The causes of secondary glaucoma are as follows: 1) inflammation caused by various reasons, such as uveitis, in which inflammatory cells in the eye block the atrial angle and obstruct the outflow of atrial fluid, causing an increase in intraocular pressure: 2) trauma may cause bleeding in the eye, and blood cells may also block the atrial angle and cause poor outflow of atrial fluid; 3) vascular diseases, such as diabetic retinopathy, venous embolism, and so on. This is because diabetic retinopathy or venous embolism can cause retinal ischemia and produce neovascularization, which can grow from the retina to the atrial angle, thus blocking the atrial angle and impeding the outflow of atrial fluid, which is also clinically known as neovascular glaucoma. 4. Other eye surgeries and occupational eye lesions can cause secondary glaucoma. The condition of secondary glaucoma is more complex and the prognosis is often worse.