Flying mosquitoes, also known as vitreous turbidity, can be divided into physiological and pathological two, physiological flying mosquitoes is congenital, people in the embryonic development of the eye vitreous cavity is vascular, after birth, the intravitreal vascular degeneration disappeared. However, some people’s blood vessels or blood cells did not completely degenerate, a little bit of residual, the formation of vitreous clouding. Pathological vitreous clouding is due to some lesions of the vitreous body, such as inflammation, trauma, vitreous hemorrhage caused by systemic diseases, high myopia, and various other causes. Physiological clouding does not require treatment. For pathological clouding, treatment should be given according to different causes. Mild clouding can be treated conservatively with medication, while severe clouding can be treated with vitrectomy.