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Intraindividual comparison of capsule behavior of 2 hydrophobic acrylic intraocular lenses during a 5-year follow-up
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ARTICLE
Intraindividual comparison of capsule behavior of 2 hydrophobic acrylic intraocular lenses during a 5-year follow-up Guenal Kahraman, MD, Clara Ferdinaro, MD, Barbara Wetzel, MD, Clemens Bernhart, MD, Franz Prager, MD, Michael Amon, MD
Purpose: To evaluate and compare the 5-year postoperative anterior (ACO) and posterior capsule opacification (PCO), the occurrence of glistenings, and the level of anterior capsule retraction after implantation of 2 designs of 1-piece hydrophobic acrylic IOLs. Setting: Hospital St. John, Vienna, Austria. Design: Randomized controlled prospective case series. Methods: Patients had an Acrysof SA60AT IOL (Group A) implanted in 1 eye and a Tecnis ZCB00 IOL (Group B) implanted in the fellow eye. At 1, 3, and 5 years, the PCO level was evaluated with the Evaluation of Posterior Capsule Opacification software. The level of ACO and capsule retraction was graded subjectively. Glistenings were scored as present or not present.
P
osterior capsule opacification (PCO) is a common complication of uncomplicated cataract surgery, leading to unsatisfying results from decreased visual function.1–3 Although the PCO treatment with neodymium: YAG (Nd:YAG) laser capsulotomy is a fast and effective procedure, it remains a secondary intervention with associated risks and costs. The material and design of an intraocular lens (IOL), especially of the optic edge, seem to play a major role in the development of anterior (ACO) and posterior capsule opacification (PCO).1–4 Sharp optic edges have been shown to prevent migration of epithelial cells between the capsular bag and the IOL.1–3 A comparative study evaluating the PCO rate 2 years postoperatively in eyes with a continuous 360degree sharp square-edged IOL (Tecnis AAB00, Abbott Medical Optics, Inc.) and an IOL with interruption of the square edge at the optic–haptic junction (Acrysof SA60AT
Results: Fifty eyes of 25 patients were evaluated after 5 years. No significant differences in PCO scores were found between the 2 groups at all follow-up visits (1 year: 0.06 G 0.12 [SD] versus 0.07 G 0.13, P Z .35; 3 years: 0.23 G 0.36 versus 0.22 G 0.32, P Z .66; 5 years: 0.36 G 0.41 versus 0.36 G 0.54, P Z .98). A significant increase in PCO score was found between 3 and 5 years (P < .01). Anterior capsule opacification was present in Group A and Group B in 18.0% and 2.7% of eyes (P Z .03), in 92.0% and 24.0% of eyes, and in 100% and 52% of eyes (P < .01) at 1, 3, and 5 years, respectively. Glistenings (5 years 100%) were observed in Group A. Conclusion: Both IOLs had a comparable PCO rate 5 years after surgery, although more ACO and retraction as well as glistenings were observed in Group A. J Cataract Refract Surg 2017; 43:228–233 Q 2017 ASCRS and ESCRS
or SN60AT, Alcon Surgical, Inc.) showed a significant lower PCO rate of the continuous square-edged IOL.5 Another study found no difference in PCO development between similar IOL models.6 With regard to ACO and capsule retraction, our research group confirmed the presence of significant differences between 2 IOLs with sharp square optic edges, 1 with a continuous edge and the other with an interrupted edge.7,8 The purpose of the current study was to evaluate PCO, ACO, and retraction as well as glistenings 5 years after implantation of 2 designs of 1-piece hydrophobic acrylic IOLs, 1 with a 360-degree continuous sharp optic edge (Tecnis AAB00) and the other with an interrupted square edge (Acrysof SA60AT or SN60AT). PATIENTS AND METHODS In this randomized controlled consecutive prospective and double-masked study, the ACO and PCO outcomes as well as
Submitted: July 25, 2016 | Final revision submitted: November 27, 2016 | Accepted: December 2, 2016 From the Academic Teaching Hospital of St. Johns, Vienna, Austria. Presented at the 20th Winter Meeting of the European Society of Cataract and Refractive Surgeons, Athens, Greece, February 2016, and the XXXIV Congress of the European Society of Cataract and Refractive Surgeons, Copenhagen, Denmark, September 2016. Corresponding author: Guenal Kahraman, MD, Academic Teaching Hospital of St. Johns, Johannes von Gottplatz 1, 1020 Vienna, Austria. E-mail: [email protected]. Q 2017 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter http://dx.doi.org/10.1016/j.jcrs.2016.12.015
INTRAINDIVIDUAL COMPARISON OF CAPSULE BEHAVIOR OF 2 IOLS
capsule phimosis and the occurrence of glistenings were evaluated with 2 types of IOLsdthe spherical Acrysof SA60AT (Group A) and the aspheric Tecnis ZCB00 (Group B). The study was performed at the Hospital of St. John of God (Vienna) between October 2009 and February 2016. The local ethics committee approved the protocol and all patients provided written informed consent before inclusion in the study. The study followed the tenets of the Declaration of Helsinki. Patients with bilateral senile cataract inducing a significant visual deterioration were enrolled. The exclusion criteria were a history of ocular disease such as corneal opacities or irregularities, pseudoexfoliation syndrome, narrow pupils, retinal abnormalities or glaucoma, younger than age 60 years or older than 80 years, previous ocular surgical procedures, and surgical complications. In this intraindividual comparative study, each patient had implantation of 1 IOL model in 1 eye and the other model in the fellow eye in a randomized fashion. Randomization was based on the first operated eye. All surgeries were performed using the same surgical procedure with a well-centered continuous curvilinear capsulorhexis (w5.0 mm). The surgeon was masked until implantation of the IOL. The IOL power ranged from 14.5 to 26.0 diopters. Examination Protocol Patients were examined 1 day, 1 month, and 1, 3, and 5 years after surgery. At the first postoperative visit, slitlamp biomicroscopy was performed to determine the anterior segment integrity of the IOL position. Cases in which the IOL optic did not overlap the anterior capsule were excluded from the study. A complete ophthalmologic examination including slitlamp biomicroscopy, applanation tonometry, and fundus examination was performed at the remaining postoperative visits. An evaluation of the level of capsule opacification was performed 1, 3, and 5 years after surgery. Retroillumination photographs were taken after pupil dilation with tropicamide 1.0%. The presence of PCO, anterior capsule fibrosis, capsule phimosis, and glistenings was assessed. For PCO quantification, the Evaluation of Posterior Capsule Opacification (EPCO) software developed by Tetz et al.9 was used. With this software, a PCO score, which was calculated as the product of the density of the opacification (graded from 0 to 4) and the fractional PCO area involved behind the IOL optic (pixel counts), was obtained for each eye. The ACO was subjectively graded as grade 0, no opacification; grade 1, mild, only the edge of anterior capsulorhexis opacification; grade 2, moderate diffuse opacification with folds; grade 3, severe intense opacification with folds; and grade 4, constriction of the capsulorhexis opening (Figures 1 to 3). Capsule phimosis was graded from 0 (none) to 2 (significant). Glistenings were assessed qualitatively (present or not present).
Figure 1. Anterior capsule opacification grade 0. The anterior capsule is clear with no signs of fibrosis (Group B).
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Statistical Analysis Statistical analysis of the outcomes was performed using Excel 2010 software (Microsoft Corp.). The tests and parameters performed included values calculated as means G SD, the chisquare test for comparing percentages between groups, the Spearman correlation coefficient, and the Wilcoxon signed-rank test for independent samples (nonparametric distributions checked by Kolmogorov-Smirnov test). A P value less than 0.05 was considered statistically significant. According to sample-size calculations, the statistical power of this analysis assuming a significance level of 0.05 was 70.5% (Ene 3.0 software, GlaxoSmithKline).
RESULTS The study enrolled 50 patients. Of those, 25 patients were available for the follow-up examinations 5 years after surgery. Patient age ranged from 61 to 80 years, with a mean value of 70.2 years G 9.3 (SD). Patients were masked to the type of IOL implanted because the surgical procedures were the same for both eyes and both eyes were operated on during the same session. All surgeries were uneventful. One year postoperatively, the mean PCO score was 0.06 G 0.12 (median 0.01; range 0.00 to 0.57) and 0.07 G 0.13 (median 0.01; range 0.00 to 0.68) in Group A and Group B, respectively. This differences between the 2 groups was not statistically significant (P Z .35). Three years postoperatively, no statistically significant differences between the 2 groups were found (P Z .66), with a mean PCO score of 0.23 G 0.36 (median 0.04; range 0.00 to 1.43) and 0.22 G 0.32 (median 0.08; range 0.00 to 1.57) in Group A and Group B, respectively. After 5 years, the PCO score was 0.36 G 0.41 (median 0.18; range 0.00 to 1.492) in Group A, and 0.36 G 0.54 in Group B (median 0.12; range 0.00 to 2.00) (P Z .98). In both groups, a significant increase in the PCO score between the follow-up visits was found (P ! .01). Three years after surgery, the PCO score was 0.5 or less in 40 eyes (80%) and 45 eyes (90%) in Group A and Group B, respectively. This difference between groups did not reach statistical significance (P Z .16). The 5-year PCO score was 0.5 or less in 20 eyes (80%) in both groups.
Figure 2. Anterior capsule opacification grade 2. Moderate opacification with folds. Posterior capsule opacification growth from optic– haptic junction (Group A).
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Figure 3. Anterior capsule opacification grade 3. Severe opacification with capsule folds.
A moderate and significant correlation was found between the PCO score in Group A and Group B (r Z 0.40, P ! .05). Figure 4 shows the PCO scores after 5 years between Group A and Group B. A great variability was present with no trend of 1 specific IOL to develop more PCO. Anterior capsule opacification was present in 9 eyes (18.0%) and 2 eyes (2.7%) 1 year after surgery in Group A and Group B, respectively. These percentages increased 3 years postoperatively in 46 eyes (92.0%) and 12 eyes (24%), and after 5 years in 25 eyes (100%) and 13 eyes (52%) in Group A and Group B, respectively. This difference in the presence of ACO between groups reached statistical significance at all follow-up visits (1 year, P Z .03; 3 years, P ! .01; 5 years, P ! .01) after surgery. The mean ACO score (scale 1 to 4) was 0.30 G 0.71 (median 0; range 0 to 3) and 0.04 G 0.20 (median 0; range 0 to 1) at 1 year, 1.44 G 0.67 (median 1.5; range 0 to 3) and 0.26 G 0.49 (median 0; range 0 to 2) at 3 years, and 1.8 G 0.4 (median 2; range 1 to 2) and 0.6 G 0.63 (median 1; range 0 to 2) at 5 years postoperatively in Group A and Group B, respectively. Differences in ACO score between groups at all follow-ups were found to be statistically significant (1 year, P Z .02; 3 and 5 years, P ! .01). Moderate to severe cases of ACO (grade 2 or more) were found in 20 eyes (80%) in Group A and in 2 eyes (8%) in Group B (Figure 5). Capsule phimosis was observed significantly (P ! .01) more frequently in Group A (1 year, 9 eyes [18.0%]; 3 years,
Figure 5. Distribution of the ACO levels in Group A and Group B.
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Figure 4. Relationship between the PCO scores 5 years after surgery in Group A and Group B. Each circle corresponds to 1 patient (PCO Z posterior capsule opacification).
15 eyes [30.0%]; 5 years, 12 eyes [48%]) than in Group B (1 and 3 years, 0 eyes; 5 years, 1 eye [4%]). Glistenings (1 year, 33 eyes [66.0%]; 3 years, 43 eyes [86.0%]; 5 years, 25 eyes [100%]) were only observed in Group A. Neodymium:YAG capsulotomy was required during the follow-up in 9 eyes (36%) and 7 eyes (28%) in Group A and Group B, respectively. The difference between groups in Nd:YAG capsulotomy rate was not statistically significant (P Z .5). DISCUSSION In the current study, the capsule behavior with regard to PCO, ACO, and capsule phimosis, as well as the level of glistenings over a 5-year follow-up period, were evaluated with 2 different types of hydrophobic acrylic IOLs. There were no significant differences in PCO scores (EPCO) between both IOLs after 5 years. The IOL material seems to be a key factor for these low levels of PCO. Several studies10–12 found higher values of EPCO PCO scores with other materials, such as poly(methyl methacrylate) (PMMA), silicone, or hydrophilic acrylic IOLs. In vitro studies13 have shown that the migration of human lens epithelial cells (LECs) under a hydrophobic acrylic IOL is substantially blocked compared with PMMA and silicone IOLs. However, our PCO scores are slightly higher than those reported by other studies1,5,10–12,14,15 for other or even the same hydrophobic acrylic IOLs (Table 1). The different follow-up periods and evaluation methods of these previous studies might account for this. Results similar to those in our study were reported by Leydolt et al.,6 who used an objective PCO evaluation system (the Automated Quantification of After-Cataract) and found no significant differences in the PCO score or Nd:YAG capsulotomy rate. An increase in the expansion of the PCO area with time has been documented with some models of IOLs.16 In our cohort, a significant increase was found in PCO scores between 1 year and 3 years as
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Table 1. Overview of studies reporting PCO scores using the EPCO software. Study (Y)* Current study (2016)
5
Nixon (2010)
Kohnen (2008)1
Khandwala (2007)11
Nishi (2007)10
14
Mester (2004)
Wedje (2004)15
Auffarth (2003)12
Eyes (n)
IOL Model
IOL Design
IOL Material
IOL Optic Edge
25
Acrysof SA60AT
1 piece
Hydrophobic acrylic
Sharp
0.36 G 0.41
25
Tecnis ZCB00
1 piece
Hydrophobic acrylic
Sharp
0.36 G 0.54
16
Tecnis AAB00
1 piece
Hydrophobic acrylic
Sharp
0.08
16
Acrysof SA60AT or SN60AT
1 piece
Hydrophobic acrylic
Sharp
0.39
58
Ceeon Edge 911A
3 piece
Silicone
Sharp
0.00
58
Acrysof MA60BM
3 piece
Hydrophobic acrylic
Sharp
0.01
55
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.02
27
Akreos Adapt
1 piece
Hydrophilic acrylic
Sharp
0.199
75
Akreos Fit
1 piece
Hydrophilic acrylic
Sharp
0.146
31
Centerflex 570H
1 piece
Hydrophilic acrylic
Sharp
0.35 G 0.22
37
C-flex 570C
1 piece
Hydrophilic acrylic
Sharp
0.16 G 0.20
103
Ceeon Edge 911A
3 piece
Silicone
Sharp
0.00 G 0.01
72
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.03 G 0.08 0.01 G 0.02
103
Acrysof
3 piece
Hydrophobic acrylic
Sharp
60
Acrysof MA60BM
3 piece
Hydrophobic acrylic
Sharp
Mean PCO Score ± SD
0.05z
Mean FU (Mo) ± SD 60
24, 30†
36
30.0 G 10.3
12
11, 14†
36
z
59
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.22
21
Corneal ACR6
1 piece
Hydrophilic acrylic
Round
1.64 G 0.96
17.0 G 2.6
20
Acrysof
3 piece
Hydrophobic acrylic
Sharp
0.08 G 0.21
17.1 G 3.0
27
Sensar AR40
3 piece
Hydrophobic acrylic
Round
0.22 G 0.32
12.0 G 2.1
24
Pharmacia 811
1 piece
PMMA
Round
0.49 G 0.39
16.3 G 4.0
29
Pharmacia 911A
3 piece
Silicone
Sharp
0.06 G 0.11
11.2 G 1.2
FU Z follow-up; IOL Z intraocular lens; PMMA Z poly(methyl methacrylate) *First author † Range z Median
well as 3 years and 5 years after surgery for both evaluated IOL models. In contrast, Praveen et al.17 found a significant increase in PCO up to 3 years with the Acrysof SN60AT IOL; however, they found a stabilization between 3 years and 5 years with no difference at 5 years. Other factors such as IOL design, optical configuration, and placement might also explain the discrepancies between PCO studies.18 Nixon and Woodcock5 found significantly less PCO in eyes implanted with an IOL with a continuous optic edge (Tecnis AAB00) than in eyes with a square-edged IOL with interruption at the optic–haptic junction (SA60AT or SN60AT IOLs). This is in contrast with the finding of the current series, showing no difference in PCO between IOLs with and without an interrupted square optic edge. The difference between studies in follow-up time, sample size, IOL models, or even in the surgical procedure, might have accounted for this discrepancy.
Differences in IOL designs with regard to the asphericity of the lens optic might also play a role in PCO development because the curvature of the surface is slightly different. Biber et al.19 performed a retrospective chart review of spherical and aspheric monofocal and multifocal IOLs. They found a PCO rate of 34.8% for the monofocal spherical Acrysof Natural (SN60AT) and 18.6% for the monofocal aspheric Acrysof IQ SN60WF (Alcon Surgical, Inc.). In addition, Nd:YAG rates were lower in the aspheric IOL group, with 4.7% versus 21.7% in the spherical IOL group. They concluded that the retrospective and monocentric nature were limitations of their study. They attributed the reason for this difference to the symmetric biconvex configuration of the aspheric IOLs, which should maximize the contact between the posterior surface of the optic and the posterior capsule. In their publication, they postulate that the central posterior surface of the aspheric
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IOL is more convex than that of the flatter spherical IOLs, and that the lower posterior convexity of the spherical IOL might create a space between the IOL and the capsule, which is entered by migrating and proliferating LECs. As Nanavaty et al.20 point out, this conclusion is based on a wrong assumption because the Acrysof SN60WF has an aspheric posterior surface that is less convex than its anterior surface. Nanavaty et al.20 performed a prospective randomized intraindividual comparison of the aspheric IOL (Acrysof SN60WF) and the spherical IOL (Acrysof SN60AT) of the same platform. The aspheric IOL was randomized to the first eye of 47 patients and fellow-eye surgery was performed within 3 weeks with the spherical IOL. The patients were followed for 24 months. The PCO was not significantly different between the spherical and aspheric IOLs. The authors concluded that additional asphericity of an existing IOL model does not influence PCO performance. In our study, we compared a spherical IOL (Acrysof) with an aspheric IOL (Tecnis). However, in contrast to aspheric Acrysof IOLs, the asphericity of the Tecnis IOL is on the anterior surface. Therefore, we did not expect the asphericity of the IOL to affect the PCO results. Significantly higher percentages of ACO and higher ACO scores were found in eyes that had the interrupted square optic edge IOL compared with eyes that had the continuous optic edge IOL, which is in line with our earlier results 1 year and 3 years postoperatively.7,8 Because each type of IOL was implanted in the eyes of 1 patient (intraindividual comparison), these differences in ACO might be attributed to differences in IOL surface properties and design. Both IOLs are of a hydrophobic acrylic material; however, the materials and the manufacturing processes are not the same. The Acrysof SA60AT is a biconvex IOL with a 0-degree haptic angulation, whereas the Tecnis ZCB00 is a biconvex IOL with an offset haptic design providing 3 points of fixation. Earlier studies compared the level of ACO in eyes with 3-piece and 1-piece hydrophobic acrylic IOLs21 and found less ACO in the latter. In our cohort, both eyes were implanted with 1-piece IOLs. This suggests that the difference in the optic edge design accounts for the discrepancy in the ACO outcomes of the current series. Other factors, such as the chemical composition of the acrylic material or the treatment of the IOL surface, might also play a role in ACO development; however, this is proprietary manufacturing information and therefore difficult to assess. The interruption of the square optic edge at the optic–haptic junction as well as the configuration of the IOL optic surface might influence the migration of LECs between the anterior capsule and the IOL, facilitating this migration via the breaks of the edge barrier at the optic–haptic junctions. Our results show a significant increase in the levels of ACO and PCO throughout the follow-up. It seems that the opacification of the anterior and posterior capsule are simultaneous processes in eyes implanted
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with a square optic edge IOL. Sacu et al.22 found a negative correlation between PCO and ACO when they compared IOLs of the same design, although 1 IOL had a round posterior edge and the other IOL had a sharp posterior edge. The PCO scores after 1 year were lower in eyes with the sharp-edged IOL. The same group found different results for ACO. Compared with the round-edged IOLs, the modified sharp-edged acrylic and silicone IOLs lead to significantly less PCO but slightly more ACO. The sharp posterior edge prevents migration of anterior capsule LECs behind the optic, resulting in slightly more ACO. The gunnel, a type of circular groove in the periphery of the Tecnis ZCB00 IOL, might further prevent LECs from migrating on the anterior surface of the IOL. Other potential postoperative complications, such as capsule phimosis and glistenings, were also evaluated. The contraction of the capsule opening after cataract surgery can lead to decreased vision and IOL decentration.23 So far, only the optic material (silicone) has been shown to significantly affect the degree of anterior capsule contraction. However, other factors, such as optic design, haptic material, and haptic design, might play a role as well. In our series, capsule phimosis was only observed with the Acrysof IOL, although this was not related to more significant levels of tilt or decentration according to the slitlamp examination, as reported in other studies.24 As hydrophobic acrylic IOLs were implanted in both eyes of the same patient, we assume that metabolic or physiologic factors can be excluded. Therefore, certain IOL design parameters may account for this significant trend to capsule contraction with the Acrysof IOL. Corydon et al.25 also found significant capsulorhexis contraction after hydrophobic acrylic IOL implantation; however, Miyata et al.26 found that sharp-edged IOLs did not appear to be a risk factor for anterior capsule contraction. Finally, as expected according to previous studies,27,28 glistenings were only observed in eyes implanted with the Acrysof IOL; even after 5 years, none of the eyes with the Tecnis IOL showed any glistenings. This outcome is consistent with the results reported by Nagata et al.,28 who evaluated and compared the incidence of glistenings in eyes implanted with 3 different types of IOLs: Acrysof SA60AT, AF-1 VA-60BB (Hoya Surgical Optics GmbH), and Tecnis ZA9003 (Abbott Medical Optics, Inc.) IOLs. The results of their study suggest that Acrysof SA60AT and AF-1 VA-60BB IOLs were more likely to develop glistenings over time compared with the Tecnis IOL. In conclusion, there was no significant difference in the PCO rate between the 2 IOL models after 5 years, although 1 IOL has a continuous square optic edge whereas the other IOL has an interrupted edge. In contrast, there were significant differences with respect to ACO development and anterior capsule retraction between both IOLs. Significantly less ACO and capsule phimosis were observed with the Tecnis IOL. Glistenings
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were observed in all patients with the Acrysof IOL and in no patient with the Tecnis IOL.
WHAT WAS KNOWN The interruption of the sharp optic edge of an IOL at the optic– haptic junction seems to have an influence on the anterior capsule behavior in the short term after cataract surgery.
WHAT THIS PAPER ADDS The interruption of the sharp optic edge of an IOL at the optic–haptic junction had no influence on the development of PCO in a long-term follow-up after cataract surgery. Anterior capsule opacification development and anterior capsule retraction were more frequent in a long-term followup after cataract surgery when an IOL with an interrupted sharp optic edge at the optic–haptic junction was implanted than when an IOL with a continuous edge was implanted.
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€tz W, Strobel J, Hoyer H, 1. Kohnen T, Fabian E, Gerl R, Hunold W, Hu Mester U. Optic edge design as long-term factor for posterior capsular opacification rates. Ophthalmology 2008; 115:1308–1314; e1–3 2. Findl O, Menapace R, Sacu S, Buehl W, Rainer G. Effect of optic material on posterior capsule opacification in intraocular lenses with sharp-edge optics; randomized clinical trial. Ophthalmology 2005; 112:67–72 3. Buehl W, Findl O, Menapace R, Sacu S, Kriechbaum K, Koeppl C, Wirtitsch M. Long-term effect of optic edge design in an acrylic intraocular lens on posterior capsule opacification. J Cataract Refract Surg 2005; 31:954–961 4. Smith SR, Daynes T, Hinckley M, Wallin TR, Olson RJ. The effect of lens edge design versus anterior capsule overlap on posterior capsule opacification. Am J Ophthalmol 2004; 138:521–526 5. Nixon DR, Woodcock MG. Pattern of posterior capsule opacification models 2 years postoperatively with 2 single-piece acrylic intraocular lenses. J Cataract Refract Surg 2010; 36:929–934 6. Leydolt C, Kriechbaum K, Schriefl S, Pachala M, Menapace R. Posterior capsule opacification and neodymium:YAG rates with 2 single-piece hydrophobic acrylic intraocular lenses: three-year results. J Cataract Refract Surg 2013; 39:1886–1892 7. Kahraman G, Schrittwieser H, Walch M, Storch F, Nigl K, Ferdinaro C, Amon M. Anterior and posterior capsular opacification with the Tecnis ZCB00 and AcrySof SA60AT IOLs: a randomised intraindividual comparison. Br J Ophthalmol 2014; 98:905–909 8. Kahraman G, Amon M, Ferdinaro C, Nigl K, Walch M. Intraindividual comparative analysis of capsule opacification after implantation of 2 single-piece hydrophobic acrylic intraocular lenses models: three-year follow-up. J Cataract Refract Surg 2015; 41:990–996 €lcker HE. Photographic im9. Tetz MR, Auffarth GU, Sperker M, Blum M, Vo age analysis system of posterior capsule opacification. J Cataract Refract Surg 1997; 23:1515–1520 10. Nishi Y, Rabsilber TM, Limberger I-J, Reuland AJ, Auffarth GU. Influence of 360-degree enhanced optic edge design of a hydrophilic acrylic intraocular lens on posterior capsule opacification. J Cataract Refract Surg 2007; 33:227–231 11. Khandwala MA, Marjanovic B, Kotagiri AK, Teimory M. Rate of posterior capsule opacification in eyes with the Akreos intraocular lens. J Cataract Refract Surg 2007; 33:1409–1413 €lcker HE. Quantification of posterior 12. Auffarth GU, Golescu A, Becker KA, Vo capsule opacification with round and sharp edge intraocular lenses. Ophthalmology 2003; 110:772–780 13. Yan Q, Perdue N, Sage EH. Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs. Graefes Arch Clin Exp Ophthalmol 2005; 243:1253–1262
€tz W, Strobel J, Hoyer H, 14. Mester U, Fabian E, Gerl R, Hunold W, Hu Kohnen T. Posterior capsule opacification after implantation of CeeOn Edge 911A, PhacoFlex SI-40NB, and AcrySof MA60BM lenses: one-year results of an intraindividual comparison multicenter study. J Cataract Refract Surg 2004; 30:978–985 €m C. Position of anterior capsulorhexis and 15. Wejde G, Kugelberg M, Zetterstro posterior capsule opacification. Acta Ophthalmol Scand 2004; 82:531–534. Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0420.2004. 00322.x/pdf. Accessed December 23, 2016 16. Neumayer T, Findl O, Buehl W, Sacu S, Menapace R, Georgopoulos M. Long-term changes in the morphology of posterior capsule opacification. J Cataract Refract Surg 2005; 31:2120–2128 17. Praveen MR, Shah GD, Vasavada AR, Dave KH. The effect of single-piece hydrophobic acrylic intraocular lenses on the development of posterior capsule opacification. Am J Ophthalmol 2015; 160:470–478 18. Martin RG, Sanders DR, Souchek J, Raanan MG, DeLuca M. Effect of posterior chamber intraocular lens design and surgical placement on postoperative outcome. J Cataract Refract Surg 1992; 18:333–341 19. Biber JM, Sandoval HP, Trivedi RH, Fernandez de Castro LE, French JW, Solomon KD. Comparison of the incidence and visual significance of posterior capsule opacification between multifocal spherical, monofocal spherical, and monofocal aspheric intraocular lenses. J Cataract Refract Surg 2009; 35:1234–1238 20. Nanavaty MA, Spalton DJ, Gala KB, Dhital A, Boyce J. Effect of intraocular lens asphericity on posterior capsule opacification between two intraocular lenses with same acrylic material: a fellow-eye study. Acta Ophthalmol 2012; 90:e104–e108. Available at: http://onlinelibrary.wiley.com/doi/10. 1111/j.1755-3768.2011.02286.x/epdf. Accessed December 23, 2016 21. Wallin TR, Hinckley M, Nilson C, Olson RJ. A clinical comparison of singlepiece and three-piece truncated hydrophobic acrylic intraocular lenses. Am J Ophthalmol 2003; 136:614–619 22. Sacu S, Findl O, Menapace R, Buehl W. Influence of optic edge design, optic material, and haptic design on capsular bend configuration. J Cataract Refract Surg 2005; 31:1888–1894 23. Cochener B, Jacq P-L, Colin J. Capsule contraction after continuous curvilinear capsulorhexis: Poly(methyl methacrylate) versus silicone intraocular lenses. J Cataract Refract Surg 1999; 25:1362–1369 24. Hayashi H, Hayashi K, Nakao F, Hayashi F. Anterior capsule contraction and intraocular lens dislocation in eyes with pseudoexfoliation syndrome. Br J Ophthalmol 1998; 82:1429–1432 25. Corydon C, Lindholt M, Knudsen EB, Graakjaer J, Corydon TJ, DamJohansen M. Capsulorhexis contraction after cataract surgery: Comparison of sharp anterior edge and modified anterior edge acrylic intraocular lenses. J Cataract Refract Surg 2007; 33:796–799 26. Miyata K, Kato S, Nejima R, Miyai T, Honbo M, Ohtani S. Influences of optic edge design on posterior capsule opacification and anterior capsule contraction. Acta Ophthalmol Scand 2007; 85:99–102. Available at: http://online library.wiley.com/doi/10.1111/j.1600-0420.2006.00758.x/pdf. Accessed December 23, 2016 27. Colin J, Orignac I, Touboul D. Glistenings in a large series of hydrophobic acrylic intraocular lenses. J Cataract Refract Surg 2009; 35:2121–2126 28. Nagata M, Matsushima H, Mukai K, Terauchi W, Senoo T, Wada H, Yoshida S. Clinical evaluation of the transparency of hydrophobic acrylic intraocular lens optics. J Cataract Refract Surg 2010; 36:2056–2060
Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
First author: Guenal Kahraman, MD Academic Teaching Hospital of St. Johns, Vienna, Austria
Volume 43 Issue 2 February 2017
ARTICLE
Intraindividual comparison of capsule behavior of 2 hydrophobic acrylic intraocular lenses during a 5-year follow-up Guenal Kahraman, MD, Clara Ferdinaro, MD, Barbara Wetzel, MD, Clemens Bernhart, MD, Franz Prager, MD, Michael Amon, MD
Purpose: To evaluate and compare the 5-year postoperative anterior (ACO) and posterior capsule opacification (PCO), the occurrence of glistenings, and the level of anterior capsule retraction after implantation of 2 designs of 1-piece hydrophobic acrylic IOLs. Setting: Hospital St. John, Vienna, Austria. Design: Randomized controlled prospective case series. Methods: Patients had an Acrysof SA60AT IOL (Group A) implanted in 1 eye and a Tecnis ZCB00 IOL (Group B) implanted in the fellow eye. At 1, 3, and 5 years, the PCO level was evaluated with the Evaluation of Posterior Capsule Opacification software. The level of ACO and capsule retraction was graded subjectively. Glistenings were scored as present or not present.
P
osterior capsule opacification (PCO) is a common complication of uncomplicated cataract surgery, leading to unsatisfying results from decreased visual function.1–3 Although the PCO treatment with neodymium: YAG (Nd:YAG) laser capsulotomy is a fast and effective procedure, it remains a secondary intervention with associated risks and costs. The material and design of an intraocular lens (IOL), especially of the optic edge, seem to play a major role in the development of anterior (ACO) and posterior capsule opacification (PCO).1–4 Sharp optic edges have been shown to prevent migration of epithelial cells between the capsular bag and the IOL.1–3 A comparative study evaluating the PCO rate 2 years postoperatively in eyes with a continuous 360degree sharp square-edged IOL (Tecnis AAB00, Abbott Medical Optics, Inc.) and an IOL with interruption of the square edge at the optic–haptic junction (Acrysof SA60AT
Results: Fifty eyes of 25 patients were evaluated after 5 years. No significant differences in PCO scores were found between the 2 groups at all follow-up visits (1 year: 0.06 G 0.12 [SD] versus 0.07 G 0.13, P Z .35; 3 years: 0.23 G 0.36 versus 0.22 G 0.32, P Z .66; 5 years: 0.36 G 0.41 versus 0.36 G 0.54, P Z .98). A significant increase in PCO score was found between 3 and 5 years (P < .01). Anterior capsule opacification was present in Group A and Group B in 18.0% and 2.7% of eyes (P Z .03), in 92.0% and 24.0% of eyes, and in 100% and 52% of eyes (P < .01) at 1, 3, and 5 years, respectively. Glistenings (5 years 100%) were observed in Group A. Conclusion: Both IOLs had a comparable PCO rate 5 years after surgery, although more ACO and retraction as well as glistenings were observed in Group A. J Cataract Refract Surg 2017; 43:228–233 Q 2017 ASCRS and ESCRS
or SN60AT, Alcon Surgical, Inc.) showed a significant lower PCO rate of the continuous square-edged IOL.5 Another study found no difference in PCO development between similar IOL models.6 With regard to ACO and capsule retraction, our research group confirmed the presence of significant differences between 2 IOLs with sharp square optic edges, 1 with a continuous edge and the other with an interrupted edge.7,8 The purpose of the current study was to evaluate PCO, ACO, and retraction as well as glistenings 5 years after implantation of 2 designs of 1-piece hydrophobic acrylic IOLs, 1 with a 360-degree continuous sharp optic edge (Tecnis AAB00) and the other with an interrupted square edge (Acrysof SA60AT or SN60AT). PATIENTS AND METHODS In this randomized controlled consecutive prospective and double-masked study, the ACO and PCO outcomes as well as
Submitted: July 25, 2016 | Final revision submitted: November 27, 2016 | Accepted: December 2, 2016 From the Academic Teaching Hospital of St. Johns, Vienna, Austria. Presented at the 20th Winter Meeting of the European Society of Cataract and Refractive Surgeons, Athens, Greece, February 2016, and the XXXIV Congress of the European Society of Cataract and Refractive Surgeons, Copenhagen, Denmark, September 2016. Corresponding author: Guenal Kahraman, MD, Academic Teaching Hospital of St. Johns, Johannes von Gottplatz 1, 1020 Vienna, Austria. E-mail: [email protected]. Q 2017 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter http://dx.doi.org/10.1016/j.jcrs.2016.12.015
INTRAINDIVIDUAL COMPARISON OF CAPSULE BEHAVIOR OF 2 IOLS
capsule phimosis and the occurrence of glistenings were evaluated with 2 types of IOLsdthe spherical Acrysof SA60AT (Group A) and the aspheric Tecnis ZCB00 (Group B). The study was performed at the Hospital of St. John of God (Vienna) between October 2009 and February 2016. The local ethics committee approved the protocol and all patients provided written informed consent before inclusion in the study. The study followed the tenets of the Declaration of Helsinki. Patients with bilateral senile cataract inducing a significant visual deterioration were enrolled. The exclusion criteria were a history of ocular disease such as corneal opacities or irregularities, pseudoexfoliation syndrome, narrow pupils, retinal abnormalities or glaucoma, younger than age 60 years or older than 80 years, previous ocular surgical procedures, and surgical complications. In this intraindividual comparative study, each patient had implantation of 1 IOL model in 1 eye and the other model in the fellow eye in a randomized fashion. Randomization was based on the first operated eye. All surgeries were performed using the same surgical procedure with a well-centered continuous curvilinear capsulorhexis (w5.0 mm). The surgeon was masked until implantation of the IOL. The IOL power ranged from 14.5 to 26.0 diopters. Examination Protocol Patients were examined 1 day, 1 month, and 1, 3, and 5 years after surgery. At the first postoperative visit, slitlamp biomicroscopy was performed to determine the anterior segment integrity of the IOL position. Cases in which the IOL optic did not overlap the anterior capsule were excluded from the study. A complete ophthalmologic examination including slitlamp biomicroscopy, applanation tonometry, and fundus examination was performed at the remaining postoperative visits. An evaluation of the level of capsule opacification was performed 1, 3, and 5 years after surgery. Retroillumination photographs were taken after pupil dilation with tropicamide 1.0%. The presence of PCO, anterior capsule fibrosis, capsule phimosis, and glistenings was assessed. For PCO quantification, the Evaluation of Posterior Capsule Opacification (EPCO) software developed by Tetz et al.9 was used. With this software, a PCO score, which was calculated as the product of the density of the opacification (graded from 0 to 4) and the fractional PCO area involved behind the IOL optic (pixel counts), was obtained for each eye. The ACO was subjectively graded as grade 0, no opacification; grade 1, mild, only the edge of anterior capsulorhexis opacification; grade 2, moderate diffuse opacification with folds; grade 3, severe intense opacification with folds; and grade 4, constriction of the capsulorhexis opening (Figures 1 to 3). Capsule phimosis was graded from 0 (none) to 2 (significant). Glistenings were assessed qualitatively (present or not present).
Figure 1. Anterior capsule opacification grade 0. The anterior capsule is clear with no signs of fibrosis (Group B).
229
Statistical Analysis Statistical analysis of the outcomes was performed using Excel 2010 software (Microsoft Corp.). The tests and parameters performed included values calculated as means G SD, the chisquare test for comparing percentages between groups, the Spearman correlation coefficient, and the Wilcoxon signed-rank test for independent samples (nonparametric distributions checked by Kolmogorov-Smirnov test). A P value less than 0.05 was considered statistically significant. According to sample-size calculations, the statistical power of this analysis assuming a significance level of 0.05 was 70.5% (Ene 3.0 software, GlaxoSmithKline).
RESULTS The study enrolled 50 patients. Of those, 25 patients were available for the follow-up examinations 5 years after surgery. Patient age ranged from 61 to 80 years, with a mean value of 70.2 years G 9.3 (SD). Patients were masked to the type of IOL implanted because the surgical procedures were the same for both eyes and both eyes were operated on during the same session. All surgeries were uneventful. One year postoperatively, the mean PCO score was 0.06 G 0.12 (median 0.01; range 0.00 to 0.57) and 0.07 G 0.13 (median 0.01; range 0.00 to 0.68) in Group A and Group B, respectively. This differences between the 2 groups was not statistically significant (P Z .35). Three years postoperatively, no statistically significant differences between the 2 groups were found (P Z .66), with a mean PCO score of 0.23 G 0.36 (median 0.04; range 0.00 to 1.43) and 0.22 G 0.32 (median 0.08; range 0.00 to 1.57) in Group A and Group B, respectively. After 5 years, the PCO score was 0.36 G 0.41 (median 0.18; range 0.00 to 1.492) in Group A, and 0.36 G 0.54 in Group B (median 0.12; range 0.00 to 2.00) (P Z .98). In both groups, a significant increase in the PCO score between the follow-up visits was found (P ! .01). Three years after surgery, the PCO score was 0.5 or less in 40 eyes (80%) and 45 eyes (90%) in Group A and Group B, respectively. This difference between groups did not reach statistical significance (P Z .16). The 5-year PCO score was 0.5 or less in 20 eyes (80%) in both groups.
Figure 2. Anterior capsule opacification grade 2. Moderate opacification with folds. Posterior capsule opacification growth from optic– haptic junction (Group A).
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Figure 3. Anterior capsule opacification grade 3. Severe opacification with capsule folds.
A moderate and significant correlation was found between the PCO score in Group A and Group B (r Z 0.40, P ! .05). Figure 4 shows the PCO scores after 5 years between Group A and Group B. A great variability was present with no trend of 1 specific IOL to develop more PCO. Anterior capsule opacification was present in 9 eyes (18.0%) and 2 eyes (2.7%) 1 year after surgery in Group A and Group B, respectively. These percentages increased 3 years postoperatively in 46 eyes (92.0%) and 12 eyes (24%), and after 5 years in 25 eyes (100%) and 13 eyes (52%) in Group A and Group B, respectively. This difference in the presence of ACO between groups reached statistical significance at all follow-up visits (1 year, P Z .03; 3 years, P ! .01; 5 years, P ! .01) after surgery. The mean ACO score (scale 1 to 4) was 0.30 G 0.71 (median 0; range 0 to 3) and 0.04 G 0.20 (median 0; range 0 to 1) at 1 year, 1.44 G 0.67 (median 1.5; range 0 to 3) and 0.26 G 0.49 (median 0; range 0 to 2) at 3 years, and 1.8 G 0.4 (median 2; range 1 to 2) and 0.6 G 0.63 (median 1; range 0 to 2) at 5 years postoperatively in Group A and Group B, respectively. Differences in ACO score between groups at all follow-ups were found to be statistically significant (1 year, P Z .02; 3 and 5 years, P ! .01). Moderate to severe cases of ACO (grade 2 or more) were found in 20 eyes (80%) in Group A and in 2 eyes (8%) in Group B (Figure 5). Capsule phimosis was observed significantly (P ! .01) more frequently in Group A (1 year, 9 eyes [18.0%]; 3 years,
Figure 5. Distribution of the ACO levels in Group A and Group B.
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Figure 4. Relationship between the PCO scores 5 years after surgery in Group A and Group B. Each circle corresponds to 1 patient (PCO Z posterior capsule opacification).
15 eyes [30.0%]; 5 years, 12 eyes [48%]) than in Group B (1 and 3 years, 0 eyes; 5 years, 1 eye [4%]). Glistenings (1 year, 33 eyes [66.0%]; 3 years, 43 eyes [86.0%]; 5 years, 25 eyes [100%]) were only observed in Group A. Neodymium:YAG capsulotomy was required during the follow-up in 9 eyes (36%) and 7 eyes (28%) in Group A and Group B, respectively. The difference between groups in Nd:YAG capsulotomy rate was not statistically significant (P Z .5). DISCUSSION In the current study, the capsule behavior with regard to PCO, ACO, and capsule phimosis, as well as the level of glistenings over a 5-year follow-up period, were evaluated with 2 different types of hydrophobic acrylic IOLs. There were no significant differences in PCO scores (EPCO) between both IOLs after 5 years. The IOL material seems to be a key factor for these low levels of PCO. Several studies10–12 found higher values of EPCO PCO scores with other materials, such as poly(methyl methacrylate) (PMMA), silicone, or hydrophilic acrylic IOLs. In vitro studies13 have shown that the migration of human lens epithelial cells (LECs) under a hydrophobic acrylic IOL is substantially blocked compared with PMMA and silicone IOLs. However, our PCO scores are slightly higher than those reported by other studies1,5,10–12,14,15 for other or even the same hydrophobic acrylic IOLs (Table 1). The different follow-up periods and evaluation methods of these previous studies might account for this. Results similar to those in our study were reported by Leydolt et al.,6 who used an objective PCO evaluation system (the Automated Quantification of After-Cataract) and found no significant differences in the PCO score or Nd:YAG capsulotomy rate. An increase in the expansion of the PCO area with time has been documented with some models of IOLs.16 In our cohort, a significant increase was found in PCO scores between 1 year and 3 years as
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Table 1. Overview of studies reporting PCO scores using the EPCO software. Study (Y)* Current study (2016)
5
Nixon (2010)
Kohnen (2008)1
Khandwala (2007)11
Nishi (2007)10
14
Mester (2004)
Wedje (2004)15
Auffarth (2003)12
Eyes (n)
IOL Model
IOL Design
IOL Material
IOL Optic Edge
25
Acrysof SA60AT
1 piece
Hydrophobic acrylic
Sharp
0.36 G 0.41
25
Tecnis ZCB00
1 piece
Hydrophobic acrylic
Sharp
0.36 G 0.54
16
Tecnis AAB00
1 piece
Hydrophobic acrylic
Sharp
0.08
16
Acrysof SA60AT or SN60AT
1 piece
Hydrophobic acrylic
Sharp
0.39
58
Ceeon Edge 911A
3 piece
Silicone
Sharp
0.00
58
Acrysof MA60BM
3 piece
Hydrophobic acrylic
Sharp
0.01
55
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.02
27
Akreos Adapt
1 piece
Hydrophilic acrylic
Sharp
0.199
75
Akreos Fit
1 piece
Hydrophilic acrylic
Sharp
0.146
31
Centerflex 570H
1 piece
Hydrophilic acrylic
Sharp
0.35 G 0.22
37
C-flex 570C
1 piece
Hydrophilic acrylic
Sharp
0.16 G 0.20
103
Ceeon Edge 911A
3 piece
Silicone
Sharp
0.00 G 0.01
72
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.03 G 0.08 0.01 G 0.02
103
Acrysof
3 piece
Hydrophobic acrylic
Sharp
60
Acrysof MA60BM
3 piece
Hydrophobic acrylic
Sharp
Mean PCO Score ± SD
0.05z
Mean FU (Mo) ± SD 60
24, 30†
36
30.0 G 10.3
12
11, 14†
36
z
59
Phaco Flex SI-40NB
3 piece
Silicone
Round
0.22
21
Corneal ACR6
1 piece
Hydrophilic acrylic
Round
1.64 G 0.96
17.0 G 2.6
20
Acrysof
3 piece
Hydrophobic acrylic
Sharp
0.08 G 0.21
17.1 G 3.0
27
Sensar AR40
3 piece
Hydrophobic acrylic
Round
0.22 G 0.32
12.0 G 2.1
24
Pharmacia 811
1 piece
PMMA
Round
0.49 G 0.39
16.3 G 4.0
29
Pharmacia 911A
3 piece
Silicone
Sharp
0.06 G 0.11
11.2 G 1.2
FU Z follow-up; IOL Z intraocular lens; PMMA Z poly(methyl methacrylate) *First author † Range z Median
well as 3 years and 5 years after surgery for both evaluated IOL models. In contrast, Praveen et al.17 found a significant increase in PCO up to 3 years with the Acrysof SN60AT IOL; however, they found a stabilization between 3 years and 5 years with no difference at 5 years. Other factors such as IOL design, optical configuration, and placement might also explain the discrepancies between PCO studies.18 Nixon and Woodcock5 found significantly less PCO in eyes implanted with an IOL with a continuous optic edge (Tecnis AAB00) than in eyes with a square-edged IOL with interruption at the optic–haptic junction (SA60AT or SN60AT IOLs). This is in contrast with the finding of the current series, showing no difference in PCO between IOLs with and without an interrupted square optic edge. The difference between studies in follow-up time, sample size, IOL models, or even in the surgical procedure, might have accounted for this discrepancy.
Differences in IOL designs with regard to the asphericity of the lens optic might also play a role in PCO development because the curvature of the surface is slightly different. Biber et al.19 performed a retrospective chart review of spherical and aspheric monofocal and multifocal IOLs. They found a PCO rate of 34.8% for the monofocal spherical Acrysof Natural (SN60AT) and 18.6% for the monofocal aspheric Acrysof IQ SN60WF (Alcon Surgical, Inc.). In addition, Nd:YAG rates were lower in the aspheric IOL group, with 4.7% versus 21.7% in the spherical IOL group. They concluded that the retrospective and monocentric nature were limitations of their study. They attributed the reason for this difference to the symmetric biconvex configuration of the aspheric IOLs, which should maximize the contact between the posterior surface of the optic and the posterior capsule. In their publication, they postulate that the central posterior surface of the aspheric
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IOL is more convex than that of the flatter spherical IOLs, and that the lower posterior convexity of the spherical IOL might create a space between the IOL and the capsule, which is entered by migrating and proliferating LECs. As Nanavaty et al.20 point out, this conclusion is based on a wrong assumption because the Acrysof SN60WF has an aspheric posterior surface that is less convex than its anterior surface. Nanavaty et al.20 performed a prospective randomized intraindividual comparison of the aspheric IOL (Acrysof SN60WF) and the spherical IOL (Acrysof SN60AT) of the same platform. The aspheric IOL was randomized to the first eye of 47 patients and fellow-eye surgery was performed within 3 weeks with the spherical IOL. The patients were followed for 24 months. The PCO was not significantly different between the spherical and aspheric IOLs. The authors concluded that additional asphericity of an existing IOL model does not influence PCO performance. In our study, we compared a spherical IOL (Acrysof) with an aspheric IOL (Tecnis). However, in contrast to aspheric Acrysof IOLs, the asphericity of the Tecnis IOL is on the anterior surface. Therefore, we did not expect the asphericity of the IOL to affect the PCO results. Significantly higher percentages of ACO and higher ACO scores were found in eyes that had the interrupted square optic edge IOL compared with eyes that had the continuous optic edge IOL, which is in line with our earlier results 1 year and 3 years postoperatively.7,8 Because each type of IOL was implanted in the eyes of 1 patient (intraindividual comparison), these differences in ACO might be attributed to differences in IOL surface properties and design. Both IOLs are of a hydrophobic acrylic material; however, the materials and the manufacturing processes are not the same. The Acrysof SA60AT is a biconvex IOL with a 0-degree haptic angulation, whereas the Tecnis ZCB00 is a biconvex IOL with an offset haptic design providing 3 points of fixation. Earlier studies compared the level of ACO in eyes with 3-piece and 1-piece hydrophobic acrylic IOLs21 and found less ACO in the latter. In our cohort, both eyes were implanted with 1-piece IOLs. This suggests that the difference in the optic edge design accounts for the discrepancy in the ACO outcomes of the current series. Other factors, such as the chemical composition of the acrylic material or the treatment of the IOL surface, might also play a role in ACO development; however, this is proprietary manufacturing information and therefore difficult to assess. The interruption of the square optic edge at the optic–haptic junction as well as the configuration of the IOL optic surface might influence the migration of LECs between the anterior capsule and the IOL, facilitating this migration via the breaks of the edge barrier at the optic–haptic junctions. Our results show a significant increase in the levels of ACO and PCO throughout the follow-up. It seems that the opacification of the anterior and posterior capsule are simultaneous processes in eyes implanted
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with a square optic edge IOL. Sacu et al.22 found a negative correlation between PCO and ACO when they compared IOLs of the same design, although 1 IOL had a round posterior edge and the other IOL had a sharp posterior edge. The PCO scores after 1 year were lower in eyes with the sharp-edged IOL. The same group found different results for ACO. Compared with the round-edged IOLs, the modified sharp-edged acrylic and silicone IOLs lead to significantly less PCO but slightly more ACO. The sharp posterior edge prevents migration of anterior capsule LECs behind the optic, resulting in slightly more ACO. The gunnel, a type of circular groove in the periphery of the Tecnis ZCB00 IOL, might further prevent LECs from migrating on the anterior surface of the IOL. Other potential postoperative complications, such as capsule phimosis and glistenings, were also evaluated. The contraction of the capsule opening after cataract surgery can lead to decreased vision and IOL decentration.23 So far, only the optic material (silicone) has been shown to significantly affect the degree of anterior capsule contraction. However, other factors, such as optic design, haptic material, and haptic design, might play a role as well. In our series, capsule phimosis was only observed with the Acrysof IOL, although this was not related to more significant levels of tilt or decentration according to the slitlamp examination, as reported in other studies.24 As hydrophobic acrylic IOLs were implanted in both eyes of the same patient, we assume that metabolic or physiologic factors can be excluded. Therefore, certain IOL design parameters may account for this significant trend to capsule contraction with the Acrysof IOL. Corydon et al.25 also found significant capsulorhexis contraction after hydrophobic acrylic IOL implantation; however, Miyata et al.26 found that sharp-edged IOLs did not appear to be a risk factor for anterior capsule contraction. Finally, as expected according to previous studies,27,28 glistenings were only observed in eyes implanted with the Acrysof IOL; even after 5 years, none of the eyes with the Tecnis IOL showed any glistenings. This outcome is consistent with the results reported by Nagata et al.,28 who evaluated and compared the incidence of glistenings in eyes implanted with 3 different types of IOLs: Acrysof SA60AT, AF-1 VA-60BB (Hoya Surgical Optics GmbH), and Tecnis ZA9003 (Abbott Medical Optics, Inc.) IOLs. The results of their study suggest that Acrysof SA60AT and AF-1 VA-60BB IOLs were more likely to develop glistenings over time compared with the Tecnis IOL. In conclusion, there was no significant difference in the PCO rate between the 2 IOL models after 5 years, although 1 IOL has a continuous square optic edge whereas the other IOL has an interrupted edge. In contrast, there were significant differences with respect to ACO development and anterior capsule retraction between both IOLs. Significantly less ACO and capsule phimosis were observed with the Tecnis IOL. Glistenings
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INTRAINDIVIDUAL COMPARISON OF CAPSULE BEHAVIOR OF 2 IOLS
were observed in all patients with the Acrysof IOL and in no patient with the Tecnis IOL.
WHAT WAS KNOWN The interruption of the sharp optic edge of an IOL at the optic– haptic junction seems to have an influence on the anterior capsule behavior in the short term after cataract surgery.
WHAT THIS PAPER ADDS The interruption of the sharp optic edge of an IOL at the optic–haptic junction had no influence on the development of PCO in a long-term follow-up after cataract surgery. Anterior capsule opacification development and anterior capsule retraction were more frequent in a long-term followup after cataract surgery when an IOL with an interrupted sharp optic edge at the optic–haptic junction was implanted than when an IOL with a continuous edge was implanted.
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Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
First author: Guenal Kahraman, MD Academic Teaching Hospital of St. Johns, Vienna, Austria
Volume 43 Issue 2 February 2017