(20 13? According to the survey, the incidence of myopia in China ranks second in the world, especially in recent years, myopia is getting younger and younger, and it is on the rise year by year.

(1). In the process of eyeball imaging, lens 2 and vitreous body refract light, among which lens 2 is the main one, and lens has adjustment function, so we can see objects at different distances by adjusting the curvature of lens.

(2) Only when the object falls on the retina can we see the object clearly. As shown in the figure, if the curvature of the lens is too large, the object will fall in front of the retina, and the distant object cannot be seen clearly, thus forming myopia, which can be corrected by glasses equipped with concave lenses.

(3) The process of vision formation is that the light reflected by external objects passes through 1 cornea and aqueous humor, enters the eyeball from the pupil, and then refracts through the second lens and vitreous body to form a clear object image on the third retina. The image of the object stimulates the photoreceptor cells on the third retina, and the nerve impulses generated by these photoreceptor cells travel along the optic nerve to the visual center of the cerebral cortex, thus forming vision; From the process of visual formation, we can know that someone's eyeball structure is complete, but he can't see the surrounding objects, so the lesion may be the posterior optic nerve or the visual center.

(4) The driver stops when he sees a red light, which is a reaction of people to the stimulation of a specific signal (red light), with the participation of the cerebral cortex, which belongs to conditioned reflex, also called complex reflex.

So the answer is: (1)[2] lens [2] [3] retina? Concave? (3) Optic nerve or visual center? (4) conditions? cerebral cortex