ISSN 0721-832X, Volume 248, Number 8
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Graefes Arch Clin Exp Ophthalmol (2010) 248:1155–1158 DOI 10.1007/s00417-010-1373-2
CATARACT
Comparison of anterior capsule contraction between hydrophobic and hydrophilic intraocular lens models Ioannis T. Tsinopoulos & Konstantinos T. Tsaousis & George D. Kymionis & Chrysanthos Symeonidis & Michael A. Grentzelos & Vasilios F. Diakonis & Maria Adaloglou & Stavros A. Dimitrakos
Received: 19 December 2009 / Revised: 23 February 2010 / Accepted: 18 March 2010 / Published online: 23 April 2010 # Springer-Verlag 2010
Abstract Background To compare the incidence of anterior capsule contraction syndrome (ACCS) after hydrophobic and hydrophilic intraocular lens (IOLs) implantation. Methods In this retrospective study, 639 eyes of 639 patients (one eye from each patient) were included, and were divided in two groups according to the type of IOL implanted [hydrophobic (group 1: 273 eyes) or hydrophilic (group 2: 366 eyes, two different IOL models: group 2a, 267 eyes and group 2b, 99 eyes)]. ACCS incidence between groups 1 and 2 as well as between hydrophilic group IOL models was compared. Results ACCS was significantly (p=0.012) less frequent in group 1 (hydrophobic) than group 2 (hydrophilic) (four eyes versus 19 eyes respectively). In the hydrophilic group, no statistically significant difference was observed between the two IOL models (ACCS was observed in 13 eyes of the Quatrix and six eyes of the ACR6D IOL model: p=0.65). Conclusions ACCS was significantly greater after hydrophilic IOL implantation when compared with hydrophobic The authors have no financial or proprietary interest in any materials or methods described herein. I. T. Tsinopoulos : K. T. Tsaousis (*) : C. Symeonidis : S. A. Dimitrakos 2nd Department of Ophthalmology “Papageorgiou” General Hospital, Faculty of Medicine, Aristotle University of Thessaloniki, 56429 Thessaloniki, Greece e-mail:
[email protected] G. D. Kymionis : M. A. Grentzelos : V. F. Diakonis Department of Medicine, Institute of Vision & Optics, University of Crete, Heraklion, Crete, Greece M. Adaloglou Department of Informatics, Papageorgiou General Hospital, Thessaloniki, Greece
lenses, while there was no statistical significant difference between the two hydrophilic IOL models. Keywords Anterior capsule contraction syndrome . Hydrophilicity . Intraocular lens . Cataract surgery
Introduction Late complications of cataract surgery include capsule opacification, fibrosis and subsequent contraction. Even though fibrosis is more frequent in the posterior pole of the capsule, it may also involve the anterior part, resulting in opacification and capsulorhexis shrinkage [1, 2]. Anterior capsule contraction typically progresses for up to 3 months after surgery, and may lead to IOL decentration and/or tilt; when visual function of the patients is disturbed substantially, anterior capsulotomy using a neodymium laser becomes necessary [3, 4]. Anterior capsule contraction syndrome (ACCS) is the result of fibrosis and collagen production that occurs when residual lens epithelial cells (LECs) in the anterior capsule near the continuous curvilinear capsulorhexis (CCC) margin come in contact with an IOL that is fixated in the capsular bag [5–7]. Numerous conditions (pseudoexfoliation syndrome, uveitis, advanced age, retinitis pigmentosa, trauma and diabetes mellitus) have been identified as risk factors for ACCS development [8–13]. Furthermore, the composition of the IOL implanted is also thought to influence the degree of ACCS; reports demonstrate that ACCS is more extensive in eyes implanted with silicone or hydrogel optic IOL than in eyes implanted with polymethyl methacrylate (PMMA) or acrylic optic IOL [14–16]. However, the exact cause is unclear, and the prevention of ACCS remains difficult.
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The aim of the current study is to compare the incidence of ACCS with respect to IOL optic material properties (water–material interaction) after implantation of hydrophobic and hydrophilic IOLs.
Methods This retrospective clinical study includes patients who received phacoemulsification and IOL implantation at the 2nd Department of Ophthalmology, Aristotle University of Thessaloniki between January 2005 and December 2007. Two types of IOLs (with respect to IOL optic material) were used (randomly selected for each case and depending on availability), hydrophobic (group 1: Acrysof - SN60AT, Alcon, Fort Worth, TX, USA) and hydrophilic (group 2). The hydrophilic group was further divided in two subgroups in respect with IOL manufacturer (group 2a: Quatrix, Corneal Laboratories, La Rochelle, France and group 2b: ACR6D, Corneal Laboratories, La Rochelle, France). The SN60AT used in group 1 is a one-piece, foldable, hydrophobic acrylic posterior chamber IOL. The Quatrix Aspheric Preloaded IOL is a one-piece hydrophilic acrylic lens, which features four haptics, consists of eight supports to prevent capsular folds, and includes a 360º square-edge to avoid cell migration. ACR6D SE preloaded in the Premier shooter is a one-piece hydrophilic acrylic intraocular lens with optic diameter 6 mm (total diameter 12 mm) and 10º angulation. Inclusion criteria included successful creation of a complete CCC and IOL fixation in the capsular bag; exclusion criteria included patients with systemic and ophthalmic history (pseudoexfoliation syndrome, history of uveitis, diabetic retinopathy and retinitis pigmentosa) and intra-operative complications. The study included 639 eyes of 639 patients (one eye from each patient, the one that was operated first, was included) with bilateral age-related cataract. All patients underwent uncomplicated cataract surgery using phacoemulsification and subsequent IOL implantation. All surgical procedures were performed by the same experienced cataract surgeon (I.T.) using the same technique (divide and conquer) and platform (Infinity®, Alcon, Fort Worth, TX, USA). All patients were appropriately informed of risks and benefits prior to operation, and they gave a written informed consent in accordance with the institutional guidelines and the Declaration of Helsinki. All patients were re-examined 1 day, 1, 3 and 6 months postoperatively. The presence of anterior contraction capsule syndrome was subjectively graded according to Toto et al. [17], using a standardized grading scale from 0 to 2: 0= none, 1=moderate (mild opacification not involving the entire capsulorhexis), 2=severe (complete whitening of the capsule over the IOL optic). Standardized digital slit-lamp
Fig. 1 ACCS observed after implantation of a hydrophilic intraocular lens
images of anterior capsule opacification (ACO) and capsulorhexis shrinkage were taken following initial diagnosis of the syndrome (Fig. 1). The chi-square test for proportions was used to detect any statistically significant difference concerning ACCS incidence between group 1 and group 2 IOLs. Statistical significance level was p=0.05. Comparison of incidence of ACCS between groups 2a and 2b was conducted. Data were collected retrospectively and the completed data forms were analyzed with Microsoft Excel 2007 for Windows (Microsoft Corporation, Redmond, WA, USA) and SPSS version 16.0 for Windows (SPSS Inc., Chicago, IL, USA).
Results This retrospective study included 639 eyes of 639 patients (277 males and 362 females), aged between 65 and 82 years old (mean age of 71.2±9.4 years). Group 1 included 273 eyes and group 2 included 366 eyes (group 2a, 267 eyes and group 2b, 99 eyes).
Table 1 Types of IOLs included in the study and incidence of anterior capsule contraction syndrome (ACCS) IOL type
Group 1 Group 2
Total
ACCS grade scale
Hydrophobic ACRYSOF SN60AT Hydrophilic QUATRIX (2a) ACR6D (2b)
0
1
2
Total
121
148
4
273
89 34 244
165 59 372
13 6 23
267 99 639
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ACCS was observed in four eyes in group 1 and in 19 eyes in group 2 (Table 1). The chi-square test for these proportions revealed a statistically significant difference regarding the incidence of the syndrome between the two groups (p= 0.012). Statistical analysis between the IOLs of groups 2a (13 ACCS cases observed) and 2b (six ACCS cases observed) revealed a non-significant difference (p=0.65).
In conclusion, the results of the current study suggest that use of hydrophobic IOLs may result in a significantly lower risk for ACCS development when compared with hydrophilic IOLs. Further studies are necessary in order to investigate the role of hydrophilic and hydrophobic material in the pathophysiology of the anterior capsule contraction syndrome.
Discussion
References
Surgical techniques and IOL materials have been improving over the past decades; however, anterior capsule contraction still occurs, and can affect isual outcomes post cataract surgery. It has been demonstrated that anterior capsule contraction is likely to occur in patients with retinitis pigmentosa, diabetic retinopathy or pseudoexfoliation syndrome. Furthermore, IOL optic material and haptic shape have been implicated in ACCS formation. Reports have revealed that ACCS is more frequent when using silicone IOLs than with acrylic IOLs and with plate-haptic IOLs or IOLs with a thin optic that causes less capsule dilation of the centrifugal haptics [18–23]. As was recently suggested by Kramer et al. [24], identification of one or several potential factors that may contribute to postoperative capsular opacification may dictate the choice of the IOL implanted; in eyes with pseudoexfoliation or a history of uveitis, a hydrophilic IOL may be a prudent choice, since it may cause less cellular reaction and potentially inflammation. Conversely, a hydrophobic IOL may be preferable in posterior subcapsular cataracts, in order to prevent considerable capsular fibrosis. Intraocular lenses demonstrate another significant property in respect with material–water interaction, and therefore IOLs can be divided into hydrophilic and hydrophobic. These properties have been also linked with ACCS development, while hydrophobic IOLs appear to have better biocompatibility in terms of anterior capsule contraction syndrome and posterior capsular opacification [14, 25–27]. In our study, the incidence of ACCS was significantly higher when implanting hydrophilic compared to hydrophobic IOL implantation. This outcome is similar with the findings of previous studies. Hydrophobic IOL material may prevent attachment of migrating epithelial cells on the optic and haptic surfaces, and therefore demonstrate a smaller incidence of ACCS formation. The study demonstrates several limitations. Firstly, the diagnosis of the anterior capsule contraction syndrome was based on subjective assessment due to lack of a generally accepted quantifying method. Secondly, although the known additional risk factors for the appearance of ACCS were excluded from the study, other intrinsic factors may affect the syndrome development apart from IOL material.
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