Patient: “Doctor, my right eye is suddenly red in front of my eyes, like it’s blocked by a red cloth, what’s going on?” Ophthalmologist: “Let’s see …… you have a vitreous humor.” Vitreous humor, is the eye colorless transparent jelly-like tissue, located between the lens and retina, supporting the eye wall and retina, and as refractive interstitial involved in the process of visual formation, when the vitreous humor liquefaction turbidity will appear in our life often hear “mosquito”. The vitreous itself has no blood vessels, when the adjacent retina, uveal blood vessels or neovascular hemorrhage into the vitreous body will form the vitreous blood, the typical symptom is that there is a red shadow in front of the eyes, such as the red cloth in general, the accumulation of blood is less only appeared in front of the eyes of the shadows fluttering, similar to the “flying mosquito”, the accumulation of blood is more will cause obvious vision When there is more blood accumulation, it will cause obvious blurring of vision, loss of vision, and in severe cases, only the sense of light is left. There are many causes of vitreous hemorrhage, including fundus diseases, intraocular surgery, trauma, etc. Diabetic retinopathy is the most likely cause of vitreous hemorrhage among the fundus diseases, and there are also retinal vein obstruction, hypertensive fundus disease, retinal vein periphlebitis, retinopathy of prematurity, etc. which can also lead to vitreous hemorrhage. For vitreous hemorrhage, it is generally advocated to observe before surgery, that is to say, to observe for about 3 months, those who can self-absorb will not be operated, and will be given conservative treatment with medicines that can stop bleeding and promote blood absorption; those who have more blood accumulation and difficulty in absorbing it, and will be subjected to vitrectomy after 3 months of ineffective conservative treatment, so as to prevent vitreous blood from mechanically pulling the retina to form a hole and detachment. If you have a red eye, you should go to the ophthalmology department of the hospital in time to see if there is vitreous hemorrhage, and if it is diagnosed, then you will be treated accordingly, and you will have to have regular checkups under the guidance of the doctor to observe the changes of the blood. In addition, vitreous humor is often a secondary change of ophthalmic diseases and systemic diseases, the sudden appearance of vitreous humor suggests that there are likely to be other diseases, the need for a comprehensive examination, and for their own suffering from fundus diseases and high blood pressure, diabetes and other systemic diseases friends should pay more attention to the appearance of vitreous humor should be timely medical treatment, and active treatment, to prevent the aggravation of the blood accumulation, resulting in impaired vision.