viscoelastic and using a capsule scissors to create a tangential cut. This can then be enlarged to the desired size with capsulorrhexis forceps (Fig. 5–4). Enlargement of the capsulotomy may be necessary for cortex removal and lens implantation. This twostage CCC technique can also be used in cases with a small traumatic opening in the anterior capsule and for corneal endothelial protection in intracapsular and endocapsular cataract extraction.8,23

INTRAOPERATIVE CAPSULAR

COMPLICATIONS

ANTERIOR CAPSULAR TEARS

Anterior capsular tears can be avoided by using the techniques described above. In some cases, such as a small pupil or a mature cataract as noted earlier, a planned two-staged capsulorrhexis may be indicated. This technique allows for control and visualization during CCC and allows for enlargement of the capsulorrhexis as needed for lens implantation. By purposefully creating an initially small capsular opening, tears resulting from loss of control during CCC may be avoided. However, tears or the creation of a zonular dehiscence during phacoemulsification becomes a greater risk by means of contacting the CCC edge with the phaco tip, or by puncturing, tearing, or pulling on the anterior capsule with a second instrument.

Anterior capsule tears may also occur during cortex removal. This is of particular concern when removing the subincisional cortex. With a one-handed technique, using the standard rigid irrigation and aspiration (I&A) tip, in an effort to reach the cortex, the aspiration port must often be placed out of view under the iris. Often, the tip is rotated such that the aspiration port is facing superiorly or posteriorly. These maneuvers, while necessary to engage the cortex, cause distortion to the incision, creating poor visibility, and increase the chance of inadvertently engaging the capsular edge and creating a tear. In an effort to prevent this problem, some surgeons advocate the use of a two-handed I&A technique—one cannula in one hand for BSS inflow and the other cannula in the other hand for aspiration. The cannulae are placed through two paracenteses. This will improve visibility and control for aspiration of subincisional cortex. Alternatively, the soft tipped steerable I&A probe is well suited to removal of subincisional cortical material. The maneuverability combined with the softer tip in this type of I&A handpiece provides better visibility and protection against anterior and posterior capsule tears. Finally, it should be noted that subincisional cortex, when present, is more easily removed if a cortical cleaving hydrodissection has been performed.

Should a short anterior capsule tear occur during phaco or I&A, one method of management would be to inject viscoelastic above and below the tear to support it. Using capsular forceps, the torn capsule is grasped at its furthest extent and redirected centrally, converting it into a rounded outgrowth of the capsulorrhexis. Alternatively, employing a Vannas scissors to create a larger tear of the anterior capsule, which incorporates the original tear, will prevent extension of the tear. These techniques result in an eccentric capsulorrhexis. However, in this setting, the maintenance of capsular integrity and prevention of further complications, which may result from extension of an anterior capsular tear, are of primary importance (Fig. 5–5).

NONCONTINUOUS CAPSULORRHEXIS

If, during the capsulorrhexis, the tear is lost toward the equator and must be completed from the opposite direction, if the tear is not completed from the outside in leaving a notch, if the tearing edge is lost due to disturbance of the underlying cortex from excessive manipulation while searching for the tearing edge, or if an anterior tear occurs during phaco and cannot be turned back into the CCC, extreme care must be taken throughout the remainder of the procedure. Pressure on the posterior capsule must be avoided. Any pressure on the capsule could cause radial extension of the tear through the equator and into the posterior capsule. If the tear occurs prior to the hydrosteps and the surgeon is concerned about the integrity of the posterior capsule, the capsulorrhexis should be enlarged enough to allow for the unimpeded prolapse of the nucleus into the anterior chamber. The hydrodissection should be carefully performed with gentle injection of fluid. The lens is prolapsed into the AC and retentive viscoelastic (Viscoat) is placed above and below the nucleus. This isolates the nucleus and prevents its possible subsequent falling into the vitreous through a large posterior capsular tear during phacoemulsification. Emulsification can then be carried out in the anterior chamber in between the layers of viscoelastic. Viscoelastic should be refreshed as is necessary. Some surgeons advocate converting to a can-opener style capsulotomy in the presence of radial extension of an anterior capsular tear.27 However, with a gentle touch and careful technique, conversion to a canopener capsulotomy is not necessary.

IOL SELECTION

When the capsulorrhexis is not continuous, silicone plate-haptic lens implantation is contraindicated as

these IOLs may subluxate into the anterior or posterior chamber as the capsule contracts postoperatively.

A three-piece intraocular lens with an extruded polymethylmethacrylate (PMMA) C-loop design or a once-piece IOL no longer than 11.5 mm can be implanted in the capsular bag. A bimanual technique and adequate viscoelastic to fill and stabilize the bag is necessary to minimize pressure on the weakened bag. This will help to avoid extension of the tear. The haptics should be placed perpendicular to the tear and a matched tear (created with the Vannas scissors) created 180 degrees away from the initial tear. This will neutralize forces created by postoperative capsule contraction and prevent postoperative lens decentration (Fig. 5–6). A further discussion of IOL selection after vitrectomy can be found in Chapter 20.

POSTERIOR CAPSULE TEARS

Posterior capsule tears, if managed properly, may not result in a poor visual outcome. However, any case in which the posterior capsule is ruptured has a higher risk of vitreous loss, cystic macular edema (CME), retinal detachment (RD), and loss of nuclear fragments posteriorly.9,23,27 As discussed previously, the surgeon must keep in mind the anatomic features of the lens capsule during phacoemulsification and aspiration; at the posterior pole the capsule may be as thin as 2 to 4 m. Avoidance of posterior capsular tears requires judicious use of phacoemulsification settings that are tailored to both the surgical technique and the type of cataract being removed. For example, in younger patients in whom the nucleus is

soft, lower power settings are appropriate. The posterior capsule can be aspirated in the phaco tip, and, if immediately released or refluxed, will not tear. If the phaco tip has burrs, or it is moved while the capsule is occluded on the phaco tip, it will tear. The vitreous face, however, often will remain intact. Care must be taken during all phacoemulsification and cracking maneuvers to avoid contacting the capsule with simultaneous vacuum and ultrasound. This will immediately tear the posterior capsule and rupture the vitreous face with instantaneous prolapse of vitreous into the anterior chamber. Obviously, care must also be taken to avoid contact of sharp second instruments with the posterior capsule.

If the posterior capsule is vacuumed, a “cap-vac” setting of 5 mm Hg vacuum and 5 cc per minute of aspiration flow rate (if available) are helpful to prevent inadvertent tears. During this maneuver, when the capsule, engaged by the vacuum, is within the 0.3 mm tip orifice, very slow movements of the tip are necessary to avoid snagging and tearing the capsule. Be sure the I&A tip has no sharp burrs.

The posterior capsule, despite being incredibly thin, does have remarkable elasticity and structural integrity. It will withstand blunt pressure. Therefore, although a gentle touch is advisable, blunt-tipped instruments such as cracking instruments do not typically pose a high risk of posterior capsular rupture.

POSTERIOR CAPSULORRHEXIS

In the event that a small tear occurs in the posterior capsule, it may be converted to a posterior CCC to

prevent it from enlarging radially and further compromising capsular integrity.10,11,23 The creation of this posterior CCC is similar in technique to the anterior CCC (Fig. 5–7). After adding viscoelastic (I prefer Healon GV) to stabilize the capsule, to push the intact vitreous face back, or prevent further vitreous herniation through the tear, the advancing tear flap is grasped with the forceps and directed in a curvilinear manner such that the entire tear is contained centrally. To complete the tear, it is blended from the periphery. The posterior opening thus created should be kept as small as possible to ensure support for the IOL. This technique may not be feasible if the end of the posterior capsular tear cannot be visualized because it is too far peripheral or has a subincisional location. Sometimes only one end of a long tear can be reached. With courage and skill, it can be turned back and rounded off. This may then still allow for in-the-bag IOL placement.

This method of posterior CCC can be employed intentionally for removal of posterior plaques and in pediatric cataract cases for primary posterior cap- sulectomy.12–14 Posterior CCC with optic capture has been used successfully to prevent secondary opacification in pediatric cataract cases; with this technique the haptics remain in the capsular bag and the optic is gently guided through the posterior CCC such that the optic is captured (Fig. 5–8).12–15,23 This requires that the size of the posterior opening be carefully controlled such that the optic is about 1 mm larger than the posterior CCC and will be captured when in proper position. The posterior CCC is performed either before or after IOL implantation but after inflating the capsular bag with viscoelastic. After IOL implantation the viscoelastic is aspirated from in front of the IOL but is left to remain posterior to the IOL to avoid aspiration of vitreous requiring subsequent vitrectomy.

ANTERIOR CAPSULAR IOL

OPTIC CAPTURE

The technique of anterior capsular optic capture described by Neuhann (unpublished data) may be employed in cases in which a posterior capsular rupture cannot be converted to a posterior CCC. In these cases an intact anterior CCC of a diameter smaller than the IOL optic is required. The haptics of the IOL are placed in the sulcus. The optic is then pushed through the anterior capsular opening and is captured by the intact CCC.12,23

In any case in which complications occur, the surgeon must make the decision as to which of these methods to use to optimize the visual outcome and minimize associated risks. Larger posterior tears with vitreous loss or loss of nuclear material into the vitreous will be discussed further in Chapters 18 and 19.

ZONULAR DIALYSIS

Zonular integrity can be compromised by a variety of conditions including prior trauma and pseudoexfoliation. These cases pose a challenge for phacoemulsification and for safe and stable placement of the IOL in the bag. Stability and centration of the implant may not be achieved or maintained because of zonular dehiscence and the postoperative contraction of the capsular bag. The senior author, who is a surgeon, and others have found that the use of endocapsular tension rings when zonular support is compromised guards against capsular collapse and vitreous presentation during phacoemulsification. In addition they stabilize the contour of the capsular bag such that the IOL can be placed securely within the bag and with excellent centration.16–20 We have reported on the use of a PMMA capsular tension ring (Morcher GMBH,

Stuttgart, Germany) in 14 cases with loose or broken zonules with good results (Fig. 5–9).15

If zonular weakness is noted preoperatively, utilizing the proper techniques, a CCC can be performed without further disruption of zonules. In a location away from the dehiscence, the rhexis should be initiated with a sharp needle. Thus, the capsule is incised without pulling on the zonules. A vigilant shearing rhexis is then performed. In the area near the absent or weakened zonules, the tearing forces are performed tangential to the weakened capsular edge. The capsular tension ring may then be placed in the capsular bag prior to phacoemulsification. This serves to enhance safety and stability during nuclear and cortex removal.

Unexpected excessive movement of the lens during CCC, hydrodissection, nuclear rotation, or phacoemulsification may indicate intraoperative zonu-

lar weakness. Excessively aggressive lens maneuvers will cause further disruption of the zonules. Aspirating the equatorial capsular bag with the phaco tip or I&A tip may tear the bag away from the zonule. Other signs of zonular weakness may include vitreous herniation around the bag with resultant iris bulge, and/or decentration of the crystalline lens. An endocapsular tension ring can be placed immediately when these signs are noted. This will prevent collapse of the capsular bag and further zonular dehiscence. Capsular tension rings may also prevent migration and proliferation of lens epithelial cells and the attendant capsular contraction and opacification through compression inhibition. This has been described by Hara et al16 in the rabbit model.

In cases with loose or broken zonules, the endocapsular tension ring with in-the-bag IOL placement