Floaters include physiological floaters, denatured floaters and pathological floaters. Physiological floaters account for 20%, mostly young people under 40 years old. This is due to the projection of embryonic cell fibers or red blood cells in retinal blood vessels remaining in vitreous body on retina. Denatured floaters account for 75%, mostly in people over 40 years old. With the increase of age, the vitreous body is liquefied and turbid, and then detached. The rest belong to pathological floaters, such as retinal breaks, peripheral retinal degeneration, fundus hemorrhagic diseases, uveitis and other vitreous opacity.