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Minimizing risk to the capsule during surgery for posterior polar cataract
techniques Minimizing risk to the capsule during surgery for posterior polar cataract David Allen, FRCS, FRCOphth, Christopher Wood, FRCS, FRCOphth Posterior polar cataract is associated with a deficiency of the posterior capsule in a high percentage of cases, leading to a high incidence of capsule rupture and potential vitreous loss. We describe an approach that minimizes the risk of vitreous loss. The key is viscodissection, a technique that can be applicable in other situations. J Cataract Refract Surg 2002; 28:742–744 © 2002 ASCRS and ESCRS
A
s cataract surgery is performed in many cases at a much earlier stage in the disease than previously, more patients are having surgery while there is a reasonable view through the lens. As a result, more patients are being recognized as possibly having posterior polar cataract. It can be difficult to distinguish a true congenital posterior polar cataract from a marked posterior subcapsular cataract or cataracta complicata occurring in younger patients. An important clinical feature of posterior polar cataract is a significant incidence of extreme capsule weakness (or perhaps even absence) in the area of polar opacity.1 Osher and coauthors2 report a 26% incidence of posterior capsule rupture in these cases. They cite possible adherence of the opacity to the capsule as an added factor.
Hydrodissection of the cortex, particularly cortical cleaving hydrodissection,3 has been a significant factor in increasing the safety and efficacy of cataract surgery. Prestripping the corticocapsular adhesions has made cortical irrigation/aspiration (I/A) easier and therefore safer as well as increased the thoroughness of cortical cleanup. This is thought to have influenced the gradual reduction in posterior capsule opacification rates over the past 10 years.4 However, in the presence of a weakened or deficient posterior capsule, this technique is hazardous and can result in blowout of the posterior capsule with loss of the nucleus into the vitreous. We report a technique that is helpful in cases of a weak or deficient posterior capsule. The goal is to leave the posterior cortex undisturbed until the very last moment. We also use the technique in all cases of markedly localized posterior subcapsular cataracts in case they are in fact unrecognized posterior polar opacities.
Accepted for publication March 12, 2001. From Sunderland Eye Infirmary, Sunderland, England. Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, May 2000, and San Diego, California, USA, April 2001. Neither author has a financial or proprietary interest in any material or device mentioned. Reprint requests to Mr. David Allen, FRCOphth, Sunderland Eye Infirmary, Queen Alexandra Road, Sunderland SR2 9DF, England. [email protected]. © 2002 ASCRS and ESCRS Published by Elsevier Science Inc.
Surgical Technique The initial preparation stages of the surgery are unchanged up to and including the capsulorhexis. Gentle hydrodelineation (Figure 1,A) is then performed, attempting to separate the nucleus from the epinucleus/ cortex. Extreme care is taken not to inject until the cannula is deeply embedded in the lens and to ensure there is no injection during withdrawal of the cannula. 0886-3350/02/$–see front matter PII S0886-3350(02)01244-0
TECHNIQUES: ALLEN
Figure 1.
(Allen) A: Hydrodelineation is performed. B: Viscodissection of residual cortex begins. C: Gentle I/A of loosened cortex/epinucleus is performed. D: The residual posterior plaque is ready to be removed.
This predissection allows careful removal of the nucleus without putting rotational or aspirational forces on the posterior cortex, which should remain as undisturbed as possible. It is important at this point not to test for completeness of hydrodelineation by trying to rotate the nucleus, which risks breaking what might be a tenuous posterior capsule. The nucleus is then carefully removed by gentle phacoemulsification, again avoiding rotation, with the aim of disturbing the cortex as little as possible. A reduced flow rate and bottle height are used to minimize fluid flow and turbulence through the eye. Because of the reduced bottle height, the maximum vacuum is lowered to prevent post-occlusion surge. Because of the different fluidic characteristics of phaco machines, it is not possible to give categorical advice about settings during nucleus removal. However, with a peristaltic or flow-based Concentrix system, the flow rate might be approximately 20 to 25 mL/min, the maximum vacuum 150 to 200 mm Hg, and the bottle height 60 to 70 cm. With a vacuum-based (venturi or rotary vane) system, the vacuum might be approximately 75 to 100 mm Hg and the bottle height 60 to 70 cm. Next, an ophthalmic viscosurgical device (OVD) is used to create a viscodissection plane between capsule and cortex (Figures 1,B and 2). A high-viscosity OVD, such as sodium hyaluronate 2.3% (Healon威5) or sodium hyaluronate 1.4% (Healon GV威), facilitates this step. Viscodissection is safe in this context because it is gentle and controlled and can be stopped when part way
around the posterior capsule. If this is applied in 4 quadrants, a shell of cortex/epinucleus can be made to fold in on itself toward the center of the lens while the posterior pole remains undisturbed. The shell is gently removed from each quadrant with the I/A handpiece (Figure 1,C) using a low-flow, low-vacuum technique. This leaves a small posterior plaque (Figure 1,D) containing cortex and the posterior polar plug. The plaque can be gently peeled from the capsule with gentle aspiration or the OVD. If there is a hole in the capsule at this stage, little cortex and no nucleus is left to complicate the management and the chances of extending the defect or experiencing vitreous loss are greatly reduced.
Figure 2. (Allen) A still from an intraoperative videorecording shows viscodissection at the stage shown in Figure 1,A.
J CATARACT REFRACT SURG—VOL 28, MAY 2002
743
TECHNIQUES: ALLEN
If the preoperative diagnosis of posterior polar cataract is incorrect and a dense posterior subcapsular cataract is found at this stage, there is often a “fibrotic” plaque remaining on the posterior capsule. In some cases, the plaque can be carefully peeled from the posterior capsule after an edge is defined or the existing edge lifted. A Corydon forceps is useful for this. If the plaque cannot be peeled and is sufficiently dense to potentially reduce vision, a posterior curvilinear capsulorhexis can be performed. This preserves the anterior vitreous face and reduces the risk of later retinal complications.5
Discussion We learned the technique of viscodissection from Krag and coauthors6 and Burton and Pickering7 and believe it is useful, although underused, in the management of more complicated cataracts. The dissection achieved occurs at a slower, more controlled rate, and filling the capsular bag supports the capsule, tamponades the vitreous, and stabilizes or moves the lens nucleus. Thus, the technique is useful in cases of zonular weakness, preexisting capsule tears, or similar surgically induced problems arising perioperatively.
744
References 1. Hejtmancik JF, Datilles M. Congenital and inherited cataracts. In: Tasman W, Jaeger EA, eds, Duane’s Clinical Ophthalmology, CD ROM edition. Baltimore, MD, Lippincott Williams & Wilkins, 2001; vol 1, chap 74 2. Osher RH, Yu BC-Y, Koch DD. Posterior polar cataracts: a predisposition to intraoperative posterior capsular rupture. J Cataract Refract Surg 1990; 16:157–162 3. Fine I. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508 –512 4. Apple DJ, Peng Q, Visessook N, et al. Eradication of posterior capsule opacification; documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem. Ophthalmology 2001; 108:505– 518 5. Galand A, van Cauenberge F, Moosavi J. Posterior capsulorhexis in adult eyes with intact and clear capsules. J Cataract Refract Surg 1996; 22:458 – 461 6. Krag S, Thim K, Corydon L. Hydroexpression and viscoexpression of the nucleus through a continuous circular capsulorhexis. (reply to letter) J Cataract Refract Surg 1993; 19:666 – 667 7. Burton RL, Pickering S. Extracapsular cataract surgery using capsulorhexis with viscoexpression via a limbal section. J Cataract Refract Surg 1995; 21:297–301
J CATARACT REFRACT SURG—VOL 28, MAY 2002
A
s cataract surgery is performed in many cases at a much earlier stage in the disease than previously, more patients are having surgery while there is a reasonable view through the lens. As a result, more patients are being recognized as possibly having posterior polar cataract. It can be difficult to distinguish a true congenital posterior polar cataract from a marked posterior subcapsular cataract or cataracta complicata occurring in younger patients. An important clinical feature of posterior polar cataract is a significant incidence of extreme capsule weakness (or perhaps even absence) in the area of polar opacity.1 Osher and coauthors2 report a 26% incidence of posterior capsule rupture in these cases. They cite possible adherence of the opacity to the capsule as an added factor.
Hydrodissection of the cortex, particularly cortical cleaving hydrodissection,3 has been a significant factor in increasing the safety and efficacy of cataract surgery. Prestripping the corticocapsular adhesions has made cortical irrigation/aspiration (I/A) easier and therefore safer as well as increased the thoroughness of cortical cleanup. This is thought to have influenced the gradual reduction in posterior capsule opacification rates over the past 10 years.4 However, in the presence of a weakened or deficient posterior capsule, this technique is hazardous and can result in blowout of the posterior capsule with loss of the nucleus into the vitreous. We report a technique that is helpful in cases of a weak or deficient posterior capsule. The goal is to leave the posterior cortex undisturbed until the very last moment. We also use the technique in all cases of markedly localized posterior subcapsular cataracts in case they are in fact unrecognized posterior polar opacities.
Accepted for publication March 12, 2001. From Sunderland Eye Infirmary, Sunderland, England. Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, USA, May 2000, and San Diego, California, USA, April 2001. Neither author has a financial or proprietary interest in any material or device mentioned. Reprint requests to Mr. David Allen, FRCOphth, Sunderland Eye Infirmary, Queen Alexandra Road, Sunderland SR2 9DF, England. [email protected]. © 2002 ASCRS and ESCRS Published by Elsevier Science Inc.
Surgical Technique The initial preparation stages of the surgery are unchanged up to and including the capsulorhexis. Gentle hydrodelineation (Figure 1,A) is then performed, attempting to separate the nucleus from the epinucleus/ cortex. Extreme care is taken not to inject until the cannula is deeply embedded in the lens and to ensure there is no injection during withdrawal of the cannula. 0886-3350/02/$–see front matter PII S0886-3350(02)01244-0
TECHNIQUES: ALLEN
Figure 1.
(Allen) A: Hydrodelineation is performed. B: Viscodissection of residual cortex begins. C: Gentle I/A of loosened cortex/epinucleus is performed. D: The residual posterior plaque is ready to be removed.
This predissection allows careful removal of the nucleus without putting rotational or aspirational forces on the posterior cortex, which should remain as undisturbed as possible. It is important at this point not to test for completeness of hydrodelineation by trying to rotate the nucleus, which risks breaking what might be a tenuous posterior capsule. The nucleus is then carefully removed by gentle phacoemulsification, again avoiding rotation, with the aim of disturbing the cortex as little as possible. A reduced flow rate and bottle height are used to minimize fluid flow and turbulence through the eye. Because of the reduced bottle height, the maximum vacuum is lowered to prevent post-occlusion surge. Because of the different fluidic characteristics of phaco machines, it is not possible to give categorical advice about settings during nucleus removal. However, with a peristaltic or flow-based Concentrix system, the flow rate might be approximately 20 to 25 mL/min, the maximum vacuum 150 to 200 mm Hg, and the bottle height 60 to 70 cm. With a vacuum-based (venturi or rotary vane) system, the vacuum might be approximately 75 to 100 mm Hg and the bottle height 60 to 70 cm. Next, an ophthalmic viscosurgical device (OVD) is used to create a viscodissection plane between capsule and cortex (Figures 1,B and 2). A high-viscosity OVD, such as sodium hyaluronate 2.3% (Healon威5) or sodium hyaluronate 1.4% (Healon GV威), facilitates this step. Viscodissection is safe in this context because it is gentle and controlled and can be stopped when part way
around the posterior capsule. If this is applied in 4 quadrants, a shell of cortex/epinucleus can be made to fold in on itself toward the center of the lens while the posterior pole remains undisturbed. The shell is gently removed from each quadrant with the I/A handpiece (Figure 1,C) using a low-flow, low-vacuum technique. This leaves a small posterior plaque (Figure 1,D) containing cortex and the posterior polar plug. The plaque can be gently peeled from the capsule with gentle aspiration or the OVD. If there is a hole in the capsule at this stage, little cortex and no nucleus is left to complicate the management and the chances of extending the defect or experiencing vitreous loss are greatly reduced.
Figure 2. (Allen) A still from an intraoperative videorecording shows viscodissection at the stage shown in Figure 1,A.
J CATARACT REFRACT SURG—VOL 28, MAY 2002
743
TECHNIQUES: ALLEN
If the preoperative diagnosis of posterior polar cataract is incorrect and a dense posterior subcapsular cataract is found at this stage, there is often a “fibrotic” plaque remaining on the posterior capsule. In some cases, the plaque can be carefully peeled from the posterior capsule after an edge is defined or the existing edge lifted. A Corydon forceps is useful for this. If the plaque cannot be peeled and is sufficiently dense to potentially reduce vision, a posterior curvilinear capsulorhexis can be performed. This preserves the anterior vitreous face and reduces the risk of later retinal complications.5
Discussion We learned the technique of viscodissection from Krag and coauthors6 and Burton and Pickering7 and believe it is useful, although underused, in the management of more complicated cataracts. The dissection achieved occurs at a slower, more controlled rate, and filling the capsular bag supports the capsule, tamponades the vitreous, and stabilizes or moves the lens nucleus. Thus, the technique is useful in cases of zonular weakness, preexisting capsule tears, or similar surgically induced problems arising perioperatively.
744
References 1. Hejtmancik JF, Datilles M. Congenital and inherited cataracts. In: Tasman W, Jaeger EA, eds, Duane’s Clinical Ophthalmology, CD ROM edition. Baltimore, MD, Lippincott Williams & Wilkins, 2001; vol 1, chap 74 2. Osher RH, Yu BC-Y, Koch DD. Posterior polar cataracts: a predisposition to intraoperative posterior capsular rupture. J Cataract Refract Surg 1990; 16:157–162 3. Fine I. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508 –512 4. Apple DJ, Peng Q, Visessook N, et al. Eradication of posterior capsule opacification; documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem. Ophthalmology 2001; 108:505– 518 5. Galand A, van Cauenberge F, Moosavi J. Posterior capsulorhexis in adult eyes with intact and clear capsules. J Cataract Refract Surg 1996; 22:458 – 461 6. Krag S, Thim K, Corydon L. Hydroexpression and viscoexpression of the nucleus through a continuous circular capsulorhexis. (reply to letter) J Cataract Refract Surg 1993; 19:666 – 667 7. Burton RL, Pickering S. Extracapsular cataract surgery using capsulorhexis with viscoexpression via a limbal section. J Cataract Refract Surg 1995; 21:297–301
J CATARACT REFRACT SURG—VOL 28, MAY 2002