We appreciate the comments by Sun about our recent publications on the impact of performing an additional primary PCCC with the angulated Corneal ACR6D SE and the nonangulated Rayner C-flex 570C single-piece IOL models. There has been no published prospective randomized bilateral comparison using the same IOL style. However, we do have significant clinical experience with a PCCC performed with other IOL styles demonstrating a similarly significant reduction in central visual axis opacification (VAO; the term PCO is inappropriate since the posterior capsule is lacking). One of our studies1 shows a significant difference in LEC ongrowth onto the free optic within the PCCC opening with different IOL materials: In this prospective randomized bilateral study with similar-in-design open-loop IOLs, the LEC ongrowth was significantly less with a silicone IOL model than with a hydrophilic IOL model. Our experience with a large number of PCCC cases performed over more than 10 years with various IOL styles differing in design and material leaves no doubt that compared with standard in-the-bag placement, performing a PCCC brings about a permanent reduction in central VAO.
There is no doubt that PCCC requires extra knowledge and skill. However, similar to any other step in cataract surgery, it is well-controlled when the surgical guidelines are appropriately followed. In about 2000 PCCC consecutive procedures, vitreous presented intraoperatively in only 1 early case (R. Menapace, MD, unpublished data). Phacoemulsification was initially also considered a challenging if not dangerous procedure to be reserved for specific indications and experienced surgeons. However, as long as neodymium:YAG (Nd:YAG) laser treatment is financially overvalued while effective but demanding preventive measures are not reimbursed, there is little incentive for surgeons to adopt such measures to improve after-cataract performance.
Performing PCCC is also a safe procedure. We have shown there is no clinically relevant pressure spiking in the early postoperative period.2,3 There is also no increase in aqueous–vitreous or blood–aqueous barrier disruption evaluated with a fluorophotometer4 or a cell–flare meter5 and no change in the morphology and thickness of the central retina measured by optical coherence tomography (R. Menapace MD, E. Stifter MD, “Macular Integrity After Posterior Capsulorhexis with Optic Buttonholing as Assessed by Optical Coherence Tomography,” presented at the XXV Congress of the European Society of Cataract & Refractive Surgeons, Stockholm, Sweden, September 2007. Abstract available at: http://www.escrs.org/EVENTS/07Stockholm/sessiondetails.asp?id=2085&category=Free&sessiondate=12/09/2007. Accessed September 18, 2007). In a prospective series of more than 500 PCCC cases combined with posterior buttonholing of the optic,6 there was no case of clinically significant cystoid macular edema (CME) and only 1 case of spontaneous retinal detachment (RD). Since the RD occurred in the highly myopic eye of a young man 4 months after surgery, the causative relationship is at least questionable. For standard in-the-bag placement of IOLs, Ripandelli et al.7 recently reported a 5-year risk of 0.7% and 21% for postoperative RDs depending on the absence or presence, respectively, of lattice degeneration, Therefore, a PCCC may even reduce retinal complications when combined with posterior optic buttonholing since the more posteriorly positioned optic stabilizes the vitreous body (R. Menapace, MD, unpublished data). A retrospective study by van Cauwenberge et al.8 also shows no increase in the risk for CME or RD after PCCC.
Clinical observations as well as our understanding of the mechanism of barrier formation at the optic rim do not support the concern that the physical barrier effect created at the square edge may be compromised by a PCCC. On the contrary, the barrier effect may be enhanced: Even after the central 3.0 to 4.0 mm portion of the posterior capsule is removed, the integrity and function of the residual peripheral portion is fully maintained. Creation of a physical barrier and LEC migration blockage do not seem to be affected by capsule tension or close contact between the posterior IOL optic surface and the posterior capsule. In fact, a space can be detected between the posterior optic surface and the posterior capsule in about 20% of all eyes regardless of the IOL style.9 There is evidence that haptic angulation and thus pressure of the posterior sharp edge on the posterior capsule plays a subordinate, if any, role in the barrier effect.10,11 Rather, the latter is initiated by capsular bag fusion occurring during the first weeks after surgery12 and the consecutive collagenous sealing of both capsules along the optic rim.13 The consecutive contraction of the anterior capsule leaf stretches the posterior capsule and firmly pulls it around the posterior optic edge, inducing a capsular bend that blocks LEC migration by contact inhibition14 or intense mechanical contact between the posterior capsule and optic edge.15 The permanence of this effect is only guaranteed if the collagenous sealing line is strong enough to withstand secondary capsule redivision, with consequent loss of the capsular bend by delayed Soemmerring's ring formation, which occurs mainly after 3 to 5 years (“secondary barrier failure”).13 This explains the increase in the PCO and Nd:YAG laser capsulotomy rates during this period (L. Vock, MD, et al., unpublished data) and even thereafter, with 10-year capsulotomy rates between 19% (blunted edge silicone) and 42% (sharp-edged hydrophobic acrylic) depending on the fibrogenetic potential of the optic material used (L. Vock, MD, R. Menapace, MD, M. Georgopoulos, 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 & Refractive Surgeons, Stockholm, Sweden, September 2007. Abstract available at: http://www.escrs.org/EVENTS/07Stockholm/sessiondetails.asp?id=1617&category=Free&sessiondate=09/09/2007. Accessed September 18, 2007). Differences in the latter explain why in the long term silicone IOLs outperform hydrophobic acrylic IOLs with regard to after-cataract.
It is correct that a reduction in the elastic countertraction exerted by the posterior capsule may promote fibrotic contraction of the anterior capsule leaf and thus induce haptic deformation with consecutive optic tilt and decentration. This, however, has been observed with the Corneal ACR6D SE IOL only and is not surprising when the flexibility and angulation of the fenestrated single-piece haptics are considered. This has also been observed with plate-haptic IOLs16 but not with standard open-loop IOLs, which easily adapt to a shrinking capsular bag.
Why, then, did we choose these particular single-piece IOL styles for these studies? The answer is that these IOL models, in particular the Corneal ACR6D SE IOL, early on exhibited unusually high PCO and Nd:YAG laser capsulotomy rates. Since these IOL models are widely used in some European countries, we intended to enhance the after-cataract performance by adding a PCCC. Because of the observed haptic deformation and occasional posterior buttonholing of the optic, especially with a larger PCCC, we do not recommend performing a PCCC with the Corneal ACR6D SE IOL model, although it was effective in reducing central VAO and eliminated the need for a Nd:YAG laser capsulotomy.
In summary, creating a 360-degree physical barrier is a very effective approach to reduce PCO but it is not effective enough when the long-term performance is considered. This is especially true for the most widely used hydrophobic acrylic IOLs, which show a significant increase in PCO and Nd:YAG laser capsulotomy rates after 3 to 5 years (L. Vock, MD, unpublished data), culminating in a Nd:YAG laser capsulotomy rate of over 40% after 10 years (L. Vock, MD, R. Menapace, MD, M. Georgopoulos, 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 & Refractive Surgeons, Stockholm, Sweden, September 2007. Abstract available at: http://www.escrs.org/EVENTS/07Stockholm/sessiondetails.asp?id=1617&category=Free&sessiondate=09/09/2007. Accessed September 18, 2007). When the decreasing mean age of patients having cataract surgery and the increasing number of patients operated on at a younger age are weighed against the increasing life expectancy, it becomes obvious that something better is needed, at least if we are unwilling to use silicone as an IOL material. The questionable usefulness of stronger and more angulated haptics must be weighed against their tendency to distort the capsular bag ovally and impede capsular bag fusion, thereby interfering with circumferential capsular bag sealing and bend formation. A sharp-edged optic rim by itself may create negative dysphotopsia, a problem recently identified by Olson17 as the number one complaint in uneventful modern cataract surgery.
Creating an additional PCCC is a well-controlled measure that significantly reduces PCO and Nd:YAG laser capsulotomy rates by adding a “second line of defense” while not compromising the barrier effect at the optic edge. The PCCC still requires capsule–optic overlap and is still dependent on the optic edge and optic material. Combining the PCCC with posterior buttoning of the IOL optic is an effective additional measure that excludes retrolental opacification by migrating LECs independent of the optic material and edge design.6 Although more demanding, this technique can be mastered by an experienced and dedicated surgeon as it is well-controlled and safe when the guidelines are meticulously followed.
1. Georgopulos 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. 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.
3. Wirtitsch MG, Menapace R, Georgopoulos M, et al. Intraocular pressure rise after primary posterior continuous curvilinear capsulorhexis with fixed dorzolamide-timolol combination: randomized safety study with intraindividual comparison using an angulated and a nonangulated intraocular lens. J Cataract Refract Surg. 2007;33:1754-1759.
4. De Groot V, Hubert M, Van Best JA, et al. Lack of fluorophotometric evidence of aqueous-vitreous barrier disruption after posterior capsulorhexis. J Cataract Refract Surg. 2003;29:2330-2338.
5. 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. May 15; [Epub ahead of print].
6. 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.
7. Ripandelli G, Coppé AM, Parisi V, et al. Posterior vitreous detachment and retinal detachment after cataract surgery. Ophthalmology. 2007;114:692-697.
8. van Cauwenberge F, Rakic J-M, Galand A. Complicated posterior capsulorhexis: aetiology, management, and outcome. Br J Ophthalmol. 1997;81:195-198.
9. Findl O, Drexler W, Menapace R, et al. Accurate determination of effective lens position and lens-capsule distance with 4 intraocular lenses. J Cataract Refract Surg. 1998;24:1094-1098.
10. Leydolt C, Davidovic S, Sacu S, et al. Long-term effect of 1-piece and 3-piece hydrophobic acrylic intraocular lens on posterior capsule opacification: a randomized trial. Ophthalmology. 2007;114:1663-1669.
11. Sacu S, Menapace R, Findl O, et al. Long-term efficacy of adding a sharp posterior optic edge to a three-piece silicone intraocular lens on capsule opacification: five-year results of a randomized study. Am J Ophthalmol. 2005;139:696-703.
12. 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.
13. Menapace R., 2004. Prevention of posterior capsule opacification. In: Kohnen T, Koch DD, editors., Cataract and Refractive Surgery (Essentials in Ophthalmology). Springer, Berlin, Germany, pp. 101-122.
14. Nishi O, Yamamoto N, Nishi K, Nishi Y. Contact inhibition of migrating lens epithelial cells at the capsular bend created by a sharp-edged intraocular lens after cataract surgery. J Cataract Refract Surg. 2007;33:1065-1070.
15. Nagamoto T, Fujiwara T. Inhibition of lens epithelial cell migration at the intraocular lens optic edge; role of capsular bending and contact pressure. J Cataract Refract Surg. 2003;29:1605-1612.
16. Menapace R, Skorpik C, Wedrich A. Evaluation of 150 consecutive cases of poly HEMA posterior chamber lenses implanted in the bag using a small-incision technique. J Cataract Refract Surg. 1990;16:567-577. erratum 1991; 17:111.
17. Olson RJ. Consultation section: cataract surgical problems. J Cataract Refract Surg. 2005;31:653-654.