Red eyes may be caused by iritis, iridocyclitis, keratitis and so on. 1. Iritis: mainly caused by microbial infections such as bacterial, viral, fungal and other microorganisms, but also related to systemic immune diseases, which will lead to red eyes, accompanied by eye pain, photophobia, tearing, vision loss and other symptoms. 2. Iridocyclitis: If affected by trauma, surgery, infection, immunity, and some diseases, patients may have red eyes, accompanied by photophobia, pain, blurred vision, vision loss and other symptoms. 3. Keratitis: when the cornea’s defense ability is weakened, external pathogens or their own diseases and other factors will cause the emergence of such a situation, resulting in patients with red eyes, with sore throat, photophobia, tearing and other symptoms. It is recommended that patients go to the hospital in time and follow the doctor’s instructions for standardized treatment.