Glaucoma is now divided into three categories: primary glaucoma, which is divided into primary closed-angle glaucoma and primary open-angle glaucoma, and primary closed-angle glaucoma, which is divided into acute closed-angle glaucoma and chronic closed-angle glaucoma. Secondary glaucoma is mostly caused by various diseases of the eye, such as cataract secondary glaucoma, uveitis secondary glaucoma and retinal detachment secondary glaucoma. The main treatment for glaucoma is to lower the intraocular pressure through medication, surgery and other methods.