Itchy eyes, especially upper eyelids, may be due to allergic reactions induced by pollen, dust and other stimuli, or due to conjunctivitis, blepharitis and other diseases. 1. Allergic reaction: Usually after contacting pollen, dust and other allergy-prone substances, patients may have an allergic reaction, which can be manifested as very itchy eyes, and some patients may also be accompanied by localized redness and swelling and other symptoms. 2. Conjunctivitis: the cause of the disease is more, may be due to immune lesions, microbial infections, etc., mostly related to not pay attention to personal hygiene, decreased immunity and other factors. Patients often appear conjunctival congestion, conjunctival secretion, papillary hyperplasia and other symptoms, inflammation involving the eyelids, can also appear very itchy eyes, especially the upper eyelid. 3. canthus blepharitis: often due to bacterial infection, occurring in the corner of the eye area, the patient consciously itchy eyes, foreign body sensation, burning sensation, accompanied by eyelid margins and corners of the skin of the eyelid congestion, swelling, and impregnation of the vesicles. It is recommended that the patient exists in the case of very itchy eyes, actively consult a doctor for examination, and after clarifying the cause of the disease, follow the doctor’s instructions for treatment.