Many friends will have this symptom, there are often dark spots or dark shadows fluttering in front of the eyes, sometimes more and sometimes less, some like mosquitoes, some like drizzle, circles, clouds, amoebas or spiders, especially in the light, monochrome background more obvious, these phenomena are collectively known as “flying mosquitoes”. Most of the flying mosquitoes are caused by vitreous liquefaction, myopia and elderly patients prone to appear. The normal vitreous humor of the human eye is a transparent gel, as we age, the vitreous humor will gradually liquefy, and in the intersection of gel and liquid, concentrated aggregation of gel will produce shadows projected on the retina, so the formation of mosquito symptoms. A small number of mosquitoes are caused by fundus lesions, such as retinal fissures, fundus hemorrhage, vitreous hemorrhage, retinal detachment and so on. It can be ruled out by dilated pupil examination of the fundus, especially triangulation and other examinations. In terms of treatment, physiological mosquitoes, no obvious abnormalities in the fundus, no special treatment. However, if the sudden appearance of flying mosquitoes, combined with a sense of flash, or systemic diseases (hypertension, diabetes, etc.), or a clear history of trauma, it is recommended to go to the hospital as soon as possible for a detailed examination of the fundus to avoid delay.