For anyone undergoing lens surgery, the risk of PCO is unavoidable. In lens surgery, the eyes natural lens must be removed from the lens capsule (think of it as a tiny bag in which the lens lives) and is then replaced with an artificial lens. This initially restores high visual quality but unfortunately, in a small proportion of patients a regrowth of cells takes place on the back of the capsule which obscures light from entering the eye causing vision to appear cloudy again.