Contact lenses are attached to the surface of the cornea and are actually a foreign body, which may cause some problems if used improperly. It has the following disadvantages compared with frame glasses: 1. sometimes there may be a foreign body feeling. 2. 2, improper wearing such as unskilled operation, unsuitable lens tightness, overtime wearing, unhygienic, etc., may appear conjunctival and corneal damage, secondary inflammatory infection. In addition, there may be allergic reactions to the drug components of the care system or lens materials and denatured lens materials. 3, unless the ophthalmologist used for the treatment of certain eye diseases other than general refractive error patients with dry eyes or other eye diseases should not wear contact lenses. 4, eye secretions, poor environment such as sandy places and workplaces with volatile acids and bases, fumes, dusty places are not suitable for contact lens wear. 5, wear lenses before practice. 6, the usual lens maintenance more trouble. 7, the price is high.