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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. 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.〔''U.S. News and World Report'', December 17, 2007, page 64.〕 Following surgical removal of the natural lens, an artificial intraocular lens implant is inserted (eye surgeons say that the lens is "implanted"). Cataract surgery is generally performed by an ophthalmologist (eye surgeon) in an ambulatory (rather than inpatient) setting, in a surgical center or hospital, using local anesthesia (either topical, peribulbar, or retrobulbar), 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.〔University of Illinois Eye Center. ("Cataracts." ) Retrieved August 18, 2006.〕 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. ==Types== Two main types of surgical procedures are in common use throughout the world. The first procedure is phacoemulsification (phaco) and the second involves two different types of extracapsular cataract extraction (ECCE). In most surgeries an intraocular lens is inserted. Foldable lenses are generally used for the 2-3mm phaco incision, while non-foldable lenses are placed through the larger extracapsular incision. The small incision size used in phacoemulsification (2-3mm) often allows "sutureless" incision closure. ECCE utilises a larger incision (10-12mm) and therefore usually requires stitching, and this in part led to the modification of ECCE known as manual small incision cataract surgery (MSICS). Cataract extraction using intracapsular cataract extraction (ICCE) has been superseded by phaco & ECCE, and is rarely performed. Phacoemulsification is the most commonly performed cataract procedure in the developed world. However, the high cost of a phacoemulsification machine and of the associated disposable equipment means that ECCE and MSICS remain the most commonly performed procedure in developing countries. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cataract surgery」の詳細全文を読む スポンサード リンク
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