Abstract: the word ametropia is not familiar to ordinary people, but it is not strange to mention myopia, hyperopia and astigmatism. Ametropia refers to abnormal refractive states such as myopia, hyperopia, astigmatism and anisometropia., Many people are very familiar with myopia, but they don’t know much about ametropia. According to experts, ametropia refers to the visual problems caused by incorrect imaging when the line of sight enters the eyes. It includes three clinical symptoms: myopia, hyperopia and astigmatism. Let’s introduce it in detail., The word ametropia is not familiar to ordinary people, but it is not strange to mention myopia, hyperopia and astigmatism. Ametropia refers to abnormal refractive states such as myopia, hyperopia, astigmatism and anisometropia.
Many people are very familiar with myopia, but they don’t know much about ametropia. According to experts, ametropia refers to the visual problems caused by incorrect imaging when the line of sight enters the eyes. It includes three clinical symptoms: myopia, hyperopia and astigmatism. Let’s introduce it in detail. The word
Ametropia is not familiar to ordinary people, but it is not strange to mention myopia, hyperopia and astigmatism. Ametropia refers to abnormal refractive states such as myopia, hyperopia, astigmatism and anisometropia.
People often compare the eyes to the “camera” of the human body. The structure and function of the eye have many similarities with the camera, but the eye is a living human organ, which is much more exquisite and complex than the camera. The lens of the camera is a convex lens. The light is refracted through the lens. Adjusting the front and rear positions of the lens can focus the light on the photographic plate and become a clear inverted image. What does mean?
The transparent part of the eyeball (cornea, lens and vitreous body) can also refract and focus the light entering the eye. The thickness and curvature of the lens can be changed by the activities of the ciliary muscle. Appropriate adjustment can make the incoming light just focus on the retina and become a clear inverted image, which is similar to the camera.
When photographing objects at different distances with a camera, the distance between the lens and the base plate must be changed accordingly so that the light is just focused on the base plate, so that the photo can be clear. The distance between the refractive stroma in the human eye can not be changed at will. People can see objects at different distances by changing the refractive power of the lens, that is, through the adjustment function of the eye.
When tuning is not used (adjustment can be understood as the ability of the eye to see from far to near). The parallel light from more than 5 meters away focuses on the retina through the refraction of the eye to form a clear object image. The eye in this normal refractive state is called emmetropia. If the light focuses on the front and back of the retina, or cannot focus, the object image on the retina is blurred. Such an eye is non emmetropia, or flexion Light is not right. When the parallel light is focused on the retina, it is myopia, and after the retina, it is hyperopia. Astigmatism cannot focus on the same plane. There is a significant difference in diopter between the two eyes, which is called anisometropia.
Ametropia can generally be corrected with glasses. In appearance, people wear similar glasses, but the properties of glasses for myopia, hyperopia and astigmatism are different. They need concave lenses for myopia, convex lenses for hyperopia and cylindrical lenses for astigmatism.