What is the cause of eye itching?

Eye pain and itching are normally caused by the following reasons: 1. It is caused by allergic conjunctivitis, that is, the conjunctival tissue of the eye surface contacts allergens such as pollen, dust and smoke suspended in the air, causing allergic reactions. 2. It is caused by mild keratitis. In the early stage of keratitis, normal eye pain symptoms are not particularly obvious, mainly manifested as mild itching and pain. 3. It is caused by sty, which is the itching of eyelid parts, mainly due to lack of attention to eye hygiene, causing bacterial infection of meibomian glands inside eyelids.