See black dots flying in front of the eye, as if flying mosquitoes so named. Flying mosquitoes is intravitreal opaque object projection on the retina produced. In bright light or white background, more obvious. Sensitive people can even depict them in a variety of different shapes. Many mosquitoes exist for a long time, unchanged throughout the year, do not affect vision, after examination there is no ocular pathology, there is little clinical importance, no need to worry about. Some older people suddenly appear one or two black shadow in front of the eyes without other symptoms, often due to the vitreous membrane detachment, and generally not much harm. However, if a large number of black dots suddenly appear, one should think of retinal vascular rupture and bleeding or retinal fissure formation, which may be a precursor of retinal detachment, and further detailed examination of the fundus should be performed. Choroiditis when many sex-like cells or exudates can enter the vitreous, is also a common cause of pathological flying mosquitoes, but often because of the simultaneous presence of visual impairment and not easily detected. Myopic patients feel the flying mosquitoes, often related to the vitreous liquefaction degeneration.