21

Divide and Conquer Nucleofractis

Techniques

Howard V Gimbel

Ellen Anderson Penno

Introduction

Phacoemulsification, since its origin in the 1960s, has changed through the years and phacotechniques are still evolving. Besides the advantages of a smaller wound, phacoemulsification allows for the removal of even dense brunescent nuclei through continuous curvilinear capsulorhexis (CCC) openings. In the early 1980s, as phacoemulsification was being applied to more and more dense nuclei, the author developed in-situ nuclear fracturing techniques which added to the safety and efficiency of phacoemulsification.1–3 With the preservation of an intact capsular bag using CCC, fixation and centration of the intraocular lens (IOL), is ensured after safe and efficient in- the-bag phacoemulsification.3

The two-instrument nucleofractis technique was developed to facilitate subdivision of the nucleus into small pieces so that they could be removed more efficiently through the phacoemulsification handpiece and thus through a small cataract incision. The term derives from the Latin divide et impera, and nucleofractis comes from the prefix nucleo (nucleus) and the Greek suffix fractis (to fracture). Good nucleofractis skills can be learned by most ophthalmologists. Recent studies have demonstrated rates of vitreous loss by third-year resident surgeons learning nucleofractis techniques to be comparable to those found with standard extracapsular techniques.4–6 Because the fracturing procedure in divide and conquer places a stretching force on the anterior capsular opening, can- opener-type capsulotomies are associated with an unacceptably high rate of peripheral capsular tears. This led to the development of the CCC, which provides a strong tearresistant border that maintains its integrity despite the stretching forces produced with nucleofractis.3,7,8

The basic technique of nucleofractis is founded on the anatomic relationship of the lens fibers and the lenticular sutures. During embryologic development lens fibers elongate and join, forming the two Y sutures, one anterior and one posterior. As more fibers are added, these sutures branch out into increasingly complex patterns.9 These radially oriented sutures create potential cleavage planes that are susceptible to fracturing. The lens epithelial cells lay down concentric layers of nuclear tissue that become more dense peripherally. These concentric layers resemble the lamellar organization of a treetrunk or an onion. Radial and lamellar zones form cleavage planes within the lens nucleus and may be split by instruments and divided into smaller and more manageable pieces for phacoemulsification.

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deep sculpting is done from just inside the continuous curvilinear capsulorhexis to the center of the lens: Then the tip will travel parallel to the concave slope of the posterior aspect of the nucleus and the posterior capsule

Down-slope sculpting in the upper pole of the lens to just past the center reduces the chance of posterior capsule rupture with the phaco port. If the lens is nudged inferiorly by the second instrument and deep sculpting is done from just inside the continuous curvilinear capsulorhexis to the center of the lens, then the tip will travel parallel to the concave slope of the posterior aspect of the nucleus and the posterior capsule. Although the surgeon cannot visualize the tip when going “down-slope”, the depth of the sculpting is determined by visualizing the depth of the groove and translucency of the remaining tissue.

Furthermore, with traditional sculpting techniques the deepest part of the sculpting inevitably ends up inferior to the center of the lens. If the surgeon rotates the lens 90° after sculpting each quadrant, then the nuclear material deep in the center or posterior pole of the nucleus may still impede complete fracturing to the center, and the sections will tend to hang together in the middle of the lens. However, with down-slope sculpting, complete and efficient fracturing and subsequent emulsification can be accomplished by sculpting deeply and fracturing through the entire posterior plate of the nucleus.

The surgeon must be cautious when the CCC is small to avoid tearing the edge of the anterior capsule superiorly with the tip or the sleeve of the phaco instrument. In the author’s experience, small CCCs are most likely to occur in cases with poor visualization, such as when hypermature, white cataracts are present. Ordinarily, the risk is low because one is not sculpting much past the center when first beginning the trench.

Care must also be exercised in displacing the nucleus within the capsular bag so that the whole bag is not displaced, and the upper zonular ligaments are not unduly stretched and broken. Adequate hydrodissection is essential to allow inferior nucleus displacement while minimizing stress to the upper zonular apparatus. Also, when tipping the handle of the phaco handpiece upto sculpt down towards the posterior pole, the surgeon must not push the tip posteriorly faster than the tip is chiselling its way through the lens material. The zonular ligaments may also be torn with such a maneuver. These risks are greatest in lenses with hard epinuclei and where the zonules are already weakened.

Limiting sculpting to the superior part of the nucleus adds safety because of the reduced risk of contacting the posterior capsule and adds efficiency because of the rapidity with which the posterior pole of the nucleus is reached with the phaco tip. With instruments this deep in the nucleus, the fracturing can be effectively initiated and safely completed.

The Fracture

The fundamental principle underlying nucleofractis is the creation of fractures within the nucleus to facilitate the removal of the cataract through a small incision while causing the least possible trauma to the eye. If the nuclear rim is very hard or if the CCC is not intact, splitting the nucleus along a groove is achieved using a bimanual technique or a nuclear cracker. Regardless of the fracturing technique used, nucleofractis is facilitated by deep sculpting of the posterior pole of the lens nucleus. This will be discussed in more detail under “polar expenditions”.

With the parallel instrument technique, a deep central groove is sculpted within the lens nucleus and the phaco probe is placed deep within the groove against the right-hand wall (for right-handed surgeons). A second instrument is placed in the groove against the other wall. The fracture is created by pushing the two walls away from each other.

Alternatively, with a cross-handed technique, each instrument is placed against the opposite wall of the groove. With both the parallel instrument and cross-handed techniques, placing the two instruments as deeply as possible within the groove provides the most efficient application of the cracking force.

An alternative fracturing technique involves creating a full diameter groove, aligning the groove midway between the main incision and moving the two instruments away from each other deep within the trench. The density of the lens and the preference of the surgeon will dictate the appropriate fracturing techniques necessary to achieve consistent and predictable results in nucleofractis. All fracturing techniques currently used by the author use the principles of deep sculpting followed by fracturing of the posterior plate of the nucleus and then the posterior rim. Once the initial fracture is achieved, rotation and additional fractures are used to break away wedge-shaped sections of the lens nucleus for emulsification.

FIGURE 21.2 The phaco tip is used in a lateral motion (nasal to temporal and back again) to sculpt the central nucleus quickly and deeply while maintaining constant visualization of the tip of the instrument. With a 30°

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Kelman tip, the removal of lens material is more efficient and easier to perform. However, this technique is also possible with standard straight tip phacoemulsification handpieces

Phaco Sweep

Another variation on the theme of sculpting is a technique the author calls “phaco sweep”.11 In traditional sculpting techniques, the phaco tip is moved from the superior to the inferior portion of the nucleus to create a groove. By using the phaco tip in a lateral motion (nasal to temporal and back again), the central nucleus can be sculpted quickly and deeply while maintaining constant visualization of the tip of the instrument. The author prefers to use a 30° Kelman tip to perform phaco sweep (Fig. 21.2). With this tip, the removal of lens material is more efficient and easier to perform. However, this technique is also possible with standard straight tip phacoemulsification handpieces. The engineers at Alcon Surgical explain this difference on the basis of a three-dimensional propagation of the ultrasound wave front from the bent Kelman tip. Standard handpieces tend to direct their ultrasound power primarily in the forward direction, somewhat limiting their cutting efficiency for this technique.

As sculpting proceeds to deeper layers, the phaco tip is moved in a lateral sweeping motion. It is important to avoid occlusion of the tip during this

FIGURE 21.3 Phaco sweep—as sculpting proceeds to deeper layers the phaco tip is moved in a lateral sweeping motion. It is important to avoid occlusion of the tip during this procedure. The lens is stabilized inferior to the groove with a second instrument through the paracentesis

procedure. The lens is stabilized inferior to the groove with a second instrument through the paracentesis (Fig. 21.3). After lateral sculpting is sufficiently deep, a horizontal fracture is created as described later in the “multidirectional divide and conquer” section of this chapter (Fig. 21.4). Phaco sweep is a variation of down-slope sculpting which enhances visualization of the phaco tip and results in increased safety for the removal of central nuclear

FIGURE 21.4 Phaco sweep—after the lateral sculpting is sufficiently deep, a horizontal fracture is created

FIGURE 21.5 Crater divide and conquer (CDC)—after adequate hydrodissection, a deep crater is sculpted into the center of the nucleus, leaving a dense peripheral rim that can later be fractured into multiple sections. It is important that the crater include the posterior plate of the nucleus, otherwise, fracturing of the rim will be much more difficult

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material. In addition, the motion of the probe remains parallel to the posterior capsule, diminishing the risk of its inadvertent rupture.

Crater Divide and Conquer (CDC) Technique

Divide and conquer nucleofractis phaco, described by the author was the first nucleofractis (two-instrument) cracking technique developed.1,12 It is still used for hard lenses and is now combined with the phaco chop for dense brunescent nuclei. The phaco chop technique will be discussed later in this chapter.

After adequate hydrodissection, a deep crater is sculpted into the center of the nucleus, leaving a dense peripheral rim that can later be fractured into multiple sections (Fig. 21.5). The crater must include the posterior plate of the nucleus, otherwise, fracturing of the rim will be much more difficult. A shaving action is used to sculpt away the central nuclear material. When the central material is no longer accessible to the phaco probe, the lens should be rotated and additional central sculpting performed to enlarge and deepen the crater. The size of the central crater should be expanded for progressively denser nuclei. Enough of the dense material must be left in place, however, to allow the phaco

FIGURE 21.6 Crater divide and conquer (CDC)—rather than emulsify the sections as they are broken away the sections should be left in place within the rim to maintain the circular rim and the tension on the capsule. Leaving the sections in place also facilitates rotation and the progressive fracturing of the remaining rim

probe and second instrument to engage the rim and fracture the lens into sections.

The surgeon uses experience as a guide to determine how deeply the central crater should be sculpted. The peripheral nuclear rim stretches the entire capsular bag and acts as a safety mechanism to prevent the posterior capsule from suddenly moving anteriorly and being cut by the phacoprobe. For harder nuclei, small sections should be fractured

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be brought to the center of the capsule for safe emulsification

the entirety of its circumference, each segment can then be brought to the center of the capsule for safe emulsification (Fig. 21.8). One must be more cautious at this point because as more segments are removed, less lens material is available to expand the capsule, and the capsule will have a greater tendency to be aspirated into the phaco tip, especially if high aspiration flow rates are used (Fig. 21.9).

Trench Divide and Conquer (TDC) Technique

Recognizing the efficiency of fracturing maneuvers during CDC, the author stopped sculpting the right side of soft lenses after making the central trench

FIGURE 21.9

Crater divide and conquer (CDC)—as segments are removed less lens material is available to expand the capsule and the capsule will have a greater tendency to be aspirated into the phaco tip, especially if high aspiration flow rates are used

FIGURE 21.10 Trench divide and conquer (TDC)—using the down-slope sculpting technique described earlier enables the phaco tip to remove more of the upper part of the nucleus during sculpting and to reach the posterior pole of the lens very early for effective fracturing

and instead made a central fracture. Using the down-slope sculpting technique described earlier allows the phaco the tip to remove more of the upper part of the nucleus during sculpting and to reach the posterior pole of the lens very early for effective fracturing

(Fig. 21.10). Then the left side is divided by fracturing, and also the right side. These variations were named “trench divide and conquer (TDC)” techniques.10,13,14

FIGURE 21.11 Trench divide and conquer (TDC)—using a 30° or 45° tip, the TDC technique begins with a shallow trench or trough sculpted slightly to the right of the center of the

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after impaling the tip with a short burst of ultrasound, pushing with the phaco tip toward the 6 O’clock position while stabilizing the upper portion. The piece can then be fractured into halves or thirds and emulsified as they are fractured

Rather than utilizing grooves to start the fractures, the surgeon simply needs to get the instruments deep into the center of the lens to fracture through the naturally occuring radial fault lines of the lens. Except in brunescent nuclei where notches are sculpted in the nuclear rim so that the spatula has a wall to push against, the principal advantage of the technique is that pregrooving the nucleus for subsequent fracturing is completely unnecessary.

FIGURE 21.15 Multidirectional divide and conquer (MDC)—the phaco sweep technique is initiated with small lateral movements of the phacotip at the bottom of the previously formed groove. The Kelman tip works very well for this side-to-side movement to create a deep groove horizontally. The phaco tip is then used to stabilize the upper portion, while the spatula pushes inferiorly against the wall, creating a horizontal fracture

Multidirectional Divide and Conquer (MDC) Technique

Down-slope multidirectional nucleofractis is begun by debulking the superior part of the lens. The phaco sweep technique is initiated with small lateral movements of the phaco tip at the bottom of the previously formed groove. The Kelman tip works very well for this side-to-side movement to create a deep groove horizontally. The phaco tip is then used to stabilize the upper portion while the spatula pushes inferiorly against the wall, creating a horizontal fracture (Fig. 21.15).

This horizontal fracture is a combination of separation, and shearing. The second instrument pushes towards 6 O’clock and the phaco tip pushes down and away so that these opposing forces result in the splitting of the nucleus as the horizontal fracture.

FIGURES 21.16 TO 21.18

Multidirectional divide and conquer

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(MDC)—Multidirectional nucleofractis occurs when the phaco tip is used to engage the inferior hemisection and multiple pie-shaped sections are fractured using the second instrument to stabilize the nucleus. The multidirectional fracturing is accomplished without rotating the lens

Multidirectional nucleofractis occurs when the phaco tip is used to engage the inferior hemisection and multiple pie-shaped sections are fractured using the second instrument to stabilize the nucleus (Figs 21.16 to 21.18). The sections are brought into the central pupillary zone for safe emulsification. The multidirectional fracturing is accomplished without rotating the lens. With the natural fault lines in the lens, this can be accomplished very easily without the chopping technique through the use of two-instrument separation. The fracturing is enhanced by not only separation but again by shearing (pushing down on one segment and away on the other) so that the separation is in two planes.

The superior hemisection is rotated inferiorly and emulsified in a similar fashion. Alternatively, the superior section is nudged inferiorly with the spatula and the phaco tip is burrowed into the bulk of the nucleus, which is fractured without rotation.

Phaco Chop

Kunihiro Nagahara first introduced the phaco chop technique in 1993 at the annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS) in Seattle, Washington. This technique also uses the lamellar structure of the nucleus to create radial fractures in the lens. The phacoemulsification probe is directed into the central core of the nucleus until occlusion of the port occurs. A modified lens hook is then inserted just beneath the anterior capsular leaflet at the 6 O’clock position just adjacent to the phaco probe, but extending to the equator of the lens. The tip is drawn centrally from the equator of the lens towards the phaco tip. This chop must encompass at least half of the anteroposterior diameter of the lens. The two instruments can then be used in a standard bimanual technique to complete the fracture. The nucleus is rotated slightly after the first chop and the procedure is repeated until pie-shaped wedges are created throughout the lens. These wedges can then be aspirated into the center of the capsular bag for safe emulsification.

While the phaco chop technique can reduce phacoemulsification time significantly, this technique poses a persistent threat to anterior capsular integrity. Traversing the chopping instrument through the cortex towards the equator ensures that the anterior capsule remains anterior to the chopping instrument. The risk to capsular integrity with the phaco chop technique is greatest for surgeons with limited experience.

FIGURES 21.19 AND 21.20 Crater divide and conquer (CDC) variation using phaco chop—in this modified technique the central nucleus is sculpted away. Rather than fracture the remaining nucleus by traditional nucleofractis techniques, the chop maneuver is used to split and than separate the nuclear rim using shearing forces. Creating a central crater provides a space where rim segments can be easily maneuvered following the chop

As discussed earlier, the author has incorporated this phaco chop technique into the crater divide and conquer method for dense brunescent nuclei.15 It can be difficult to separate the nuclear rim in very hard lenses. In this modified technique, the central nucleus is sculpted away as described earlier (see “Crater Divide and Conquer” section). However, rather than fracture the remaining nucleus by traditional nucleofractis techniques, the chop maneuver is used to split and then separate the nuclear rim using shearing forces (Figs 21.19 and 21.20). Creating a central crater provides a space where rim segments

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can be easily maneuvered following the chop. Fracturing is thus made easier and zonular and capsular stress is reduced.

The use of the chop technique is safer in the presence of anterior capsular tears because stretching of the capsule is reduced. For soft and moderately soft nuclei, the chop technique does not offer sufficient added efficacy to offset the increased risk of capsular tears.

Steve Arshinoff recently presented his “slice and separate” modified phaco chop technique at the 1997 annual meeting of the American Society of Cataract and Refractive Surgery. This method is designed to be used for moderately dense nuclei. Dr Arshinoff describes impaling the nucleus and using a phaco chopper to slice across the nuclear part of the lens from anterior to posterior, passing by the phaco tip. The nucleus is then rotated 15° to 20°, and the same maneuver is repeated on the distal half. After the second slice, the segment is vacuumed out and the procedure is repeated—slice and vacuum—until the nucleus is removed. The slice maneuver is always started in the lens center, and the posterior capsule remains protected by the remaining nuclear and cortical material. Dr. Arshinoff emphasizes the need for good hydrodissection for success in this technique and notes that the slice and separate technique is difficult to perform on very soft nuclei due to difficulty in stabilizing the lens.

Polar Expeditions

Regardless of the fracturing technique used—crater divide and conquer (CDC), trench divide and conquer (TDC), or multidirectional divide and conquer (MDC)—the key is to sculpt nuclear material away centrally, leaving a thin layer of epinuclear material. Deep sculpting to the posterior pole of the lens facilitates the fracturing of the nucleus because it provides for safe and efficient segmentation and removal of the nuclear segments by taking advantage of the natural fault lines of the lens. Deep sculpting also allows one to obtain the mechanical advantage required to effectively fracture through the entire lens. Sculpting should be deep enough to be right through the nucleus into the epinucleus. The bent Kelman tip facilitates this deep sculpting.

The expedition to the posterior pole can be accomplished with forward sculpting or phaco sweep lateral sculpting to thin the posterior plate before fracturing is attempted.16 Once a thin posterior plate is achieved, the segments fracture very easily with the twohanded technique. In a brunescent lens, the phaco chop instrument is used to fracture segments in the crater chop so that the segments are smaller and more easily managed.

In trench divide and conquer (TDC) nucleofractis, polar sculpting is limited to a central trough or trench. This works best in a very soft nucleus where one has to maintain most of the nucleus which is firm enough to fracture. The nucleus is nudged slightly inferiorly and stabilized with the second instrument. Then the polar expedition for the posterior pole of the lens begins. The trench has to be wide enough to allow the phaco sleeve to get down into the nucleus. Once deep enough, the fracture is obtained with the two instruments. The segments are broken away, similar to the other nucleofractis techniques. Once the fracture is through the posterior plate of the lens, the fractured segments fracture completely without being tied together at the apices, and small segments are easier to manage than large segments. Only low-ultrasound power is necessary for these small nuclear segments to be emulsified.

In multidirectional divide and conquer, downslope sculpting towards the posterior pole is used initially. The upper part of the nucleus is removed, and then with phaco sweep, polar expedition involves sculpting of the posterior pole before the horizontal fracture. The lens is stabilized and nudged inferiorly, and the sculpting is done with forward passes until one is deep in the lens. Then phaco sweep is used to delicately sculpt through the deepest part of the nucleus to the epinucleus before the horizontal fracture is made.

The Small Pupil

The most important goal in small pupil cataract surgery is to limit serious surgical complications. Relatively complication-free surgery in small pupil cases can be achieved with phacoemulsification techniques. These techniques also help to attain other goals such as the use of a small incision, the minimal use of pupil enlarging surgery and certain verification, of in-the-bag placement of a posterior chamber intraocular lens. The placement verification, long-term stability, and centration can be virtually assured by obtaining and maintaining a continuous curvilinear capsulorhexis opening in the anterior capsule.17 The lens nucleus, even though dense and large, can be fractured into small segments and removed by emulsification through relatively small capsule openings, small pupil openings, small scleral incisions and small conjunctival incisions. These are important considerations in many glaucoma patients who have small pupils from longterm miotic therapy and who have had or may in the future require filtering surgery

The author developed the down-slope sculpting method, as described earlier in this chapter, in small pupil cases to quickly reach the posterior pole of the nucleus for efficient fracturing. The lens is nudged inferiorly, using a second instrument and the phacotip sculpts down the concave posterior capsule towards the posterior pole as described earlier, parallel to the capsule as opposed to perpendicular to it. Once the pole is reached, the two-instruments are held deep in the center. The spatula pushes inferiorly while the phaco tip pushes superiorly to create a horizontal fracture. The two instruments are repositioned to create a vertical fracture. The fractured segments can remain in the bag to stabilize it or be removed piece by piece. The second instrument holds back segments, while other segments are emulsified in the center of the lens. As well, the spatula brings nuclear material to the phaco tip to be emulsified. The phaco tip itself, stays mainly in the center of the lens.

Small pupil cases demonstrate the distinct advantage of nucleofractis techniques in that the phaco tip does not have to be put under the iris or under the small openings in the capsule. As such there is little risk of iris or capsule flowing unexpectedly with the lens material into the tip of the phaco port. One should use a lower flow when the pupil is small. This may reduce efficiency, but certainly increases safety. Again, epinuclear material is brought to the phaco port using the second instrument. The phaco port itself does not go searching for this material in a small pupil case.

Intumescent Lens

The nucleus in an intumescent lens can be safely and efficiently fractured and phacoemulsified using the down-slope sculpting technique.18 In intumescent cases with

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primary, small capsulorhexis openings, the nucleus is nudged inferiorly with a second instrument. The upper portion of the nucleus is then sculpted using the down-slope sculpting technique. The nudging maneuver allows the phacotip to get very deep into the nucleus for subsequent fracturing. The phaco tip should be maintained centrally to avoid stress on either the small capsulorhexis rim or a can-opener margin. Mechanical stress to the ring of the can-opener with the use of the phaco handpiece, or by a second instrument, should be avoided. This is another instance in which down-slope sculpting nucleofractis is advantageous for safe emulsification, because the phaco tip always stays in the center of the lens. The second instrument is used to rotate, maneuver, and help fracture the nuclear rim.

The depth of the sculpting is quite easy to gauge in an intumescent lens due to the whiteness of the nucleus and the red reflex exposed during fracturing. In doing phacoemulsification out near the periphery or up near the capsule in the epinucleus, a low flow and low vacuum should be used so that a sudden breakthrough with a high flow and high vacuum can be avoided. This will avoid engaging the equatorial capsule with the phaco tip. The intumescent lens is usually easy to fracture and quite often the lens will fracture spontaneously just with the attempt at rotation.

Capsular Tension Rings

Since phacoemulsification and continuous curvilinear capsulorhexis were developed, it has become possible to remove a cataract through a small incision and implant an intraocular lens (IOL) into the capsular bag. The centration and stability of the IOL in- the-bag is critical for maintaining excellent visual outcome. In some situations, placing an IOL in the capsular bag may be insecure, as in the case of a traumatic cataract with broken or loose zonules. To manage this situation, many anterior segment surgeons (including the first author) prefer to use phacoemulsification if possible, even if the capsular bag cannot be used for IOL placement. A sutured posterior chamber IOL (PCIOL) or an anterior chamber IOL (AC-IOL) may be placed after phacoemulsification is completed. Sutured fixation of a PC-IOL significantly increases surgery time and axial tilt of the IOL often occurs postoperatively. Implantation of an AC-IOL may be associated with postoperative corneal pathology, chronic cystoid macular edema, or secondary glaucoma.

In 1991, Hara et al introduced an equator ring for maintaining the circular contour of the capsular bag after cataract removal.19 Following their work, different types of rings of varied material were developed. Cionni and Osher reported on four cataract surgery cases with extensive zonular dialysis managed with endocapsular rings.20 The results showed that the ring facilitated phacoemulsification and PC-IOL in-the-bag implantation. In January 1995, the author began using a polymethylmethacrylate (PMMA) capsular tension ring (Morcher GMBH, Germany) to manage patients with zonular dialysis requiring cataract surgery (Fig. 21.21).21

FIGURE 21.21

Polymethylmethacrylate (PMMA) capsular tension ring (Morcher GMBH, Stuttgart, Germany) type 14 (dimensions 12.5 ×10.0 mm)

A capsular tension ring may have potential benefits for cataract surgery patients with zonular dialysis—a capsular tension ring appears to enhance safety and efficacy during the phacoemulsification and PC-IOL implantation, it may help to avoid vitreous herniation, it maintains the circular contour of the capsular bag, it may reduce IOL decentration, and it may inhibit lens epithelial cell proliferation on the posterior capsule by compression, which may reduce the incidence of secondary cataract.

Clinically, cataracts with loose zonules or broken zonules are commonly seen which present a challenge for surgeons when performing phacoemulsification and PC-IOL implantation. The capsular tension ring provides an alternative means to manage this situation.

Challenges to Topical Anesthesia in Small-Incision Cataract Surgery

The use of topical anesthesia in cataract operations requires that surgeons learn new techniques and adapt to challenges not faced with the use of local or general anesthesia.22 The transition to topical anesthesia means that surgeons cannot use some of the techniques that have been entirely safe on the immobilized eye. Under topical anesthesia, one cannot rely on the patient’s fixation or on voluntary immobilization of the eye, and persistent ocular movements on a regular or irregular basis may occur. In some circumstances, the globe must be immobilized with a second instrument.

The author began using topical anesthesia for cataract surgery in 1993, specifically because of a case involving a very myopic eye with an axial length of 36.3 mm. In this case, it was felt that the risks of using peribulbar or even pin-point anesthesia were too high. The patient was relatively co-operative and communicative and fixated well. The author became convinced that topical anesthesia in long eyes adds an element of safety, reducing or eliminating the risks of the local anesthetic.

Topical anesthesia introduces new challenges to cataract surgery. A learning curve presents itself with changes in surgical technique, and modifications must be made in

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reflex and habit that have evolved while doing surgery with peribulbar anesthesia surgery. Two-handed cataract extraction techniques are relatively advantageous in topical anesthesia cases, particularly because the second instrument—at almost 90° from the first—helps to stabilize the eye against unwanted movements in both the vertical and horizontal directions.

In general, the learning curve involves modifications to almost every stage of cataract surgery. The eye must be stable even before the paracentesis is done. If an eye is not very quiet, it is valuable to use a ring to stabilize the eye while making the paracentesis. Next, the eye needs to be stabilized with forceps during the incision. The surgeon cannot afford any sudden movements (particularly when using diamond knives) of an eye anesthetized only topically. Scleral incisions under topical anesthetic must be made with the eye stabilized with forceps (unlike clear corneal incision where the eye is stabilized by a ring), grasping and regrasping the sclera before continuing with dissection. Sometimes, with local anesthesia, when the incision is being made, the grasp on the sclera is released and reapplied in a different place when the blade is in the tunnel. In eyes under topical anesthesia, the author advocates that the blade be removed from the tunnel before the forceps are released and the sclera be grasped at another location before the blade is reentered. One should never release the eye with the second instrument unless the sharp instrument is taken away first, because if the eye moves unexpectedly with only the sharp instrument in the tunnel, the sclera could be inadvertently cut.

Another area of concern is the injection of viscoelastic. One cannot simply insert the cannula into the eye to inject viscoelastic, because the eye can move before the surgeon has an opportunity to fill the chamber. Any sudden movement may cause a tear to the anterior or posterior capsule. It is best to hold the eye while injecting viscoelastic. Furthermore, instead of inserting the viscoelastic cannula directly perpendicular to the eye, insert it so that it approaches the eye tangentially so that the side of the cannula is pushing or nudging the side of the wound. Any sudden movement of the eye towards the cannula will push the side of the cannula rather than allow the cannula to puncture the capsule unexpectedly.

Some extremely nervous patients do not agree to topical anesthesia even after sedation. In patients with language barriers we now bring an interpreter or family member into the operating room. When faced with communication difficulties with extremely deaf or demented patients, we sometimes opt for a local anesthetic. However, nonverbal communication for instructions allows surgery to be done under topical anesthesia in many cases.

Topical anesthesia appears to be the growing trend in cataract surgery. It avoids the potential risks of damage to vessels, globe, and nerves that exist when a needle is used. Surgeons who use topical anesthesia should already be experienced in phacoemulsification. A surgeon in the transition to phacoemulsification should probably not consider topical anesthesia until confident with phacoemulsification first. Initially, a surgeon should use topical anesthesia only on routine unchallenging cases. At the outset, surgeons should avoid using topical anesthesia on uncooperative patients or with patients who have difficulty in communicating. As one becomes more experienced and more confident, topical anesthesia can be used in more challenging cases. Cases in which local or general anesthesia is preferred will always exist, and these include patients who are

unable to co-operate, have extremely small pupils, or very dense or subluxated lenses, and those requiring more complex surgery or delicate dissection.

Summary

Each of the nucleofractis techniques described in this chapter are variations of four basic steps: (i) sculpting to obtain a thin posterior plate of nucleus, (ii) fracturing the posterior plate and nuclear rim, (iii) breaking away wedge-shaped sections of nuclear material for emulsification, and (iv) rotating the nucleus for further fracturing and emulsification. The techniques of continuous curvilinear capsulorhexis, down-slope sculpting, phaco sweep and polar expeditions are refinements which add efficacy and safety to the divide and conquer nucleofractis techniques. The surgeon should be familiar with the variety of nucleofractis techniques described and be able to modify the surgical strategy as dictated by specific patient characteristics and intraoperative events.

References

1.Gimbel HV: Divide and conquer nucleofractis phacoemulsification—development and variations. J Cataract Refract Surg 17:281–91, 1991.

2.Gimbel HV, Ellant JP, Chin PK: Divide and conquer nucleofractis. Ophthalmol Clin North Am 8(3):457–69, 1995.

3.Gimbel HV, Neuhann T: Development, advantages, and methods of the continuous circular capsulorhexis technique. J Cataract Refract Surg 16:31–37, 1990.

4.Cruze OA, Wallace GW, Gay CA et al: Visual results and complications of phacoemulsification with intraocular lens implantation performed by ophthalmology residents. Ophthalmology 99:448–52, 1992.

5.Noecker RJ, Allinson RW, Snyder RW: Resident phacoemulsification experience using the in situ nuclear fracture technique. Ophthalmology 25:215–21, 1994.

6.Pearson PA, Owen DG, Van Meter WS et al: Vitreous loss rates in extracapsular cataract surgery by residents. Ophthalmology 96:1225–27, 1989.

7.Gimbel HV, Neuhann T: Continuous curvilinear capsulorhexis (letter). J Cataract Refract Surg 17:110, 1991.

8.Neuhann T: Theorie und operationstechnik der kapsulorhexis. Klin Monatsble Augenheilkd 190:542–45, 1987.

9.Hogan M, Alvaradd J, Weddell J: Histology of the Human Eye. Philadelphia: WB Saunders 1971.

10.Gimbel HV: Down slope sculpting. J Cataract Refract Surg 18:614–18, 1992.

11.Gimbel HV, Chin PK: Phaco Sweep. J Cataract Refract Surg 21:493–96, 1995.

12.Gimbel HV: Divide and Conquer. (Video) Presented at the European Intraocular Implant Lens Council meeting 1987.

13.Gimbel HV: CCC and nucleus fracturing. Ophthalmol Clin North Am 4:235, 1991.

14.Gimbel HV: Evolving techniques of cataract surgery—continuous curvilinear capsulorhexis, down-slope sculpting and nucleofractis. Semin Ophthalmol 7:193–207, 1992.

15.Gimbel HV: Nuclear phacoemulsification—alternative methods. In: Steinert RF (Ed) Cataract Surgery: Technique, Complications, and Management Philadelphia: WB Saunders 148–81, 1995.

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16.Gimbel HV, Austin A: ‘Polar expedition’ technique expedites phaco. Ocular Surgery News 15(9): 27–32, 1997.

17.Gimbel HV: Nucleofractis phacoemulsification through a small pupil. Can J Ophthalmol 27(3):115–19, 1992.

18.Gimbel HV, Willerscheidt AB: What to do with limited view—the intumescent cataract. J Cataract Refract Surg 19: 657–61, 1993.

19.Hara T: Endocapsular phacoemulsification and aspiration (ECPEA—recent surgical technique and clinical results. Ophthalmic Surg 20:469–75, 1989.

20.Cionni RJ, Osher RH: Endocapsular ring approach to the subluxated cataractous lens. Cataract Refract Surg 21:245–49, 1995.

21.Gimbel HV, Sun R, Heston JP: Management of zonular dialysis in phacoemulsification and IOL implantation using the capsular tension ring. Ophthalmic Surgery and Lasers 28(4):273– 81, 1997.

22.Gimbel HV: Challenges of topical anesthesia in small incision cataract surgery. Ophthalmic Practice 14(3):123–24, 1996.