Reply: Clinical effects of primary posterior continuous curvilinear capsulorhexis

LETTERS

Clinical effects of primary posterior continuous curvilinear capsulorhexis We would like to commend Vock et al.,1 whose study demonstrated that primary posterior continuous curvilinear capsulorhexis (PCCC) could significantly reduce posterior capsule opacification (PCO) in routine cataract surgery. Although in our center it is not routine practice to perform PCCC in adult cataract cases, we are impressed by the low PCO and neodymium:YAG (Nd:YAG) laser capsulotomy rates reported in the study. However, we would be grateful if the authors would elaborate on a few issues concerning the effects of primary PCCC. A similar study by the same group of investigators was published in 2003.2 In that study, surgery was performed by the same experienced surgeon using similar surgical techniques, hydrophilic intraocular lens (IOL), and image analysis methods. However, the outcome was significantly less favorable than that in the present study. Lens epithelial cell (LEC) migration occurred in 79% of eyes, causing PCCC ongrowth and closure in 55% and 7%, respectively. In the present study, PCCC ongrowth and closure rates were as low as 6.5% and 0%, respectively. We noticed that the types of IOLs were different in the 2 studies. Hydrophilic hydrogel IOLs with round optic edges were used in the previous study, but hydrophilic acrylic IOLs with sharp posterior optic edges were used in the present one. This may be a significant confounding factor accounting for the low PCO rate in the present study since the barrier effect of a sharp optic edge on LEC migration and hence prevention of PCO has been established by several earlier studies.3,4 We believe the use of a control group without PCCC may make the clinical effects of primary PCCC on PCO prevention more conclusive. We hope the authors can also provide more information on the profile of intraoperative complications, such as vitreous disruption or herniation, and postoperative complications, such as retinal detachment (RD) or cystoid macular edema (CME), which have been shown to be more common if the posterior capsule is breached.5 We believe this information will help us formulate a working risk-to-benefit ratio for performing primary PCCC in routine adult cataract surgeries. For a long time, PCO has been a major unresolved issue in cataract surgery. We commend and look forward to the authors’ continuous efforts in investigating methods of preventing PCO. Hoi Fan, MRCSEd Vincent Yau Wing Lee, FRCSEd David Ta Li Liu, MRCSEd Dennis Shun Chiu Lam, MD, FRCOphth Hong Kong, China 2002

Q 2007 ASCRS and ESCRS Published by Elsevier Inc.

REFERENCES 1. Vock L, Menapace R, Stifter E, et al. Clinical effects of primary posterior continuous curvilinear capsulorhexis in eyes with single-piece hydrophilic acrylic intraocular lenses with and without haptic angulation. J Cataract Refract Surg 2007; 33: 258–264 2. Georgopoulos M, Menapace R, Findl O, et al. After-cataract in adults with primary posterior capsulorhexis; comparison of hydrogel and silicone intraocular lenses with round edges after 2 years. J Cataract Refract Surg 2003; 29:955–960 3. Peng Q, Visessook N, Apple DJ, et al. Surgical prevention of posterior capsule opacification. Part 3: intraocular lens optic barrier effect as a second line of defense. J Cataract Refract Surg 2000; 26:198–213 4. Nishi O, Nishi K, Wickstro¨m K. Preventing lens epithelial cell migration using intraocular lenses with sharp rectangular edges. J Cataract Refract Surg 2000; 26:1543–1549 5. Kraff MC, Sanders DR, Jampol LM, Lieberman HL. Factors affecting pseudophakic cystoid macular edema: five randomized trials. Am Intra-Ocular Implant Soc J 1985; 11:380–385

REPLY: As pointed out in the letter by Fan et al., the study published in 20031 includes different IOLs than those used in the recent study. The main outcome measure in the earlier study was to elucidate the impact of different IOL materialsda hydrophobic acrylic versus a hydrophobic siliconedon the development of posterior optic ongrowth of LECs. Looped IOLs of comparable design were used. The 2003 study demonstrated that silicone optics led to significantly lower rates of posterior optic ongrowth and reclosure of the PCCC. The significantly higher overall rates in the recent study are mainly explained by the difference in the optic edge design: round-edged in the 2003 study and sharp-edged in the recent study. With a greater number of LECs overcoming the round optic edge and populating the residual peripheral posterior capsule, the possibility of ongrowth onto and reclosure of the PCCC opening will also increase. Moreover, the IOL material might play a role. Tognetto et al.2 found that the hydrophilic materials in our 2 studies differ in their propensity for LEC ongrowth because of differences in their biocompatibility. Differences in haptic design are another factor. In fact, the main outcome measure of the recent study was to establish the influence of haptic angulation (angulated with the ACR6D SE and nonangulated with the C-flex 570C) by using IOLs with otherwise comparable design: 1-piece hydrophilic with fenestrated flange-loop haptics. Fan et al. proposed that a control group be used to elucidate the effect of the PCCC itself. Actually, we recently published the results of PCCC versus in-the-bag implantation using the ACR6D SE hydrophilic acrylic IOL with angulated haptics.3 In that study, visual axis opacification was significantly lower in the PCCC group than in the non-PCCC group. 0886-3350/07/$dsee front matter doi:10.1016/j.jcrs.2007.09.012

LETTERS

Regarding the complication profile of the PCCC itself, there is widespread hesitation about the routine use of a PCCC because of concern about intraoperative and postoperative complications. Following the surgical guidelines, which have been described,4 a PCCC can be safely performed under topical anesthesia without running the risk for vitreous presentation in the anterior chamber. In a retrospective study by Van Cauwenberge et al.,5 performing a PCCC did not increase the risk for RD or CME. In a recent series of 500 consecutive PCCC cases combined with optic buttonholing,4 Menapace found only 1 case of delayed (4 months postoperatively) localized peripheral RD emerging from a group of small round holes in the highly myopic eye of a young man. With this risk profile and an intact anterior hyaloid surface, it seems unlikely that this complication was due to the PCCC procedure. In a number of prospective randomized trials to follow, Stifter and Menapace et al. specifically investigated the effect of adding a PCCC combined with posterior optic buttonholing on intraocular pressure,6 flare,7 and the thickness and morphology of the macula shown by optical coherence imaging in pertinent intraindividual comparison studies (R. Menapace, MD, E. Stifter, MD, ‘‘Macular Thickness and Morphology Following Cataract Surgery with Posterior Capsulorhexis and Optic Buttonholing,’’ presented at the XXV Congress of the European Society of Cataract and Refractive Surgeons, Stockholm, Sweden, September 2007). There was no difference between the group with PCCC and the group with standard in-the-bag placement in any of these parameters, nor was there a difference between the patients with an intact anterior hyaloid surface and a subgroup of patients with a punctured anterior hyaloid surface. In one of the comparative trials mentioned above, a patient developed a delayed RD in the non-PCCC eye. When buttonholed posteriorly into a PCCC, the optics remain in a stable posterior position, whereas there is an axial anterior optic shift with angulated IOLs placed in the bag (E. Stifter, MD, R. Menapace, MD, ‘‘Postoperative Anterior Chamber Depth and Posterior Chamber Lens Position Following Cataract Surgery with Posterior Capsulorhexis and Optic Buttonholing,’’ presented at the 21 Kongreß der Deutschsprachigen Gesellschaft fu¨r Intraokularlinsen-Implantation und refraktive Chirurgie, Potsdam, Germany, March 2007). The lack of anterior shift may prevent anterior movement of the vitreous body and thus counteract posterior vitreous detachment as a source of RD. It therefore appears that PCCC is a safe procedure that does not increase the incidence of retinal complications. We welcome Fan et al.’s suggestion for a risk– benefit assessment of performing a PCCC in adult eyes. It seems clear that such an assessment will be

2003

multifactorial, depending on the design and material of the IOL among other factors. However, we believe that performing a PCCC with or without adjunctive surgical techniques, such as posterior optic buttonholing to reduce PCO,4 may become more widespread in the future. We believe that in addition to current findings, the speed of capsule fusion described by Nishi et al.8 is only one important factor of LEC migration early postoperatively. A delayed progressive failure of the barrier formed by the sharp optic edges becomes obvious 3 to 5 years postoperatively, leading to a high rate of Nd:YAG laser capsulotomies (W. Bu¨hl, MD, et al., ‘‘Effect of Optic Material on Posterior Capsule Opacification in Intraocular Lenses with Sharp Edge Optics,’’ presented at the joint meeting of the European Society of Ophthalmology and the American Academy of Ophthalmology, Vienna, Austria, June 2007). In our own retrospective study, capsulotomy rates at 10 years with a hydrophobic acrylic IOL with sharp posterior edges were as high as 42% (L. Vock, MD, et al., ‘‘PCO Preventive Effect of Sharp-edged Hydrophobic Acrylic IOLs and Round-edged Silicone IOLs 10 Years After Surgery,’’ presented at the XXV Congress of the European Society of Cataract and Refractive Surgeons, Stockholm, Sweden, September 2007). Posterior continuous curvilinear capsulorhexis as an adjunctive procedure is effective and safe if appropriately performed by experienced surgeons. One-piece IOLs with fenestrated flange-loop haptics should not be used because of possible haptic distortion, which might result in optic tilt and decentration.dRupert Menapace, MD, Lorenz Vock, MD

REFERENCES 1. Georgopoulos M, Menapace R, Findl O, et al. After-cataract in adults with primary posterior capsulorhexis; comparison of hydrogel and silicone intraocular lenses with round edges after 2 years. J Cataract Refract Surg 2003; 29:955–960 2. Tognetto D, Toto L, Ballone E, Ravalico G. Biocompatibility of hydrophilic intraocular lenses. J Cataract Refract Surg 2002; 28:644–651 3. Vock L, Menapace R, Stifter E, et al. Effect of primary posterior continuous curvilinear capsulorhexis on clinical performance of ACR6D SE single-piece hydrophilic acrylic intraocular lenses. J Cataract Refract Surg 2007; 33:628–634 4. Menapace R. Routine posterior optic buttonholing for eradication of posterior capsule opacification in adults; report of 500 consecutive cases. J Cataract Refract Surg 2006; 32:929–943; erratum, 1410 5. Van Cauwenberge F, Rakic J-M, Galand A. Complicated posterior capsulorhexis: aetiology, management, and outcome. Br J Ophthalmol 1997; 81:195–198 6. Stifter E, Luksch A, Menapace R. Postoperative course of intraocular pressure after cataract surgery with combined primary posterior capsulorhexis and posterior optic buttonholing. J Cataract Refract Surg 2007; 33:1585–1590

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2004

LETTERS

7. Stifter E, Menapace R, Luksch A, et al. Objective assessment of intraocular flare after cataract surgery with combined primary posterior capsulorhexis and posterior optic buttonholing in adults In press. Br J Ophthalmol 2007; Abstract available at: http:// bjo.bmj.com/cgi/content/abstract/bjo.2007.120535v1. Accessed June 26, 2007 8. Nishi O, Nishi K, Akura J. Speed of capsular bend formation at the optic edge of acrylic, silicone, and poly(methyl methacrylate) lenses. J Cataract Refract Surg 2002; 28:431–437

Advantage and disadvantage of posterior continuous curvilinear capsulorhexis Recently, Vock et al.1,2 published 2 interesting articles. In the first, they compared the clinical results of posterior continuous curvilinear capsulorhexis (PCCC) in eyes with 2 types of single-piece hydrophilic acrylic intraocular lenses (IOLs) with and without haptic angulation. The results showed significantly lower intensity of posterior capsule opacification (PCO) within the PCCC area than within the peripheral area of the posterior capsule with both types of IOL implantation. However, haptic deformation was found in 9 eyes (29%) with an angulated IOL and in no eye with a nonangulated IOL. In the second article, Vock et al. compared the incidence of PCO in eyes with and without a PCCC following implantation of a single-piece hydrophilic acrylic IOL. They found that the incidence of PCO in the visual axis area was significantly lower in the PCCC eyes than in the non-PCCC eyes. During the follow-up, 40% of the non-PCCC eyes had a neodymium:YAG laser capsulotomy compared with none of the PCCC eyes. I have a few comments on the articles and the surgical technique. Several approaches to reduce the incidence of PCO have been evaluated clinically. One approach is to perform a PCCC during cataract surgery. The advantage of this technique is that it stops lens epithelial cell (LEC) migration and proliferation on the central area of the posterior capsule by surgically removing the central area. Consequently, a PCCC should reduce the incidence of PCO. This technique was initially performed during cataract surgery in infants and children with good results.3 However, PCO still occurred and the LEC grew on an intact vitreous face or IOL optic surface. Eventually, dense PCO could form. To address this issue, Gimbel and DeBroff4,5 performed PCCC with an optic capture. This technique has been evaluated in clinical studies with favorable results.6 In the second article by Vock et al.,2 the incidence of PCO was significantly lower in the PCCC eyes than in the non-PCCC eyes. Since only 1 type of IOL was used in that study, we do not know whether the results would be the same if different IOLs were used. We do not

know whether PCO could form over time in the eyes with the ruffled PCCC rim. The disadvantage of PCCC is the difficulty of the surgical technique, which may be challenging for the average cataract surgeon. More important, PCCC significantly compromises the integrity of the posterior capsule and diminishes the physical barrier effect created by the square-edged IOL optic and intact posterior capsule. If a PCCC is too large or oval in shape, the posterior capsule may weaken and could provide less IOL support. As we know, the square-edged optic requires tension on the posterior capsule or close contact between the IOL optic and the posterior capsule to create a physical barrier and block LEC migration. When a PCCC is created, the posterior capsule has little tension and is more flexible and less supportive; the physical barrier effect may be too weak. Without a strong physical barrier, the LEC will migrate to the posterior capsule freely and proliferate to eventually form dense PCO. Creating a PCCC may trigger capsule fibrosis and contraction and consequently induce IOL haptic deformation, optic tilt, and decentration. In the first article by Vock et al.,1 haptic deformation was reported in 9 eyes (29%) with angulated IOLs but no eye with a nonangulated IOL. It was probably caused by capsule contraction and fibrosis. Physically, the angulated haptic should deform and change shape easier than the nonangulated haptic if capsule contraction or fibrosis occurs. Of course, the haptic material and type are also important factors. Surprisingly, no haptic deformation was reported in the second article by Vock et al., even with the same IOL type. Another interesting observation in the first article was that eyes with angulated IOLs had significantly less anterior capsule opacification than eyes with nonangulated IOLs (P Z .012). A persistent anterior lenticular gap was found in 97% of eyes in the angulated IOL group compared with 29% of eyes in the nonangulated IOL group. The angulated IOL group showed a slightly higher incidence of central PCO and a higher incidence of LEC growth and proliferation. These results suggest that direct contact between the IOL optic and lens capsule may be associated with LEC growth and proliferation. Currently, most cataract surgeons think the most effective approach to reduce PCO is to create a 360-degree physical barrier between the IOL optic and the posterior capsule immediately after IOL implantation. To create a physical barrier, a square-edged design is critical and complete cortical cleanup with removal of the lens material is important. Creating tension on the posterior capsule around the optic edge is also important. To achieve this goal, an IOL should have stronger haptics and greater haptic angulation to be able to stretch the posterior capsule.7

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