Cataract surgery is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision. In addition to these age-related changes, infants may be born with congenital cataracts, and certain environmental factors may also lead to cataract formation. Early symptoms may include strong glare from lights and small light sources at night, and reduced acuity at low light levels.
During cataract surgery, a patient's cloudy natural cataract lens is removed, either by emulsification in place or by cutting it out. An artificial intraocular lens (IOL) implant is inserted (eye surgeons say that the lens is "implanted") in its place. Cataract surgery is generally performed by an ophthalmologist in an ambulatory setting rather than an inpatient setting, in a surgical center or hospital. Either topical, peribulbar, or retrobulbar local anesthesia is used, usually causing little or no discomfort to the patient.
Well over 90% of operations are successful in restoring useful vision, with a low complication rate. Day care, high volume, minimally invasive, small incision phacoemulsification with quick post-op recovery has become the standard of care in cataract surgery all over the world.