The goal in modern cataract surgery is not only the removal of the cataract, but also the replacement of the cataract with an intraocular lens (IOL). The IOL is typically placed during the cataract surgery, and may be placed in the capsular bag as a posterior chamber lens (PCIOL), in the ciliary sulcus, as a sulcus lens, or in the anterior chamber anterior to the iris as an anterior chamber lens (ACIOL). There are multiple types of IOLs that may be used in modern cataract surgery, including monofocal, multifocal, accomodative, and astigmatism-correcting lenses. The goal of all IOLs is to improve vision and limit dependency upon spectacles or contact lenses.
Posterior capsular opacification, also known as after-cataract, is a condition in which months or years after successful cataract surgery, vision deteriorates or problems with glare and light scattering recur, usually due to thickening of the back or posterior capsule surrounding the implanted lens, so-called 'posterior lens capsule opacification'. Growth of natural lens cells remaining after the natural lens was removed may be the cause, and the younger the patient, the greater the chance of this occurring. Management involves cutting a small, circular area in the posterior capsule with targeted beams of energy from a laser, called Nd:YAG laser capsulotomy, after the type of laser used. The laser can be aimed very accurately, and the small part of the capsule which is cut falls harmlessly to the bottom of the inside of the eye. This procedure leaves sufficient capsule to hold the lens in place, but removes enough to allow light to pass directly through to the retina. Serious side effects are rare.  Posterior capsular opacification is common and occurs following up to one in four operations, but these rates are decreasing following the introduction of modern intraocular lenses together with a better understanding of the causes.