Flying mosquitoes, the cause of which is vitreous turbidity. Vitreous turbidity is a common clinical ophthalmic condition. Vitreous clouding, divided into two categories: physiological and pathological. In general, the former has little impact on visual function, good prognosis, no need for treatment; the latter seriously affects vision, poor prognosis, the need for treatment. Physiological clouding, mainly occurs in high myopia and the elderly. The cause is physiological degenerative changes in the vitreous humor, and the physical and chemical properties of the vitreous humor become liquefied and cloudy due to aging. The manifestation is: varying degrees of sensation of dark shadows floating in front of the eyes, flying mosquito-like, thread and coil-like, water ripple-like, etc., generally does not affect vision. It does not require treatment. Although there are eye drops or oral medications to treat physiological vitreous clouding, the physical and chemical changes in the vitreous body due to aging are completely irreversible. Therefore, it cannot be called “curable”. The recent vitreous laser treatment can break up large pieces of cloudiness and make the patient’s miosis disappear. Pathological clouding, the main causes are: uveitis, infectious endophthalmitis, acute retinal necrosis due to viral infection, diabetic retinopathy and retinal vascular obstructive disease resulting in vitreous blood, posterior vitreous detachment, retinal detachment, ocular trauma and intraocular foreign bodies. All of these conditions can seriously affect vision. Treatment must address the cause and be aggressive with different medications or surgery. After treatment, vitreous turbidity can be reduced, but most patients will still be left with some cloudiness that cannot be completely absorbed. However, since there is no single treatment option for vitreous turbidity that can reach the point where it can be cured, all that can be said now is that the best results are possible when treatment is given as early as possible, for which dynamic monitoring is needed.