Contact lenses are synthetic corneal contact lenses made of artificial materials that snap on top of the cornea like a cap. Whether wearing contact lenses is harmful to the eyes depends on the time and method of wearing them, the quality of the contact lenses and daily care. If used correctly, they are generally not too harmful to the eyes; if used incorrectly, they may cause corneal infections, corneal ulcers and other undesirable symptoms.1. Time of use: Ophthalmologists recommend that the time spent wearing contact lenses should not add up to more than 10 hours a day. Some people forget to take them off after use, or directly wear contact lenses to sleep, seriously exceeding the required wearing time, easily affecting the permeability of the cornea, which in turn makes the cornea hypoxic. In the long run, it may adversely affect the health of the cornea, and in serious cases even cause corneal inflammation, ulcers, etc.; 2, use method: when wearing contact lenses, the technique needs to be as gentle as possible, not forcefully touch the eye or strong yank down, otherwise it will hurt the epithelial cells of the cornea; 3, contact lens quality: be sure to wear regular manufacturers of contact lenses, if the contact lens material is inferior, poor oxygen permeability. Will affect the physiological health of the cornea, and even lead to allergies; 4, daily care: when wearing contact lenses, try to use professional tools, if you can not guarantee the tools and hand hygiene, bacteria will enter the eye to cause inflammation. People who are used to wearing contact lenses by hand, pay attention to the cleanliness and hygiene of the hands. In addition to daily disposable contact lenses, other types of contact lenses should be soaked and disinfected daily and replaced regularly as required to protect eye health.