The black bright spot fluttering in the eye may be caused by mosquito, conjunctival nevus, vitreous clouding and so on. 1. Mosquitoes: when affected by vitreous liquefaction, posterior detachment, vitreous blood accumulation, vitreous inflammation and other factors, it will lead to the patient’s eyes with black bright spot fluttering, accompanied by blurred vision, eye pain, tearing and other symptoms. 2. Conjunctival nevus: If affected by ultraviolet radiation, trauma, heredity, drugs, hormone levels, immunosuppression and other factors, it will cause the eyes to have black bright spots floating. 3. Vitreous clouding: this disease is mainly related to vitreous degeneration, vitreous detachment, inflammation, hemorrhage and other factors, opaque material appears in the vitreous body of the eye, there are black dots or black bars floating in front of the eyes, and severe patients will have a loss of vision. It is recommended to go to the regular hospital in a timely manner, under the diagnosis of the doctor, according to the patient’s specific condition, to take targeted treatment, life need to pay attention to protection, to ensure adequate sleep, avoid staying up all night.