| Capsulorhexis ： ウィキペディア英語版|
Capsulorhexis is a technique used to remove the lens capsule during cataract surgery. The spelling has varied between having one or two 'r's. It generally refers to removal of a part of the anterior lens capsule, but in situations like a developmental cataract a part of the posterior capsule is also removed by a similar technique.
It is also termed ''Continuous Curvilinear Capsulorhexis (CCC), the term describing the exact surgical technique. Shear and stretch forces are used. Howard Gimbel was the pioneer in the technique.
In order to remove a cataract with modern techniques, the capsule of the lens must be opened. In older style surgery (intracapsular cataract extraction), the whole lens and capsule was removed. This was done to prevent the inflammatory response to leftover lens material. Since it was all removed en-bloc, there was no residual. With modern techniques, however, the removal of practically all the material can be achieved while leaving the intact capsule. This is important since it provides a barrier between the front and back of the eye, and prevents the vitreous from moving forwards. In addition, this allows the artificial intraocular lens an ideal place to be located in the eye, away from contact with other structures yet solidly held in place.
Prior to the advent of the CCC, a "can opener" approach was used, with a small bent needle making small incisions around the anterior surface of the lens, forming a somewhat continuous hole that the lens could be removed through. However, any of these ragged edges could promote a tear that could proceed outwards. A CCC when done correctly, does not have any edges, and any forces applied to the capsule during surgery are distributed and do not result in a tear.
The usual method is to use the same bent needle to begin a tear in the capsule, and then either guide the edge with the same needle around the anterior surface, or use a special forceps to do the same. There are advantages and disadvantages of both approaches, and most surgeons will use both instruments as the situation requires.
As noted in children, often an anterior and posterior capsulorhexis is made, since the posterior capsule becomes cloudy even more commonly in children than adults. Since a simple office procedure using a Nd:YAG laser commonly performed on adults is difficult with a child (since they cannot sit still at the machine), it is better to deal with the posterior capsule at the time of surgery. Since the vitreous in children is much more formed, the loss of vitreous is less common (since as a solid it stays put), though often an anterior vitrectomy is still performed.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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