The reason for this phenomenon may be keratitis, conjunctivitis, inverted eyelashes, dry eye, visual fatigue, astigmatism, astigmatism, foreign objects in the eyes, etc. The corneal epithelium is damaged due to various irritations, such as keratitis, conjunctivitis, and inverted eyelashes. Because of various stimuli, such as keratitis, conjunctivitis, inverted eyelashes, etc., resulting in corneal epithelium damage, will cause the corneal tissue within the sensory nerve fiber sensitivity increases, encounter sunlight and other bright light stimulation will trigger eye discomfort symptoms, the emergence of tears and reluctance to open the eyes of the manifestation of corneal irritation sign. The patient needs to go to the ophthalmology department of the hospital in time for examination, and the doctor will use the slit lamp microscope to examine and confirm whether there is keratitis, conjunctivitis, inverted eyelashes, etc. If there is, it should be treated. If there is, it is important to target treatment. Keratitis and conjunctivitis can be treated with antibacterial or antiviral eye drops under doctor’s supervision. Inverted eyelashes, depending on the cause and severity, can be treated with extraction or surgery. In addition to keratitis, conjunctivitis and impingement, there are other factors that may cause tearing and inability to open the eyes when seeing the sun, such as dry eye, visual fatigue, astigmatism, dilated pupils, and the presence of foreign objects in the eyes. If you have any of these symptoms, you should seek medical advice to find out the cause and follow the doctor’s instructions.