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Myopia
近视
Origin of the word It comes from the Greek word muōps, meaning short-sighted.
近视一词来源于希腊语muops，意思是近视。
These people cannot see distant objects clearly.
患近视的人看不清远处的物体。
Anatomy
解剖学
Before we describe myopia, let's compare the eyeball to a camera for better understanding.
在解释近视之前，为了更好的理解，让我们把眼球比作相机。
When we take a picture, light after reflecting from an object enters the camera and passes through following：
当我们拍照时，从物体反射回来的光线进入相机，并通过：
Firstly, it passes a transparent glass in front of the aperture of the camera.
首先，它通过相机光圈前面的透明玻璃。
Then secondly, it passes a camera lens that helps us in focusing light rays and lastly, there is a camera film on which light is focused for a clear picture.
其次，它通过一个帮助我们聚焦光线的相机镜头，最后是相机胶片，光线聚集在相机胶片上，以获得清晰的图像。
Eye is somewhat similar as when we see an object, light after reflection from that object enters our eye through:
眼睛和相机原理类似，我们看到一个物体时，物体反射后的光通过以下途径进入我们的眼睛：
Firstly, it passes cornea, the transparent curved front part of the eye,
首先，它通过角膜，角膜是眼睛前面透明的弯曲部分，
then secondly, it passes through the crystalline lens that helps us in focusing light rays
然后，它穿过帮助我们聚焦光线的晶体
and lastly, there is the retina, light sensitive receptor cells in the posterior part of the eyeball on which light is focused for a clear image.
最后，还有视网膜也就是眼球后部的感光细胞，光线聚焦在视网膜上以获得清晰的图像。
Definition of Myopia
近视的定义
It is a form of refractive error, inability to refract, bend, focus the light rays properly in which parallel rays of light i.E. coming from a distinct object, after entering the eye, are focused in front of the retina instead of on retina with eye muscles at rest.
近视是屈光不正的一种形式，无法折射、弯曲、聚焦光线，即平行来自一个物体的特定光线，进入眼睛后，聚焦在视网膜前面，而不是在眼肌休息时聚焦在视网膜上。
Causes:
原因：
Curvature; increase of curvature of cornea or lens causes light rays to be focused in front of retina and hence Myopia occurs.
曲率；角膜或晶状体曲率的增加会导致光线聚焦在视网膜前方，从而发生近视。
Axial; increase in axial length of eye increases the converging power and cause light rays to be focused in front of retina.
轴向；眼轴长度的增加会增加眼球的辐合能力，使光线聚焦在视网膜前面。
Index; increase in refractive index i.E. light bending/focusing power of the lens, for example in cataract.
指数；增加折射指数，即晶状体的光弯曲或聚焦能力，例如白内障。
Positional; anterior displacement of lens E.G. after trauma.
位置；例如外伤后晶状体前移。
This again causes light rays to be focused in front of retina.
会再次导致光线聚焦在视网膜前面。
Types
类型
Congenital : from birth.
1.先天的：从出生开始就近视。
Simple: most common, starts from 5-10 years till 15-20 years and is mostly due to curvature or length problem of eyeball.
普通的：最常见的，从5-10岁开始到15-20岁，主要是由于眼球弯曲或长度问题。
Pathological: hereditary, progressive and is due to degenerative changes in the eyes.
病理性：遗传性的，渐进性的，是由于眼睛的退行性变化引起的。
