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视力,是指人的视觉器官对周围环境物体形态的精细辨别能力。人的眼睛是一个精密的光学系统,有人将其比作一部照相机,这再好不过了。人之所以能看见物体,是由于外界物体的光线通过眼的角膜、房水、晶状体、玻璃体等折光调节装置的作用,使光点落在视网膜上,引起视网膜感光细胞兴奋,产生视觉冲动,再沿视觉神经传导道,传入大脑皮层中枢引起视觉。视网膜内有两种感光细胞。一种是视锥细胞,主要分布在视网膜中心凹的部分,对白天视物时起作用,医学上习惯称为中心视力;另一种是视杆细胞,分布在离中心凹10
Vision, refers to the human visual organs on the surrounding objects fine shape recognition ability. The human eye is a sophisticated optical system, some people likened to a camera, this is no better. The reason why people can see the object is due to the light from the outside world through the cornea of the eye, aqueous humor, lens, vitreous and other refractive adjustment device, the light spot on the retina, causing retinal photoreceptor cells excited, resulting in visual impulses, and then Along the optic nerve conduction pathway, the introduction of cerebral cortex central vision. There are two types of photoreceptor cells in the retina. One is the cones, mainly distributed in the fovea part of the retina, as the daytime play a role, the medical habit known as the central vision; the other is rod cells, located in the fovea 10