Redness of the eyes on the 20th day after cataract surgery needs to be examined in the ophthalmology department of the hospital in time to clarify the cause of the disease and take targeted treatment according to different causes, common causes include conjunctivitis, subconjunctival hemorrhage and so on. About 20 days after cataract surgery, the redness of the eyes caused by the surgery has usually subsided, and the redness of the eyes should be examined in time. Conjunctivitis: Inflammation can cause eye redness. Conjunctivitis caused by cataract surgery is mainly a bacterial infection, which can be treated with antibiotic eye drops to eliminate the infection, commonly used are levofloxacin eye drops, tobramycin eye drops, moxifloxacin eye drops and so on. The medication should be used according to the doctor’s prescription. Subconjunctival hemorrhage: Bleeding can cause the eye to turn red, cold compresses are needed in the early stage, and after two days, warm towels can be used on the eye for hot compresses to promote the absorption of bleeding. There are many reasons for the redness of the eyes on the 20th day after cataract surgery, so you should improve the examination and carry out targeted treatment under the guidance of your doctor.