If contacts are worn backwards, they will have a distinct foreign body sensation, slide around, follow blinks and not stay in place, or even crease or fall out. Because the edges of contact lenses that are worn backwards are curved up, they are obviously not fully attached to the surface of the eye, so if you look at the curvature of the edges a little closer before wearing them, you can basically tell if they are right or wrong. After all, contacts are a type of contact lens, and no matter how good the quality of the lens is and how high the oxygen permeability is, it directly impedes the contact between the cornea and the air, which hinders the cornea’s need for oxygen. If you don’t pay attention to personal hygiene, it’s easy to get a bacterial infection. Wearing contact lenses in an incorrect or unhygienic way or not taking them off for a long time can cause persistent corneal hypoxia and epithelial erosion, which, when combined with bacterial infection, can lead to keratitis or corneal ulcers. The most important issue in wearing contacts is to have good personal protection and control the length of time you wear them.