In outpatient clinics, patients often tell their doctors that they have had cataract surgery and their vision has improved greatly. But after 1-2 weeks, but seems to find a small flying insects in front of the eyes, small cotton wool-like black dots or translucent “comma, question mark” in front of the eyes floating around, especially when you go out or look at the white wall more obvious, can not help but some worry. We are not too familiar with “flying mosquitoes”, it is more common in the middle-aged and elderly degenerative changes in the vitreous, sometimes myopic young people will also appear. Many people may have had more or less feel, there will be small flying insects in front of the eyes occasionally sense, the general public will not be too nervous. However, after cataract surgery, patients will feel a little worried, as if before the surgery, but do not feel much flying mosquitoes, how to do the surgery but obvious, will it be cataract surgery did not do clean ah? We all have such experience in life, when the bright sun shines into the clean window, we can see the dense dust along the beam, but in the dim place or in the room with the window screen we can not see these tiny particles at all. Cataracts are like a veil over a vitreous window, blocking light from entering the eye. After the cataract is removed and replaced with a clear IOL, the light passes through the pupil and the IOL and reaches the retina at the bottom of the eye, and some of the “flying mosquitoes” in the vitreous body are clearly perceived. Therefore, it is our eyes that are more sensitive to these subtle changes after surgery. Usually for ordinary elderly cataract patients, some small floating mosquitoes in front of the eyes after surgery, generally will not affect the vision, in the post-operative recovery period to avoid heavy physical activity, breath holding, long time low reading, etc., will gradually adapt to improve. However, if some of the following situations occur, you should go to the hospital in time: the black shadow gradually becomes deeper and larger or fixed, the visual field appears defective or lines bent and deformed, combined with frequent flashing sensation in front of the eyes, sudden loss of vision, etc., that may be some other fundus problems. Especially for patients with diabetes, high myopia and other patients who originally have some systemic or fundus problems, special attention should be paid to post-operative rest and care. It is best to review the fundus regularly after surgery to exclude possible potential fundus lesions, vitreous hemorrhage, retinal fissure detachment, etc.