- Email: [email protected]
Ultrasmall-incision bimanual phacoemulsification and AcrySof SA30AL implantation through a 2.2 mm incision
Ultrasmall-incision bimanual phacoemulsification and AcrySof SA30AL implantation through a 2.2 mm incision Hiroshi Tsuneoka, MD, Ayako Hayama, MD, Michiko Takahama, MD Phacoemulsification and aspiration were performed with a sleeveless ultrasound tip through an ultrasmall incision (1.2 to 1.4 mm) using a 20-gauge irrigating hook through a side port to infuse the anterior chamber. After the lens was extracted, the incision was enlarged to 2.2 mm and a single-piece intraocular lens (AcrySof姞 SA30AL, Alcon) with an optic diameter of 5.5 mm was inserted. By modifying the new injector system, the AcrySof SA30AL could be inserted through a 2.2 mm incision in 100% of cases (63 eyes) in which it was feasible to use a thin lens having a central thickness of less than 20 diopters (D). A 2.2 mm incision was also used successfully in 54% of cases (42 of 78 eyes) that required a lens with a central thickness of 20 D or higher. J Cataract Refract Surg 2003; 29:1070 –1076 © 2003 ASCRS and ESCRS
T
he widespread adoption of ultrasound technology in cataract surgery and the advent of foldable intraocular lenses (IOLs) have made it possible to perform cataract surgery and IOL implantation through a small incision of 3.0 to 4.0 mm. Now surgeons are experimenting with even smaller incisions. Considerable interest has been focused on neodymium:YAG laser surgery to extract the lens through an ultrasmall incision of less than 1.5 mm.1 However, laser surgery technology needs further improvement before it will be fully mature, and some time will be required before it is widely used. In 1999, we began using a standard phacoemulsification and aspiration (PEA) machine to perform bimanual PEA with a sleeveless phaco tip through an ultrasmall incision of less than 1.5 mm.2,3 With this surgical technique, we insert a 21-gauge or 20-gauge ultrasound tip with the infusion sleeve removed (sleeveless phaco tip) through a corneal incision of 1.2 to 1.4 mm, slightly Accepted for publication December 23, 2002.
larger than the outer diameter of the tip, with infusion through a 1.2 mm side port. The use of 2 incisions allows us to perform bimanual nucleofractis. As of June 2002, we had performed this surgery in more than 900 eyes with a success rate comparable to that of conventional surgery. Although this surgical technique makes it possible to remove the lens safely through an incision of 1.2 to 1.4 mm, until recently we had to enlarge the incision to 2.8 to 4.1 mm to insert the IOL.4 – 6 Recently, however, we successfully modified a commercially available IOL injector so the cartridge can insert a soft acrylic lens with an optic diameter of 5.5 mm (AcrySof威 SA30AL, Alcon) through a 2.2 mm incision. This development increases the importance of being able to perform lens extraction through an ultrasmall incision of less than 1.5 mm. In this article, we describe how to safely extract the lens by bimanual PEA using a sleeveless phaco tip as well as our technique for using a modified injector to insert a soft acrylic lens through a 2.2 mm incision.
From the Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan.
Surgical Techniques
None of the authors has a financial interest in any product mentioned.
Bimanual PEA Using a Sleeveless Phaco Tip A 19-gauge or 20-gauge microvitreoretinal (MVR) keratome is used to make a temporal clear corneal incision in the anterior chamber for a small phaco tip. The
Reprint requests to Hiroshi Tsuneoka, MD, Department of Ophthalmology, Jikei University School of Medicine, 3-19-18 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan. © 2003 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/03/$–see front matter doi:10.1016/S0886-3350(03)00076-2
TECHNIQUES: TSUNEOKA
incision is approximately 0.9 mm in length (Figure 1, A). An infusion side port is also created at the desired location in clear cornea using a 20-gauge MVR keratome (Figure 1, B).
A 26-gauge needle or an ultrasmall-incision anterior capsule forceps is used to perform continuous curvilinear capsulorhexis with a diameter of approximately 5.0 mm, after which hydrodissection is started
Figure 1. (Tsuneoka) Bimanual phaco surgery using a sleeveless phaco tip. A: Temporal clear corneal incision, 19-gauge or 20-gauge MVR blade. B: Formation of side port, 20-gauge MVR blade. C: During hydrodissection, it is important to press down on the incision with the base of the needle. This allows the infusion solution to leak through the incision and prevents sudden elevation of anterior chamber pressure. D: A 20-gauge Tsuneoka irrigating hook is inserted through the side port, and a 20-gauge sleeveless phaco tip is inserted through the temporal corneal incision. E: The irrigating hook is used for nucleofractis, and the nucleus is emulsified and aspirated. F: Residual cortical fragments are aspirated using a side-port aspiration cannula.
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Figure 2. (Tsuneoka) The Tsuneoka irrigating hook has a 20gauge outer diameter, but the inner walls have been thinned to increase the inner diameter to at least 0.7 mm so a satisfactory infusion flow can be maintained. The tip is bent into a hook suitable for use in nucleofractis.
(Figure 1, C). To prevent an abrupt rise in anterior chamber pressure, it is important to press the base of the hydrodissection needle firmly against the lower side of the incision so excess fluid can leak out of the incision during the procedure. The infusion cannula is inserted through the side port, the sleeveless phaco tip is inserted through the temporal clear corneal incision, nucleofractis is carried out using the hook at the tip of the infusion cannula, and PEA is performed. The surgeon sits at the patient’s head. A side port is created at 1 o’clock in the right eye or 11 o’clock in the left eye. When working in the right eye, the surgeon holds the infusion cannula in the left hand and the ultrasound probe in the right hand. For the left eye, the instruments are reversed, with the ultrasound probe in the surgeon’s left hand and the infusion cannula in the right hand.
Bimanual nucleofractis is used to emulsify and aspirate the nucleus. Depending on nucleus hardness, the divide-and-conquer, quick-chop (karate chop), or crater divide-and-conquer method is used (Figure 1, D and E). For safe PEA, anterior chamber collapse is prevented by maintaining a stable depth in the anterior chamber during surgery. It is also important to avoid scattering nuclear fragments in the anterior chamber. To keep the anterior chamber depth stable, the settings for phaco tip aspiration (flow rate and maximum aspiration pressure) are balanced with the rate of sideport infusion. To obtain satisfactory infusion flow, a specially designed infusion cannula, a 20-gauge irrigating hook (ASICO) with the inner diameter enlarged (Figure 2), is used. When the infusion bottle is elevated to 110 cm, the modified irrigating hook permits a flow volume of at least 45 mL/min through the side port. The parameters of the PEA unit (flow rate and maximum aspiration pressure) are set to provide the appropriate aspiration level so a balance between infusion and aspiration is maintained. The settings are shown in Table 1. Infusion flow may not keep up with aspiration flow if aspiration is continued when there are no nuclear particles to be captured by the aspiration port on the phaco tip. Surgery can be performed more safely if aspiration is turned off when it is not needed. To improve the safety of this surgery, it is important to prevent the dispersion of nuclear fragments in the anterior chamber. Because nuclear fragments tend to disperse more readily with PEA procedures than with other conventional techniques, it is best to set the ultrasound power as low as possible, reducing the extent of endothelial injury from the nucleus “kick.” Care must also be taken when using the nucleofractis hook to handle nuclear fragments.
Table 1. Phacoemulsification/aspiration settings currently used in our department with the Legacy 20,000 phaco machine and the 20-gauge Kelman tip. Nucleus Hardness
MVR Keratome for Incision
1–3
20-gauge
4–5
19-gauge
Flow Rate (mL/min)
Maximum Aspiration Pressure (mm Hg)
Ultrasound Power (%)
Pulse Mode (pulse/min)
Mode 1
20
60
40
10
Mode 2
25
250
30
10
Mode 1
20
60
60
Continuous
Mode 2
25
250
40–50
Continuous
MVR ⫽ microvitreoretinal
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In the emulsification of hard nuclei, considerable heat can be generated by the phaco tip, making it necessary to provide sufficient leakage of infusion solution through the incision to cool the tip and prevent thermal burn. In such cases, a 19-gauge MVR (1.4 mm) is used to create the incision for the 20-gauge phaco tip.2 With relatively soft nuclei, the tip temperature can be reduced by turning down the ultrasound power and performing PEA in pulse mode. Under these conditions, there is less need to cool the phaco tip by increasing the leakage of infusion solution through the incision. If the nucleus is soft, the initial corneal incision can be reduced even further using a 20-gauge MVR keratome (1.2 mm) to make the incision for a 20-gauge phaco tip. This increases the stability of the anterior chamber during surgery and reduces injury to the corneal endothelium from the dispersion of nuclear fragments. The residual cortical fragments can be aspirated through an ultrasmall incision using a sleeveless infusion and aspiration tip or a 23-gauge sideport aspiration cannula (Figure 1, F). If it is difficult to aspirate cortical fragments below the incision, the position of the infusion cannula and the aspiration cannula can be reversed so the fragments can be safely aspirated. Intraocular Lens Implantation Through a 2.2 mm Incision After the ultrasmall incision of 1.2 to 1.4 mm is enlarged using a 2.2 mm keratome, a 5.5 mm optic, single-piece, soft acrylic lens (AcrySof SA30AL) is loaded into a new model Monarch威 IIC cartridge. An injector manufactured by ASICO and then modified in
our laboratory (Figure 3) is used to insert the IOL into the eye. The injector is positioned so the cartridge tip is pressed against the incision but does not project into the anterior chamber (Figure 4, A). As the tip of the lens moves through the incision, an appropriate tool is inserted through the side port and pressure is applied to ensure that the patient’s eye is turned toward the incision. After the cartridge tip is positioned so it elevates the inner edge of the corneal incision and presses down on the outer edge, the injector plunger is slowly pressed (Figure 4, B) without decreasing the pressure of the cartridge on the incision until the entire optic and trailing loop are within the anterior chamber (Figure 4, C). The hook is then used to rotate the lens and insert the trailing loop in the capsular bag (Figure 4, D). Immediately after the IOL is implanted, the incision size is verified with a Tsuneoka microincision caliper (ASICO) (Figure 4, E). The viscoelastic substance is aspirated, and the incision is allowed to self-seal; hydration is provided if needed (Figure 4, F).
Results As of June 2002, bimanual ultrasonic phacoemulsification with an incision of 1.4 mm or smaller was performed in 965 eyes with no cases of thermal burn. The overall incidence of posterior capsule rupture was 1.7% (16 eyes). However, in the 53 eyes in which the nucleus was soft and a 20-gauge phaco tip could be inserted through an incision made with a 20-gauge MVR keratome, there were no cases of posterior capsule rupture,
Figure 3. (Tsuneoka) The IOL inserter can be held in 1 hand during IOL insertion. A plunger length has been adjusted with a rubber ring to improve safety during IOL insertion. J CATARACT REFRACT SURG—VOL 29, JUNE 2003
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Figure 4. (Tsuneoka) Acrysof SA30AL implantation through a 2.2 mm incision. A: During IOL insertion, the front tip of the cartridge is placed in the corneal incision so it presses against the incision wall but does not enter the anterior chamber. A suitable instrument is inserted through the side port, and pressure is applied to ensure the patient’s eye is turned toward the incision. B: With the cartridge tip elevating the inner edge of the corneal incision and pressing down on the outer edge, the surgeon slowly advances the injector plunger. C: The entire IOL, including the trailing loop, is inserted in the anterior chamber. D: The hook is used to rotate the IOL and insert the trailing loop in the capsular bag. E: After the IOL has been implanted, final incision width is confirmed using a Tsuneoka micro internal caliper. F: The viscoelastic material is removed, infusion solution is injected into the anterior chamber, and the incision self-seals.
perhaps because of the improved anterior chamber stability due to the smaller incision. The AcrySof SA30AL was used in 141 eyes. In the 63 eyes in which an IOL with a power of less than 1074
20 diopters (D) was implanted, it was possible to insert the lens through a 2.2 mm incision. However, in 36 of the 78 eyes in which an IOL of 20 D or greater was used, the lens could not be inserted through the 2.2 mm inci-
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sion and the incision was enlarged to 2.4 mm. In the 105 eyes in which the SA30AL could be inserted through a 2.2 mm incision, the final incision was 2.2 mm in 61 eyes (58.1%), 2.3 mm in 36 eyes (34.3%), and 2.4 mm in 8 eyes (7.6%) (Table 2). Central positioning of the inserted IOL was satisfactory, and no damage to the IOL optic or haptic was noted. After aspiration of the viscoelastic substance, all incisions self-sealed. No suturing was required in any patient.
Discussion In 1984, Hara and Hara7 experimented with a sleeveless phaco tip for PEA. Their objective was to use intracapsular phacoemulsification as part of a lens refilling procedure. At that time, the surgical techniques for lens emulsification and aspiration were complex, however, and no suitable lens refilling materials were available, so the procedure never came into wide use. In 1999, 15 years after Hara and Hara reported their findings, we began experimenting with bimanual PEA using a sleeveless phaco tip to reduce the incision size.2,3 This surgical procedure, which makes it possible to remove the nucleus through an ultrasmall incision, has the advantage of enabling safe and relatively noninvasive surgery using familiar procedures that are widely practiced.8 Because we were concerned about thermal burn at the incision site, we made the incision slightly larger than the diameter of the phaco tip. The leakage of infusion solution through the incision disseminates friction heat from the phaco tip and cools the tissue at the incision site, preventing thermal burn. New phaco machines that use computer software to control ultrasound generation (WhiteStar, Allergan)
have recently become available. Except in cases in which the nucleus is extremely hard, these machines make it easier to avoid thermal burn at the incision site even with little leakage of infusion solution through the incision.9 The new machines have further improved the safety of these procedures since even a small reduction in incision size can greatly improve the stability of the anterior chamber during surgery and reduce the risk of posterior capsule rupture. If the incision is small, there is greater risk that movement of the phaco tip will produce corneal deformation, excessive stromal hydration, and clouding around the incision. The surgeon must be particularly careful to avoid excessive movement of the phaco tip during emulsification and aspiration through an ultrasmall incision. We have adapted the Kelman phaco tip (curved tip) to minimize tip movement during surgery. Because the central thickness of the AcrySof SA30AL varies depending on the lens dioptric power, it is not possible to insert IOLs of all diopter levels through a 2.2 mm incision. We experienced no problem when using IOLs less than 20 D, but it may be safer to use an incision of 2.3 to 2.4 mm for IOLs of 20 D or higher. When using the ASICO injector, the plunger can be operated with 1 hand, which leaves the other hand free to stabilize the eye. When inserting an IOL of 20 D or higher, because the lens is slightly thicker, it is necessary to press firmly on the plunger during insertion. However, too much pressure can cause the lens to be inserted too deeply in the eye, which can result in posterior capsule rupture. Because the plunger on ASICO’s commercially available injector is a little too long, we adjusted the plunger length by placing a rubber ring at the back end of the plunger. This allows the surgeon to press
Table 2. Final incision size in 141 eyes following AcrySof SA30AL implantation. IOL Diopter
n
Incision Before IOL (Keratome) (mm)
IOL Insertion (n)
Incision After IOL (Internal Caliper) (mm)
Insertion (n)
⬍20
63
2.2
63
2.2
49
2.3
13
2.4
1
2.2
12
2.3
23
ⱖ20
78
2.2
2.4
42
36
2.4
7
2.4
36
n ⫽ number of eyes
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firmly on the plunger during insertion without placing the IOL too deeply in the eye and avoids posterior capsule rupture. Since the stopper is made of rubber, one can press slowly on the plunger again to adjust the position of the lens after most of the IOL is inserted in the eye. Until recently, even if we could remove the original lens through an incision smaller than 1.5 mm, it was necessary to enlarge the incision to 2.8 to 4.1 mm to insert the IOL. It is thus significant that we are now able to implant the AcrySof SA30AL, which is highly reliable and one of the most widely used foldable IOLs in the world, through an incision of 2.2 to 2.4 mm. Currently, several companies are working to develop soft acrylic lenses that are thinner than the foldable IOLs now commercially available, and insertion systems are also being improved. It is likely that soon we will have IOLs that can be inserted through a 1.5 mm incision. At that point, it will be important to be able to remove the original lens through an incision of 1.5 mm or smaller, and bimanual phaco surgery using a sleeveless ultrasound tip will appear even more promising as a technique for lens removal.
5.
References
9.
1. Kanellopoulos AJ, Dodick JM, Brauweiler P, Alzner E. Dodick photolysis for cataract surgery; early experience
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2.
3.
4.
6.
7.
8.
with the Q-switched neodymium:YAG laser in 100 consecutive patients. Ophthalmology 1999; 106:2197– 2202 Tsuneoka H, Shiba T, Takahashi Y. Feasibility of ultrasound cataract surgery with a 1.4 mm incision. J Cataract Refract Surg 2001; 27:934 –940 Tsuneoka H, Shiba T, Takahashi Y. Ultrasonic phacoemulsification using a 1.4 mm incision: clinical results. J Cataract Refract Surg 2002; 28:81–86 Moreno-Montan˜ e´s J, Maldonado MJ, Garcı´a-Layana A, et al. Final clear corneal incision size for AcrySof intraocular lenses. J Cataract Refract Surg 1999; 25:959 –963 Mamalis N. Incision width after phacoemulsification with foldable intraocular lens implantation. J Cataract Refract Surg 2000; 26:237–241 Coombes AG, Sheard R, Gartry DS, Allan BD. Silicone plate-haptic lens injection without prior incision enlargement. J Cataract Refract Surg 2001; 27:1542– 1544 Hara T, Hara T. Clinical results of endocapsular phacoemulsification and complete in-the-bag intraocular lens fixation. J Cataract Refract Surg 1987; 13:279 – 286 Agarwal A, Agarwal A, Agarwal S, et al. Phakonit: phacoemulsification through a 0.9 mm corneal incision. J Cataract Refract Surg 2001; 27:1548 –1552 Soscia W, Howard JG, Olson RJ. Microphacoemulsification with WhiteStar; a wound-temperature study. J Cataract Refract Surg 2002; 28:1044 –1046
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he widespread adoption of ultrasound technology in cataract surgery and the advent of foldable intraocular lenses (IOLs) have made it possible to perform cataract surgery and IOL implantation through a small incision of 3.0 to 4.0 mm. Now surgeons are experimenting with even smaller incisions. Considerable interest has been focused on neodymium:YAG laser surgery to extract the lens through an ultrasmall incision of less than 1.5 mm.1 However, laser surgery technology needs further improvement before it will be fully mature, and some time will be required before it is widely used. In 1999, we began using a standard phacoemulsification and aspiration (PEA) machine to perform bimanual PEA with a sleeveless phaco tip through an ultrasmall incision of less than 1.5 mm.2,3 With this surgical technique, we insert a 21-gauge or 20-gauge ultrasound tip with the infusion sleeve removed (sleeveless phaco tip) through a corneal incision of 1.2 to 1.4 mm, slightly Accepted for publication December 23, 2002.
larger than the outer diameter of the tip, with infusion through a 1.2 mm side port. The use of 2 incisions allows us to perform bimanual nucleofractis. As of June 2002, we had performed this surgery in more than 900 eyes with a success rate comparable to that of conventional surgery. Although this surgical technique makes it possible to remove the lens safely through an incision of 1.2 to 1.4 mm, until recently we had to enlarge the incision to 2.8 to 4.1 mm to insert the IOL.4 – 6 Recently, however, we successfully modified a commercially available IOL injector so the cartridge can insert a soft acrylic lens with an optic diameter of 5.5 mm (AcrySof威 SA30AL, Alcon) through a 2.2 mm incision. This development increases the importance of being able to perform lens extraction through an ultrasmall incision of less than 1.5 mm. In this article, we describe how to safely extract the lens by bimanual PEA using a sleeveless phaco tip as well as our technique for using a modified injector to insert a soft acrylic lens through a 2.2 mm incision.
From the Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan.
Surgical Techniques
None of the authors has a financial interest in any product mentioned.
Bimanual PEA Using a Sleeveless Phaco Tip A 19-gauge or 20-gauge microvitreoretinal (MVR) keratome is used to make a temporal clear corneal incision in the anterior chamber for a small phaco tip. The
Reprint requests to Hiroshi Tsuneoka, MD, Department of Ophthalmology, Jikei University School of Medicine, 3-19-18 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan. © 2003 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/03/$–see front matter doi:10.1016/S0886-3350(03)00076-2
TECHNIQUES: TSUNEOKA
incision is approximately 0.9 mm in length (Figure 1, A). An infusion side port is also created at the desired location in clear cornea using a 20-gauge MVR keratome (Figure 1, B).
A 26-gauge needle or an ultrasmall-incision anterior capsule forceps is used to perform continuous curvilinear capsulorhexis with a diameter of approximately 5.0 mm, after which hydrodissection is started
Figure 1. (Tsuneoka) Bimanual phaco surgery using a sleeveless phaco tip. A: Temporal clear corneal incision, 19-gauge or 20-gauge MVR blade. B: Formation of side port, 20-gauge MVR blade. C: During hydrodissection, it is important to press down on the incision with the base of the needle. This allows the infusion solution to leak through the incision and prevents sudden elevation of anterior chamber pressure. D: A 20-gauge Tsuneoka irrigating hook is inserted through the side port, and a 20-gauge sleeveless phaco tip is inserted through the temporal corneal incision. E: The irrigating hook is used for nucleofractis, and the nucleus is emulsified and aspirated. F: Residual cortical fragments are aspirated using a side-port aspiration cannula.
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Figure 2. (Tsuneoka) The Tsuneoka irrigating hook has a 20gauge outer diameter, but the inner walls have been thinned to increase the inner diameter to at least 0.7 mm so a satisfactory infusion flow can be maintained. The tip is bent into a hook suitable for use in nucleofractis.
(Figure 1, C). To prevent an abrupt rise in anterior chamber pressure, it is important to press the base of the hydrodissection needle firmly against the lower side of the incision so excess fluid can leak out of the incision during the procedure. The infusion cannula is inserted through the side port, the sleeveless phaco tip is inserted through the temporal clear corneal incision, nucleofractis is carried out using the hook at the tip of the infusion cannula, and PEA is performed. The surgeon sits at the patient’s head. A side port is created at 1 o’clock in the right eye or 11 o’clock in the left eye. When working in the right eye, the surgeon holds the infusion cannula in the left hand and the ultrasound probe in the right hand. For the left eye, the instruments are reversed, with the ultrasound probe in the surgeon’s left hand and the infusion cannula in the right hand.
Bimanual nucleofractis is used to emulsify and aspirate the nucleus. Depending on nucleus hardness, the divide-and-conquer, quick-chop (karate chop), or crater divide-and-conquer method is used (Figure 1, D and E). For safe PEA, anterior chamber collapse is prevented by maintaining a stable depth in the anterior chamber during surgery. It is also important to avoid scattering nuclear fragments in the anterior chamber. To keep the anterior chamber depth stable, the settings for phaco tip aspiration (flow rate and maximum aspiration pressure) are balanced with the rate of sideport infusion. To obtain satisfactory infusion flow, a specially designed infusion cannula, a 20-gauge irrigating hook (ASICO) with the inner diameter enlarged (Figure 2), is used. When the infusion bottle is elevated to 110 cm, the modified irrigating hook permits a flow volume of at least 45 mL/min through the side port. The parameters of the PEA unit (flow rate and maximum aspiration pressure) are set to provide the appropriate aspiration level so a balance between infusion and aspiration is maintained. The settings are shown in Table 1. Infusion flow may not keep up with aspiration flow if aspiration is continued when there are no nuclear particles to be captured by the aspiration port on the phaco tip. Surgery can be performed more safely if aspiration is turned off when it is not needed. To improve the safety of this surgery, it is important to prevent the dispersion of nuclear fragments in the anterior chamber. Because nuclear fragments tend to disperse more readily with PEA procedures than with other conventional techniques, it is best to set the ultrasound power as low as possible, reducing the extent of endothelial injury from the nucleus “kick.” Care must also be taken when using the nucleofractis hook to handle nuclear fragments.
Table 1. Phacoemulsification/aspiration settings currently used in our department with the Legacy 20,000 phaco machine and the 20-gauge Kelman tip. Nucleus Hardness
MVR Keratome for Incision
1–3
20-gauge
4–5
19-gauge
Flow Rate (mL/min)
Maximum Aspiration Pressure (mm Hg)
Ultrasound Power (%)
Pulse Mode (pulse/min)
Mode 1
20
60
40
10
Mode 2
25
250
30
10
Mode 1
20
60
60
Continuous
Mode 2
25
250
40–50
Continuous
MVR ⫽ microvitreoretinal
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In the emulsification of hard nuclei, considerable heat can be generated by the phaco tip, making it necessary to provide sufficient leakage of infusion solution through the incision to cool the tip and prevent thermal burn. In such cases, a 19-gauge MVR (1.4 mm) is used to create the incision for the 20-gauge phaco tip.2 With relatively soft nuclei, the tip temperature can be reduced by turning down the ultrasound power and performing PEA in pulse mode. Under these conditions, there is less need to cool the phaco tip by increasing the leakage of infusion solution through the incision. If the nucleus is soft, the initial corneal incision can be reduced even further using a 20-gauge MVR keratome (1.2 mm) to make the incision for a 20-gauge phaco tip. This increases the stability of the anterior chamber during surgery and reduces injury to the corneal endothelium from the dispersion of nuclear fragments. The residual cortical fragments can be aspirated through an ultrasmall incision using a sleeveless infusion and aspiration tip or a 23-gauge sideport aspiration cannula (Figure 1, F). If it is difficult to aspirate cortical fragments below the incision, the position of the infusion cannula and the aspiration cannula can be reversed so the fragments can be safely aspirated. Intraocular Lens Implantation Through a 2.2 mm Incision After the ultrasmall incision of 1.2 to 1.4 mm is enlarged using a 2.2 mm keratome, a 5.5 mm optic, single-piece, soft acrylic lens (AcrySof SA30AL) is loaded into a new model Monarch威 IIC cartridge. An injector manufactured by ASICO and then modified in
our laboratory (Figure 3) is used to insert the IOL into the eye. The injector is positioned so the cartridge tip is pressed against the incision but does not project into the anterior chamber (Figure 4, A). As the tip of the lens moves through the incision, an appropriate tool is inserted through the side port and pressure is applied to ensure that the patient’s eye is turned toward the incision. After the cartridge tip is positioned so it elevates the inner edge of the corneal incision and presses down on the outer edge, the injector plunger is slowly pressed (Figure 4, B) without decreasing the pressure of the cartridge on the incision until the entire optic and trailing loop are within the anterior chamber (Figure 4, C). The hook is then used to rotate the lens and insert the trailing loop in the capsular bag (Figure 4, D). Immediately after the IOL is implanted, the incision size is verified with a Tsuneoka microincision caliper (ASICO) (Figure 4, E). The viscoelastic substance is aspirated, and the incision is allowed to self-seal; hydration is provided if needed (Figure 4, F).
Results As of June 2002, bimanual ultrasonic phacoemulsification with an incision of 1.4 mm or smaller was performed in 965 eyes with no cases of thermal burn. The overall incidence of posterior capsule rupture was 1.7% (16 eyes). However, in the 53 eyes in which the nucleus was soft and a 20-gauge phaco tip could be inserted through an incision made with a 20-gauge MVR keratome, there were no cases of posterior capsule rupture,
Figure 3. (Tsuneoka) The IOL inserter can be held in 1 hand during IOL insertion. A plunger length has been adjusted with a rubber ring to improve safety during IOL insertion. J CATARACT REFRACT SURG—VOL 29, JUNE 2003
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Figure 4. (Tsuneoka) Acrysof SA30AL implantation through a 2.2 mm incision. A: During IOL insertion, the front tip of the cartridge is placed in the corneal incision so it presses against the incision wall but does not enter the anterior chamber. A suitable instrument is inserted through the side port, and pressure is applied to ensure the patient’s eye is turned toward the incision. B: With the cartridge tip elevating the inner edge of the corneal incision and pressing down on the outer edge, the surgeon slowly advances the injector plunger. C: The entire IOL, including the trailing loop, is inserted in the anterior chamber. D: The hook is used to rotate the IOL and insert the trailing loop in the capsular bag. E: After the IOL has been implanted, final incision width is confirmed using a Tsuneoka micro internal caliper. F: The viscoelastic material is removed, infusion solution is injected into the anterior chamber, and the incision self-seals.
perhaps because of the improved anterior chamber stability due to the smaller incision. The AcrySof SA30AL was used in 141 eyes. In the 63 eyes in which an IOL with a power of less than 1074
20 diopters (D) was implanted, it was possible to insert the lens through a 2.2 mm incision. However, in 36 of the 78 eyes in which an IOL of 20 D or greater was used, the lens could not be inserted through the 2.2 mm inci-
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sion and the incision was enlarged to 2.4 mm. In the 105 eyes in which the SA30AL could be inserted through a 2.2 mm incision, the final incision was 2.2 mm in 61 eyes (58.1%), 2.3 mm in 36 eyes (34.3%), and 2.4 mm in 8 eyes (7.6%) (Table 2). Central positioning of the inserted IOL was satisfactory, and no damage to the IOL optic or haptic was noted. After aspiration of the viscoelastic substance, all incisions self-sealed. No suturing was required in any patient.
Discussion In 1984, Hara and Hara7 experimented with a sleeveless phaco tip for PEA. Their objective was to use intracapsular phacoemulsification as part of a lens refilling procedure. At that time, the surgical techniques for lens emulsification and aspiration were complex, however, and no suitable lens refilling materials were available, so the procedure never came into wide use. In 1999, 15 years after Hara and Hara reported their findings, we began experimenting with bimanual PEA using a sleeveless phaco tip to reduce the incision size.2,3 This surgical procedure, which makes it possible to remove the nucleus through an ultrasmall incision, has the advantage of enabling safe and relatively noninvasive surgery using familiar procedures that are widely practiced.8 Because we were concerned about thermal burn at the incision site, we made the incision slightly larger than the diameter of the phaco tip. The leakage of infusion solution through the incision disseminates friction heat from the phaco tip and cools the tissue at the incision site, preventing thermal burn. New phaco machines that use computer software to control ultrasound generation (WhiteStar, Allergan)
have recently become available. Except in cases in which the nucleus is extremely hard, these machines make it easier to avoid thermal burn at the incision site even with little leakage of infusion solution through the incision.9 The new machines have further improved the safety of these procedures since even a small reduction in incision size can greatly improve the stability of the anterior chamber during surgery and reduce the risk of posterior capsule rupture. If the incision is small, there is greater risk that movement of the phaco tip will produce corneal deformation, excessive stromal hydration, and clouding around the incision. The surgeon must be particularly careful to avoid excessive movement of the phaco tip during emulsification and aspiration through an ultrasmall incision. We have adapted the Kelman phaco tip (curved tip) to minimize tip movement during surgery. Because the central thickness of the AcrySof SA30AL varies depending on the lens dioptric power, it is not possible to insert IOLs of all diopter levels through a 2.2 mm incision. We experienced no problem when using IOLs less than 20 D, but it may be safer to use an incision of 2.3 to 2.4 mm for IOLs of 20 D or higher. When using the ASICO injector, the plunger can be operated with 1 hand, which leaves the other hand free to stabilize the eye. When inserting an IOL of 20 D or higher, because the lens is slightly thicker, it is necessary to press firmly on the plunger during insertion. However, too much pressure can cause the lens to be inserted too deeply in the eye, which can result in posterior capsule rupture. Because the plunger on ASICO’s commercially available injector is a little too long, we adjusted the plunger length by placing a rubber ring at the back end of the plunger. This allows the surgeon to press
Table 2. Final incision size in 141 eyes following AcrySof SA30AL implantation. IOL Diopter
n
Incision Before IOL (Keratome) (mm)
IOL Insertion (n)
Incision After IOL (Internal Caliper) (mm)
Insertion (n)
⬍20
63
2.2
63
2.2
49
2.3
13
2.4
1
2.2
12
2.3
23
ⱖ20
78
2.2
2.4
42
36
2.4
7
2.4
36
n ⫽ number of eyes
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firmly on the plunger during insertion without placing the IOL too deeply in the eye and avoids posterior capsule rupture. Since the stopper is made of rubber, one can press slowly on the plunger again to adjust the position of the lens after most of the IOL is inserted in the eye. Until recently, even if we could remove the original lens through an incision smaller than 1.5 mm, it was necessary to enlarge the incision to 2.8 to 4.1 mm to insert the IOL. It is thus significant that we are now able to implant the AcrySof SA30AL, which is highly reliable and one of the most widely used foldable IOLs in the world, through an incision of 2.2 to 2.4 mm. Currently, several companies are working to develop soft acrylic lenses that are thinner than the foldable IOLs now commercially available, and insertion systems are also being improved. It is likely that soon we will have IOLs that can be inserted through a 1.5 mm incision. At that point, it will be important to be able to remove the original lens through an incision of 1.5 mm or smaller, and bimanual phaco surgery using a sleeveless ultrasound tip will appear even more promising as a technique for lens removal.
5.
References
9.
1. Kanellopoulos AJ, Dodick JM, Brauweiler P, Alzner E. Dodick photolysis for cataract surgery; early experience
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2.
3.
4.
6.
7.
8.
with the Q-switched neodymium:YAG laser in 100 consecutive patients. Ophthalmology 1999; 106:2197– 2202 Tsuneoka H, Shiba T, Takahashi Y. Feasibility of ultrasound cataract surgery with a 1.4 mm incision. J Cataract Refract Surg 2001; 27:934 –940 Tsuneoka H, Shiba T, Takahashi Y. Ultrasonic phacoemulsification using a 1.4 mm incision: clinical results. J Cataract Refract Surg 2002; 28:81–86 Moreno-Montan˜ e´s J, Maldonado MJ, Garcı´a-Layana A, et al. Final clear corneal incision size for AcrySof intraocular lenses. J Cataract Refract Surg 1999; 25:959 –963 Mamalis N. Incision width after phacoemulsification with foldable intraocular lens implantation. J Cataract Refract Surg 2000; 26:237–241 Coombes AG, Sheard R, Gartry DS, Allan BD. Silicone plate-haptic lens injection without prior incision enlargement. J Cataract Refract Surg 2001; 27:1542– 1544 Hara T, Hara T. Clinical results of endocapsular phacoemulsification and complete in-the-bag intraocular lens fixation. J Cataract Refract Surg 1987; 13:279 – 286 Agarwal A, Agarwal A, Agarwal S, et al. Phakonit: phacoemulsification through a 0.9 mm corneal incision. J Cataract Refract Surg 2001; 27:1548 –1552 Soscia W, Howard JG, Olson RJ. Microphacoemulsification with WhiteStar; a wound-temperature study. J Cataract Refract Surg 2002; 28:1044 –1046
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