Abstract: fundus changes, mild myopia patients generally have no fundus changes. The optic papilla of patients with moderate myopia or above is large and light in color, with crescent or half moon arc spots at the edge. Patients with high myopia often have vitreous liquefaction and turbidity, and the fundus is leopard shaped. In severe cases, the visual omentum shrinks and degenerates one after another, resulting in holes, leading to retinal detachment and seriously affecting vision. To form a clear image (focus) of something, our eyes must bend the light reflected from the object and make the light fall directly on the retina. Nearsighted people can only see objects at close range. Objects at long range look blurred because the image is focused in front of the retina. The correction method is to let the myopia wear a concave lens, which can make the focused light move back slightly and fall on the retina. The cause of hyperopia is that the anterior posterior diameter of the eyeball becomes shorter. The light from close objects is focused behind the retina, so it looks very blurred. Only long-distance objects can see clearly. Hyperopia patients can wear convex lenses to bend the light slightly inward to help the light fall on the retina.
myopia and hyperopia belong to spherical ametropia, and its refractive system is spherically symmetrical. This spherically symmetric refractive anomaly has the same refractive power on different meridional planes of the corneal interface.
high myopia: the causes of high myopia are complex, and there are many influencing factors. The main factors are roughly divided into genetic factors, environmental factors and nutritional factors.
1. Genetic factors: the genetic type of high myopia. Most conclusions are autosomal recessive inheritance. Therefore, parents and children can not have myopia at the same time.
2. Environmental factors: from a large number of relevant investigation and research reports at home and abroad, it has been recognized that heredity and environment are the main causes of myopia, It is pointed out that environmental conditions (especially light brightness / indoor lighting) are the main objective factors determining the formation of myopia 3. Nutritional constitution theory: according to some data analysis, the lack of trace elements such as cadmium, strontium and zinc and the weakness of constitution can also affect the occurrence of myopia, but there are different opinions on how these factors affect myopia and to what extent. Self identification of
myopia are mainly due to the gradual decline of far vision, blurred far objects and normal near vision, but high myopia is often caused by refractive interstitial opacity and degeneration of retina and choroid. Its far and near vision is not good, and sometimes accompanied by the floating of black shadow in front of eyes. Visual fatigue of
is manifested by eye swelling, eye pain, headache, double shadow virtual edge and other conscious symptoms. The fundus of
changed, and there was generally no change in the fundus of patients with mild myopia. The optic papilla of patients with moderate myopia or above is large and light in color, with crescent or half moon arc spots at the edge. Patients with high myopia often have vitreous liquefaction and turbidity, and the fundus is leopard shaped. In severe cases, the visual omentum shrinks and degenerates one after another, resulting in holes, leading to retinal detachment and seriously affecting vision.
are exophthalmos. Due to the growth of the clothing axis, the eyeball of high myopia becomes larger, and the appearance shows the state of exophthalmos.
astigmatism is different. It is an asymmetric refractive system. Astigmatic eyes have different refractive power on different meridian planes of the cornea. Because the corneal curvature of astigmatic eye is asymmetric, the light from point light source cannot form a clear point image on the retina after refraction by this eye. The light reaching different meridional surfaces of the cornea cannot be focused simultaneously in the eye, so it is called astigmatism. As a result, the object image is deformed or blurred.
astigmatism are divided into regular astigmatism and irregular astigmatism. Generally speaking, astigmatism generally refers to regular astigmatism. Regular astigmatism is often divided into the following five types:
(1) monosexual hyperopia astigmatism: one main meridian is hyperopia and the other main meridian is emmetropia; (2) Simple myopia astigmatism: one main meridian is myopia, and the other main meridian is emmetropia; (3) Compound hyperopia astigmatism: both main meridians are hyperopia, but their diopters are different; (4) compound myopia astigmatism: both main meridians are myopia, but their diopters are different; (5) Mixed astigmatism: one main meridian is hyperopia and the other main meridian is myopia. The correction methods of
astigmatism eyes vary according to the type of astigmatism. For simple hyperopia astigmatism, a convex cylindrical lens with appropriate degree and certain axis should be worn; For simple myopia astigmatism, concave cylindrical lens with appropriate degree and certain axis should be worn; However, no matter which type of astigmatism eye belongs to, the axial direction of the cylindrical lens shall be strictly measured for the glasses, so that the astigmatism eye can be effectively corrected on the meridional plane to be corrected.
for irregular astigmatism, because the diopter is also different on the same meridian plane, the correction effect of cylindrical lens is not good, so contact lens (contact lens) can be used for correction.