What is “Peeco”?

I once had a patient repeatedly ask about “peeco.” Initially, I did not understand what she was talking about, but then I realized that she was pronouncing the acronym “PCO.” PCO stands for Posterior Capsular Opacification. Well what the heck is that? When a cataract is removed surgically, we usually leave the capsule that contains the cataract in place. Then we place the lens implant into the capsule. The back of the capsule (the posterior part) is still in place after the cataract surgery. Sometimes, a few small cataract cells (microscopic cells that are left behind after the cataract surgery is performed) can grow across that back part of the capsule. When those cells grow, they form a membrane that blocks light. This opacification of the posterior capsule by the membrane often creates a big problem with vision. If this occurs, we can laser the posterior capsule to clear the opacity, which we do commonly.