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Phacoemulsification Without Ultrasound
Phacoemulsification Without Ultrasound ROBERT C. DREWS
OBJECTIVE: to produce grooving of cataract without using ultrasound energy. BASIC PROBLEM: Phacoemulsification is expensive. YAG laser energy can be used to demonstrate both lamellar and radial structure within the nucleus of cataractous lenses. This knowledge gives a rational basis for the grooving of a cataract in phacoemulsification. RESULTS: We find that grooving can also be accomplished using a sharpened Charleux cannula in most cases. The fragments can be delivered with an irrigating spoon. CONCLUSIONS: This knowledge allows inexpensive planned extracapsular cataract extraction through a small wound. Key words: Phacoemulsification; Ultrasound; Lens anatomy; YAG laser; Grooving; Charleux cannula A great deal has been written about the anatomy of the lens capsule. The features of importance to the extracapsular surgeon have been summarized [1], one need only add the importance of a smooth edge for situations in which strength of a capsulotomy is important. Likewise, the anatomy of the lens cortex is well known, with its arcuate fibrils. The striking demonstration of the zipper-like connection between the fibrils by Worst [2] (Fig. 1) helps us to understand why cortex tends to strip as wedge-like sheets when grasped in the opening of an aspiration cannula. The anatomy of the nucleus presents a dilemma. It is well understood that the nucleus is comprised of compressed cortex. If so, it should have a radial structure as well as lamellar. In young people both histologically and at slit lamp examination there are distinct nuclear lamellae and radial sutures. Using YAG laser energy [3] it is possible to demonstrate the lamellar anatomy of the nucleus and the radial anatomy even of the nuclear core (Fig. 2). Hydrodissection of the lens is a standard procedure now in both extracapsular surgery and phacoemulsification. Hirschman first demonstrated hydrodissection of the cortex. His diagram clearly showed hydrodissection from both anterior and posterior lens capsule [4]. My studies in cadaver eyes with milk failed to confirm the dissection from the posterior capsule, [5] but in retrospect this apparently was because my flow rate (force) was too small. Fine [6] has now popularized this technique using a larger bore cannula under the flap of the anterior lens capsule to produce a fluid wave posteriorly. Injection deep between the anterior epinucleus and Paper presented at 10 MSG meeting 4-8 October 1992. 0955-3681/93/020080+02 $08.00/0
© 1993 Bailliere Tindall
the nuclear core produces the so-called golden ring at the boundary between these structures, seen when there is sufficient red reflex. Purposeful hydrodissection of the posterior cortex from the posterior lens capsule is also a useful technique when a thick layer of cortex remains after delivery of the nucleus [5]. YAG laser demonstration of radial fracture lines within the nuclear core gives an anatomical basis for the formation of grooves across the nucleus in phacoemulsification. Phacoemulsification makes use of ultrasound to pulverize the nucleus. The dynamics of the shock wave generated by this ultrasound have been well demonstrated in Schlieren photographs by Krey [7]. Maloney [8] and others have advocated using lower power settings for ultrasound: 20% seems adequate in many instances. The question arises whether the ultrasonic energy could be dispensed with completely. · If a cystotome is used gently so as not to engage the nucleus and rock it free of its attachments to the posterior cortex, it is possible to scratch deep grooves across the diameters of the nucleus. Utilizing this information I had Charleux 1/A cannulas prepared with a sharp tip (Fig. 3). With these cannulas it turns out to be remarkably easy in most patients to produce grooves in the lens. One need only to be careful to work gently. It is also important to avoid pressure posteriorly-both for this technique as well as for phacoemulsification-to avoid pushing the nucleus through the posterior capsule. Maldonado of Cordoba, Argentina has independently invented the same sharpened cannula (personal communication). He prefers to leave the nucleus attached to the posterior cortex and uses the cannula for sculpting the nucleus much as was done with phacoemulsification Eur J Implant Ref Surg, Vol5, June 1993
81
Phacoemulslfication Without Ultrasound
Fig. 1 The demonstration by Jan Worst of the zipper-like anatomy of the cortical fibrils
before nuclear cracking became popular. I tend to do all of my hydrodissection first, then groove the nucleus deeply once or twice dividing it into halves or quarters; or to sculpt it at 6:00, rotating a fresh-area to 6:00 as needed. I find it unfeasible to attempt to further carve and aspirate the nuclear pieces. Instead these are delivered with an irrigating spoon [8), taking care not to bring the fragments forward against the corneal endothelium. Using this technique, one can deliver most nuclei through a 5.5 mm wound. As in phacoemulsification, for the average surgeon the extremely hard nucleus is probably more safely removed by standard planned extracapsular techniques with a larger incision.
REFERENCES 1 RC Drews. The lens capsule: a lens implant surgeon's understanding. The Mary Louise Prentice Montgomery Lecture. Trans. Ophthalmol. Soc. UK., 1986; 105: 265-272. 2 J Worst. Some aspects of cataract morphology: a SEM study. Doc. Ophthalmol., 1988; 70: 155-163. 3 · RC Drews. YAG laser demonstration of nuclear anatomy. Ophthalmic Surg., 1992; 23: 822-824. 4 H Hirschman. Loosening the nucleus without disinsertion or rupture. Ocular Surg. News, 1985; Nov: 41. 5 RC Drews. Hydrodissection in extracapsular cataract extraction. Eur. J. Implant Ref Surg., 1989; 1: 99-100. 6 H Fine. Cortical cleaving hydrodissection. J . Cataract Refract. Surg., 1991; 17: 508-512. 7 H Krey. Ultrasonic turbulences at the phacoemulsification tip. J . Cataract Refract. Surg., 1989; 15: 343-344. 8 WF Maloney. Phaco light: new and improved for 1992. Ocular Surg. News, 1992; Jan: 22. Fig. 2 Bursts of energy from a YAG laser can be used to demonstrate both the lamellar and radial anatomy of even a hard brunescent nucleus
Fig. 3 Using a sharp Charleux cannula, one can groove or sculpt the nucleus without ultrasound. This patient was 87 years old. The sculpting needs to be done gently, in small layers Eur J Implant Ref Surg, Vol5, June 1993
OBJECTIVE: to produce grooving of cataract without using ultrasound energy. BASIC PROBLEM: Phacoemulsification is expensive. YAG laser energy can be used to demonstrate both lamellar and radial structure within the nucleus of cataractous lenses. This knowledge gives a rational basis for the grooving of a cataract in phacoemulsification. RESULTS: We find that grooving can also be accomplished using a sharpened Charleux cannula in most cases. The fragments can be delivered with an irrigating spoon. CONCLUSIONS: This knowledge allows inexpensive planned extracapsular cataract extraction through a small wound. Key words: Phacoemulsification; Ultrasound; Lens anatomy; YAG laser; Grooving; Charleux cannula A great deal has been written about the anatomy of the lens capsule. The features of importance to the extracapsular surgeon have been summarized [1], one need only add the importance of a smooth edge for situations in which strength of a capsulotomy is important. Likewise, the anatomy of the lens cortex is well known, with its arcuate fibrils. The striking demonstration of the zipper-like connection between the fibrils by Worst [2] (Fig. 1) helps us to understand why cortex tends to strip as wedge-like sheets when grasped in the opening of an aspiration cannula. The anatomy of the nucleus presents a dilemma. It is well understood that the nucleus is comprised of compressed cortex. If so, it should have a radial structure as well as lamellar. In young people both histologically and at slit lamp examination there are distinct nuclear lamellae and radial sutures. Using YAG laser energy [3] it is possible to demonstrate the lamellar anatomy of the nucleus and the radial anatomy even of the nuclear core (Fig. 2). Hydrodissection of the lens is a standard procedure now in both extracapsular surgery and phacoemulsification. Hirschman first demonstrated hydrodissection of the cortex. His diagram clearly showed hydrodissection from both anterior and posterior lens capsule [4]. My studies in cadaver eyes with milk failed to confirm the dissection from the posterior capsule, [5] but in retrospect this apparently was because my flow rate (force) was too small. Fine [6] has now popularized this technique using a larger bore cannula under the flap of the anterior lens capsule to produce a fluid wave posteriorly. Injection deep between the anterior epinucleus and Paper presented at 10 MSG meeting 4-8 October 1992. 0955-3681/93/020080+02 $08.00/0
© 1993 Bailliere Tindall
the nuclear core produces the so-called golden ring at the boundary between these structures, seen when there is sufficient red reflex. Purposeful hydrodissection of the posterior cortex from the posterior lens capsule is also a useful technique when a thick layer of cortex remains after delivery of the nucleus [5]. YAG laser demonstration of radial fracture lines within the nuclear core gives an anatomical basis for the formation of grooves across the nucleus in phacoemulsification. Phacoemulsification makes use of ultrasound to pulverize the nucleus. The dynamics of the shock wave generated by this ultrasound have been well demonstrated in Schlieren photographs by Krey [7]. Maloney [8] and others have advocated using lower power settings for ultrasound: 20% seems adequate in many instances. The question arises whether the ultrasonic energy could be dispensed with completely. · If a cystotome is used gently so as not to engage the nucleus and rock it free of its attachments to the posterior cortex, it is possible to scratch deep grooves across the diameters of the nucleus. Utilizing this information I had Charleux 1/A cannulas prepared with a sharp tip (Fig. 3). With these cannulas it turns out to be remarkably easy in most patients to produce grooves in the lens. One need only to be careful to work gently. It is also important to avoid pressure posteriorly-both for this technique as well as for phacoemulsification-to avoid pushing the nucleus through the posterior capsule. Maldonado of Cordoba, Argentina has independently invented the same sharpened cannula (personal communication). He prefers to leave the nucleus attached to the posterior cortex and uses the cannula for sculpting the nucleus much as was done with phacoemulsification Eur J Implant Ref Surg, Vol5, June 1993
81
Phacoemulslfication Without Ultrasound
Fig. 1 The demonstration by Jan Worst of the zipper-like anatomy of the cortical fibrils
before nuclear cracking became popular. I tend to do all of my hydrodissection first, then groove the nucleus deeply once or twice dividing it into halves or quarters; or to sculpt it at 6:00, rotating a fresh-area to 6:00 as needed. I find it unfeasible to attempt to further carve and aspirate the nuclear pieces. Instead these are delivered with an irrigating spoon [8), taking care not to bring the fragments forward against the corneal endothelium. Using this technique, one can deliver most nuclei through a 5.5 mm wound. As in phacoemulsification, for the average surgeon the extremely hard nucleus is probably more safely removed by standard planned extracapsular techniques with a larger incision.
REFERENCES 1 RC Drews. The lens capsule: a lens implant surgeon's understanding. The Mary Louise Prentice Montgomery Lecture. Trans. Ophthalmol. Soc. UK., 1986; 105: 265-272. 2 J Worst. Some aspects of cataract morphology: a SEM study. Doc. Ophthalmol., 1988; 70: 155-163. 3 · RC Drews. YAG laser demonstration of nuclear anatomy. Ophthalmic Surg., 1992; 23: 822-824. 4 H Hirschman. Loosening the nucleus without disinsertion or rupture. Ocular Surg. News, 1985; Nov: 41. 5 RC Drews. Hydrodissection in extracapsular cataract extraction. Eur. J. Implant Ref Surg., 1989; 1: 99-100. 6 H Fine. Cortical cleaving hydrodissection. J . Cataract Refract. Surg., 1991; 17: 508-512. 7 H Krey. Ultrasonic turbulences at the phacoemulsification tip. J . Cataract Refract. Surg., 1989; 15: 343-344. 8 WF Maloney. Phaco light: new and improved for 1992. Ocular Surg. News, 1992; Jan: 22. Fig. 2 Bursts of energy from a YAG laser can be used to demonstrate both the lamellar and radial anatomy of even a hard brunescent nucleus
Fig. 3 Using a sharp Charleux cannula, one can groove or sculpt the nucleus without ultrasound. This patient was 87 years old. The sculpting needs to be done gently, in small layers Eur J Implant Ref Surg, Vol5, June 1993