In the clinic, we encountered many patients, we all have a common confusion: like a small mosquito flying around in front of the eyes, hit and can not hit, drive also can not drive away, do not know what is going on. This is what people usually call mosquito flying syndrome. Flying mosquito phenomenon is very common in the clinic, it refers to the eye with the eye rotation of the small black shadow, its shape has a round, oval, dotted and linear, very similar to the mosquito, so named. When looking at the white or bright background, it is easier to find the presence of black shadow. Flying mosquitoes are often seen in middle-aged and elderly people over 40 years old, highly myopic patients and post-cataract surgery patients, other patients such as intraocular inflammation, etc., will also appear this phenomenon. In addition, normal people can also have a similar dark shadow floating in front of the eyes, sometimes can be seen with closed eyes, but objective examination can not detect any lesions, it is generally believed that this is due to vitreous residual embryonic cell fibers or retinal blood vessels in the retina projection of red blood cells. Before recognizing mosquito flying, we first understand the structure of the vitreous humor of the eye. The vitreous body is a colorless transparent gel, located behind the lens, filled in the lens and retina between, with refraction, fixed retina role. The vitreous body is not glass, it is a glass-like substance in the human eye, colorless and transparent, its main component is water, accounting for about 99% of the volume of the vitreous body. As we age, just as people develop gray hair, the vitreous body also “ages”, i.e., the vitreous body becomes degenerative, such as liquefaction, and the vitreous cavity becomes cloudy, which we call vitreous opacity, and sometimes can lead to separation of the vitreous body from the retina, which we call posterior vitreous detachment. It is these reasons lead to many patients appear in front of the eyes, many patients due to accidental or suddenly see the phenomenon of flying mosquitoes in front of the eyes, the shape can be various, some can be seen ring, round, filiform, etc., black spots appear more, feel more “scary”. However, most of this flying mosquitoes, we call these “good mosquitoes”, which is a normal physiological phenomenon, usually does not affect vision. People with high myopia, compared with people without myopia, earlier, a higher proportion of vitreous liquefaction, vitreous detachment, therefore, the phenomenon of mosquitoes in highly myopic people is a common phenomenon, most also belong to the “good mosquitoes”. Most of the mosquitoes belong to the normal physiological phenomenon, there is no special treatment, therefore, once the phenomenon of flying mosquitoes, do not be too nervous, can slowly adapt to these mosquitoes ignore, most of the flying mosquitoes will gradually reduce the phenomenon. In addition, in the early stage of the phenomenon of flying mosquitoes, especially with a sense of flash, it is recommended not to do strenuous sports, especially diving, bungee jumping and other sports, because strenuous sports will accelerate the vitreous detachment, and lead to retinal tear. General work and life activities are not a problem. In addition, there will be some “bad mosquitoes”, may seriously affect vision and lead to visual field defects, this situation and retinal fissures, retinal detachment and other diseases, if the short-term, flying mosquito phenomenon increasingly aggravated, especially with a significant sense of flash or visual field defects, or should go to the hospital for examination, need to dilate the pupil, detailed examination of the fundus, if necessary, can be supplemented by eye ultrasound. If necessary, it can be supplemented with eye ultrasound examination. After the examination, if the mosquito phenomenon is due to disease, then we should treat the disease. However, a normal examination does not mean that there is no problem in the future, once there is a sense of flash, flying mosquitoes suddenly increased and other phenomena, you need to go to the hospital again for examination.