Cataract surgery is the removal of the natural lens of the eye 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. Many patients' first symptoms are strong glare from lights and small light sources at night, along with reduced acuity at low light levels. During cataract surgery, a patient's cloudy natural cataract lens is removed and replaced with a synthetic lens to restore the lens's transparency.

Following surgical removal of the natural lens, an artificial intraocular lens implant is inserted. Cataract surgery is generally performed by an ophthalmologist in an ambulatory setting, in a eye care center or hospital, using local anesthesia usually causing little or no discomfort to the patient.

The surgical process of cataract removal involves microscopic extraction of the cloudy lens while the eye is in its normal position. The eye is not removed during cataract surgery. Once the opacity has been removed an artificial lens may be inserted in the lens capsule from where the opacity was removed. If the intraocular lens is not inserted, then soon after surgery they fit for a special contact lens which the patient will be trained how to care for, or glasses will be dispensed. Cataract extraction of the pediatric age group is a complicated surgical procedure involving specialized planning pre-operatively, complex intra-operative skill and post-operative care.