The contents of the human eye, which plays a supporting role in the structure is called the vitreous body, the transparent vitreous body with cloudy material can be manifested as mosquitoes, clinically known as vitreous turbidity. Minor vitreous turbidity does not affect the life and vision, serious cases can cause vision loss, a large number of vitreous accumulation of blood vision can be reduced to the front of the manual. (1) Physiological vitreous clouding: often due to congenital or age-related changes in vitreous metabolism, resulting in metabolized cells or metabolites floating in the vitreous, this type of vitreous clouding usually has little impact on vision and life, patients complain of small floating black shadows in front of the eyes, no significant changes over time, may change position or disappear, such cases However, if there is a sudden increase in the number of small black shadows floating in front of the eyes, a feeling of flashing in front of the eyes, or a fixed black shadow obscuring the eyes, you should go to the hospital promptly. (2) Pathological vitreous clouding: this kind of vitreous clouding is mostly caused by inflammation or hemorrhage, which is manifested by floating black shadows in front of the eyes, such as filiform, dotted and blocky, and can gradually diffuse into a piece. If it is caused by inflammation, such as endophthalmitis, uveitis, retinitis, for inflammatory cells in the vitreous body into a group caused by the floating black shadow in front of the eyes; if it is caused by hemorrhage, such as diabetic retinopathy stage IV, retinal vein obstruction, retinal fissure, intraocular tumor hemorrhage, etc., can cause vitreous blood clouding, at first the hemorrhage manifested as ink scattered look, such as line floating, and later slowly diffuse to The entire vitreous cavity, manifested as blurred vision vision loss. In summary, mosquito flying is vitreous clouding, physiological vitreous clouding is a common sign, highly myopic eyes and older people are prone to appear, can be observed; pathological vitreous clouding exists in a variety of eye diseases, should be promptly to the hospital for treatment.