Continuous Curvilinear Capsulorrhexis
After the main incision has been made, the next step is to open the lens capsule. Opening the capsule with a continuous curvilinear capsulorrhexis (CCC) offers a number of advantages:
allows the surgeon to choose from a wide range of phacoemulsification techniques (Fig 8-9)
resists radial anterior capsule tears that could extend around and open the posterior capsule
stabilizes the lens nucleus, allowing maneuvers to disassemble it within the capsular bag (thereby reducing trauma to the corneal endothelium)
transfers haptic forces circumferentially and helps stabilize and center the lens implant
In addition, a CCC sized just smaller than the IOL optic may allow for tighter contact between the posterior surface of the posterior chamber IOL (PCIOL) and the posterior capsule, possibly reducing the incidence of posterior capsule opacification.
The surgeon begins a CCC with a central, radial cut in the anterior capsule using a cystotome needle or capsulorrhexis forceps with special tips for grasping and tearing. At the end of the radial cut, the needle is either pushed or pulled in the direction of the desired tear, allowing the anterior capsule to fold over on itself. The surgeon then engages the free edge with either forceps or the cystotome needle, and the flap is carried around in a circular manner (Video 8-1). For maximum control of the size of the CCC, frequent regrasping of the flap near the tear is helpful. An OVD may be added to keep the lens surface flat and reduce the likelihood of peripheral extension.
Figure 8-9 A capsulorrhexis is initiated with a puncture into the anterior capsule, which is then extended radially, and a flap turned over. A cystotome or forceps is then used to grasp this flap and tear circumferentially.
(Courtesy of Lisa Park, MD.)
Continuous curvilinear capsulorrhexis. Courtesy of Lisa Park, MD.
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If the capsulorrhexis tear is allowed to turn too far inward, it can result in a central opening that is too small. If the tear turns too far outward, it can result in an opening that is too large or to extension of the tear to the posterior capsule. An opening that is too small complicates most nucleus disassembly techniques and may contract postoperatively (capsular phimosis). A capsulorrhexis that is too large may allow the IOL optic or haptic to become decentered or dislocate anteriorly. For these reasons, many surgeons advocate a size that just allows the capsular rim to cover the optic edge for 360°. This technique has become increasingly important with the use of premium IOLs, which require a stable position within the eye for optimal refractive results.
If a CCC cannot be completed, conversion to a can-opener capsulotomy is an acceptable strategy (see the Appendix, Fig A-3). A can-opener capsulotomy is performed by using a cystotome or bent 27-gauge needle to create multiple small tears or punctures in the anterior capsule. These are circumferential to the equator and pulled centrally in a clockwise or counterclockwise direction to create a complete opening. However, this type of anterior capsulotomy makes hydrodissection, hydrodelineation, and endocapsular phacoemulsification more challenging because of the increased likelihood of an anterior capsule tear extending around to the posterior capsule.
Alternatively, a circular capsulotomy may be made by a handheld electronic capsulotomy device or by a femtosecond laser (see the section Alternative Technologies for Cataract Extraction later in this chapter).
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.