Often encounter such a number of elderly patients, their complaints are a hair or a small insect or a gray cloud and other things floating in front of their eyes, lingering, wipe it off, it is very uncomfortable, and suspect that they have cataracts or glaucoma and other diseases and feel very nervous. In fact, most of this phenomenon is called a “vitreous liquefaction” of the lesion caused by, commonly known as “mosquito flying”. The 4/5 space at the back of the human eye is filled with a substance called vitreous humor. Under normal conditions, the vitreous is gel-like, colorless and transparent, formed by the collagen scaffold and intertwined with the hyaluronic acid molecules, 99% of which is water, external things need to pass through it in the retina imaging. When the vitreous gel state is disrupted and becomes liquid, this is vitreous liquefaction. When some cells around the vitreous tissue detach, in the liquefied cavity to form some white cloudy dots or membranous material; or due to the vitreous liquefaction so that the formation of posterior detachment of posterior fissure, can lead to a reduction in internal transparency, if the cloudy material or posterior fissure is located in the light pathway, it will make a person appear some flying black shadow. Flying mosquitoes should belong to the physiological lesions, mostly seen in myopic eyes (mainly highly myopic) and the elderly, here we mainly talk about the elderly flying mosquitoes. Flying mosquitoes in the elderly usually occurs after the age of 40, the main manifestations are: the eye such as hair, gray clouds, small circles, mosquitoes, flies, small black dots, lines and even a picture and other black shadow, sometimes accompanied by a sense of flash, can not be erased or erased, the eye itself no pain, no red, does not affect vision. The most important feature is that these black shadows will float and generally move with the rotation of the eye, and the position is relatively fixed, but the number is small and faint. The development of the lesions is also more stable, with no significant changes over time, more pronounced in sunlight or bright environments, and fading at night or in the room. For this kind of disease, generally do not need to feel very nervous, usually can pay attention to rest, avoid excessive use of eyes, strain, carrying heavy objects, suffer trauma, etc.. Especially for the elderly, try not to read books, newspapers, TV, mahjong, etc. for a long time, and sleep well at night. Most people can improve their symptoms or even disappear through these methods, but there are some people who have no significant changes. Here especially to emphasize the attention is, for the first time such symptoms or more serious patients must go to the hospital to ask the doctor dilated pupil examination to clarify the diagnosis, to exclude retinal fissure, vitreous hemorrhage and other diseases. If you find a significant increase in “flying mosquitoes” in front of the eyes or a thick fixed black shadow covering the field of vision, and affect vision, blurred vision, you must go to the hospital in a timely manner, because that is mostly caused by fundus hemorrhage or retinal detachment, must be treated in a timely manner, otherwise there will be a risk of blindness.