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Implantation of AcrySof acrylic intraocular lenses
Implantation of AcrySof acrylic intraocular lenses Joel K. Shugar, MD
ABSTRACT A surgical technique is described to facilitate safe implantation of acrylic posterior chamber intraocular lenses through the smallest incisions allowed by currently available implantation technology. The technique includes warming the lens before insertion, protecting the optic with viscoelastic before grasping it with insertion forceps, and using a Sinskey hook through the side port during lens rotation and unfolding. J Cataract Refract Surg 1996; 22:1355-1359
A
crylic intraocular lenses (lOLs) offer advantages over lenses made of other available materials, including controlled unfolding movement, lower aqueous flare intensity, and clear capsules postoperatively. 1 Most authors recommend implanting the first commercially available acrylic lens, the AcrySof® model MA60BM (Alcon Laboratories), through a 3.5 to 4.1 mm incision. 1,2 Vrabec and coauthors3 recently recommended a 4.3 mm incision for implanting this lens mode1. 3 This requires enlarging the incision after phacoemulsification, increasing the potential for induced astigmatism and surgical trauma. From January 1995 through August 1996, I implanted 545 acrylic AcrySof MA60BM and 94 AcrySof MA30BA 10Ls; 518 model MA60BM and all 94 MA30BA lenses were inserted through unmodified phacoemulsification incisions with an internal wound width of 3.2 mm. The MA60BM was implanted
From the Visual Enhancement Center, Perry, Florida. The author has no financial interest in any company or product mentioned. David Eister, senior product manager, Alcon Surgical, and John Snowden, Captured Light Studios, provided technical assistance in preparing the figures. Reprint requests to Joel K Shugar, MD, Visual Enhancement Center, 1211 North Center Street, Perry, Florida 32347.
through a scleral tunnel and the MA30BA, through a clear corneal incision. Twenty incisions were enlarged to facilitate placement of a MA60BM lens: 1 to 3.5 mm (preplan ned) in an eye with pseudoexfoliation syndrome; 2 to 3.5 mm because of suboptimal wound architecture; 9 to 3.5 or 4.1 mm to facilitate astigmatic reduction achieved by on-axis surgery; 8 to 3.5 mm to allow implantation of a MA60BM lens though a clear corneal incision. In addition to these 20 cases, 7 MA60BM 10Ls were implanted in eyes having concomitant penetrating keratoplasty or trabeculectomy. My technique for implanting these lenses through an unmodified phacoemulsification incision, while protecting the lenses from scratching and simultaneously maximizing control within the anterior segment, has evolved since it was last reported O.K. Shugar, MD, "Implantation Technique for the AcrySof Lens Through an Unenlarged 3.2 mm Incision," Phaco & Foldables, Fall 1995, pages 3-4,12) to include the steps presented below.
Surgical Technique Implantation of the MA60BM is performed through a two-plane scleral tunnel with a 3.5 mm width scleral groove and a 3.5 mm length corneoscleral tunnel with a 3.2 mm internal width corneal valve. The
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MA30BA is implanted through a clear corneal incision with a hinged architecture4 using a 0.6 mm deep, 3.5 mm wide groove; a 0.3 mm deep, 2.0 mm long clear corneal tunnel; and a 3.2 mm internal width corneal valve. When possible, the lens package is placed in a warm environment before lens implantation. The circulating nurse places the MA60BM in its packaging on top of the instrument sterilizer, where the temperature measures lOO°F, for 15 minutes. The MA30BA package is warmed for only 10 minutes because this lens is thinner and more malleable. The lenses should not be heated above this temperature as fogging can occur. In addition, if these lenses are heated to an excessive temperature, the acrylic material can weaken (David Eister, Alcon Surgical, personal communication, September 1996). Some surgeons have the circulating nurse place the lens package in a pocket to bring the lens to body temperature while avoiding the possibility of overheating (Stephen Lane, MD, personal communication, October 1996). Such warming is helpful but not mandatory. After wetting with balanced salt solution (BSS®), the lens is placed on a drop of viscoelastic and then grasped by folding forceps (Alcon Surgical #8065977720). Lens folding is initiated along the 6 to 12 o'clock axis with a closed, smooth forceps (Figure O. All forceps coming in contact with the lens are inspected
to ensure the tips are meticulously clean. Alternately, the wagon-wheel packaging may be used to initiate the fold (Kerry Solomon, MD, personal communication, October 1996). The optic is coated with sodium chondroitin sulfate-sodium hyaluronate (Viscoat®) before being grasped as peripherally as possible with implantation forceps (Alcon Surgical #8065977730). This same viscoelastic is used to inflate the anterior chamber before lens insertion. Less dispersive viscoelastic, such as 1% sodium hyaluronate, has a greater tendency to be forced out of the eye during implantation. Next, the lens is regrasped more peripherally with the folding forceps while it is held with the implantation forceps. Then, the lens is regrasped with the implantation forceps while it is held with the folding forceps (Figure 2). These maneuvers maximize how peripherally the optic is engaged (Figure 3). This reduces "fishmouthing" of the leading edge of the optic, which reduces the implantation profile size presented by the leading edge of the optic to minimize the wound size necessary for implantation. The leading haptic is placed into the tunnel with Calibri forceps and implanted into the anterior chamber before the optic enters the tunnel (Figure 4). Implantation occurs slowly. The lens may continue folding within the tunnel. As the leading edge of the optic reaches the internal corneal valve, the fit may occasionally feel tight. Increasing the force on the forceps is con-
Figure 1. (Shugar) A smooth forceps is used to initiate folding the MA30BA lens in the proper direction as the lens is folded with the folding forceps. The optic is coated with Viscoat and then grasped with an implantation forceps.
Figure 2. (Shugar) Implantation forceps are used to grasp the optic from folding forceps. The lens is typically regrasped to engage the optic more peripherally before lens implantation.
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Figure 3. (Shugar) The lens optic is held peripherally by implantation forceps.
traindicated and could damage the optic. Instead, redirecting the angle of implantation more posteriorly will usually facilitate passage of the distal optic through the internal corneal valve. If the lens cannot easily be implanted, the symmetry of the fold, location of the forceps on the optic, and wound architecture are examined. Ifwound architecture is suboptimal or the lens cannot easily be inserted despite adequate positioning of the optic within the folding for-
Figure 4. (Shugar) Implantation of the distal haptic through temporal, clear comeal incision.
ceps, the incision should be enlarged to 3.5 mm. This incision size is also required if an MA60BM lens is to be inserted through a clear corneal incision. In my experience, it has never been necessary to enlarge the incision beyond 3.5 mm to achieve effortless insertion. If necessary, a Calibri forceps may be used to stabilize the globe during insertion; however, care must be taken that the forceps does not scratch the lens surface or cause subconjunctival hemorrhage. If such stabilization is necessary for eyes with clear corneal incisions, I grasp the posterior lip of the paracentesis port with the Calibri to avoid trauma to the IOL, main incision, or conjunctiva. The lens initially enters the eye directed toward the anterior chamber angle opposite from the internal wound. The distal haptic is then redirected more posteriorly and placed beneath the opposite capsulorhexis margin and into the capsular bag. Care is taken to maximize control as the proximal optic clears the tunnel. The implantation forceps is rotated counterclockwise. A Sinskey hook is then placed through the side port to maximize the distance between the optic and the corneal endothelium (Figure 5). The Sinskey hook is used to disengage the proximal (Figure 6) and then the distal aspect of the optic from the forceps. Opening the forceps rapidly allows the lens to be more easily disengaged. In most cases, the proximal haptic is implanted by depressing the proximal part of the optic with the Sinskey hook
Figure 5. (Shugar) A Sinskey hook is used through the side port to maximize distance between the proximal optic and endothelium.
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Figure 6. (Shugar) A Sinskey hook is used to disengage the optic from the implantation forceps and to implant the proximal haptic.
(Figure 6). Alternately, the proximal haptic can be implanted with forceps while the Sinskey hook is used to depress the center of the optic.
Discussion A recent case report3 described extensive scratches on an AcrySof MA60 BM 10L that were likely caused by excessive insertion force. If ordinary insertion force is insufficient, the position of the folding forceps on the optic is re-evaluated and the lens grasped more peripherally if necessary. Excessive force is contraindicated, however, and implantation should require minimal insertion force. If it is suspected that excessive force may have been applied, the optic should be unfolded and inspected before implantation. If wound architecture is suboptimal or if the cause of a tight fit cannot be identified, the incision should be enlarged. I recommend that surgeons gain clinical experience and are comfortable with handling these lenses before attempting to insert them through 3.2 mm internal incisions. Recent studies describe enlargement of incision width during phacoemulsification and foldable IOL implantation. 5 ,6 These studies suggest that every incision undergoes some degree of enlargement during phacoemulsification and again during foldable lens implantation. In my clinical experience, most acrylic lenses are implanted as easily through 3.2 mm internal corneal 1358
incisions as was the AMO SI-30NB, which was my lens of choice immediately before acrylic lenses became available. I am currently studying how much the internal wound enlarges with acrylic IOL implantation using currently available instrumentation. Direct-acting Fine II Universal forceps should not be used to insert these lenses as they may scratch or crack the lenses? A direct-acting forceps (Fine III, Rhein Medical) is currently marketed for use with acrylic lenses. I have no experience with this instrument. In contrast to a recent recommendation to fold acrylic lenses along the 10 to 4 o'clock axis, 8 I recommend folding currently available acrylic lenses along the 6 to 12 o'clock axis to facilitate implantation through the smallest phacoemulsification incision through which atraumatic implantation can be achieved. Because the Sinskey hook is used through the side port, implantation of the proximal haptic requires minimal additional manipulation. In conclusion, acrylic lenses can be safely inserted through 3.2 to 3.5 mm phacoemulsification incisions without surface damage and with exquisite control within the anterior segment of the eye. Although I use an unenlarged 3.2 mm internal incision for IOL implantation, within several months I anticipate changing to a phacoemulsification tip requiring a keratome incision less than 3.0 mm and plan to use a 3.5 mm incision for implantation because wound enlargement will be required. Acrylic has the highest index of refraction of any approved IOL. Thus, these lenses are the thinnest and should have the lowest bulk for a given dioptric power, edge thickness, and optic diameter. This suggests that their insertion profile may be further reduced by improvements in insertion technology such as the development of a "shooter" or a method for rolling the lens for implantation.
References 1. Oshika T, Suzuki Y, Kizaki H, Yaguchi S. Two year clin-
ical study of a soft acrylic intraocular lens. J Cataract Refract Surg 1996; 22:104-109 2. Anderson C, Koch DD, Green G, et al. Alcon AcrySofll' acrylic intraocular lens. In: Martin RG, Gills JP, Sanders DR, eds, Foldable Intraocular Lenses. Thorofare, NJ, Slack Inc, 1993; 161-177 3. Vrabec MP, Syverud lC, Burgess q. Forceps-induced
J CATARACT REFRACT SURG-VOL 22, SUPPLEMENT 2 1996
ACRYSOF IOL IMPLANTATION
scratching of a foldable acrylic intraocular lens. Arch Ophthalmol1996; 114:777 4. Langerman OW. Architectural design of a self-sealing corneal tunnel, single-hinge incision. J Cataract Refract Surg 1994; 20:84-88 5. Steinert RF, Deacon J. Enlargement of incision width during phacoemulsification and folded intraocular lens implant surgery. Ophthalmology 1996; 103:220-225
6. Mackool RJ, Russell RS. Effect of foldable intraocular lens insertion on incision width. J Cataract Refract Surg 1996; 22:571-574 7. Carlson KH, Johnson OW. Cracking of acrylic intraocular lenses during capsular bag insertion. Ophthalmic Surg Lasers 1995; 26:572-573 8. Oh KT, Oh KT. Optimal folding axis for acrylic intraocular lenses. J Cataract Refract Surg 1996; 22:667-670
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ABSTRACT A surgical technique is described to facilitate safe implantation of acrylic posterior chamber intraocular lenses through the smallest incisions allowed by currently available implantation technology. The technique includes warming the lens before insertion, protecting the optic with viscoelastic before grasping it with insertion forceps, and using a Sinskey hook through the side port during lens rotation and unfolding. J Cataract Refract Surg 1996; 22:1355-1359
A
crylic intraocular lenses (lOLs) offer advantages over lenses made of other available materials, including controlled unfolding movement, lower aqueous flare intensity, and clear capsules postoperatively. 1 Most authors recommend implanting the first commercially available acrylic lens, the AcrySof® model MA60BM (Alcon Laboratories), through a 3.5 to 4.1 mm incision. 1,2 Vrabec and coauthors3 recently recommended a 4.3 mm incision for implanting this lens mode1. 3 This requires enlarging the incision after phacoemulsification, increasing the potential for induced astigmatism and surgical trauma. From January 1995 through August 1996, I implanted 545 acrylic AcrySof MA60BM and 94 AcrySof MA30BA 10Ls; 518 model MA60BM and all 94 MA30BA lenses were inserted through unmodified phacoemulsification incisions with an internal wound width of 3.2 mm. The MA60BM was implanted
From the Visual Enhancement Center, Perry, Florida. The author has no financial interest in any company or product mentioned. David Eister, senior product manager, Alcon Surgical, and John Snowden, Captured Light Studios, provided technical assistance in preparing the figures. Reprint requests to Joel K Shugar, MD, Visual Enhancement Center, 1211 North Center Street, Perry, Florida 32347.
through a scleral tunnel and the MA30BA, through a clear corneal incision. Twenty incisions were enlarged to facilitate placement of a MA60BM lens: 1 to 3.5 mm (preplan ned) in an eye with pseudoexfoliation syndrome; 2 to 3.5 mm because of suboptimal wound architecture; 9 to 3.5 or 4.1 mm to facilitate astigmatic reduction achieved by on-axis surgery; 8 to 3.5 mm to allow implantation of a MA60BM lens though a clear corneal incision. In addition to these 20 cases, 7 MA60BM 10Ls were implanted in eyes having concomitant penetrating keratoplasty or trabeculectomy. My technique for implanting these lenses through an unmodified phacoemulsification incision, while protecting the lenses from scratching and simultaneously maximizing control within the anterior segment, has evolved since it was last reported O.K. Shugar, MD, "Implantation Technique for the AcrySof Lens Through an Unenlarged 3.2 mm Incision," Phaco & Foldables, Fall 1995, pages 3-4,12) to include the steps presented below.
Surgical Technique Implantation of the MA60BM is performed through a two-plane scleral tunnel with a 3.5 mm width scleral groove and a 3.5 mm length corneoscleral tunnel with a 3.2 mm internal width corneal valve. The
J CATARACf REFRACT SURG-VOL 22, SUPPLEMENT 21996
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ACRYSOF IOL IMPLANTATION
MA30BA is implanted through a clear corneal incision with a hinged architecture4 using a 0.6 mm deep, 3.5 mm wide groove; a 0.3 mm deep, 2.0 mm long clear corneal tunnel; and a 3.2 mm internal width corneal valve. When possible, the lens package is placed in a warm environment before lens implantation. The circulating nurse places the MA60BM in its packaging on top of the instrument sterilizer, where the temperature measures lOO°F, for 15 minutes. The MA30BA package is warmed for only 10 minutes because this lens is thinner and more malleable. The lenses should not be heated above this temperature as fogging can occur. In addition, if these lenses are heated to an excessive temperature, the acrylic material can weaken (David Eister, Alcon Surgical, personal communication, September 1996). Some surgeons have the circulating nurse place the lens package in a pocket to bring the lens to body temperature while avoiding the possibility of overheating (Stephen Lane, MD, personal communication, October 1996). Such warming is helpful but not mandatory. After wetting with balanced salt solution (BSS®), the lens is placed on a drop of viscoelastic and then grasped by folding forceps (Alcon Surgical #8065977720). Lens folding is initiated along the 6 to 12 o'clock axis with a closed, smooth forceps (Figure O. All forceps coming in contact with the lens are inspected
to ensure the tips are meticulously clean. Alternately, the wagon-wheel packaging may be used to initiate the fold (Kerry Solomon, MD, personal communication, October 1996). The optic is coated with sodium chondroitin sulfate-sodium hyaluronate (Viscoat®) before being grasped as peripherally as possible with implantation forceps (Alcon Surgical #8065977730). This same viscoelastic is used to inflate the anterior chamber before lens insertion. Less dispersive viscoelastic, such as 1% sodium hyaluronate, has a greater tendency to be forced out of the eye during implantation. Next, the lens is regrasped more peripherally with the folding forceps while it is held with the implantation forceps. Then, the lens is regrasped with the implantation forceps while it is held with the folding forceps (Figure 2). These maneuvers maximize how peripherally the optic is engaged (Figure 3). This reduces "fishmouthing" of the leading edge of the optic, which reduces the implantation profile size presented by the leading edge of the optic to minimize the wound size necessary for implantation. The leading haptic is placed into the tunnel with Calibri forceps and implanted into the anterior chamber before the optic enters the tunnel (Figure 4). Implantation occurs slowly. The lens may continue folding within the tunnel. As the leading edge of the optic reaches the internal corneal valve, the fit may occasionally feel tight. Increasing the force on the forceps is con-
Figure 1. (Shugar) A smooth forceps is used to initiate folding the MA30BA lens in the proper direction as the lens is folded with the folding forceps. The optic is coated with Viscoat and then grasped with an implantation forceps.
Figure 2. (Shugar) Implantation forceps are used to grasp the optic from folding forceps. The lens is typically regrasped to engage the optic more peripherally before lens implantation.
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Figure 3. (Shugar) The lens optic is held peripherally by implantation forceps.
traindicated and could damage the optic. Instead, redirecting the angle of implantation more posteriorly will usually facilitate passage of the distal optic through the internal corneal valve. If the lens cannot easily be implanted, the symmetry of the fold, location of the forceps on the optic, and wound architecture are examined. Ifwound architecture is suboptimal or the lens cannot easily be inserted despite adequate positioning of the optic within the folding for-
Figure 4. (Shugar) Implantation of the distal haptic through temporal, clear comeal incision.
ceps, the incision should be enlarged to 3.5 mm. This incision size is also required if an MA60BM lens is to be inserted through a clear corneal incision. In my experience, it has never been necessary to enlarge the incision beyond 3.5 mm to achieve effortless insertion. If necessary, a Calibri forceps may be used to stabilize the globe during insertion; however, care must be taken that the forceps does not scratch the lens surface or cause subconjunctival hemorrhage. If such stabilization is necessary for eyes with clear corneal incisions, I grasp the posterior lip of the paracentesis port with the Calibri to avoid trauma to the IOL, main incision, or conjunctiva. The lens initially enters the eye directed toward the anterior chamber angle opposite from the internal wound. The distal haptic is then redirected more posteriorly and placed beneath the opposite capsulorhexis margin and into the capsular bag. Care is taken to maximize control as the proximal optic clears the tunnel. The implantation forceps is rotated counterclockwise. A Sinskey hook is then placed through the side port to maximize the distance between the optic and the corneal endothelium (Figure 5). The Sinskey hook is used to disengage the proximal (Figure 6) and then the distal aspect of the optic from the forceps. Opening the forceps rapidly allows the lens to be more easily disengaged. In most cases, the proximal haptic is implanted by depressing the proximal part of the optic with the Sinskey hook
Figure 5. (Shugar) A Sinskey hook is used through the side port to maximize distance between the proximal optic and endothelium.
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Figure 6. (Shugar) A Sinskey hook is used to disengage the optic from the implantation forceps and to implant the proximal haptic.
(Figure 6). Alternately, the proximal haptic can be implanted with forceps while the Sinskey hook is used to depress the center of the optic.
Discussion A recent case report3 described extensive scratches on an AcrySof MA60 BM 10L that were likely caused by excessive insertion force. If ordinary insertion force is insufficient, the position of the folding forceps on the optic is re-evaluated and the lens grasped more peripherally if necessary. Excessive force is contraindicated, however, and implantation should require minimal insertion force. If it is suspected that excessive force may have been applied, the optic should be unfolded and inspected before implantation. If wound architecture is suboptimal or if the cause of a tight fit cannot be identified, the incision should be enlarged. I recommend that surgeons gain clinical experience and are comfortable with handling these lenses before attempting to insert them through 3.2 mm internal incisions. Recent studies describe enlargement of incision width during phacoemulsification and foldable IOL implantation. 5 ,6 These studies suggest that every incision undergoes some degree of enlargement during phacoemulsification and again during foldable lens implantation. In my clinical experience, most acrylic lenses are implanted as easily through 3.2 mm internal corneal 1358
incisions as was the AMO SI-30NB, which was my lens of choice immediately before acrylic lenses became available. I am currently studying how much the internal wound enlarges with acrylic IOL implantation using currently available instrumentation. Direct-acting Fine II Universal forceps should not be used to insert these lenses as they may scratch or crack the lenses? A direct-acting forceps (Fine III, Rhein Medical) is currently marketed for use with acrylic lenses. I have no experience with this instrument. In contrast to a recent recommendation to fold acrylic lenses along the 10 to 4 o'clock axis, 8 I recommend folding currently available acrylic lenses along the 6 to 12 o'clock axis to facilitate implantation through the smallest phacoemulsification incision through which atraumatic implantation can be achieved. Because the Sinskey hook is used through the side port, implantation of the proximal haptic requires minimal additional manipulation. In conclusion, acrylic lenses can be safely inserted through 3.2 to 3.5 mm phacoemulsification incisions without surface damage and with exquisite control within the anterior segment of the eye. Although I use an unenlarged 3.2 mm internal incision for IOL implantation, within several months I anticipate changing to a phacoemulsification tip requiring a keratome incision less than 3.0 mm and plan to use a 3.5 mm incision for implantation because wound enlargement will be required. Acrylic has the highest index of refraction of any approved IOL. Thus, these lenses are the thinnest and should have the lowest bulk for a given dioptric power, edge thickness, and optic diameter. This suggests that their insertion profile may be further reduced by improvements in insertion technology such as the development of a "shooter" or a method for rolling the lens for implantation.
References 1. Oshika T, Suzuki Y, Kizaki H, Yaguchi S. Two year clin-
ical study of a soft acrylic intraocular lens. J Cataract Refract Surg 1996; 22:104-109 2. Anderson C, Koch DD, Green G, et al. Alcon AcrySofll' acrylic intraocular lens. In: Martin RG, Gills JP, Sanders DR, eds, Foldable Intraocular Lenses. Thorofare, NJ, Slack Inc, 1993; 161-177 3. Vrabec MP, Syverud lC, Burgess q. Forceps-induced
J CATARACT REFRACT SURG-VOL 22, SUPPLEMENT 2 1996
ACRYSOF IOL IMPLANTATION
scratching of a foldable acrylic intraocular lens. Arch Ophthalmol1996; 114:777 4. Langerman OW. Architectural design of a self-sealing corneal tunnel, single-hinge incision. J Cataract Refract Surg 1994; 20:84-88 5. Steinert RF, Deacon J. Enlargement of incision width during phacoemulsification and folded intraocular lens implant surgery. Ophthalmology 1996; 103:220-225
6. Mackool RJ, Russell RS. Effect of foldable intraocular lens insertion on incision width. J Cataract Refract Surg 1996; 22:571-574 7. Carlson KH, Johnson OW. Cracking of acrylic intraocular lenses during capsular bag insertion. Ophthalmic Surg Lasers 1995; 26:572-573 8. Oh KT, Oh KT. Optimal folding axis for acrylic intraocular lenses. J Cataract Refract Surg 1996; 22:667-670
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