Pain in one eye may be related to conjunctivitis, glaucoma, keratitis and so on. 1. Conjunctivitis: including bacterial, viral, allergic conjunctivitis, patients usually manifested as conjunctival congestion, increased secretion, eye pain, and so on. 2. Glaucoma: eye pain with obvious vision loss, headache on the same side, more serious. 3. Keratitis: it contains many kinds, including bacterial keratitis, viral keratitis, fungal keratitis, etc. It can manifest as photophobia, pain, tearing and other symptoms in one eye. During the treatment period, you should eat a light diet, do not eat stimulating, spicy food, pay attention to eye hygiene. It is recommended to go to the hospital in time to find out the cause of the disease, and under the guidance of the doctor to give the corresponding treatment and treatment.