A dark shadow floating in front of your eyes after cataract surgery? This is actually a sign of vitreous opacification, mainly due to vitreous liquefaction and posterior detachment. The symptoms are black fluttering shadows in front of the eyes, especially on a bright white background, and may be accompanied by a flashing sensation, commonly known as mosquito flying. The incidence of vitreous liquefaction increases with age and eye axis length, and posterior detachment occurs on top of liquefaction. Cataract surgery itself does not usually cause vitreous opacification. Before surgery, because of the cataract blockage, the flying mosquitoes can not be felt, after surgery the cloudy lens is removed, the lens after the vitreous clouding can be seen by the patient. So some patients after surgery “appear” in front of the black shadow or the original black shadow “increased”, in fact, not new or increased, but the original, but after surgery can be more sensitive to feel it.