1, the eyeball consists of the eyeball wall and eyeball contents. The eye wall (except the anterior cornea) can be divided into three layers, the outer layer is fibrous membrane, the middle layer is uvea, and the inner layer is retina. The contents of the eyeball, including aqueous humor, lens and vitreous body, are the channels through which light enters the eye and reaches the retina. Together with cornea, they are called refractive media of eyes.

2. Puppy's reflected light-refractive medium of eyes-retina-optic nerve-optic chiasma-optic bundle-lateral geniculate body-optic radiation-occipital lobe optic center When you get here, your brain will see the puppy.

3. Myopia In a relaxed state, parallel light passes through the refractive system of the eyeball and focuses on the retina, which is called myopia. Anatomically speaking, myopia can be divided into:

1) refractive myopia: mainly due to the excessive curvature of cornea or lens, the refractive power is beyond the normal range, while the axial length is within the normal range;

2) Axial myopia: the axial length is beyond the normal range, and the curvature of cornea and lens is within the normal range.

4. Presbyopia With the increase of age, the lens gradually hardens, the elasticity is weakened, and the function of ciliary muscle is gradually reduced, resulting in the gradual decline of the adjustment function of the eye. This weakening of physiological regulation caused by age is called presbyopia, which is commonly called presbyopia.