Abstract: concave lens is used for correction. The characteristics of this kind of lens are: thin in the middle and thick on both sides. According to this feature, we choose the small frame as much as possible. For patients with high myopia, the edge of the small frame lens is relatively thin compared with the large frame.
the difference between normal eyes, myopia and hyperopia
normal eyes: when the eye is adjusted and relaxed, the focus of parallel light falls on the retina after refraction through the refractive system of the eye. Is what people call normal vision.
myopia: after the light passes through the refractive system of the eye, the focus of the light forms in front of the retina. The subjective feeling is that the near object is clear and the far object is fuzzy.
hyperopia: after the light passes through the refractive system of the eye, the focus of the light is formed behind the retina, so it can not form a clear picture on the retina. The subjective feeling is to see the distance blurred, see the near more blurred. Many people think that hyperopia is to see clearly in the distance, which is wrong.
myopia Causes of hyperopia
causes of myopia hyperopia: the common causes are the short anterior and posterior axis of the eye (called axial hyperopia), followed by the weak refractive power of the eye (called refractive hyperopia).
Hyperopia can also be considered as ocular hypoplasia. It is usually hyperopia in children, and the degree decreases with age. Hyperopia is prone to visual fatigue because it is in a state of tension for a long time.
myopia and hyperopia correction methods
myopia: concave lens is used to correct. The characteristics of this kind of lens are: thin in the middle and thick on both sides. According to this feature, we choose the small frame as much as possible. For patients with high myopia, the edge of the small frame lens is relatively thin compared with the large frame.
hyperopia: use convex lens to correct. The characteristics of this kind of lens: thick in the middle and thin on both sides. According to this feature, when choosing the frame, we try to choose the large frame. For patients with high myopia, the edge of the large frame lens is relatively thinner than that of the small frame.
precautions for myopia and hyperopia
myopia shows that far vision is not clear, near vision is clear, mild hyperopia should have no symptoms, and high hyperopia is not clear. Therefore, we still need to go to the hospital or professional glasses shop for visual examination to determine the type of your ametropia, so as to correct it in time!
hyperopia patients with eye diseases will increase the excitability of internal rectus muscle after their regulatory power is strengthened. If the hyperopia of one eye is serious, in order to make the eye see the scenery clearly, adjustment must be increased. The excitability of internal rectus muscle must be increased than that of normal eyes. Therefore, some hyperopia eye diseases form esotropia. Therefore, strabismus mostly occurs in children with high hyperopia. Most patients with hyperopia and strabismus with anisometropia are used to working and learning with gaze eyes (eyes with low degree of hyperopia), and put aside the unused strabismus eyes. After a long time, strabismus eyes will become amblyopia eyes.
hyperopia eyes need to increase their refractive power to see long-range targets, and need more adjustment to see short-range targets. The vision of hyperopia can be normal near and far vision or poor myopia, good far vision, or poor far and near vision due to the depth of hyperopia and age. Hyperopia is prone to visual fatigue, and the time of close work or reading can not last long.