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Fundamentals of Clinical Ophthalmology Cataract Surgery - part 4

Hydrodissection tốt là cần thiết và thích hầu hết các kỹ thuật cắt, hydrodelamination là có lợi. Nagahara chop sử dụng 0-15 ° PHACO đầu và chân không cao. Một nổ ngắn của siêu âm là lần đầu tiên được sử dụng để đâm và kiểu cầm vợt hạt nhân (hình 5.16a). Ống kính sau đó rút ra một chút đối với bác sĩ phẫu thuật | PHACOEMULSIFICATION TECHNIQUE b Figure 5.15 The Bowl technique . a Debulking the nucleus to create a bowl. b Removal of the bowl. Chopping techniques Nagahara chop horizontal chopping Nagahara15 was the first to report nuclear disassembly using chopping and described a technique that does not require sculpting. This is therefore also known as non-stop chop or pure chop . Because the chopper passes from the periphery toward the centre of the lens it is classified as a type of horizontal chopping technique. Good hydrodissection is required and like for most chopping techniques hydrodelamination is beneficial. Nagahara chop employs a 0-15 phaco tip and high vacuum. A short burst of ultrasound is first used to impale and grip the nucleus Figure 5.16a . The lens is then drawn slightly toward the surgeon as the chopper is inserted under the rhexis edge and around the periphery of the nucleus. The chopper is next pulled through the lens toward the phaco tip Figure 5.16b . Just before contact between the two instruments is made they are slightly separated to propagate a fracture through the entire lens Figure 5.16c . The lens-nucleus complex is next rotated approximately 30 clockwise in the case of a surgeon holding the phaco hand piece in his right hand reimpaled by the phaco probe and chopped in the same manner Figure 5.16d . A small wedge-shaped segment of nucleus held by the phaco probe is thus broken off the main nucleus. By maintaining high vacuum this is then moved into the central safe zone of the capsular bag where it is phacoemulsified Figure 5.16e . The process is then repeated Figure 5.16f until the entire nucleus is removed. Quick chop vertical chopping This differs from the technique described by Nagahara by using a modified chopper to penetrate the nucleus vertically while it is held by the phaco probe Figure 5.17a . Upward force simultaneously applied to the lens by the probe results in shearing forces that create a fracture Figure 5.17b . This fracture is