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Stop and chop phacoemulsification
techn
-q I
ue
Stop and chop phacoemulsification PaulS. Koch, M.D., Leeds E. Katzen, M.D.
ABSTRACT We present a method for phacoemulsification within the capsular bag in which sculpting is performed to provide space for nuclear manipulation and then the posterior plate is cracked into two halves. The nuclear rim is chopped into bite-size pieces for removal using a modified lens hook that is buried in the nuclear periphery and pulled toward the center. The procedure begins as a routine nuclear cracking technique and then stops. It continues as a chop technique. Key Words: cataract extraction, cortical cleaving hydrodissection, divide and conquer, in situ fracture, nucleofractis, phaco-chop, phacoemulsification, spring surgery
Many cataract surgeons consider fragmentation of the nucleus a prerequisite for removal from the capsular bag, and many procedures have been designed to facilitate this step. Gimbel 1 described the first set of procedures that established a strategy for nuclear fracturing, divide and conquer nucleofractis. Within this family of procedures were two variations: trench divide and conquer for soft cataracts and crater divide and conquer for firm cataracts. In either case, the plan was to clean out space in the middle of the cataract and then split the nuclear rim into small, bite-size pieces. Gimbel split the nucleus by placing his phaco tip and his spatula parallel to each other in the nuclear rim prior to separation. In a film presented at a recent meeting ("PhacoChop," presented at the 3rd American-International Congress on Cataract, IOL and Refractive Surgery, Seattle, May 1993), Nagahara described a new technique for splitting the nucleus. He used a modified lens hook in an appositional fashion, pulling it through the nucleus from the periphery to the phaco tip. Sculpting and trench construction were neither necessary nor performed. This technique seemed an easy alternative to Gimbel's parallel split; however, the phaco-chop technique left the pieces of nucleus wedged together tightly, making initial and subsequent removal of those pieces difficult (Figures l to 5). In many cases, nuclear fragments had to be pulled into the anterior chamber for removal. We have found that limitations of each technique can
Fig. 1.
(Koch) Phaco-chop: The phaco tip is driven into the superior nucleus at 12 o'clock and held there while the chopper is buried into the nucleus inferiorly.
be overcome by combining portions of each. The surgeon can begin with one technique, stop, and continue with the other, resulting in a technique we refer to as stop and chop phacoemulsification.
SURGICAL TECHNIQUE Unique to the chop method of splitting the nuclear rim is an instrument called a chopper. This was described in Nagahara's video as "a modified lens hook"
Reprint requests to PaulS. Koch, M.D., Koch Eye Associates, 566 Tollgate Road, Warwick, Rhode Island 02886. 566
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
Fig. 2.
(Koch) Phaco-chop: While the phaco tip is held motionless, the chopper is pulled toward it, cracking the nucleus.
Fig. 3. (Koch) Phaco-chop: When the chopper gets close to the phaco tip, the two instruments are separated, chopping the nucleus in half.
and seemed to be a simple manipulator with a right angle tip on the end. We made a variety of choppers by breaking off the tip of a Sinskey hook and bending it again to make longer versions. These choppers measured 1.00 mm, 1.25 mm, 1.50 mm, 1.75 mm, and 2.00 mm from the 90 degree bend to the distal tip. We found that the 1.50 mm chopper worked most reliably and efficiently, and this is the size we currently use. In the stop and chop technique, capsulorhexis is followed by hydrodissection. Cortical cleaving hydrodissection as described by Fine2 is always attempted, but its success or failure does not affect the subsequent steps of nuclear removal. Nuclear sculpting is performed according to the principles Gimbel 1 originally described. It is important to clean out space in the middle of the nucleus so there will be room to manipulate the nuclear fragments in the confines of the posterior chamber, obviating the necessity of pulling fragments up into the anterior chamber.
At the same time, the amount of sculpting must be tempered by the realization that nuclear manipulation depends on preserving a firm nucleus. Therefore, less sculpting is performed in soft cataracts and Il!lore in firm cataracts. This balance permits us to "trenq:h" the soft cataracts and "crater" the firm cataracts (Figures 6 and 7). In the case of a trench, it is carried out d,eeply so that the dark central red reflex turns bright red again as the posterior plate is approached. We like to make it as long as possible, even going slightly under the anterior capsule if necessary. In the case of a crater, it is made as deep and as wide as necessary to get to the margin where firm central nucleus begins to soften. The strategy is to remove the bulk of the firm, center nucleus while leaving enough firm material so that the nucleus can be manipulated. Too much sculpting leaves a soft nuclear shell, which is difficult to work with. When the crater is complete we
Fig. 4. (Koch) Phaco-chop: The nucleus is rotated 90 degrees and the same steps are repeated, chopping the nucleus into quarters.
Fig. 5.
(Koch) Phaco-chop: After the chops are completed, the segments are still wedged together. No significant spaces separate them. Each jagged edge fits with its mate just as in a jigsaw puzzle. It is difficult to remove each segment because of the proximity to its neighbor.
1 CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
567
Fig. 6.
(Koch) Stop and chop: Soft cataracts are prepared by sculpting a trench in the middle of the cataract, providing space for later manipulation.
Fig. 7.
(Koch) Stop and chop: Hard cataracts are prepared by sculpting a crater, removing most of the nucleus' very firm center, and leaving only the less dense rim.
carve a thin trench in its center to be a line of least resistance for the subsequent fracture. We extend this trench into the peripheral nucleus to give a defined spot where the initial nuclear fracture can split the nuclear rim. The next step is fracturing the nucleus into two halves, as is done in many other routine nuclearcracking techniques. In this case we introduce the chopper through the sideport incision and place the bent, distal tip into the trench or crater. We pull to the left with the chopper and push to the right with the phaco tip, moving and adjusting the instruments until there is a complete fracture of the posterior plate, separating the nucleus into two (Figure 8). This concludes the trench/crater nuclear fracturing step of the operation. At this point we stop, and from now on we chop. The nucleus is rotated so that one half of it lies across
the inferior capsular bag. It will be broken up into a number of bite-size pieces for easy removal. A typical medium-density cataract will have each half chopped into three pieces, a dense one more, and a soft one fewer. The phaco tip is buried using gentle emulsification into the inferior half of the nucleus about one third of the way from the right hand side and is held there using aspiration alone. The chopper is placed in the nuclear periphery at about the location of the anterior capsulotomy. If the anterior capsulotomy is too small for easy access for chopping, it can be pushed back gently by the chopper to make more room. The chopper should not perforate the anterior capsule because a radial tear can form. The chopper is then stuck into the peripheral nucleus to its angle, giving a penetration of 1.5 mm. It is then pulled toward the phaco tip, creating a very deep cut in the nucleus. When the chopper reaches the phaco tip, the
Fig. 8.
Fig. 9.
568
(Koch) Stop and chop: After sculpting is complete, the nucleus is fractured into two halves with the phaco tip and the chopper.
(Koch) Stop and chop: The phaco tip is driven into the nuclear half about a third of the way across from right to left. The chopper is buried in the periphery of the nucleus and pulled toward the phaco tip. When the instruments are close to each other, they are separated and a small segment of the nucleus is chopped off. It is already impaled on the phaco tip and can be emulsified without further manipulation.
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
chopper is pulled to the left and the phaco tip pushed to the right, creating a split in the nuclear rim with complete separation of one nuclear piece (Figure 9). The nuclear piece separated by the chop is already impaled on the phaco tip and held there with the same aspiration that held the piece steady for the chop. If the separated piece is small enough for easy removal, the phaco tip only has to go into emulsification to remove it easily without the challenging steps of pursuit, capture, rotation, or tumbling. The chopped-off piece, already attached to the phaco tip, gently follows into the tip during emulsification. The reason the piece separates off so easily and is free to glide into the phaco tip so nicely is that the initial trench or crater created space into which the nuclear piece can move. It can be manipulated in the posterior chamber and emulsified easily there without any need to free it up by pulling it into the anterior chamber, as is sometimes necessary with pure phaco chop. Once the first piece is chopped off and removed, the phaco tip and the chopper repeat the same steps, chopping a piece of the remainder of the nuclear half and emulsifying that as well. These steps-bury the phaco tip, bury the chopper, chop, separate, remove-are repeated until the entire nucleus is removed (Figure 10). Although we usually divide a nuclear rim into about six segments, more or fewer chops can be used depending on the density of the nucleus. Four segments are usually all that are necessary for a soft cataract or one in which a small endonucleus has been isolated through extensive hydrodelineation. A dense nucleus has to be broken into more small pieces because greater density requires smaller pieces to meet the bite-size criteria. Very dense cataracts may require 12 or more nuclear rim chops. In these cases, it is often best to leave the pieces in place until all of the chops are performed to keep the bag stretched and to
reduce the possibility of ripping the posterior capsule with the edge of one of them.
DISCUSSION Ever since the development of the continuous curvilinear capsulotomy, surgeons have been devising ways to remove the nucleus from within the capsular bag. Gimbel' originally advised a strategy of splitting the nuclear rim using his nucleofractis technique. Many surgeons found his method of splitting the nucleus rim difficult and eventually drifted to Shepherd's3 in situ fracture technique. In this procedure, the surgeon prepares the nucleus for fracture by forming four grooves and isolating four small quadrants. Other surgeons were uncomfortable with any procedure that requires outward separation to fracture the nucleus because of stress on the capsule and zonules, so they developed other techniques designed to provide a strategic nuclear collapse. This included the chip and flip 4 and spring surgery. 5 Hydrodelineation permitted nuclear collapse associated with cracking, as in crack and flip. 6 Despite the proliferation of strategies for removing the nucleus, the nuclear rim split strategy Gimbel proposed remained an attractive but difficult procedure for many. Nagahara's phaco-chop provides a much needed tool in phacomanipulation. The chop splits the nuclear rim with an inward motion, marrying nucleofractis with strategic nuclear collapse. Unfortunately, a pure chop provides little room for the pieces to move. Each bump and hollow formed with a chop eventually results in a jigsaw lock of these irregularities. It is difficult to remove some of the pieces, especially the first one. Pieces sometimes have to be held with high aspiration and pulled up into the anterior chamber for emulsification, with obvious risk to the endothelium. We selected the beneficial steps from the nucleofractis and the phaco-chop techniques to create an easier and gentler technique-stop and chop. The trench and the crater give room to manipulate the nuclear pieces easily and safely. Chopping simplifies nuclear rim splitting and promotes strategic nuclear collapse with less tension on the capsular bag or zonules. In stop and chop, we begin with trench or crater formation, depending on the cataract density, and then fracture the posterior plate in the usual fashion. At this point we stop performing nuclear cracking and from then on we chop the nuclear rim, hence the name, stop and chop.
SUMMARY Fig. l 0.
(Koch) Stop and chop: The phaco tip is driven into the remaining nucleus and the same steps are repeated-bury the chopper, pull it toward the phaco tip, chop, separate, remove. This sequence is repeated until the entire nucleus is emulsified.
Stop and chop phacoemulsification combines the strategy of trench or crater divide and conquer, the appositional nuclear split technique of the phaco chop, and the strategic nuclear collapse of spring surgery. It is a safe, efficient way to selectively fracture the nuclear rim
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
569
into bite-size pieces for easy removal while maintaining capsular integrity by providing space within the posterior chamber in which to manipulate and fracture each nuclear segment.
REFERENCES 1. Gimbel HV. Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281-291
570
2. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508-512 3. Shepherd JR. In situ fracture. J Cataract Refract Surg 1990; 16:436-440 4. Fine IH. The chip and flip phacoemulsification technique. J Cataract Refract Surg 1991; 17:366-371 5. Koch PS. Spring surgery. In Koch PS, Davison JA, eds, Textbook of Advanced Phacoemulsification Techniques. Thorofare, NJ, Slack, 1991; 207-238 6. Fine IH, Maloney WF, Dillman DM. Crack and flip phacoemulsification technique. J Cataract Refract Surg 1993; 19:797-802
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
-q I
ue
Stop and chop phacoemulsification PaulS. Koch, M.D., Leeds E. Katzen, M.D.
ABSTRACT We present a method for phacoemulsification within the capsular bag in which sculpting is performed to provide space for nuclear manipulation and then the posterior plate is cracked into two halves. The nuclear rim is chopped into bite-size pieces for removal using a modified lens hook that is buried in the nuclear periphery and pulled toward the center. The procedure begins as a routine nuclear cracking technique and then stops. It continues as a chop technique. Key Words: cataract extraction, cortical cleaving hydrodissection, divide and conquer, in situ fracture, nucleofractis, phaco-chop, phacoemulsification, spring surgery
Many cataract surgeons consider fragmentation of the nucleus a prerequisite for removal from the capsular bag, and many procedures have been designed to facilitate this step. Gimbel 1 described the first set of procedures that established a strategy for nuclear fracturing, divide and conquer nucleofractis. Within this family of procedures were two variations: trench divide and conquer for soft cataracts and crater divide and conquer for firm cataracts. In either case, the plan was to clean out space in the middle of the cataract and then split the nuclear rim into small, bite-size pieces. Gimbel split the nucleus by placing his phaco tip and his spatula parallel to each other in the nuclear rim prior to separation. In a film presented at a recent meeting ("PhacoChop," presented at the 3rd American-International Congress on Cataract, IOL and Refractive Surgery, Seattle, May 1993), Nagahara described a new technique for splitting the nucleus. He used a modified lens hook in an appositional fashion, pulling it through the nucleus from the periphery to the phaco tip. Sculpting and trench construction were neither necessary nor performed. This technique seemed an easy alternative to Gimbel's parallel split; however, the phaco-chop technique left the pieces of nucleus wedged together tightly, making initial and subsequent removal of those pieces difficult (Figures l to 5). In many cases, nuclear fragments had to be pulled into the anterior chamber for removal. We have found that limitations of each technique can
Fig. 1.
(Koch) Phaco-chop: The phaco tip is driven into the superior nucleus at 12 o'clock and held there while the chopper is buried into the nucleus inferiorly.
be overcome by combining portions of each. The surgeon can begin with one technique, stop, and continue with the other, resulting in a technique we refer to as stop and chop phacoemulsification.
SURGICAL TECHNIQUE Unique to the chop method of splitting the nuclear rim is an instrument called a chopper. This was described in Nagahara's video as "a modified lens hook"
Reprint requests to PaulS. Koch, M.D., Koch Eye Associates, 566 Tollgate Road, Warwick, Rhode Island 02886. 566
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
Fig. 2.
(Koch) Phaco-chop: While the phaco tip is held motionless, the chopper is pulled toward it, cracking the nucleus.
Fig. 3. (Koch) Phaco-chop: When the chopper gets close to the phaco tip, the two instruments are separated, chopping the nucleus in half.
and seemed to be a simple manipulator with a right angle tip on the end. We made a variety of choppers by breaking off the tip of a Sinskey hook and bending it again to make longer versions. These choppers measured 1.00 mm, 1.25 mm, 1.50 mm, 1.75 mm, and 2.00 mm from the 90 degree bend to the distal tip. We found that the 1.50 mm chopper worked most reliably and efficiently, and this is the size we currently use. In the stop and chop technique, capsulorhexis is followed by hydrodissection. Cortical cleaving hydrodissection as described by Fine2 is always attempted, but its success or failure does not affect the subsequent steps of nuclear removal. Nuclear sculpting is performed according to the principles Gimbel 1 originally described. It is important to clean out space in the middle of the nucleus so there will be room to manipulate the nuclear fragments in the confines of the posterior chamber, obviating the necessity of pulling fragments up into the anterior chamber.
At the same time, the amount of sculpting must be tempered by the realization that nuclear manipulation depends on preserving a firm nucleus. Therefore, less sculpting is performed in soft cataracts and Il!lore in firm cataracts. This balance permits us to "trenq:h" the soft cataracts and "crater" the firm cataracts (Figures 6 and 7). In the case of a trench, it is carried out d,eeply so that the dark central red reflex turns bright red again as the posterior plate is approached. We like to make it as long as possible, even going slightly under the anterior capsule if necessary. In the case of a crater, it is made as deep and as wide as necessary to get to the margin where firm central nucleus begins to soften. The strategy is to remove the bulk of the firm, center nucleus while leaving enough firm material so that the nucleus can be manipulated. Too much sculpting leaves a soft nuclear shell, which is difficult to work with. When the crater is complete we
Fig. 4. (Koch) Phaco-chop: The nucleus is rotated 90 degrees and the same steps are repeated, chopping the nucleus into quarters.
Fig. 5.
(Koch) Phaco-chop: After the chops are completed, the segments are still wedged together. No significant spaces separate them. Each jagged edge fits with its mate just as in a jigsaw puzzle. It is difficult to remove each segment because of the proximity to its neighbor.
1 CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
567
Fig. 6.
(Koch) Stop and chop: Soft cataracts are prepared by sculpting a trench in the middle of the cataract, providing space for later manipulation.
Fig. 7.
(Koch) Stop and chop: Hard cataracts are prepared by sculpting a crater, removing most of the nucleus' very firm center, and leaving only the less dense rim.
carve a thin trench in its center to be a line of least resistance for the subsequent fracture. We extend this trench into the peripheral nucleus to give a defined spot where the initial nuclear fracture can split the nuclear rim. The next step is fracturing the nucleus into two halves, as is done in many other routine nuclearcracking techniques. In this case we introduce the chopper through the sideport incision and place the bent, distal tip into the trench or crater. We pull to the left with the chopper and push to the right with the phaco tip, moving and adjusting the instruments until there is a complete fracture of the posterior plate, separating the nucleus into two (Figure 8). This concludes the trench/crater nuclear fracturing step of the operation. At this point we stop, and from now on we chop. The nucleus is rotated so that one half of it lies across
the inferior capsular bag. It will be broken up into a number of bite-size pieces for easy removal. A typical medium-density cataract will have each half chopped into three pieces, a dense one more, and a soft one fewer. The phaco tip is buried using gentle emulsification into the inferior half of the nucleus about one third of the way from the right hand side and is held there using aspiration alone. The chopper is placed in the nuclear periphery at about the location of the anterior capsulotomy. If the anterior capsulotomy is too small for easy access for chopping, it can be pushed back gently by the chopper to make more room. The chopper should not perforate the anterior capsule because a radial tear can form. The chopper is then stuck into the peripheral nucleus to its angle, giving a penetration of 1.5 mm. It is then pulled toward the phaco tip, creating a very deep cut in the nucleus. When the chopper reaches the phaco tip, the
Fig. 8.
Fig. 9.
568
(Koch) Stop and chop: After sculpting is complete, the nucleus is fractured into two halves with the phaco tip and the chopper.
(Koch) Stop and chop: The phaco tip is driven into the nuclear half about a third of the way across from right to left. The chopper is buried in the periphery of the nucleus and pulled toward the phaco tip. When the instruments are close to each other, they are separated and a small segment of the nucleus is chopped off. It is already impaled on the phaco tip and can be emulsified without further manipulation.
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
chopper is pulled to the left and the phaco tip pushed to the right, creating a split in the nuclear rim with complete separation of one nuclear piece (Figure 9). The nuclear piece separated by the chop is already impaled on the phaco tip and held there with the same aspiration that held the piece steady for the chop. If the separated piece is small enough for easy removal, the phaco tip only has to go into emulsification to remove it easily without the challenging steps of pursuit, capture, rotation, or tumbling. The chopped-off piece, already attached to the phaco tip, gently follows into the tip during emulsification. The reason the piece separates off so easily and is free to glide into the phaco tip so nicely is that the initial trench or crater created space into which the nuclear piece can move. It can be manipulated in the posterior chamber and emulsified easily there without any need to free it up by pulling it into the anterior chamber, as is sometimes necessary with pure phaco chop. Once the first piece is chopped off and removed, the phaco tip and the chopper repeat the same steps, chopping a piece of the remainder of the nuclear half and emulsifying that as well. These steps-bury the phaco tip, bury the chopper, chop, separate, remove-are repeated until the entire nucleus is removed (Figure 10). Although we usually divide a nuclear rim into about six segments, more or fewer chops can be used depending on the density of the nucleus. Four segments are usually all that are necessary for a soft cataract or one in which a small endonucleus has been isolated through extensive hydrodelineation. A dense nucleus has to be broken into more small pieces because greater density requires smaller pieces to meet the bite-size criteria. Very dense cataracts may require 12 or more nuclear rim chops. In these cases, it is often best to leave the pieces in place until all of the chops are performed to keep the bag stretched and to
reduce the possibility of ripping the posterior capsule with the edge of one of them.
DISCUSSION Ever since the development of the continuous curvilinear capsulotomy, surgeons have been devising ways to remove the nucleus from within the capsular bag. Gimbel' originally advised a strategy of splitting the nuclear rim using his nucleofractis technique. Many surgeons found his method of splitting the nucleus rim difficult and eventually drifted to Shepherd's3 in situ fracture technique. In this procedure, the surgeon prepares the nucleus for fracture by forming four grooves and isolating four small quadrants. Other surgeons were uncomfortable with any procedure that requires outward separation to fracture the nucleus because of stress on the capsule and zonules, so they developed other techniques designed to provide a strategic nuclear collapse. This included the chip and flip 4 and spring surgery. 5 Hydrodelineation permitted nuclear collapse associated with cracking, as in crack and flip. 6 Despite the proliferation of strategies for removing the nucleus, the nuclear rim split strategy Gimbel proposed remained an attractive but difficult procedure for many. Nagahara's phaco-chop provides a much needed tool in phacomanipulation. The chop splits the nuclear rim with an inward motion, marrying nucleofractis with strategic nuclear collapse. Unfortunately, a pure chop provides little room for the pieces to move. Each bump and hollow formed with a chop eventually results in a jigsaw lock of these irregularities. It is difficult to remove some of the pieces, especially the first one. Pieces sometimes have to be held with high aspiration and pulled up into the anterior chamber for emulsification, with obvious risk to the endothelium. We selected the beneficial steps from the nucleofractis and the phaco-chop techniques to create an easier and gentler technique-stop and chop. The trench and the crater give room to manipulate the nuclear pieces easily and safely. Chopping simplifies nuclear rim splitting and promotes strategic nuclear collapse with less tension on the capsular bag or zonules. In stop and chop, we begin with trench or crater formation, depending on the cataract density, and then fracture the posterior plate in the usual fashion. At this point we stop performing nuclear cracking and from then on we chop the nuclear rim, hence the name, stop and chop.
SUMMARY Fig. l 0.
(Koch) Stop and chop: The phaco tip is driven into the remaining nucleus and the same steps are repeated-bury the chopper, pull it toward the phaco tip, chop, separate, remove. This sequence is repeated until the entire nucleus is emulsified.
Stop and chop phacoemulsification combines the strategy of trench or crater divide and conquer, the appositional nuclear split technique of the phaco chop, and the strategic nuclear collapse of spring surgery. It is a safe, efficient way to selectively fracture the nuclear rim
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994
569
into bite-size pieces for easy removal while maintaining capsular integrity by providing space within the posterior chamber in which to manipulate and fracture each nuclear segment.
REFERENCES 1. Gimbel HV. Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281-291
570
2. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508-512 3. Shepherd JR. In situ fracture. J Cataract Refract Surg 1990; 16:436-440 4. Fine IH. The chip and flip phacoemulsification technique. J Cataract Refract Surg 1991; 17:366-371 5. Koch PS. Spring surgery. In Koch PS, Davison JA, eds, Textbook of Advanced Phacoemulsification Techniques. Thorofare, NJ, Slack, 1991; 207-238 6. Fine IH, Maloney WF, Dillman DM. Crack and flip phacoemulsification technique. J Cataract Refract Surg 1993; 19:797-802
J CATARACT REFRACT SURG-VOL 20, SEPTEMBER 1994