Whether it is endothelial transplantation or penetrating transplantation, postoperative eye drops are inevitable. Some patients use certain eye drops for a long time because they feel their eyes are cool and comfortable; some patients feel more irritated after using certain eye drops or stop using them after their eyes have recovered well for a period of time. These are all wrong behaviors, which may bring very serious consequences. Commonly used these types of eye drops with the wrong time, in the end, what are the hazards? We reveal one by one. Antibiotic eye drops – with a long time will be resistant Antibiotic eye drops are mainly used for anti-inflammatory and antibacterial. In general, between two or three weeks and one month after surgery is the healing time of the wound, so antibiotic eye drops can generally be stopped after one month of drops. If patients stop taking the drops within two weeks, they will increase the risk of endophthalmitis infection. Conversely, if the drops are left on for too long they may cause bacteria to become resistant and the antibiotics will be ineffective when the infection actually occurs. In addition, eye drops contain preservatives, which can open the connection between the cells on the surface of the eye, allowing better penetration and absorption of the drug; however, at the same time, they can damage the epithelium of the eye surface and cause dry eye symptoms. Hormonal eye drops – sudden discontinuation may induce rejection Hormonal eye drops are used to combat rejection and generally need to be used for about a year. Because of their side effects, doctors will adjust the dosage or change the medication depending on how high the patient’s eye pressure is and how irritating it is. Many patients are afraid of side effects and stop using hormones as soon as their symptoms get better, which is especially likely to induce rejection reactions. The patient’s body and the foreign transplant piece are like two hostile nations, with their own immune systems and hormones being the soldiers on the battlefield, and it is difficult to distinguish between the two under normal circumstances. If the hormones are suddenly withdrawn, then there is a risk of inducing a rejection reaction and causing the surgery to fail. Cyclosporine eye drops – long-term use under the guidance of a doctor Cyclosporine eye drops are immunosuppressive and are basically similar to hormones in usage. They are usually used beyond one year. If the patient is not allergic to cyclosporine and the graft fits well with the corneal stroma, the hormone will be gradually stopped, but cyclosporine will not be stopped and will continue to be used in small amounts to maintain the efficacy. Usually once a day drops are used, and there is not much harm in long-term use. Moreover, cyclosporine can play a role in relieving dry eyes after corneal endothelial transplantation, and also has a certain inhibitory effect on ocular surface inflammation. Most patients can discontinue the drug after one year, but for combined surgery, or for patients at high risk of rejection, once-daily eye dosing may be required to maintain the eye for two years or more. Artificial tears – repairing the corneal epithelial layer, the role of artificial tears should not be underestimated Artificial tears are used for a long time after corneal transplantation, usually after one year when the patient recovers better, they will be replaced with a less viscous artificial tear solution. Because the surgery only replaces the endothelial and posterior elastic layers, but the anterior surface of the cornea is not replaced for a short period of time. This means that the patient’s original symptoms, discomfort and vision problems remain, such as large epithelial blisters. The artificial tears will promote the repair of the corneal epithelium, improve the discomfort caused by large corneal blisters, and relieve dry eyes. In addition, after corneal transplantation, the state of the eye surface is also unhealthy, and long-term drops containing preservatives can also cause some damage to the epithelium. Artificial tears allow the eye surface to slowly repair in a relatively safe environment. Originally, the cornea is an immune “pardon zone” and it is difficult for the body to detect foreign transplants. However, when some patients stop using artificial tears on their own in later stages, the epithelium is unprotected and the eye becomes susceptible to bacteria and other attacks. When the epithelial problem reaches a certain level, the body receives a request for help from the epithelial layer, initiating functions such as repair and clearing inflammation, and the entire immune system is mobilized. In this way, foreign transplanted pieces are more easily detected, increasing the risk of rejection. In addition, because of the lack of attention to ocular surface protection in the case of immunosuppression, there is a high risk of infection by pathogenic microorganisms if the epithelium is left in a long-term patchy defect caused by dry eyes. Therefore, the role of artificial tears should not be underestimated and the use of artificial tears should be taken seriously.