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Posterior capsulorhexis with optic capture: Maintaining a clear visual axis after pediatric cataract surgery
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Posterior capsulorhexis with optic capture: Maintaining a clear visual axis after pediatric cataract surgery Howard V. Gimbel, M.D., Brian M. DeBroff, M.D.
ABSTRACT We describe a technique for preventing secondary membrane formation after pediatric cataract extraction. This technique involves capture of an intraocular lens (IOL) optic through a posterior curvilinear capsulorhexis opening in an attempt to maintain a clear visual axis in children after cataract surgery. This maneuver ensures centration of the posterior chamber IOL because the haptics remain in the capsular bag and the optic is captured in the posterior capsular opening. Also, the need for an anterior vitrectomy may be eliminated. Apposition of the anterior and posterior capsule leaflets anterior to the optic may limit the migration of Elschnig pearls, reducing the incidence of secondary membranes and the need for additional procedures.
Key Words: capsulorhexis, cataract surgery, Elschnig pearls, intraocular lens, optic capture, pediatric cataracts, posterior capsule, secondary cataract
A major concern in pediatric intraocular lens (IOL) implantation surgery is the high incidence of posterior capsule opacification. Anterior lens epithelial cells proliferate, form Elschnig pearls, and demonstrate myofibroblastic differentiation. 1 This cell proliferation leads to secondary membranes that use the posterior capsule, the anterior vitreous face, and the anterior and posterior surfaces of the IOL as a scaffold. 2•3 Some authors have reported an inevitable development of secondary cataract in children unless the posterior capsule is generously opened and an anterior vitrectomy performed at the time of cataract extraction and IOL implantation. 4 - 17 In our observational study of 61 posterior chamber IOL implantations in patients from two to 18 years of age, 14 there was a 17% cumulative probability of developing posterior capsule opacification that required capsulotomy by one year postoperatively, even with meticulous cortical removal and posterior capsule polishing. By four years after sur-
gery, there was a 59% Kaplan-Meier projected probability of developing posterior capsule opacification. 14 In a study by Hiles and Hered, 18 63% of children's visual axes became re-occluded by secondary membranes and required secondary capsulotomies, even after primary posterior capsulotomy. In children six years and older, the eye responds to surgery with less inflammation and posterior capsule opacification than does the infant's eye. 14 In this population, the best approach is to use the neodymium: YAG (Nd:YAG) laser if secondary cataract formation occurs. 18- 20 For children younger than six years, less cooperative children, and infants, a vertically mounted Nd:YAG laser in the operating room can be used to perform posterior capsulotomies at the time of surgery or weeks to months later. Laser capsulotomy in the pediatric population, however, requires a second procedure under general anesthesia and often the use of high ~nergy lev-
Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, Apri/1994. Maria Ferensowicz, B.Sc., M.A., Gimbel Eye Centre, provided editorial assistance. Reprint requests to Howard V. Gimbel, M.D., Gimbel Eye Centre, #450, 4935-40 Avenue N. W, Calgary, Alberta, Canada TJA 2NJ. 658
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els. Also, some membranes are too dense to create large enough openings, and recurrence of the membrane is possible because the anterior vitreous face remains as a scaffold for secondary membrane formation. Currently many ophthalmologists routinely perform a posterior capsulotomy and a shallow anterior vitrectomy at the time of cataract extraction before IOL insertion. 21 •22 Special microinstruments have been developed (e.g., hook-shaped needles to perform primary posterior capsulotomies underneath a posterior chamber IOL). 23 A recent modification involves removing the cataract through a scleral tunnel incision and implanting a posterior chamber IOL and then repeating the procedure to perform a pars plana posterior capsulotomy and pars plana anterior vitrectomy. 24 This ensures proper IOL positioning before the capsulotomy is made and allows the surgeon to create large capsular openings. One disadvantage of primary capsulotomy and anterior vitrectomy is IOL dislocation, which occurs in 3% to 20% of cases. 24- 27 Also, posterior capsule tears may extend during anterior vitrectomy. These complications can be reduced by performing a posterior capsulorhexis and then the anterior vitrectomy.2 8 Doing an anterior vitrectomy at the time of cataract surgery, however, increases the risk of cystoid macular edema (CME)29 and may result in vitreous adhesions and vitreous incarceration in the wound, which increases the risk of retinal detachment. 3 Finally, even after primary posterior capsulectomy with vitrectomy, many children's visual axes become re-occluded by secondary membranes, 18 •24•31 necessitating repeated capsulotomies and sometimes pars plana membranectomy. 14 Other techniques have been proposed to prevent posterior capsular and vitreous face membrane formation while reducing the risk of IOL dislocation. In one technique, the IOL is placed anterior to the entire capsular bag, creating a tight adhesion between the anterior and posterior capsules. This helps prevent lens epithelial cells from migrating, proliferating, and forming Elschnig pearls. 32 To further reduce or eliminate opacification of the posterior capsule in pediatric cases while potentially eliminating the need for an anterior vitrectomy, a new technique has been proposed that uses a primary posterior continuous curvilinear capsulorhexis (PCCC) 33 •34 and placement of the IOL optic through both capsulorhexis openings. This results in PCCC optic capture while the haptics remain in the bag. Even though the posterior capsule is thinner than the anterior capsule, a smooth continuous curvilinear capsulorhexis (CCC) in the posterior capsule is resistant to radial tears. We have successfully used this technique of optic capture in eight pediatric cases since April 1993 without intraoperative or postoperative complications. As of February 1994, all cases had clear visual axes with excellent IOL centration. A similar technique of capturing the optic through a capsulorhexis opening has been described in cases of posterior capsular tears in adults. Neuhann and Neu-
°
hann have described a technique in which the IOL is placed in the sulcus and then the IOL optic is placed through the anterior capsulorhexis opening to achieve capture and stable fixation (T. Neuhann, M.D., Th. Neuhann, M.D., "The Rhexis-Fixated Lens," fllm presented at the Symposium on Cataract, IOL and Refractive Surgery," Boston, April 1991). Posterior capsulorhexis with optic capture involves placing the optic through both the anterior and posterior capsulorhexis openings to achieve capture of the lens in the posterior chamber. It is anticipated that primary PCCC with posterior capsular optic capture will maintain a clear visual axis, reducing the need for subsequent intervention because of the apposition of anterior and posterior capsule leaflets anterior to the IOL optic. These capsule leaflets are apposed 360 degrees except at the haptic-optic junctions. The theory is that this will seal and lead to formation of a Soemmering's ring anterior to the IOL or allow the release ofElschnig pearls anterior to the IOL, where they will be removed by the aqueous. Unlike the vitreous, the aqueous does not provide a scaffold for lens epithelial proliferation, and the continual turnover of aqueous disperses individual cells released in the anterior chamber. Any protein or fibrous tissue that adheres to the IOL's anterior surface may be cleared away with the Nd:YAG laser in a manner similar to that used in opening fibrosed and contracted anterior capsulorhexis openings.
SURGICAL TECHNIQUE Posterior continuous curvilinear capsulorhexis, the technique to create primary posterior capsulotomies in pediatric cataract cases, is accomplished using CCC principles after posterior chamber IOL implantation in the bag. We recommend that a lens no larger than 6 mm be implanted to minimize the diameter of posterior capsulorhexis required for capture to occur. With the assistance of a high-viscosity viscoelastic that has excellent clarity, such as Healon GV® (sodium hyaluronate), PCCC is initiated using a cystotome or bent needle (Figure 1). Placing the instrument under the IOL, the surgeon makes a small central puncture in the posterior capsule. Additional viscoelastic is placed through the central puncture of the posterior capsule to push the vitreous face away (Figure 2). In the case of a small pre-existing or inadvertent tear of the posterior capsule during surgery, posterior capsule optic capture should be attempted only after the tear is converted into a small, well-centered, circular PCCC and, if necessary, following an adequate anterior vitrectomy. The PCCC technique can also be used to remove a thickened fibrotic posterior capsule plaque. In these cases, the PCCC is made as a controlled circle that encompasses the central opacity and results in a properly sized and centered posterior capsule opening to ensure capture and centration of the IOL optic. Similar to achieving a CCC in the anterior capsule,
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Fig. 1.
(Gimbel) The PCCC is started with a central puncture of the posterior capsule using a cystotome under viscoelastic posterior to the IOL in the bag.
Fig. 2.
(Gimbel) Viscoelastic is placed through the posterior capsule opening to push vitreous posteriorly.
the posterior capsule tear is directed to 3 o'clock before being directed counterclockwise (Figure 3). After the tear is initiated, the best control of the progressing tear in the posterior capsule is achieved with an elongated Kelman-McPherson or pointed capsulorhexis forceps. The capsule flap is grasped near one point of tearing and the tear turned in the desired direction (Figure 4 ). Additional viscoelastic is added intermittently throughout the procedure to dissect the vitreous from the capsule. Care should be taken that the viscoelastic does not push the leading flap posteriorly, which can make grasping the posterior capsular tag difficult. The PCCC is kept small enough to capture the optic but large enough to allow the IOL optic to pass through so that maximum integrity of the posterior capsule is preserved and posterior capture of the IOL optic is facilitated (Figure 5). Before the posterior capsule circular tissue is removed, scissors should be used to cut any
adherent vitreous strands. An anterior vitrectomy is necessary only if vitreous presents through the posterior capsular opening. Posterior capture of the IOL optic is done after the scleral wound is sutured but before the viscoelastic is removed. Under viscoelastic, with the IOL loop oriented horizontally, for example, the IOL is slipped inferiorly and then superiorly through the PCCC using a spatula or cannula. This results in posterior capsule capture of the optic (Figure 6). Viscoelastic material behind the IOL is left in place; viscoelastic remaining in the anterior chamber is slowly removed. Irrigation with balanced salt solution (BSS®) is performed while the viscoelastic is being aspirated to maintain a deep chamber and prevent forward movement of vitreous and the IOL. Optimally, this is performed with a two-instrument technique to constantly maintain the anterior chamber. If the irrigation/aspiration (1/A) tip is used, the anterior chamber
Fig. 3.
Fig. 4.
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(Gimbel) The PCCC is extended to 3 o'clock, similar to the technique used with CCC.
(Gimbel) For better control, capsule forceps are used in directing and completing the PCCC.
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Fig. 5.
(Gimbel) A well-centered PCCC, concentric and smaller than the CCC, is achieved.
Fig. 6.
(Gimbel) Under viscoelastic, the IOL optic edge is slipped through the PCCC inferiorly and superiorly to achieve PCCC capture.
CASE REPORT A 2.5-year-old female with a monocular congenital cataract of the left eye presented for cataract extraction. Her birth and development were unremarkable. There was a family history of early cataracts (mother and maManaging Complications grandmother). The patient's right eye had been ternal If an anterior capsular radial tear occurs, in-thepatched three to five hours daily since she was six bag placement of the IOL may still be attempted, months old and when she was two, strabismus surgery but posterior capsulorhexis should probably not be was performed. attempted. There was a left exotropia of 14 prism diopters (D) When there is an existing posterior capsular tear or an with left inferior oblique overaction. Refraction was iatrogenic tear, the IOL can be placed in the sulcus and +0.75 -1.25 x 25 in the right eye and +2.50 -1.75 x the optic placed through the anterior capsulorhexis, as 1.67 in the left. Axial length was 21.56 mm and shown by Neuhann and Neuhann in their ftlm, as well 21.12 mm, respectively. Keratometry in the right eye as through the tom posterior capsule. In this situation, was 43.25 x 28 and 44.50 x 118 and in the left was a 6.5 mm or 7.0 mm diameter lens should be used. 42.75 x 167 and 45.00 x 77. Visual acuity measured If a posterior radial capsular tear occurs during pos- with a Snellen picture chart was 20/25 in the right eye terior capsulorhexis, the attempt to capture the IOL and 20/200 in the left. Fixation was central and eccenoptic will have to be aborted. If the tear does not extend tric, respectively. Anterior segment evaluation of the to the equator, the surgeon can try to blunt it by turning right eye was unremarkable. Anterior segment evaluathe tear back. The main advantage of having the IOL tion of the left eye was normal except for the lens, which already within the capsular bag is that if a tear occurs, demonstrated 1+ diffuse cortical opacities with vacuoles further manipulation can be discontinued and the lens and a 3+ central posterior polar opacity. In both eyes, will likely remain stable. If the IOL has to be placed in the posterior segment examination was unremarkable. the capsular bag after a posterior capsular tear occurs, Under general anesthesia a 6.0 mm curvilinear incithe likelihood of extending this tear and destroying the sion 2.5 mm from the limbus was made and a scleral entire capsular bag is high. tunnel extended to the vascular arcade before the anteIf the posterior capsulorhexis is not concentric, cap- rior chamber was entered just anterior to the arcade. The ture can still be attempted because the optic still tends anterior chamber was filled with viscoelastic and a to center in the visual axis. Based on one case in which 5.5 mm CCC was formed in the anterior capsule. The this has occurred, it appears that the haptics in the cap- lens was removed with an automated I/A handpiece. sular bag have a greater centering force than does the The intact posterior capsule was quite fibrotic with crysPCCC. tal granules on its surface. The anterior chamber was Capture should not be attempted if the PCCC is larger filled with viscoelastic and the wound enlarged to than the optic or quite eccentric. In these cases, a pri- 6.0 mm for IOL implantation. A one-piece Pharmacia 811B IOL of 24.5 D power mary capsulotomy will have been created and one vitrectomy. anterior an with a 6.0 mm diameter optic and overall length of with proceeding should consider
may collapse unless sutures have been placed to reduce incision size. The wound may be closed with absorbable or nonabsorbable sutures.
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12.0 mm was placed in the capsular bag. Viscoelastic was instilled under the IOL to stretch the posterior capsule. Applying the principles used during anterior CCC, a PCCC that encompassed the fibrotic opacity in the posterior capsule was performed. A central circular posterior opening of about 5.0 mm was made with capsule forceps. Gills-Welsh scissors were used in the posterior chamber before the posterior capsular tissue fragment was removed. Upon removal of the fragment, there were no obvious vitreous strands. After complete removal of the fragment, no vitreous presented through the posterior capsular opening. After the scleral wound was closed with a 10-0 polypropylene (Prolene®) continuous suture, the edge of the IOL optic was slipped through the posterior capsular opening inferiorly and then superiorly, resulting in posterior capsular capture and optic fixation. The haptics remained in the bag, which now was flattened with apposition of anterior and posterior leaflets. The PCCC, stretched when the haptics entered the capsular bag, was now oval. Because the PCCC was central, the lens maintained a central position once the optic was placed through the posterior capsular opening. The opposed capsular leaflets were positioned inside the IOL's optic border. The viscoelastic was left in the posterior chamber to avoid vitreous herniation into the anterior chamber. All of the viscoelastic was removed from the anterior chamber. Gonioscopy showed the inner portion of the wound was gaping and 10-0 nylon sutures were passed through full thickness cornea at the limbus at both sides of the wound to stabilize the inner portion of the incision. Gonioscopy subsequently revealed the inner aspect of the wound to be closed. The chamber re-formed well, although some aqueous leaked through the paracentesis site. After a single interrupted 10-0 nylon suture was placed at the paracentesis site, fluorescein testing showed no leakage from the chamber. Conjunctiva and Tenon's were closed with interrupted 9-0 polyglactin 910 (Vicryl®) sutures. One day postoperatively, the IOL was well centered. Autorefraction in the left eye was +4.0 -2.50 X 178. Visual acuity could not be obtained. Intraocular pressure by applanation tonometry was 12 mm Hg. The cornea was clear, the anterior chamber was deep with only a few cells, and the IOL remained captured posterior to the opposed capsular leaflets. Ten days postoperatively, the eye was doing well with a quiet anterior segment. Five months postoperatively, the anterior vitreous face was clear and no precipitates had formed on the anterior or posterior IOL surface.
DISCUSSION Primary PCCC with posterior capsular optic capture is a technically challenging procedure that requires skill to avoid peripheral tears in the posterior capsule and loss 662
Fig. 7.
(Gimbel) Posterior capsulorhexis with optic capture. Elschnig pearls are migrating to the anterior chamber.
of the capsular bag. It should not be attempted until the surgeon is familiar and adept with CCC in children. Difficulties of the procedure include performing capsulorhexis in the posterior capsule, which is thinner than the anterior capsule. The posterior capsular opening must be smaller than and concentric with the IOL optic. Because the posterior capsule is thin and the PCCC may not have the same stretching capacity of the anterior CCC, 35, 36 the vaulting of the intraocular optic through the PCCC requires cautious manipulation. Ways to minimize difficulty with the procedure are to maintain high magnification with the operating microscope and to use viscoelastics liberally. An anterior vitrectomy may still be necessary if vitreous herniates at the time of PCCC. If an anterior vitrectomy is necessary due to vitreous presentation, however, the PCCC opening provides an opening that is resistant to tears. Complications of the procedure include the possibility of an early postoperative rise in lOP resulting from viscoelastic that may remain in the anterior chamber. A possible late complication is contracture of the an~erior capsule CCC border, which if not recognized and cut with the Nd:YAG laser, may contract so much that the haptics may be lost. Posterior capsulorhexis with optic capture has many potential advantages. By capturing the IOL optic behind the posterior capsule while the haptics remain in the bag, stable IOL fixation is achieved. Posterior optic capture results in a stable anterior chamber by maintaining the separation between posterior and anterior segments. Lens epithelial cells are expected to migrate anterior to the IOL, preventing lens epithelial cell proliferation along the vitreous face (Figure 7). The advantages of PCCC alone include a posterior capsular opening that is resistant to tears. Also, PCCC can be used to remove dense plaques, convert congenital traumatic defects, and convert posterior capsular tears that occur during surgery.
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6. BenEzra D. The surgical approaches to paediatric cataThis technique may also be beneficial in adult cataract. Eur J Implant Refract Surg 1990; 2:241-244 ract surgery to reduce the incidence of posterior capsular 7. BenEzra D, Rose L. Intraocular versus contact lenses for opacity and the subsequent need for YAG laser capsuthe correction of aphakia in unilateral, congenital and lotomies. In adults, however, the possibility of CME developmental cataract. Eur J Implant Refract Surg 1990; after posterior capsular rupture is high; in children, CME 2:303-307 37 is rare. Also, secondary cataract formation in adults 8. Parks MM. Posterior lens capsulectomy during primary occurs with less frequency and Nd:YAG laser capsulotcataract surgery in children. Ophthalmology 1983; 90: omy is an easier procedure, often requiring less energy 344-345 and no sedation. The procedure can, however, be used 9. Metge P, Cohen H, Chemila JF. Intercapsular implantawhen the posterior capsule in adults is inadvertently tom tion in children. Eur J Implant Refract Surg 1990; 2: and a PCCC is performed to blunt the tear. Posterior 319-323 capsule capture of the IOL in this case keeps the IOL 10. BenEzra D, Hemo I. Traumatic cataract in children. Visual results following aphakic correction with contact or well centered and maintains the haptics in the bag. intraocular lenses in paediatric cataract. Eur J Implant Longer follow-up and additional cases will be reRefract Surg 1990; 2:325-328 quired to see whether Elschnig pearls will present and if 11. De Courten C, Bucher PJM, BenEzra D. Experience with so, in what location. It is possible that the site at which HEMA lenses in paediatric cataract. Eur J Implant Refract the haptics enter the capsular bag, thereby creating an Surg 1990; 2:315-318 area where the capsule is posterior to the optic, may 12. Morgan KS, Karciolglu ZA. Secondary cataracts in inprovide a site at which some pearls find their way into fants after lensectomies. J Pediatr Ophthalmol Strabismus the posterior chamber. It is expected, however, that with 1987; 24:45-48 the majority of the posterior capsule opening anterior to 13. Sinskey RM, Stoppel JO, Amin P. Long-term results of the lens optic, no Elschnig pearls will deposit on the intraocular lens implantation in pediatric patients. J Catvitreous face and the visual axis will remain clear (Figaract Refract Surg 1993; 19:405-408 ure 7). The incidence of further complications will re- 14. Gimbel HV, Ferensowicz M, Raanan M, DeLucaM. Implantation in children. J Pediatr Ophthalmol Strabismus quire monitoring and animal studies in the future may 1993; 30:69-79 provide histological patterns of lens epithelial cell pro15. Hiles DA, Johnson BL. The role of the crystalline lens liferation in the situation of optic capture. epithelium in postpseudophakos membrane formation. In conclusion, posterior capsulorhexis with optic capAm Intra-Ocular Implant Soc J 1980; 6:141-147 ture is a technically demanding procedure that may keep 16. Weidle EG, Lisch W, Thiel HJ. Management of the opathe optical axis clear while maintaining excellent supcified posterior lens capsule: an excision technique for port and centration of the posterior chamber IOL. The membranous changes. Ophthalmic Surg 1986; 17:635technique may allow surgeons to avoid planned anterior 640 vitrectomies in infants and children and minimize the 17. Mackool RJ, Chhatiawala H. Pediatric cataract surgery potential for secondary cataract formation. Additional and intraocular lens implantation: a new technique for preventing or excising postoperative secondary memcases with further follow-up are needed to evaluate the branes. J Cataract Refract Surg 1991; 17:62-66 long-term success of this technique in maintaining a clear visual axis in children after cataract surgery. Ad- 18. Hiles DA, Hered RW. Modem intraocular lens implants in children with new age limitations. J Cataract Refract ditional study is needed to document safety and longSurg 1987; 13:493-497 term efficacy before recommending the widespread 19. Sinskey RM, Karel F, Dal Ri E. Management of cataracts application of this technique.
REFERENCES 1. McDonnell PJ, Zarbin MA, Green WR. Posterior capsule opacification in pseudophakic eyes. Ophthalmology 1983; 90:1548-1553 2. Cobo LM, Ohsawa E, Chandler D, et al. Pathogenesis of capsular opacification after extracapsular cataract extraction. An animal model. Ophthalmology 1984; 91:857863 3. Nishi 0. Fibrinous membrane formation on the posterior chamber lens during the early postoperative period. J Cataract Refract Surg 1988; 14:73-77 4. Gimbel HV. Two-stage capsulorhexis for endocapsular phacoemulsification. J Cataract Refract Surg 1990; 16: 246-249 5. Oliver M, Milstein A, Pollack A. Posterior chamber lens implantation in infants and juveniles. Eur J Implant Refract Surg 1990; 2:309-314
in children. J Cataract Refract Surg 1989; 15:196-200 20. Kora Y, lnatomi M, Fukado Y, et al. Long-term study of children with implanted intraocular lenses. J Cataract Refract Surg 1992; 18:485-488 21. Hemo Y, BenEzra D. Traumatic cataracts in young children. Correction of aphakia by intraocular lens implantation. Ophthalmic Paediatr Genet 1987; 8:203-207 22. Dahan E, Salmenson BD. Pseudophakia in children: precautions, techniques, and feasibility. J Cataract Refract Surg 1990; 16:75-82 23. Lischetti P. New technique for posterior capsulotomy. Eur J Implant Refract Surg 1990; 2:77-79 24. Buckley EG, Klombers LA, Seaber JH, et al. Management of the posterior capsule during pediatric intraocular lens implantation. Am J Ophthalmol 1993; 115:722-728 25. Dutton JJ, Baker JD, Hiles DA, Morgan KS. Visual rehabilitation of aphakic children. Surv Ophthalmol 1990; 34:365-384 26. Hiles DA, Watson BA. Complications of implant surgery in children. Am Intra-Ocular Implant Soc J 1979; 5:24-32
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27. Burke JP, Willshaw HE, Young JDH. Intraocular lens implants for uniocular cataracts in childhood. Br J Ophthalmol 1979; 73:860-864 28. Mackool RJ. Management of the posterior capsule during pediatric intraocular lens implantation (letter). Am J 0phthalmol1994; 117:121-122 29. Hoyt CS, Nickel B. Aphakic cystoid macular edema; occurrence in infants and children after transpupillary lensectomy and anterior vitrectomy. Arch Ophthalmol1982; 100:746-749 30. Koenig SB, Ruttum MS, Lewandowsit MF, Schultz RD. Pseudophakia for traumatic cataracts in children. Ophthalmology 1993; 100:1218-1224 31. Wright KW, Christensen LE, Noguchi BA. Results oflate surgery for presumed congenital cataracts. Am J Ophthalmology 1992; 114:409-415 32. Simha N, Lagoutte F. Results of 87 cases of intraocular
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lens implantation at the front of the whole capsular bag. J Cataract Refract Surg 1991; 17:67-70 Gimbel HV. Posterior capsule tears using phaco-emulsification; causes, prevention and management. Eur J Implant Refract Surg 1990; 2:63-69 Castaneda VE, Legler UFC, Tsai JC, et al. Posterior continuous curvilinear capsulorhexis. An experimental study with clinical applications. Ophthalmology 1992; 99:45-50 Thim K, Krag S, Corydon L. Stretching capacity of capsulorhexis and nucleus delivery. J Cataract Refract Surg 1991; 17:27-31 AssiaEI,AppleDJ, TsaiJC,LimES. Theelasticproperties of the lens capsule in capsulorhexis. Am J Ophthalmol 1991; 111:628-632 Parks MM. Management of posterior capsule in congenital cataracts. J Pediatr Ophthalmol Strabismus 1984; 21: 114-116
J CATARACT REFRACT SURG-VOL 20, NOVEMBER 1994
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Posterior capsulorhexis with optic capture: Maintaining a clear visual axis after pediatric cataract surgery Howard V. Gimbel, M.D., Brian M. DeBroff, M.D.
ABSTRACT We describe a technique for preventing secondary membrane formation after pediatric cataract extraction. This technique involves capture of an intraocular lens (IOL) optic through a posterior curvilinear capsulorhexis opening in an attempt to maintain a clear visual axis in children after cataract surgery. This maneuver ensures centration of the posterior chamber IOL because the haptics remain in the capsular bag and the optic is captured in the posterior capsular opening. Also, the need for an anterior vitrectomy may be eliminated. Apposition of the anterior and posterior capsule leaflets anterior to the optic may limit the migration of Elschnig pearls, reducing the incidence of secondary membranes and the need for additional procedures.
Key Words: capsulorhexis, cataract surgery, Elschnig pearls, intraocular lens, optic capture, pediatric cataracts, posterior capsule, secondary cataract
A major concern in pediatric intraocular lens (IOL) implantation surgery is the high incidence of posterior capsule opacification. Anterior lens epithelial cells proliferate, form Elschnig pearls, and demonstrate myofibroblastic differentiation. 1 This cell proliferation leads to secondary membranes that use the posterior capsule, the anterior vitreous face, and the anterior and posterior surfaces of the IOL as a scaffold. 2•3 Some authors have reported an inevitable development of secondary cataract in children unless the posterior capsule is generously opened and an anterior vitrectomy performed at the time of cataract extraction and IOL implantation. 4 - 17 In our observational study of 61 posterior chamber IOL implantations in patients from two to 18 years of age, 14 there was a 17% cumulative probability of developing posterior capsule opacification that required capsulotomy by one year postoperatively, even with meticulous cortical removal and posterior capsule polishing. By four years after sur-
gery, there was a 59% Kaplan-Meier projected probability of developing posterior capsule opacification. 14 In a study by Hiles and Hered, 18 63% of children's visual axes became re-occluded by secondary membranes and required secondary capsulotomies, even after primary posterior capsulotomy. In children six years and older, the eye responds to surgery with less inflammation and posterior capsule opacification than does the infant's eye. 14 In this population, the best approach is to use the neodymium: YAG (Nd:YAG) laser if secondary cataract formation occurs. 18- 20 For children younger than six years, less cooperative children, and infants, a vertically mounted Nd:YAG laser in the operating room can be used to perform posterior capsulotomies at the time of surgery or weeks to months later. Laser capsulotomy in the pediatric population, however, requires a second procedure under general anesthesia and often the use of high ~nergy lev-
Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, Apri/1994. Maria Ferensowicz, B.Sc., M.A., Gimbel Eye Centre, provided editorial assistance. Reprint requests to Howard V. Gimbel, M.D., Gimbel Eye Centre, #450, 4935-40 Avenue N. W, Calgary, Alberta, Canada TJA 2NJ. 658
J CATARACT REFRACT SURG-VOL 20, NOVEMBER 1994
els. Also, some membranes are too dense to create large enough openings, and recurrence of the membrane is possible because the anterior vitreous face remains as a scaffold for secondary membrane formation. Currently many ophthalmologists routinely perform a posterior capsulotomy and a shallow anterior vitrectomy at the time of cataract extraction before IOL insertion. 21 •22 Special microinstruments have been developed (e.g., hook-shaped needles to perform primary posterior capsulotomies underneath a posterior chamber IOL). 23 A recent modification involves removing the cataract through a scleral tunnel incision and implanting a posterior chamber IOL and then repeating the procedure to perform a pars plana posterior capsulotomy and pars plana anterior vitrectomy. 24 This ensures proper IOL positioning before the capsulotomy is made and allows the surgeon to create large capsular openings. One disadvantage of primary capsulotomy and anterior vitrectomy is IOL dislocation, which occurs in 3% to 20% of cases. 24- 27 Also, posterior capsule tears may extend during anterior vitrectomy. These complications can be reduced by performing a posterior capsulorhexis and then the anterior vitrectomy.2 8 Doing an anterior vitrectomy at the time of cataract surgery, however, increases the risk of cystoid macular edema (CME)29 and may result in vitreous adhesions and vitreous incarceration in the wound, which increases the risk of retinal detachment. 3 Finally, even after primary posterior capsulectomy with vitrectomy, many children's visual axes become re-occluded by secondary membranes, 18 •24•31 necessitating repeated capsulotomies and sometimes pars plana membranectomy. 14 Other techniques have been proposed to prevent posterior capsular and vitreous face membrane formation while reducing the risk of IOL dislocation. In one technique, the IOL is placed anterior to the entire capsular bag, creating a tight adhesion between the anterior and posterior capsules. This helps prevent lens epithelial cells from migrating, proliferating, and forming Elschnig pearls. 32 To further reduce or eliminate opacification of the posterior capsule in pediatric cases while potentially eliminating the need for an anterior vitrectomy, a new technique has been proposed that uses a primary posterior continuous curvilinear capsulorhexis (PCCC) 33 •34 and placement of the IOL optic through both capsulorhexis openings. This results in PCCC optic capture while the haptics remain in the bag. Even though the posterior capsule is thinner than the anterior capsule, a smooth continuous curvilinear capsulorhexis (CCC) in the posterior capsule is resistant to radial tears. We have successfully used this technique of optic capture in eight pediatric cases since April 1993 without intraoperative or postoperative complications. As of February 1994, all cases had clear visual axes with excellent IOL centration. A similar technique of capturing the optic through a capsulorhexis opening has been described in cases of posterior capsular tears in adults. Neuhann and Neu-
°
hann have described a technique in which the IOL is placed in the sulcus and then the IOL optic is placed through the anterior capsulorhexis opening to achieve capture and stable fixation (T. Neuhann, M.D., Th. Neuhann, M.D., "The Rhexis-Fixated Lens," fllm presented at the Symposium on Cataract, IOL and Refractive Surgery," Boston, April 1991). Posterior capsulorhexis with optic capture involves placing the optic through both the anterior and posterior capsulorhexis openings to achieve capture of the lens in the posterior chamber. It is anticipated that primary PCCC with posterior capsular optic capture will maintain a clear visual axis, reducing the need for subsequent intervention because of the apposition of anterior and posterior capsule leaflets anterior to the IOL optic. These capsule leaflets are apposed 360 degrees except at the haptic-optic junctions. The theory is that this will seal and lead to formation of a Soemmering's ring anterior to the IOL or allow the release ofElschnig pearls anterior to the IOL, where they will be removed by the aqueous. Unlike the vitreous, the aqueous does not provide a scaffold for lens epithelial proliferation, and the continual turnover of aqueous disperses individual cells released in the anterior chamber. Any protein or fibrous tissue that adheres to the IOL's anterior surface may be cleared away with the Nd:YAG laser in a manner similar to that used in opening fibrosed and contracted anterior capsulorhexis openings.
SURGICAL TECHNIQUE Posterior continuous curvilinear capsulorhexis, the technique to create primary posterior capsulotomies in pediatric cataract cases, is accomplished using CCC principles after posterior chamber IOL implantation in the bag. We recommend that a lens no larger than 6 mm be implanted to minimize the diameter of posterior capsulorhexis required for capture to occur. With the assistance of a high-viscosity viscoelastic that has excellent clarity, such as Healon GV® (sodium hyaluronate), PCCC is initiated using a cystotome or bent needle (Figure 1). Placing the instrument under the IOL, the surgeon makes a small central puncture in the posterior capsule. Additional viscoelastic is placed through the central puncture of the posterior capsule to push the vitreous face away (Figure 2). In the case of a small pre-existing or inadvertent tear of the posterior capsule during surgery, posterior capsule optic capture should be attempted only after the tear is converted into a small, well-centered, circular PCCC and, if necessary, following an adequate anterior vitrectomy. The PCCC technique can also be used to remove a thickened fibrotic posterior capsule plaque. In these cases, the PCCC is made as a controlled circle that encompasses the central opacity and results in a properly sized and centered posterior capsule opening to ensure capture and centration of the IOL optic. Similar to achieving a CCC in the anterior capsule,
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Fig. 1.
(Gimbel) The PCCC is started with a central puncture of the posterior capsule using a cystotome under viscoelastic posterior to the IOL in the bag.
Fig. 2.
(Gimbel) Viscoelastic is placed through the posterior capsule opening to push vitreous posteriorly.
the posterior capsule tear is directed to 3 o'clock before being directed counterclockwise (Figure 3). After the tear is initiated, the best control of the progressing tear in the posterior capsule is achieved with an elongated Kelman-McPherson or pointed capsulorhexis forceps. The capsule flap is grasped near one point of tearing and the tear turned in the desired direction (Figure 4 ). Additional viscoelastic is added intermittently throughout the procedure to dissect the vitreous from the capsule. Care should be taken that the viscoelastic does not push the leading flap posteriorly, which can make grasping the posterior capsular tag difficult. The PCCC is kept small enough to capture the optic but large enough to allow the IOL optic to pass through so that maximum integrity of the posterior capsule is preserved and posterior capture of the IOL optic is facilitated (Figure 5). Before the posterior capsule circular tissue is removed, scissors should be used to cut any
adherent vitreous strands. An anterior vitrectomy is necessary only if vitreous presents through the posterior capsular opening. Posterior capture of the IOL optic is done after the scleral wound is sutured but before the viscoelastic is removed. Under viscoelastic, with the IOL loop oriented horizontally, for example, the IOL is slipped inferiorly and then superiorly through the PCCC using a spatula or cannula. This results in posterior capsule capture of the optic (Figure 6). Viscoelastic material behind the IOL is left in place; viscoelastic remaining in the anterior chamber is slowly removed. Irrigation with balanced salt solution (BSS®) is performed while the viscoelastic is being aspirated to maintain a deep chamber and prevent forward movement of vitreous and the IOL. Optimally, this is performed with a two-instrument technique to constantly maintain the anterior chamber. If the irrigation/aspiration (1/A) tip is used, the anterior chamber
Fig. 3.
Fig. 4.
660
(Gimbel) The PCCC is extended to 3 o'clock, similar to the technique used with CCC.
(Gimbel) For better control, capsule forceps are used in directing and completing the PCCC.
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Fig. 5.
(Gimbel) A well-centered PCCC, concentric and smaller than the CCC, is achieved.
Fig. 6.
(Gimbel) Under viscoelastic, the IOL optic edge is slipped through the PCCC inferiorly and superiorly to achieve PCCC capture.
CASE REPORT A 2.5-year-old female with a monocular congenital cataract of the left eye presented for cataract extraction. Her birth and development were unremarkable. There was a family history of early cataracts (mother and maManaging Complications grandmother). The patient's right eye had been ternal If an anterior capsular radial tear occurs, in-thepatched three to five hours daily since she was six bag placement of the IOL may still be attempted, months old and when she was two, strabismus surgery but posterior capsulorhexis should probably not be was performed. attempted. There was a left exotropia of 14 prism diopters (D) When there is an existing posterior capsular tear or an with left inferior oblique overaction. Refraction was iatrogenic tear, the IOL can be placed in the sulcus and +0.75 -1.25 x 25 in the right eye and +2.50 -1.75 x the optic placed through the anterior capsulorhexis, as 1.67 in the left. Axial length was 21.56 mm and shown by Neuhann and Neuhann in their ftlm, as well 21.12 mm, respectively. Keratometry in the right eye as through the tom posterior capsule. In this situation, was 43.25 x 28 and 44.50 x 118 and in the left was a 6.5 mm or 7.0 mm diameter lens should be used. 42.75 x 167 and 45.00 x 77. Visual acuity measured If a posterior radial capsular tear occurs during pos- with a Snellen picture chart was 20/25 in the right eye terior capsulorhexis, the attempt to capture the IOL and 20/200 in the left. Fixation was central and eccenoptic will have to be aborted. If the tear does not extend tric, respectively. Anterior segment evaluation of the to the equator, the surgeon can try to blunt it by turning right eye was unremarkable. Anterior segment evaluathe tear back. The main advantage of having the IOL tion of the left eye was normal except for the lens, which already within the capsular bag is that if a tear occurs, demonstrated 1+ diffuse cortical opacities with vacuoles further manipulation can be discontinued and the lens and a 3+ central posterior polar opacity. In both eyes, will likely remain stable. If the IOL has to be placed in the posterior segment examination was unremarkable. the capsular bag after a posterior capsular tear occurs, Under general anesthesia a 6.0 mm curvilinear incithe likelihood of extending this tear and destroying the sion 2.5 mm from the limbus was made and a scleral entire capsular bag is high. tunnel extended to the vascular arcade before the anteIf the posterior capsulorhexis is not concentric, cap- rior chamber was entered just anterior to the arcade. The ture can still be attempted because the optic still tends anterior chamber was filled with viscoelastic and a to center in the visual axis. Based on one case in which 5.5 mm CCC was formed in the anterior capsule. The this has occurred, it appears that the haptics in the cap- lens was removed with an automated I/A handpiece. sular bag have a greater centering force than does the The intact posterior capsule was quite fibrotic with crysPCCC. tal granules on its surface. The anterior chamber was Capture should not be attempted if the PCCC is larger filled with viscoelastic and the wound enlarged to than the optic or quite eccentric. In these cases, a pri- 6.0 mm for IOL implantation. A one-piece Pharmacia 811B IOL of 24.5 D power mary capsulotomy will have been created and one vitrectomy. anterior an with a 6.0 mm diameter optic and overall length of with proceeding should consider
may collapse unless sutures have been placed to reduce incision size. The wound may be closed with absorbable or nonabsorbable sutures.
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12.0 mm was placed in the capsular bag. Viscoelastic was instilled under the IOL to stretch the posterior capsule. Applying the principles used during anterior CCC, a PCCC that encompassed the fibrotic opacity in the posterior capsule was performed. A central circular posterior opening of about 5.0 mm was made with capsule forceps. Gills-Welsh scissors were used in the posterior chamber before the posterior capsular tissue fragment was removed. Upon removal of the fragment, there were no obvious vitreous strands. After complete removal of the fragment, no vitreous presented through the posterior capsular opening. After the scleral wound was closed with a 10-0 polypropylene (Prolene®) continuous suture, the edge of the IOL optic was slipped through the posterior capsular opening inferiorly and then superiorly, resulting in posterior capsular capture and optic fixation. The haptics remained in the bag, which now was flattened with apposition of anterior and posterior leaflets. The PCCC, stretched when the haptics entered the capsular bag, was now oval. Because the PCCC was central, the lens maintained a central position once the optic was placed through the posterior capsular opening. The opposed capsular leaflets were positioned inside the IOL's optic border. The viscoelastic was left in the posterior chamber to avoid vitreous herniation into the anterior chamber. All of the viscoelastic was removed from the anterior chamber. Gonioscopy showed the inner portion of the wound was gaping and 10-0 nylon sutures were passed through full thickness cornea at the limbus at both sides of the wound to stabilize the inner portion of the incision. Gonioscopy subsequently revealed the inner aspect of the wound to be closed. The chamber re-formed well, although some aqueous leaked through the paracentesis site. After a single interrupted 10-0 nylon suture was placed at the paracentesis site, fluorescein testing showed no leakage from the chamber. Conjunctiva and Tenon's were closed with interrupted 9-0 polyglactin 910 (Vicryl®) sutures. One day postoperatively, the IOL was well centered. Autorefraction in the left eye was +4.0 -2.50 X 178. Visual acuity could not be obtained. Intraocular pressure by applanation tonometry was 12 mm Hg. The cornea was clear, the anterior chamber was deep with only a few cells, and the IOL remained captured posterior to the opposed capsular leaflets. Ten days postoperatively, the eye was doing well with a quiet anterior segment. Five months postoperatively, the anterior vitreous face was clear and no precipitates had formed on the anterior or posterior IOL surface.
DISCUSSION Primary PCCC with posterior capsular optic capture is a technically challenging procedure that requires skill to avoid peripheral tears in the posterior capsule and loss 662
Fig. 7.
(Gimbel) Posterior capsulorhexis with optic capture. Elschnig pearls are migrating to the anterior chamber.
of the capsular bag. It should not be attempted until the surgeon is familiar and adept with CCC in children. Difficulties of the procedure include performing capsulorhexis in the posterior capsule, which is thinner than the anterior capsule. The posterior capsular opening must be smaller than and concentric with the IOL optic. Because the posterior capsule is thin and the PCCC may not have the same stretching capacity of the anterior CCC, 35, 36 the vaulting of the intraocular optic through the PCCC requires cautious manipulation. Ways to minimize difficulty with the procedure are to maintain high magnification with the operating microscope and to use viscoelastics liberally. An anterior vitrectomy may still be necessary if vitreous herniates at the time of PCCC. If an anterior vitrectomy is necessary due to vitreous presentation, however, the PCCC opening provides an opening that is resistant to tears. Complications of the procedure include the possibility of an early postoperative rise in lOP resulting from viscoelastic that may remain in the anterior chamber. A possible late complication is contracture of the an~erior capsule CCC border, which if not recognized and cut with the Nd:YAG laser, may contract so much that the haptics may be lost. Posterior capsulorhexis with optic capture has many potential advantages. By capturing the IOL optic behind the posterior capsule while the haptics remain in the bag, stable IOL fixation is achieved. Posterior optic capture results in a stable anterior chamber by maintaining the separation between posterior and anterior segments. Lens epithelial cells are expected to migrate anterior to the IOL, preventing lens epithelial cell proliferation along the vitreous face (Figure 7). The advantages of PCCC alone include a posterior capsular opening that is resistant to tears. Also, PCCC can be used to remove dense plaques, convert congenital traumatic defects, and convert posterior capsular tears that occur during surgery.
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6. BenEzra D. The surgical approaches to paediatric cataThis technique may also be beneficial in adult cataract. Eur J Implant Refract Surg 1990; 2:241-244 ract surgery to reduce the incidence of posterior capsular 7. BenEzra D, Rose L. Intraocular versus contact lenses for opacity and the subsequent need for YAG laser capsuthe correction of aphakia in unilateral, congenital and lotomies. In adults, however, the possibility of CME developmental cataract. Eur J Implant Refract Surg 1990; after posterior capsular rupture is high; in children, CME 2:303-307 37 is rare. Also, secondary cataract formation in adults 8. Parks MM. Posterior lens capsulectomy during primary occurs with less frequency and Nd:YAG laser capsulotcataract surgery in children. Ophthalmology 1983; 90: omy is an easier procedure, often requiring less energy 344-345 and no sedation. The procedure can, however, be used 9. Metge P, Cohen H, Chemila JF. Intercapsular implantawhen the posterior capsule in adults is inadvertently tom tion in children. Eur J Implant Refract Surg 1990; 2: and a PCCC is performed to blunt the tear. Posterior 319-323 capsule capture of the IOL in this case keeps the IOL 10. BenEzra D, Hemo I. Traumatic cataract in children. Visual results following aphakic correction with contact or well centered and maintains the haptics in the bag. intraocular lenses in paediatric cataract. Eur J Implant Longer follow-up and additional cases will be reRefract Surg 1990; 2:325-328 quired to see whether Elschnig pearls will present and if 11. De Courten C, Bucher PJM, BenEzra D. Experience with so, in what location. It is possible that the site at which HEMA lenses in paediatric cataract. Eur J Implant Refract the haptics enter the capsular bag, thereby creating an Surg 1990; 2:315-318 area where the capsule is posterior to the optic, may 12. Morgan KS, Karciolglu ZA. Secondary cataracts in inprovide a site at which some pearls find their way into fants after lensectomies. J Pediatr Ophthalmol Strabismus the posterior chamber. It is expected, however, that with 1987; 24:45-48 the majority of the posterior capsule opening anterior to 13. Sinskey RM, Stoppel JO, Amin P. Long-term results of the lens optic, no Elschnig pearls will deposit on the intraocular lens implantation in pediatric patients. J Catvitreous face and the visual axis will remain clear (Figaract Refract Surg 1993; 19:405-408 ure 7). The incidence of further complications will re- 14. Gimbel HV, Ferensowicz M, Raanan M, DeLucaM. Implantation in children. J Pediatr Ophthalmol Strabismus quire monitoring and animal studies in the future may 1993; 30:69-79 provide histological patterns of lens epithelial cell pro15. Hiles DA, Johnson BL. The role of the crystalline lens liferation in the situation of optic capture. epithelium in postpseudophakos membrane formation. In conclusion, posterior capsulorhexis with optic capAm Intra-Ocular Implant Soc J 1980; 6:141-147 ture is a technically demanding procedure that may keep 16. Weidle EG, Lisch W, Thiel HJ. Management of the opathe optical axis clear while maintaining excellent supcified posterior lens capsule: an excision technique for port and centration of the posterior chamber IOL. The membranous changes. Ophthalmic Surg 1986; 17:635technique may allow surgeons to avoid planned anterior 640 vitrectomies in infants and children and minimize the 17. Mackool RJ, Chhatiawala H. Pediatric cataract surgery potential for secondary cataract formation. Additional and intraocular lens implantation: a new technique for preventing or excising postoperative secondary memcases with further follow-up are needed to evaluate the branes. J Cataract Refract Surg 1991; 17:62-66 long-term success of this technique in maintaining a clear visual axis in children after cataract surgery. Ad- 18. Hiles DA, Hered RW. Modem intraocular lens implants in children with new age limitations. J Cataract Refract ditional study is needed to document safety and longSurg 1987; 13:493-497 term efficacy before recommending the widespread 19. Sinskey RM, Karel F, Dal Ri E. Management of cataracts application of this technique.
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