Constant tearing and stinging sensation in the eyes may be caused by foreign objects in the eyes, implanted eyelashes, eye inflammation and other factors. 1. Foreign body in the eye: In the case of foreign body in the eye, such as sand, dust and so on into the eye, it is easy to irritate the eye, and the problem of constant tearing and stinging sensation occurs. 2. Inverted eyelashes: When the eyelashes are inverted to the eyeball, it is easy to irritate the cornea and the conjunctiva, and then it is easy to have various problems such as eye stinging, tearing, eye redness, photophobia and so on. 3. Eye inflammation: In cases of eye inflammation, such as conjunctivitis and keratitis, irritation of the eye surface may also occur, resulting in constant tearing and stinging of the eyes. In cases where the discomfort persists and cannot be relieved, you should seek medical attention and standardize treatment under the guidance of a doctor.