Because it's impossible to scrape clean the thin, extremely delicate capsule walls, the eye surgeon cuts a hole in the back of the
capsule, and makes a window which permits light to reach the
retina and via the
brain, which makes sense of the light it receives.
There are quite a few recent scientific papers noting that some patients, especially if they are youngish, have old lens cells that aggressively try to 'heal' the window made by the laser.