The capsulorrhexis is an important step in cataract surgery and is often the most difficult for the beginning surgeon to master. The purpose and advantage of the continuous curvilinear capsulorrhexis (CCC) over a can-opener capsulotomy is safety, stability, and lens centration. The CCC contains the IOL in the capsular bag in its proper position. The ideal capsulorrhexis is a centered circle that completely covers the edge of the IOL optic. This is generally 0.5-1.0 mm in diameter smaller than the optic and will keep the IOL in optimal position. However, completing a perfect CCC can be challenging. A capsulorrhexis that is too large can allow the IOL to rest too anteriorly, one that is irregular or off center can lead to IOL decentration or tilt from asymmetric contractile forces postoperatively, one that is too small can result in capsular phimosis and interfere with vision, and one that is incomplete can result in a posterior capsular tear during cataract removal.
The CCC can be created in a variety of ways. The central capsule is punctured with an irrigating cystotome or capsulorrhexis forceps with a sharp tip. The capsule is then cut radially toward the periphery and then pushed or pulled tangentially to create a flap. This flap is folded over and dragged in the direction of the tear with the cystotome or capsule forceps until a complete circle is created. This is easier said than done, so here are some helpful hints I have learned from mentors and colleagues over the years (for additional information, I particularly recommend Barry Seibel’s Phacodynamics and Richard Mackool’s Phaco Tips - The First Ten Years):
The capsulorrhexis should be started centrally to prevent the initial tear from running too far peripherally. The actual direction in which the rhexis is created is personal preference. The flap can be initiated with a cut toward the right or left followed by a pushing or pulling motion and then advanced clockwise or counterclockwise. I prefer to start the flap by pushing the capsule up and away from the incision since this is a more mechanically favorable maneuver given the position of the cystotome from the wound down to the lens (i.e., this flicking motion is easier to accomplish than a picking motion toward the incision in which it is more difficult to maintain contact between the instrument and the capsule). I suggest to residents that they try both methods and decide which they prefer.
The motion for the CCC is that of drawing a circle, so I instruct new surgeons to tear the rhexis in the same direction as they would draw a circle because this feels most natural. However, I do recommend that surgeons practice making the capsulorrhexis in both directions, because occasionally it is necessary to restart in the opposite direction in order to salvage an errant rhexis. The tear is very well controlled by horizontally dragging the folded edge of the flap in the appropriate direction rather than grasping an unfolded flap and pulling perpendicular to the leading edge or vertically, both of which can quickly result in peripheral extension of the tear. The flap must be regrasped periodically to maintain the proper flat, folded position and level of control.
Whatever instrument is utilized for the capsulorrhexis, it is important to manipulate it correctly. Ideally, the instrument should not move the eye or distort the wound. The incision serves as an oarlock about which the instrument should pivot. When the capsule is being torn on the surgeon’s left, the instrument should be adjacent to the right edge of the incision and angled toward the left. Similarly, when the capsule is being torn on the surgeon’s right, the instrument should be adjacent to the left edge of the incision and angled toward the right. This allows maximal maneuverability of the instrument without being blocked by the incision edges. Besides pivoting in the horizontal direction, the instrument should also pivot vertically to prevent distortion of the incision. Pressing on the incision may cause chamber shallowing by expressing viscoelastic and poor visibility by inducing corneal striae.
These are the basic steps for creating the capsulorrhexis. Next, I will review pearls for making a consistent CCC and managing potential problems.
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