Swollen and painful eyes are mostly caused by eye diseases, such as conjunctivitis, keratitis, scleritis, glaucoma and so on. 1. Conjunctivitis: when the conjunctiva is allergic or infected by bacteria and other pathogens, inflammatory cells infiltrate and destroy normal cells, resulting in swelling of the eyes, which is often accompanied by increased eye secretions and conjunctival congestion. 2. Keratitis: various causes of corneal inflammation reaction, inflammation leads to local tissue degeneration, necrosis, exudation, resulting in eye swelling and pain, accompanied by tearing, blepharospasm and so on. 3. Scleritis: mainly caused by endogenous antigen-antibody-immunocomplexes, starting with redness of the eyes and loss of vision, due to the destruction of inflammatory cells, swelling and pain of the eyes can occur. 4. Glaucoma: it is mainly seen in closed-angle glaucoma, when the intraocular pressure rises, because the aqueous humor can not be discharged in time, it will lead to swelling and pain in the eyes, accompanied by photophobia, tearing, headache and so on. When there is swelling and pain in the eyes, it is recommended to go to the ophthalmology department of the hospital in time, so as not to cause progressive damage to the eyes or eye muscles.