As a potentially new form of refractive surgery, corneal inlays and onlays are special. Like LASIK and PRK, corneal inlays and onlays alter the way light rays enter the eye. However, they are different from contact lenses, which require regular removal and lens care. Corneal inlays and onlays are permanently inserted into the eye and seamlessly merge with the eye’s surface.

Before the 1950s, there were only eyeglasses for refractive vision correction. Nowadays, there are still contacts lenses and other surgeries that are used to correct refractive errors. Refractive surgeries including LASIK and PRK use laser energy to reshape the curvature of the cornea, while artificial lenses perform in refocusing light rays.