The first is vitreous disease such as vitreous opacity or vitreous hemosiderosis; the second is fundus disease such as retinopathy or macular degeneration. After this symptom appears, the first thing to do is to go to the hospital to improve the fundus examination, the treatment method and the prognosis of the disease are different. If it is physiological vitreous clouding, generally do not need treatment, this condition is also called mosquitoes; if it is vitreous blood, need to find the specific cause, generally seen in the fundus hemorrhagic diseases, such as retinal vein obstruction, diabetic retinopathy, these diseases need to give symptomatic treatment according to the specific condition, to avoid further aggravation, if the bleeding is more need to perform surgery.