Cataract surgery involves the surgical removal of the lens of an eye that has formed a cataract. Cataract extraction is the one of the most common eye surgeries performed and is widely regarded as being one of the safest procedures in the medical community. A cataract occurs when the crystalline lens of the eye becomes cloudy or opaque as a result of age, illness, or trauma. This cloudiness can interfere with the eyes natural ability to direct light and focus an image on the retina. As a result, individuals with cataracts frequently experience a loss of vision.

There is no known way to reverse the damage caused by cataracts, although the complete removal and replacement of the affected lens with an artificial lens can restore an individuals vision. The two most common procedures for cataract extraction are called ICCE (intracapsular cataract extraction) and ECCE (extracapsular cataract extraction). Both of these procedures are typically done under a local anesthetic on an out-patient basis, so cataract surgery patients are free to go home the same day.

Extra-capsular surgery involves the removal of the affected lens while leaving the majority of the elastic lens capsule intact. This allows for the direct implantation of an intraocular lens into the lens capsule. Extracapsular surgery may be performed using one of two methods: conventional ECCE or phacoemulsification. Conventional ECCE involves making a small incision into the cornea or the sclera of the eye. The cataract is then manually removed through the incision so that a replacement intraocular lens can be inserted. Conventional ECCE is best suited for those patients who suffer from very hard cataracts or who have a weak or thin epithelium covering the cornea.

The second method, phacoemulsification, makes use of an ultrasonic handpiece. Ultrasound waves vibrate the cataract, causing it to shatter and break up into a number of small pieces. These pieces are then removed through aspiration via a small incision in the cornea, after which a replacement intraocular lens can be inserted. Phacoemulsification uses a much smaller incision and may not even require stitches, with the result that this procedure often affords patients a shorter recovery period.

Intra-capsular surgery involves the removal of the entire lens of the eye including the lens capsule. This procedure was commonplace up until the 1980s in the United States, but is rarely performed today due to medical advances in cataract surgery. To extract the lens the surgeon makes a large incision in the cornea and injects medicine into the eye. This causes the zonular fibers that hold the lens in position to break apart and dissolve. A small probe is inserted into the incision and placed on the lens so that it may be frozen via a cryogenic solution, such as liquid nitrogen. The probe is then withdrawn from the eye, pulling with it the frozen lens. Once the affected lens has been removed, an intraocular lens implant may be inserted in front of the iris as a replacement. Finally the incision is stitched up.

Intra-capsular surgery has a high risk of complications due to the pressure that is placed on the vitreous body of the eye during the procedure. Patients have a prolonged period of healing (up to 6 weeks), and are at a high risk for retinal detachment and swelling of the eye. It is for this reason that nearly all modern cataract extractions are performed via the extracapsular surgery method.