Corneal inlays and onlays are tiny lenses or other optical devices inserted into the cornea to reshape the front surface of the eye to improve vision. In fact, some of these devices resemble very small contact lenses.
The primary use of current corneal inlays (the term “corneal onlays” is used less frequently these days) is to improve near vision and reduce the need for reading glasses in older adults who have presbyopia.
In some cases, corneal inlay surgery can be combined with LASIK surgery to correct both presbyopia and common refractive errors (nearsightedness, farsightedness and/or astigmatism).
Because corneal inlays are implanted within the tissue of the cornea, this type of refractive surgery is less invasive than phakic IOL procedures that involve larger implantable lenses that are placed deeper in the eye, in front of or behind the pupil.
Through use of corneal inlays and onlays for vision correction, eye surgeons may avoid complications sometimes associated with procedures such as LASIK and PRK because no corneal tissue is removed. And these devices may have fewer risks than implantable lenses because the surgery takes place within the cornea, not inside the eye.