Common systemic diseases and medications in the elderly: rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, dry syndrome, diabetes, allergic conjunctivitis, facial nerve palsy, hyperthyroidism, leprosy, antibiotics, anti-allergic drugs, antidepressants, atropine, antihistamines, antiarrhythmics, anesthetic drugs, hypertension drugs environment by airplane, use of air conditioning, smoke, ultraviolet light, air pollution, reduced humidity Occupational drivers, IT workers, frequent use of electronic products such as continuous viewing of computers, TV, cell phones, etc. Sleep deprivation. Ocular medical factors, local diseases of the eye: lid gland dysfunction, blepharitis, lid margin scarring, double row ciliary, trachoma, limbal keratitis, contact lenses long-term use of certain eye medications, diet, alcohol abuse, hormones, menopause, pregnancy, lactation and altered hormone levels in women on oral contraceptives. Categorized by population: common factors of dry eye in children and adolescents: excessive application of electronic products. Long-term continuous application of cell phone game consoles, watching TV. Allergic conjunctivitis. Common factors of dry eye in middle-aged and young people: staying up late, cell phones, electronic products, computers, etc. Common factors for dry eye in the elderly: after various eye surgeries, long-term oral administration of certain drugs, lid gland dysfunction, blepharospasm, conjunctival laxity, eyelid spasm, etc.