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Multilevel chop technique
TECHNIQUE
Multilevel chop technique Abhay R. Vasavada, MS, FRCS, Shetal M. Raj, MS, DO
It is difficult to completely divide a hard nucleus. Excessive force is required, which may inadvertently lead to capsular bag distortion and cause stress to the zonules. We describe a chop technique that enables the surgeon to consistently achieve complete division of brunescent and black cataracts. Financial Disclosure: Neither author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2011; 37:2092–2094 Q 2011 ASCRS and ESCRS Online Video
Complete division of dense nuclei is crucial to accomplishing uneventful phacoemulsification. Removal of the conjoined segments causes mechanical damage and excessive energy dissipation, endangering the integrity of the endothelium, the posterior capsule, or the uveal tissue. Many techniques to achieve nuclear division have been described.1–8,A We describe a technique that facilitates complete division of dense leathery nuclear fibers. SURGICAL TECHNIQUE This technique can be done with or without creating a central groove and can be used for vertical and horizontal chop actions. Vertical Chop Action When using the vertical chop technique, a central groove is sculpted using appropriate ultrasound energy. The groove is made well within the capsulorhexis margin. The typical parameters for this step are as follows: Preset ultrasound energy of 70% to 80%,
Submitted: March 31, 2011. Final revision submitted: July 27, 2011. Accepted: July 29, 2011. From the Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India. Presented in part at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, April, 2010. Corresponding author: Abhay R. Vasavada, MS, FRCS, Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Gurukul Road, Memnagar, Ahmedabad, 380 052 India. E-mail: icirc@ abhayvasavada.com.
2092
Q 2011 ASCRS and ESCRS Published by Elsevier Inc.
vacuum of 40 mm Hg, and aspiration flow rate of 20 to 25 cc/min. Following this, the next step is nuclear division. The phaco tip is introduced into the nucleus (Figure 1, A). The vertical element of the chopper is depressed posteriorly within the lens fibers, keeping it adjacent to the tip (Figure 1, B). This initiates a partial crack. The phaco tip is then reintroduced at a posterior plane, and the chopper is also repositioned at a posterior level within the crack (Figure 1, C). A combination of the vertical chop and lateral separation is performed with the chopper while the probe holds the occluded lens material in a stationary position (Figure 1, D). This effectively separates the posterior lens fibers completely. The preset parameters for emulsifying these cataracts are as follows: ultrasound energy of 50% to 60%, vacuum of 600 mm Hg, aspiration flow rate of 20 to 25 cc/min, bottle height of 50 to 60 cm from the patient’s eye level. In very leathery cataracts, further repositioning of the phaco tip and chopper is seldom required. Typically, the vacuum is preset to between 300 and 400 mm Hg, but in very dense cataracts, vacuum up to 600 mm Hg is used during nuclear division. For emulsification of fragments, the vacuum is reduced to between 200 and 300 mm Hg (Video, available at http://jcrsjournal.org). Horizontal Chop Action The multilevel chop technique is also applicable when using the horizontal chop principle. The probe is introduced in the lens substance in the midperipheral region (Figure 2, A). The chopper is placed at the equator and moved toward the occluded phaco tip (Figure 2, B). The probe is then repositioned centrally while the chopper is positioned inside the crack and moved toward the phaco tip (Figure 2, C and D). In our experience with the horizontal chop technique, an equally effective separation outcome can be 0886-3350/$ - see front matter doi:10.1016/j.jcrs.2011.10.002
TECHNIQUE: MULTILEVEL CHOP TECHNIQUE
2093
Figure 1. The vertical chop technique. A: The phaco tip is introduced into the nucleus. B: The vertical element of the chopper is depressed posteriorly in the lens fibers, keeping it adjacent to the tip. This initiates a partial crack. C: The phaco tip is reintroduced at a posterior plane. The chopper is also repositioned at a posterior level within the crack. D: A combination of vertical chop and lateral separation is performed with the chopper while the probe holds the occluded lens material in a stationary position. This effectively separates the posterior lens fibers.
achieved with slightly lower parameters. Typical preset parameters are ultrasound energy of 50% to 60%, vacuum of up to 500 mm Hg, and aspiration flow rate of 20 to 25 cc/min. The multilevel chop is repeated 360 degrees within the nucleus, resulting in multiple small segments. Once complete division of the nucleus is achieved, the parameters are changed appropriately to remove the lens fragments.
Results In the past 18 months, the technique has been used in more than 100 eyes with brunescent and black nucleus sclerosis as well as in eyes with mature cataracts camouflaging a dense nucleus and in eyes with compromised zonular fibers. In all cases, complete division of the posterior lens fibers was achieved. No intraoperative complications such as zonular dialysis, uveal trauma, or posterior capsule rupture were noted.
Figure 2. The horizontal chop technique. A: The probe is introduced into the midperipheral region of the lens substance. B: The chopper is placed at the equator and moved toward the occluded phaco tip. C and D: Subsequently, the probe is repositioned centrally while the chopper is positioned inside the crack and moved toward the phaco tip.
J CATARACT REFRACT SURG - VOL 37, DECEMBER 2011
2094
TECHNIQUE: MULTILEVEL CHOP TECHNIQUE
DISCUSSION The division of very dense or brunescent and black cataracts using phacoemulsification remains a challenge for cataract surgeons. Veteran surgeons have reported techniques that successfully divide the nucleus with a modest level of nuclear sclerosis.1–6,A In most division techniques, it is customary to maintain the occlusion and the chopper at a single site to achieve division.1,4,5,A Often, the single-site chop action separates the posterior lens fibers completely. In dense nuclear sclerosis, however, this maneuver may not separate the leathery fibers completely. Moreover, the single-site chop action also involves the use of excessive separation force, causing tilting of the nuclear segment within the capsular bag. The capsular bag and zonules may be distorted, endangering their integrity. To reduce these complications, we devised the stepby-step, chop-in-situ, and lateral separation technique for phacoemulsification of brunescent and black cataracts.7,8 In this technique, the occlusion is maintained at a single site while the chopper is repositioned at different sites from the anterior to the posterior of the nucleus. Using this technique, however, the separation of the posterior fibers is seldom complete with black nuclear sclerotic cataracts. We therefore conceived the multilevel chop technique to circumvent these limitations in dense leathery cataracts.B By repositioning the chopper as well as the site of occlusion with the probe at 2 planes (Figure 1), we could achieve complete division. With these maneuvers, the separation forces are distributed at multiple levels. Moreover, the division forces are brought closer to the posterior nuclear fibers that must be divided. The multilevel chop technique works well with both longitudinal and torsional ultrasound. Creating a central groove provides better space and allows removal of fragments at the posterior plane. Additionally, the recommended parameters can be used to achieve satisfactory division with both ultrasound modalities. However, it is important to reduce the preset parameters, particularly the preset vacuum and aspiration flow rate, when the divided fragments are emulsified. That is where the torsional ultrasound works more efficiently, providing superior followability and efficacy.9 The multilevel chop technique can be applied in only select cases of cataract. Surgeons can continue using their chopper and select a chop technique of their choice. They do not have to adapt to a new technique as the single-level chop technique can be applied at multiple levels. We also recommend dividing the entire nucleus into multiple fragments before commencing removal. However, these processes require different parameters and surgeons may find it tedious
to change parameters for each stage of surgery. If the fragments occupy the bag before removal, they can be safely divided. In the initial learning phase of the vertical chop, the surgeon may lower the vacuum and flow rate to perform a deeper level chop. This will enhance the safety by preventing inadvertent posterior capsule rupture, even if it means slowing down the pace of the surgery. The multilevel chop technique is safe and effective. It involves occluding and positioning the chopper at 2 or more levels to achieve complete division of black and brunescent cataracts. We have initiated a study to evaluate the intraoperative performance as well as postoperative outcomes using this technique in eyes with dense nuclear sclerosis. REFERENCES 1. Shepherd JR. In situ fracture. J Cataract Refract Surg 1990; 16:436–440 2. Gimbel HV. Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281–291 3. Fine IH, Maloney WF, Dillman DM. Crack and flip phacoemulsification technique. J Cataract Refract Surg 1993; 19:797–802 4. Koch PS, Katzen LE. Stop and chop phacoemulsification. J Cataract Refract Surg 1994; 20:566–570 5. Koch PS. Mastering Phacoemulsification: A Simplified Manual of Strategies for the Spring, Crack and Stop & Chop Technique, 4th ed. Thorofare, NJ, Slack, 1994; 99–102 6. Akahoshi T. Phaco prechop: manual nucleofracture prior to phacoemulsification. Operative Tech Cataract Refract Surg 1998; 1:69–91 7. Vasavada A, Singh R. Step-by-step chop in situ and separation of very dense cataracts. J Cataract Refract Surg 1998; 24:156–159 8. Singh R, Vasavada AR, Janaswamy G. Phacoemulsification of brunescent and black cataracts. J Cataract Refract Surg 2001; 27:1762–1769 9. Vasavada AR, Raj SM, Patel U, Vasavada V, Vasavada V. Comparison of torsional and microburst longitudinal phacoemulsification: a prospective, randomized, masked clinical trial. Ophthalmic Surg Lasers Imaging 2010; 41:109–114
OTHER CITED MATERIAL A. Nagahara K, ‘‘Phaco Chop,’’ film presented at the ASCRS 3rd American–International Congress on Cataract, IOL and Refractive Surgery, Seattle, Washington, USA, May 1993 B. Vasavada AR, Raj SM, Vasavada VA, Vasavada VA, Praveen MR, Shastri L,“The Multi- Level Chop Technique,” presented at ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, April 2010
J CATARACT REFRACT SURG - VOL 37, DECEMBER 2011
First author: Abhay R. Vasavada, MS, FRCS Iladevi Cataract IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India
Multilevel chop technique Abhay R. Vasavada, MS, FRCS, Shetal M. Raj, MS, DO
It is difficult to completely divide a hard nucleus. Excessive force is required, which may inadvertently lead to capsular bag distortion and cause stress to the zonules. We describe a chop technique that enables the surgeon to consistently achieve complete division of brunescent and black cataracts. Financial Disclosure: Neither author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2011; 37:2092–2094 Q 2011 ASCRS and ESCRS Online Video
Complete division of dense nuclei is crucial to accomplishing uneventful phacoemulsification. Removal of the conjoined segments causes mechanical damage and excessive energy dissipation, endangering the integrity of the endothelium, the posterior capsule, or the uveal tissue. Many techniques to achieve nuclear division have been described.1–8,A We describe a technique that facilitates complete division of dense leathery nuclear fibers. SURGICAL TECHNIQUE This technique can be done with or without creating a central groove and can be used for vertical and horizontal chop actions. Vertical Chop Action When using the vertical chop technique, a central groove is sculpted using appropriate ultrasound energy. The groove is made well within the capsulorhexis margin. The typical parameters for this step are as follows: Preset ultrasound energy of 70% to 80%,
Submitted: March 31, 2011. Final revision submitted: July 27, 2011. Accepted: July 29, 2011. From the Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India. Presented in part at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, April, 2010. Corresponding author: Abhay R. Vasavada, MS, FRCS, Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Gurukul Road, Memnagar, Ahmedabad, 380 052 India. E-mail: icirc@ abhayvasavada.com.
2092
Q 2011 ASCRS and ESCRS Published by Elsevier Inc.
vacuum of 40 mm Hg, and aspiration flow rate of 20 to 25 cc/min. Following this, the next step is nuclear division. The phaco tip is introduced into the nucleus (Figure 1, A). The vertical element of the chopper is depressed posteriorly within the lens fibers, keeping it adjacent to the tip (Figure 1, B). This initiates a partial crack. The phaco tip is then reintroduced at a posterior plane, and the chopper is also repositioned at a posterior level within the crack (Figure 1, C). A combination of the vertical chop and lateral separation is performed with the chopper while the probe holds the occluded lens material in a stationary position (Figure 1, D). This effectively separates the posterior lens fibers completely. The preset parameters for emulsifying these cataracts are as follows: ultrasound energy of 50% to 60%, vacuum of 600 mm Hg, aspiration flow rate of 20 to 25 cc/min, bottle height of 50 to 60 cm from the patient’s eye level. In very leathery cataracts, further repositioning of the phaco tip and chopper is seldom required. Typically, the vacuum is preset to between 300 and 400 mm Hg, but in very dense cataracts, vacuum up to 600 mm Hg is used during nuclear division. For emulsification of fragments, the vacuum is reduced to between 200 and 300 mm Hg (Video, available at http://jcrsjournal.org). Horizontal Chop Action The multilevel chop technique is also applicable when using the horizontal chop principle. The probe is introduced in the lens substance in the midperipheral region (Figure 2, A). The chopper is placed at the equator and moved toward the occluded phaco tip (Figure 2, B). The probe is then repositioned centrally while the chopper is positioned inside the crack and moved toward the phaco tip (Figure 2, C and D). In our experience with the horizontal chop technique, an equally effective separation outcome can be 0886-3350/$ - see front matter doi:10.1016/j.jcrs.2011.10.002
TECHNIQUE: MULTILEVEL CHOP TECHNIQUE
2093
Figure 1. The vertical chop technique. A: The phaco tip is introduced into the nucleus. B: The vertical element of the chopper is depressed posteriorly in the lens fibers, keeping it adjacent to the tip. This initiates a partial crack. C: The phaco tip is reintroduced at a posterior plane. The chopper is also repositioned at a posterior level within the crack. D: A combination of vertical chop and lateral separation is performed with the chopper while the probe holds the occluded lens material in a stationary position. This effectively separates the posterior lens fibers.
achieved with slightly lower parameters. Typical preset parameters are ultrasound energy of 50% to 60%, vacuum of up to 500 mm Hg, and aspiration flow rate of 20 to 25 cc/min. The multilevel chop is repeated 360 degrees within the nucleus, resulting in multiple small segments. Once complete division of the nucleus is achieved, the parameters are changed appropriately to remove the lens fragments.
Results In the past 18 months, the technique has been used in more than 100 eyes with brunescent and black nucleus sclerosis as well as in eyes with mature cataracts camouflaging a dense nucleus and in eyes with compromised zonular fibers. In all cases, complete division of the posterior lens fibers was achieved. No intraoperative complications such as zonular dialysis, uveal trauma, or posterior capsule rupture were noted.
Figure 2. The horizontal chop technique. A: The probe is introduced into the midperipheral region of the lens substance. B: The chopper is placed at the equator and moved toward the occluded phaco tip. C and D: Subsequently, the probe is repositioned centrally while the chopper is positioned inside the crack and moved toward the phaco tip.
J CATARACT REFRACT SURG - VOL 37, DECEMBER 2011
2094
TECHNIQUE: MULTILEVEL CHOP TECHNIQUE
DISCUSSION The division of very dense or brunescent and black cataracts using phacoemulsification remains a challenge for cataract surgeons. Veteran surgeons have reported techniques that successfully divide the nucleus with a modest level of nuclear sclerosis.1–6,A In most division techniques, it is customary to maintain the occlusion and the chopper at a single site to achieve division.1,4,5,A Often, the single-site chop action separates the posterior lens fibers completely. In dense nuclear sclerosis, however, this maneuver may not separate the leathery fibers completely. Moreover, the single-site chop action also involves the use of excessive separation force, causing tilting of the nuclear segment within the capsular bag. The capsular bag and zonules may be distorted, endangering their integrity. To reduce these complications, we devised the stepby-step, chop-in-situ, and lateral separation technique for phacoemulsification of brunescent and black cataracts.7,8 In this technique, the occlusion is maintained at a single site while the chopper is repositioned at different sites from the anterior to the posterior of the nucleus. Using this technique, however, the separation of the posterior fibers is seldom complete with black nuclear sclerotic cataracts. We therefore conceived the multilevel chop technique to circumvent these limitations in dense leathery cataracts.B By repositioning the chopper as well as the site of occlusion with the probe at 2 planes (Figure 1), we could achieve complete division. With these maneuvers, the separation forces are distributed at multiple levels. Moreover, the division forces are brought closer to the posterior nuclear fibers that must be divided. The multilevel chop technique works well with both longitudinal and torsional ultrasound. Creating a central groove provides better space and allows removal of fragments at the posterior plane. Additionally, the recommended parameters can be used to achieve satisfactory division with both ultrasound modalities. However, it is important to reduce the preset parameters, particularly the preset vacuum and aspiration flow rate, when the divided fragments are emulsified. That is where the torsional ultrasound works more efficiently, providing superior followability and efficacy.9 The multilevel chop technique can be applied in only select cases of cataract. Surgeons can continue using their chopper and select a chop technique of their choice. They do not have to adapt to a new technique as the single-level chop technique can be applied at multiple levels. We also recommend dividing the entire nucleus into multiple fragments before commencing removal. However, these processes require different parameters and surgeons may find it tedious
to change parameters for each stage of surgery. If the fragments occupy the bag before removal, they can be safely divided. In the initial learning phase of the vertical chop, the surgeon may lower the vacuum and flow rate to perform a deeper level chop. This will enhance the safety by preventing inadvertent posterior capsule rupture, even if it means slowing down the pace of the surgery. The multilevel chop technique is safe and effective. It involves occluding and positioning the chopper at 2 or more levels to achieve complete division of black and brunescent cataracts. We have initiated a study to evaluate the intraoperative performance as well as postoperative outcomes using this technique in eyes with dense nuclear sclerosis. REFERENCES 1. Shepherd JR. In situ fracture. J Cataract Refract Surg 1990; 16:436–440 2. Gimbel HV. Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281–291 3. Fine IH, Maloney WF, Dillman DM. Crack and flip phacoemulsification technique. J Cataract Refract Surg 1993; 19:797–802 4. Koch PS, Katzen LE. Stop and chop phacoemulsification. J Cataract Refract Surg 1994; 20:566–570 5. Koch PS. Mastering Phacoemulsification: A Simplified Manual of Strategies for the Spring, Crack and Stop & Chop Technique, 4th ed. Thorofare, NJ, Slack, 1994; 99–102 6. Akahoshi T. Phaco prechop: manual nucleofracture prior to phacoemulsification. Operative Tech Cataract Refract Surg 1998; 1:69–91 7. Vasavada A, Singh R. Step-by-step chop in situ and separation of very dense cataracts. J Cataract Refract Surg 1998; 24:156–159 8. Singh R, Vasavada AR, Janaswamy G. Phacoemulsification of brunescent and black cataracts. J Cataract Refract Surg 2001; 27:1762–1769 9. Vasavada AR, Raj SM, Patel U, Vasavada V, Vasavada V. Comparison of torsional and microburst longitudinal phacoemulsification: a prospective, randomized, masked clinical trial. Ophthalmic Surg Lasers Imaging 2010; 41:109–114
OTHER CITED MATERIAL A. Nagahara K, ‘‘Phaco Chop,’’ film presented at the ASCRS 3rd American–International Congress on Cataract, IOL and Refractive Surgery, Seattle, Washington, USA, May 1993 B. Vasavada AR, Raj SM, Vasavada VA, Vasavada VA, Praveen MR, Shastri L,“The Multi- Level Chop Technique,” presented at ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, April 2010
J CATARACT REFRACT SURG - VOL 37, DECEMBER 2011
First author: Abhay R. Vasavada, MS, FRCS Iladevi Cataract IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India