Capsulorhexis
Encyclopedia
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.
Cataract surgery
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...
. The spelling has varied between having one or two 'r's. It generally refers to removal of a part of the anterior lens capsule
Lens capsule
The lens capsule is a component of the eye. It is a clear, membrane-like structure that is quite elastic, a quality that keeps it under constant tension. As a result, the lens naturally tends towards a rounder or more globular configuration, a shape it must assume for the eye to focus at a near...
, but in situations like a developmental cataract
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
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
Shear stress
A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...
and stretch forces are used. Howard Gimbel
Howard Gimbel
Howard V. Gimbel, MD, MPH, FRCSC, AOE, FACS, CABES, is a Canadian ophthalmologist, university professor, senior editor, and amateur musician. He is better known for his invention, along with Thomas Neuhann, of the continuous curvilinear capsulorhexis , a technique employed in modern cataract...
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
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
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
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
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
Forceps
Forceps or forcipes are a handheld, hinged instrument used for grasping and holding objects. Forceps are used when fingers are too large to grasp small objects or when many objects need to be held at one time while the hands are used to perform a task. The term 'forceps' is used almost exclusively...
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
Nd:YAG laser
Nd:YAG is a crystal that is used as a lasing medium for solid-state lasers. The dopant, triply ionized neodymium, typically replaces yttrium in the crystal structure of the yttrium aluminium garnet , since they are of similar size...
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
Vitrectomy
Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous from the front structures of the eye—often because these are tangled in an intraocular lens or other structures...
is still performed.