For general keratitis and conjunctivitis, doctors will prescribe topical antibiotic eye drops or antiviral eye drops. Compared to systemic medications, eye drops have the advantages of being portable, acting directly on the lesion, and having few systemic side effects. After the disease is controlled, the number of eye drops should be gradually reduced until the disease is cured that is, to stop using drugs. But some patients can’t live without eye drops for a long time, always feel insecure about not dropping eye drops, fearing that they will get keratitis or conjunctivitis again, creating a dependency psychology. The actual fact is that any effective anti-infection drug has a certain degree of resistance, and when the eyes are resistant to the drug, if the cornea and conjunctiva are infected and inflamed again, the effect of similar eye drops will not be good. In addition, the ordinary eye drops, in the production process are added to a certain preservative to inhibit bacteria, so as to increase the stability of the drug, but the current common preservative inhibition ability is not strong, inhibition spectrum is not wide enough. Therefore, the general eye drops have a microbial contamination rate of 34.4% after 2 weeks of opening. And, the preservatives in eye drops, which have their own toxicity: 1, destroy the microvilli of the corneal epithelium, thus reducing the stability of the tear film; 2, have a similar effect on the lipid layer as a decontaminant, so that the evaporation of tears is accelerated; 3, indirectly destroy the stability of tears by reducing the density of conjunctival cup cells; 4, reduce the proliferation and vitality of corneal cells, so that the corneal epithelial barrier is damaged, delaying wound healing; 5 4. reduce the inflammatory reaction of the conjunctiva, squamous metaplasia and subconjunctival fibrosis. Patients who use eye drops for a long time, the eye is exposed to preservatives for a long time, and the balance of the eye surface is disrupted. It is important to know that antibiotic eye drops are not nutritional agents, unlike eye drops for cataracts. Therefore, once the eye has inflammation need to drop antibiotic eye drops, should try to choose the drug without preservatives or choose the drug containing low toxicity preservatives, decomposable preservatives, if the condition improves should gradually reduce the number of times a day use, until discontinued, should not be used for a long time.