliable and simplest correction method. Contact lenses are contact lenses, but they cannot be worn for a long time. Care should be taken at ordinary times, otherwise it will cause corneal congestion or inflammation. . Surgical treatment: corneal surgery, lens and intraocular lens surgery, posterior scleral reinforcement.

3. Causes, symptoms and treatment of hyperopia

(1) What is hyperopia? When the human eye is in a relaxed state, the parallel light from 5 meters away is focused on the retina after passing through the eye refractive system. After that, it is called hyperopia. Hyperopia, imaging is behind the retina (1) Causes Axial hyperopia: newborn babies are almost all hyperopia. With the development of the body, the anterior and posterior axis of the eyeball slowly grows, and the adult eyes should be emmetropia or close to emmetropia. In the process of eye development, some people stop the development of the eyeball due to the influence of internal (genetic) and external environment, and the eye axis cannot reach the length of the normal eye. For every 1mm reduction in the axial length of the eye, the degree of hyperopia increases by 300 degrees. Curvature hyperopia: It is caused by a small curvature of the surface of any of the refractive bodies in the eye's refractive system. The cornea is a site prone to such changes, as in congenital flat corneas, either as a result of trauma or from corneal disease. (2) What are the symptoms of vision loss: adolescents with low hyperopia have strong self-regulation ability, and can see far and near clearly. With age, the ability to adjust is weakened, and both distance and near vision gradually deteriorate. Visual fatigue: farsightedness requires adjustment to see far and near, causing symptoms such as eye swelling, headache, and visual fatigue, and reading or working at close range cannot last for a long time. (3) For the treatment of hyperopia, wear frame glasses or contact lenses.

4. Causes, symptoms and treatment of astigmatism

(1) What is astigmatism? When the human eye is in a state of adjustment and relaxation, the parallel light from 5 meters away cannot penetrate the retina after passing through the refractive system of the eye. form a focal point, but form multiple foci. Astigmatism, forming multiple focal points (2) Causes of astigmatism Curvature astigmatism: uneven curvature of the refractive body surface, mostly occurs in the cornea, the human cornea is slightly elliptical, generally has 25 degrees of physiological astigmatism, mild of astigmatism does not affect vision. Those with larger astigmatism are mostly congenital or formed during development. In addition, the long-term compression of the upper and lower eyelids on the cornea can also lead to curvature astigmatism. Exponential astigmatism: mostly caused by changes in the refractive index of different areas of the lens, such as various astigmatism caused by changes in the refractive medium of the lens during cataract. Optical center deviated astigmatism: such as obvious deviation of the lens position, lens subluxation caused by trauma, etc. (3) What are the symptoms of decreased visual acuity: myopic astigmatism near vision is better than distance vision, while farsighted astigmatism is poor in both distance and near vision. Astigmatism: Because the retina of astigmatism cannot converge into a single focal point, it is blurry whether it is far or near. In severe cases, there will be double shadows, eye pain, headache, and tearing. Close-up work cannot be sustained. (4) Treatment of astigmatism Wearing frame glasses, wearing corneal contact lenses, and surgical treatment

5. Causes, symptoms and treatment of presbyopia

(1) What is presbyopia People often say presbyopia, which is a normal physiological phenomenon, which gradually occurs from the age of 40. With age, the ability to accommodate the eyes gradually weakens, making it difficult to work at close range and read. Presbyopia (2) Causes of presbyopia lens sclerosis, weakened elasticity, reduced ciliary muscle contraction ability, resulting in reduced accommodation ability, near point distance, so near vision difficulties occur. (3) What symptoms are difficult to see near and small prints, and it needs to be taken a little farther to be clear. Reading requires strong luminosity. Seeing near can't last. (4) Treatment of presbyopia People without myopia or hyperopia only need to wear a pair of presbyopia glasses. People with nearsightedness or farsightedness need two pairs of glasses, one for far-sightedness and one for near-sightedness. Those with economic ability can wear progressive multifocal glasses, and one pair of glasses is used for both far-sighted and near-sighted vision. Progressive film

Six. Refractive error prevention measures

Wearing frame glasses only changes the direction of the light entering the eye, so that the image can be displayed on the retina. With eyes, the degree will gradually deepen, so everyone should take good care of their eyes. Find out what bad eye habits you have. Lying in bed at night, watching the phone, reading news or novels on the bus, watching TV for a long time, playing games for a long time...