Background. Bj orn Johansson 1,2. Acta Ophthalmologica 2017

Transcription

1 Glistenings, anterior/posterior capsular opacification and incidence of Nd:YAG laser treatments with two aspheric hydrophobic acrylic intraocular lenses a long-term intra-individual study Bj orn Johansson 1,2 1 Department of Ophthalmology, Link oping University, Link oping, Sweden 2 Department of Clinical and Experimental Medicine, Link oping University, Link oping, Sweden ABSTRACT. Purpose: To compare two hydrophobic acrylic intraocular lenses (IOLs) regarding long-term anterior/posterior capsular opacification (ACO/PCO) development and need for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser treatment due to visually disturbing PCO, and to study development of glistenings in the IOL materials. Methods: In a prospective, randomized, intra-individual, comparative trial, 50 cataract patients received either an AcrySof IQ â SN60WF (Alcon, Fort Worth, TX, USA) or a Tecnis â ZCB00 (Abbott Medical Optics, Santa Ana, CA, USA) IOL in the first operated eye, and the second eye received the IOL type not implanted in the first eye. Anterior/posterior capsular opacification (ACO/ PCO) and fibrosis were monitored with slit-lamp photography and semiautomated digital analysis 2 and 3 years postoperatively. Glistenings were semiquantitatively assessed in slit-lamp photographs. Nd:YAG laser treatment for visually disturbing PCO was monitored. Results: Visual outcomes were similar for the two IOLs. Anterior capsular fibrosis and/or opacification developed more often in SN60WF eyes. Mean PCO area percentage was larger in ZCB00 eyes 3 years after surgery, but severity score did not differ with statistical significance between the two IOLs. Six ZCB00 eyes and 2 SN60WF eyes underwent Nd:YAG laser treatment during a mean of 4 years 8 months after surgery. This difference was not statistically significant. A high amount of glistenings developed in most SN60WF IOLs, while only few ZCB00 IOLs displayed a low degree of glistenings. Conclusion: Visual outcomes, PCO development over time and need for Nd: YAG laser treatment were similar for the two IOLs. Anterior capsule fibrosis/ contraction and glistenings were more pronounced with the SN60WF IOL. Key words: glistenings hydrophobic acrylic intraocular lens posterior capsular opacification Acta Ophthalmol. 2017: 95: ª 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd doi: /aos Background The primary aim of cataract surgery with implantation of an artificial intraocular lens (IOL) is to restore a clear path for the light entering the eye. The most common reason for a postoperative decrease in visual function is PCO, which develops from remaining lens epithelial cells at the lens equator, proliferating and migrating over the posterior lens capsule behind the IOL (Apple & Sims 1996). Although vision can readily be improved with neodymium:yttrium-aluminum-garnet (Nd: YAG) laser discission of the opacified posterior capsule, PCO does have an impact on the patients quality of life during a period of time (de Juan- Marcos et al. 2012; Yotsukura et al. 2016). It is also a burden to the limited resources of healthcare systems (Cullin et al. 2014). In Sweden, the number of Nd:YAG laser treatments has been estimated to be around 15% of the number of performed cataract surgeries (Johansson & Lundh 2003), but this can vary depending on reimbursement regulations, premium IOL use, and on the material and design of IOLs used (Johansson 2010). The development of PCO has been demonstrated to be faster in eyes with hydrophilic compared to hydrophobic acrylic IOLs (Chang & Kugelberg 2016). The design of optic and haptics, the optic-haptic junction and the 671

2 posterior edge of the IOL optic plays an important role as well (Heatley et al. 2005; Nanavaty et al. 2008; Johansson 2010): a sharp posterior edge will act as a mechanical barrier for movement of lens epithelial cells across the posterior capsule from the periphery of the capsular bag to the centre where they will distort the light transmission in to the retina (Nishi & Nishi 1999; Mester et al. 2004). The hydrophobic acrylic material with a tacky surface that adheres to the posterior capsule (Oshika et al. 1998) and the posterior sharp edge design of AcrySof Ò IOLs (Alcon Laboratories, Inc., Fort Worth, TX, USA) have since the end of the 1990s proved advantageous for delaying and preventing PCO development (Mester et al. 2004). Therefore, the AcrySof Ò IOL has been considered as benchmark for newer IOL materials and designs regarding incidence of visually disturbing PCO (Wejde et al. 2003; Kugelberg et al. 2006; Raj et al. 2007; Ronbeck et al. 2009; Vasavada et al. 2011; Kahraman et al. 2015). In IOL materials, small water-filled microvacuoles, glistenings, may appear. Explantations of IOLs due to extensive glistenings suspected to cause subjective visual disturbances, or due to impaired fundus visualization, have been reported (Shiba et al. 2003; Werner et al. 2008; van der Mooren et al. 2015). The material of AcrySof Ò IOLs regularly exhibits glistenings readily visible upon slit-lamp examination (Christiansen et al. 2001; Werner 2010), but it remains controversial as to whether this may cause any visual disturbance. Several investigators have studied IOLs with glistenings and found no significant changes in optical properties, visual acuity (VA) or contrast sensitivity that could be attributed to glistenings (Hayashi et al. 2012; Ronbeck et al. 2013; Chang & Kugelberg 2015; Monestam & Behndig 2016). Nevertheless, some concern exists regarding glistenings, and IOL manufacturers make efforts to identify materials less prone for glistening formation. When an IOL is introduced, it is of interest to know how it performs with regard to both PCO development and optical quality of the material over an extended period of time. The aspheric Tecnis Ò 1-piece IOL (Abbott Medical Optics, Santa Ana, CA, USA) received Fig. 1. The two single-piece study IOLs (Acry- Sof Ò SN60WF left, Tecnis Ò ZCB00 right) are made of hydrophobic acrylic material. Both have aspherical 6-mm optics with negative spherical aberration aiming for full or partly correction of the positive spherical aberration of the cornea. The SN60WF has a blue light filtering chromophore in the material. Both IOLs have a sharp posterior optic edge aiming to prevent or delay the development of PCO. FDA approval Although several studies indicated a satisfactory PCO record, direct long-term comparisons with the aspheric AcrySof Ò SN60WF IQ IOL are sparse. The aim of this study was to compare the two hydrophobic acrylic IOLs Tecnis Ò ZCB00 and AcrySof Ò SN60WF (Fig. 1) with regard to longterm PCO development and need for Nd:YAG laser treatment due to visually disturbing PCO, as well as to study the presence of glistenings over time in the IOL material. Material and Methods This study took place at the Department of Ophthalmology at Link oping University Hospital, Sweden. A total of 54 patients with bilateral cataract were included in the study. Inclusion criteria were as follows: age 50 years or more with age-related cataract in both eyes considered suitable for surgical treatment with implantation of an IOL in the capsule; clear ocular media except for the cataract; ability to read, understand and sign an informed consent; willingness to return for postoperative controls outside routine visits 2 and 3 years after surgery; consent to all procedures for examination and treatment. Exclusion criteria were as follows: Congenital, traumatic or otherwise complicated cataract, previous intraocular surgery, ocular malformations, ocular tumours, anterior segment pathology except cataract, for example iridocyclitis, iris neovascularizations, corneal endothelial dystrophy, zonular or capsular defects. Before surgery, two patients decided to withdraw from the study. In two cases, the study IOL was unavailable at the day of surgery and these patients were excluded. All 50 operated subjects accepted and underwent immediate sequential bilateral cataract surgery. All patients signed informed consent and the tenets of the Helsinki Declaration were adhered to. The local ethics committee approved the protocol. Randomization A series of random numbers was created in Excel to provide each eye with an IOL in a randomized fashion. The patients were randomized in the same order as they were enrolled in the study, after informed consent had been signed. The first eye to be operated was randomized to receive either an Acry- Sof IQ Ò SN60WF (Alcon) or a Tecnis Ò ZCB00 (Abbott Medical Optics) aspherical monofocal hydrophobic acrylic 1-piece IOL (Fig. 1). The second eye to be operated received the other type of IOL. Surgical technique All surgeries were performed by the author in topical and intracameral anaesthesia. A clear corneal 1.8-mm incision was made with a steel knife, and a minimal limbal incision for side instrument was created 2 3 clock hours to the left of the main incision. The anterior chamber was filled with viscoelastic, and a continuous curvilinear capsulorhexis was created. After hydrodissection and hydrodelineation, the lens was emulsified and aspirated using direct chop technique. The Stellaris Ò Vision Enhancement System (Bausch and Lomb Inc., Rochester, NY, USA) with a vacuum flow module and dual-linear foot control was used for removal of the cataract. After cortical clean-up with a coaxial irrigation aspiration handpiece, the IOL was implanted with an injector into the capsular bag after the main incision had been widened as necessary. Following viscoelastic removal with the irrigation aspiration handpiece and hydration of the incisions, an injection of 1 mg cefuroxime in the anterior 672

3 chamber concluded the procedure. Operation time, effective phaco time (EPT), cases where part of the rhexis was outside the optic margin as well as any intra-operative complication were documented. Data collection Postoperative visits were scheduled 1 week, 2 years and 3 years after surgery. Refraction, distance VA (decimal chart, distance 5 m, decimal VA subsequently converted to LogMAR) with and without correction as well as intraocular pressure were recorded. Slit-lamp photographs were obtained for evaluation of anterior capsulorhexis margin, PCO development and glistenings. Fibrosis of the anterior capsulorhexis margin was graded as 0 ( none : clear margin, no contraction), 1 ( slight : white fibrosis around anterior capsular rim, no contraction), 2 ( moderate : as 1 with contraction), 3 ( severe, with visual disturbance/capsular phimosis and/or dislocation of IOL haptic/optic). POCO- MAN software (Bender et al. 2004) was used to semi-automatically grade the severity and distribution of PCO. Glistenings were semi-quantitatively graded from 0 to 4 as described by Werner (2010). A final review of digital patient records was made to detect Nd:YAG laser treatment up to 5 years after surgery. Statistical analysis For continuous data, Students paired t-test was used. Data not normally distributed were evaluated with Wilcoxon signed rank test. Ordinal data were analysed with the chi-square test. Results Of the 50 patients, all attended the first postoperative visit between 1 and 11 (mean 6.5) days after surgery. Visit 2 occurred between 671 and 778 (mean 697) days after surgery and visit 3 between 1035 and 1184 (mean 1112) days after surgery. At the time of the second visit, six patients had died and thus 44 patients returned for examination. At the time of the third visit, four patients declined examination due to general health problems, and one more patient had died. Thus, 39 patients returned for the final examination. Demographic and surgical data are displayed in Table 1. The mean age of 74.5 years is close to the mean age of all cataract patients reported to the Swedish National cataract register. A female preponderance is also in accordance with population data from the register. All surgeries except three were uneventful. In one case, the IOL was stuck in the tunnel during implantation but could be manipulated into the anterior chamber and placed in the capsular bag. In another case, the main incision was leaking until closed with one 10-0 nylon single suture. A temporary bleeding from the iris base occurred in a 3rd case when an IOL haptic after injection was located anteriorly to the iris and subsequently was relocated into the capsular bag. No surgery was complicated by capsular rifts or ruptures. The capsulorhexis margin was on the optic in all cases except for 2 ZCB00 IOL eyes. In both these cases, the rhexis margin was outside the optic in a sector 3 clock hours wide. The complications had no consequences for the visual quality in any case. No patient reported any disturbing interocular variations in colour perception in spite of the difference in colour between the two study IOLs, with a blue-blocking filter in the material of the SN60WF IOL and a clear optic in the ZCB00 IOL (Fig. 1). Postoperative complications are listed in Table 2. Encountered complications did not cause any negative impact on final outcomes regarding Table 1. Base data. visual function. Table 3 displays VA before operation and at the postoperative visits, for right and left eyes and with eyes grouped after IOL type. There were no statistically significant differences in pre- and postoperative VA between the 2 IOL groups at 2 and 3 years after surgery (p = 0.13 and p = 0.92, respectively, Student s paired t-test). Anterior capsulorhexis margin examination results are displayed in Fig. 2. Significantly more anterior capsular fibrosis and/or opacification was seen in eyes with SN60WF (p = 0.02 at 2 years, p = at 3 years, chisquare test). In one case, Nd:YAG laser treatment was performed due to visually disturbing contraction of the anterior capsular opening in an SN60WF eye, 3 years and 3 months after surgery. Posterior capsular opacification (PCO) percentage and severity scores are depicted in Fig. 3. No statistically significant differences were found between the two IOLs regarding PCO development after 2 years. Three years after surgery the PCO area percentage was higher for the ZCB00 group (p = 0.01, Wilcoxon signed rank test), while difference in PCO severity score was not statistically significant (p = 0.07). In several eyes, PCO started to appear in the vicinity of the optic haptic junction. This could be seen in both IOL types (Fig. 4). By review of digital patient records, Nd:YAG laser treatments because of visually disturbing PCO could be tracked for a mean time period of Number of patients 50 Female 35 Male 15 Mean age (years) 74.5 Female 74.2 Male 75.1 First operated eye OD 25 OS 25 Patients with SN60WF in OD, ZCB00 in OS 34 Patients with ZCB00 in OD, SN60WF in OS 16 Operation time OD, mean SD (min) Operation time OS, mean SD (min) Operation time SN60WF eyes, mean SD (min) Operation time ZCB00 eyes, mean SD [min] Effective phaco time OD, mean SD (seconds) Effective phaco time OS, mean SD (seconds) Effective phaco time SN60WF eyes, mean SD (seconds) Effective phaco time ZCB00, mean SD (seconds)

4 Table 2. Postoperative complications. Complication Time after surgery Relation to study procedure Treatment Outcome at end of study period Metamorphopsia in AcrySof eye. Small central crack in optic Posterior vitreous detachment with retinal rupture in AcrySof eye 1 day (postoperative visit 1) Definitive None Metamorphopsia not noted 8 months Uncertain Argon laser Resolved without sequelae photocoagulation + cryopexy Resolved without sequelae Cystoid macular oedema in Tecnis eye 6 weeks Definitive Topical non-steroidal anti-inflammatory agent + steroid Iritis in AcrySof eye 7 weeks Definitive Topical steroid Resolved without sequelae Table 3. Visual acuity before surgery, at 1 week, at 2 years and at 3 years after surgery. Best-corrected distance visual acuity, BCDVA (LogMAR) Preop Visit 1 Visit 2 Visit 3 OD OS AcrySof Tecnis years and 8 months (range 4 years 5 months to 5 years 3 months) after surgery. Indication for Nd:YAG laser treatment of the capsule was a subjective visual complaint from the patient in combination with clinically significant posterior capsule opacification visible at slit-lamp examination. During this period, 8 of the 100 operated eyes received an Nd:YAG laser capsulotomy. SN60WF was implanted in Grade 0 Grade 1 Grade 2 Grade 3 SN60WF 2 years ZCB00 2 years SN60WF 3 years ZCB00 3 years Fig. 2. Presence of anterior capsular opacification (ACO) observed in slit-lamp photographs obtained 2 and 3 years after surgery (Grade 0: clear margin, no contraction; Grade 1: white fibrosis of anterior capsule, no contraction; Grade 2: white fibrosis of anterior capsule, with contraction; Grade 3: white fibrosis of anterior capsule, with visual disturbance/fimosis/ dislocation of IOL optic/haptic). Significantly more ACO was seen with SN60WF both at visit 2(p= 0.02, chi-square test) and at visit 3 (p = 0.003). two of the treated eyes, and ZCB00 in the other 6. In Fig. 5, a Kaplan Meier chart shows the timing of treatments. The difference between the two IOLs in number of Nd:YAG laser treatments during the period of observation was statistically not significant (p = 0.16, chi-square test). Glistenings appeared more frequently and in larger quantities in the SN60WF IOLs with an increase between the 2-year and 3-year visits, whereas only a few ZCB00 IOLs developed a small number of glistenings with no increase in presence over time (Fig. 6). The distributions of glistening presence are shown in Fig. 7. The presence and quantity of glistenings did not correlate with visual performance or subjective visual quality. Discussion Previously published studies have compared the aspheric ZCB00 IOL with the spherical monofocal IOL type Acry- Sof Ò SN60AT (Alcon) with regard to PCO and glistening formation (Nixon & Woodcock 2010; Leydolt et al. 2013; Kahraman et al. 2015). This study confirms previous findings, with similar and low PCO development but with more ACO with the AcrySof Ò material, and it extends the relevance also to the SN60WF IOL type, with its aspherical design. Although SN60WF eyes showed significantly lower area percentage of PCO after 3 years, the PCO severity score, which also takes into account PCO thickness and localization relative to the visual axis and thus is considered more clinically relevant (Bender et al. 2004), did not differ with statistical significance. The sharp posterior edge design has been, together with properties of the hydrophobic acrylic material, suggested to prevent or delay PCO development. In this respect, the two tested IOLs seem to be similarly successful, although the haptic optic junction appears as a path of least resistance, where lens epithelial cells may start to spread centrally (Nixon & Apple 2006; Nixon & Woodcock 2010). The more pronounced development of ACO with the SN60WF IOL in this study confirms findings with the 674

5 (A) (B) Fig. 3. (A) Means and standard deviations of PCO area percentage for SN60WF and ZCB00 IOLs 2 and 3 years after phacoemulsification, obtained with retroillumination slit-lamp photographs analysed with POCOMAN software. This measures the percentage of the surface within the capsulorhexis area covered by PCO. While the difference between groups is not statistically significant at 2 years (p = 0.88, Wilcoxon signed rank test), it is statistically significant 3 years after surgery (p = 0.01). (B) Medians and ranges of PCO severity scores from photographs as in (A) analysed with POCOMAN software. PCO thickness in each sector of a grid over the capsulorhexis area is manually graded in 3 levels, and the software calculates a score from the percentage value in (A) combined with the thickness levels of each grid sector. No statistically significant difference was found between groups at 2 and 3 years (p = 0.89 and p = 0.07, respectively). OD OS Fig. 4. Retroillumination slit-lamp photographs 3 years after phacoemulsification surgery. Posterior capsular opacification has started to progress centrally from the areas of the two haptic optic junctions (red arrows). ZCB00 left, SN60WF right. At the 3-year visit, PCO development distinctively originating from the haptic optic junction was observed in 5 ZCB00 eyes, and in 4 SN60WF eyes. Fig. 6. Slit-lamp photographs obtained 3 years after surgery, right and left eye from the same patient. An SN60WF IOL was implanted in the right eye and a ZCB00 IOL in the left eye. Grade 4 glistenings are seen in the right eye and grade 0 in the left. Fig. 5. Kaplan Meier survival chart showing incidence of Nd:YAG laser treatment for eyes with SN60WF and ZCB00 IOLs, over a period of 4 years 8 months (mean; range 4 years 5 months to 5 years 3 months) after surgery. The difference in number of treatments at end of follow-up is statistically not significant (p = 0.16, chi-square test). SN60AT model. It has been suggested to relate to properties of the AcrySof Ò material (Kahraman et al. 2014). Another possible explanation could be the different anterior surface profiles of the two study IOLs. The ZCB00 IOL optic has an elevated anterior rim which lifts the anterior capsule from the anterior optic surface. When the capsule has less contact with the acrylic material, fibrosis development may therefore be less for the ZCB00 compared with the SN60WF IOL, which has an even anterior optic surface out to the anterior edge. The mechanisms behind and the visual impact of glistenings have been extensively discussed and studied (Christiansen et al. 2001; Werner 675

6 Fig. 7. Glistenings in IOL optic, graded semi-quantitatively on slit-lamp photographs. 0 =<10 glistenings, 1 = 11 20, 2 = 21 30, 3 = 31 40, 4 =>40 (Werner 2010). From 2 (A) to 3 years (B), glistenings are frequently seen and slightly increasing in SN60WF material, but remain few and stable in ZCB00 material. The difference between the two IOLs is statistically highly significant (p -, chi-square test). 2010; Hayashi et al. 2012; Ronbeck et al. 2013; Chang & Kugelberg 2015; Monestam & Behndig 2016). In published literature, it appears difficult to detect any disturbances in visual function that can be attributable to glistenings (Christiansen et al. 2001; Monestam & Behndig 2016). However, clinicians do encounter patients with visual problems in eyes with IOLs showing glistenings, and explantation and IOL exchange in such cases has been reported (Shiba et al. 2003; Werner et al. 2008; van der Mooren et al. 2015). Thus, it seems reasonable to prefer readily available materials for IOL optics that have low amounts of glistenings. In recent years, IOL manufacturers have increased their efforts to provide IOLs entering the market with glistening-free materials (Packer et al. 2013), thus minimizing the risk of patients having visual complaints that could be attributable to changes in the optic material. After the surgeries in this study were performed, a change in the manufacturing process of AcrySof Ò IOLs has been claimed to decrease glistening formation (Thomes & Callaghan 2013). Although published in vitro research supports this claim, it remains yet to be proven in clinical follow-up studies. The findings of the present study may serve as comparison with future investigations of IOLs manufactured after the process change. This study has some limitations: It is a one surgeon, one-centre study with a limited sample size. The method for PCO grading is not fully automatic, grading of glistenings is made semi-quantitatively, and as it is possible to identify the IOL type on photographs, there is a possibility for bias. However, a number of readings were repeated with good reproducibility. This decreases the probability for biased results. It should also be noted that pseudoexfoliation syndrome was not an exclusion criterion, as long as the pupil size after dilatation allowed postoperative evaluation according to the protocol. In four of the 50 study cases, pseudoexfoliations were observed before surgery. Keeping in mind that eyes with pseudoexfoliations may have excessive capsular fibrosis reaction, the intra-individual study design still is a favourable feature to keep the comparison between the IOLs balanced. Other strong sides of this study include a low number of dropouts for which the reasons are well accounted for, and a long followup time with Nd:YAG laser treatment detection extended to around 5 years after surgery. In summary, this randomized controlled intra-individual study did not reveal any statistically significant differences regarding visually disturbing PCO development over time between the two monofocal aspherical hydrophobic acrylic IOLs, Alcon Acry- Sof Ò SN60WF and Abbott Medical Optics Tecnis Ò ZCB00. Anterior capsule fibrosis and contraction as well as glistenings were significantly more pronounced in eyes with the SN60WF IOL. References Apple DJ & Sims J (1996): Harold Ridley and the invention of the intraocular lens. Surv Ophthalmol 40: Bender L, Spalton DJ, Uyanonvara B, Boyce J, Heatley C, Jose R & Khan J (2004): POCOman: new system for quantifying posterior capsule opacification. J Cataract Refract Surg 30: Chang A & Kugelberg M (2015): Glistenings 9 years after phacoemulsification in hydrophobic and hydrophilic acrylic intraocular lenses. J Cataract Refract Surg 41: Chang A & Kugelberg M (2016): Posterior capsule opacification 9 years after phacoemulsification with a hydrophobic and a hydrophilic intraocular lens. Eur J Ophthalmol. [Epub ahead of print]. Christiansen G, Durcan FJ, Olson RJ & Christiansen K (2001): Glistenings in the AcrySof intraocular lens: pilot study. J Cataract Refract Surg 27: Cullin F, Busch T & Lundstr om M (2014): Economic considerations related to choice of intraocular lens (IOL) and posterior capsule opacification frequency a comparison of three different IOLs. Acta Ophthalmol 92: Hayashi K, Hirata A, Yoshida M, Yoshimura K & Hayashi H (2012): Long-term effect of surface light scattering and glistenings of intraocular lenses on visual function. Am J Ophthalmol 154: e242. Heatley CJ, Spalton DJ, Kumar A, Jose R, Boyce J & Bender LE (2005): Comparison of posterior capsule opacification rates between hydrophilic and hydrophobic single-piece acrylic intraocular lenses. J Cataract Refract Surg 31: Johansson B (2010): Clinical consequences of acrylic intraocular lens material and design: Nd:YAG-laser capsulotomy rates in eyes 5 years after phacoemulsification. Br J Ophthalmol 94:

7 Johansson B & Lundh B (2003): Bilateral same day phacoemulsification: 220 cases retrospectively reviewed. Br J Ophthalmol 87: de Juan-Marcos L, Blanco-Blanco JF & Hernandez-Galilea E (2012): Visual function and quality of life in pseudophakic patients before and after capsulotomy. Eur J Ophthalmol 22: Kahraman G, Schrittwieser H, Walch M, Storch F, Nigl K, Ferdinaro C & Amon M (2014): Anterior and posterior capsular opacification with the Tecnis ZCB00 and AcrySof SA60AT IOLs: a randomised intraindividual comparison. Br J Ophthalmol 98: Kahraman G, Amon M, Ferdinaro C, Nigl K & Walch M (2015): 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 41: Kugelberg M, Wejde G, Jayaram H & Zetterstrom C (2006): Posterior capsule opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens: oneyear follow-up. J Cataract Refract Surg 32: Leydolt C, Kriechbaum K, Schriefl S, Pachala M & Menapace R (2013): Posterior capsule opacification and neodymium:yag rates with 2 single-piece hydrophobic acrylic intraocular lenses: three-year results. J Cataract Refract Surg 39: Mester U, Fabian E, Gerl R, Hunold W, Hutz W, Strobel J, Hoyer H & Kohnen T (2004): Posterior capsule opacification after implantation of CeeOn Edge 911A, PhacoFlex SI- 40NB, and AcrySof MA60BM lenses: oneyear results of an intraindividual comparison multicenter study. J Cataract Refract Surg 30: Monestam E & Behndig A (2016): Change in light scattering caused by glistenings in hydrophobic acrylic intraocular lenses from 10 to 15 years after surgery. J Cataract Refract Surg 42: van der Mooren M, Steinert R, Tyson F, Langeslag MJ & Piers PA (2015): Explanted multifocal intraocular lenses. J Cataract Refract Surg 41: Nanavaty MA, Spalton DJ, Boyce J, Brain A & Marshall J (2008): Edge profile of commercially available square-edged intraocular lenses. J Cataract Refract Surg 34: Nishi O & Nishi K (1999): Preventing posterior capsule opacification by creating a discontinuous sharp bend in the capsule. J Cataract Refract Surg 25: Nixon DR & Apple DJ (2006): Evaluation of lens epithelial cell migration in vivo at the haptic-optic junction of a one-piece hydrophobic acrylic intraocular lens. Am J Ophthalmol 142: Nixon DR & Woodcock MG (2010): Pattern of posterior capsule opacification models 2 years postoperatively with 2 single-piece acrylic intraocular lenses. J Cataract Refract Surg 36: Oshika T, Nagata T & Ishii Y (1998): Adhesion of lens capsule to intraocular lenses of polymethylmethacrylate, silicone, and acrylic foldable materials: an experimental study. Br J Ophthalmol 82: Packer M, Fry L, Lavery KT et al. (2013): Safety and effectiveness of a glistening-free single-piece hydrophobic acrylic intraocular lens (envista). Clin Ophthalmol 7: Raj SM, Vasavada AR, Johar SR, Vasavada VA & Vasavada VA (2007): Post-operative capsular opacification: a review. Int J Biomed Sci 3: Ronbeck M, Zetterstrom C, Wejde G & Kugelberg M (2009): Comparison of posterior capsule opacification development with 3 intraocular lens types: five-year prospective study. J Cataract Refract Surg 35: Ronbeck M, Behndig A, Taube M, Koivula A & Kugelberg M (2013): Comparison of glistenings in intraocular lenses with three different materials: 12-year follow-up. Acta Ophthalmol 91: Shiba T, Mitooka K & Tsuneoka H (2003): In vitro analysis of AcrySof intraocular lens glistening. Eur J Ophthalmol 13: Thomes BE & Callaghan TA (2013): Evaluation of in vitro glistening formation in hydrophobic acrylic intraocular lenses. Clin Ophthalmol 7: Vasavada AR, Raj SM, Shah A, Shah G, Vasavada V & Vasavada V (2011): Comparison of posterior capsule opacification with hydrophobic acrylic and hydrophilic acrylic intraocular lenses. J Cataract Refract Surg 37: Wejde G, Kugelberg M & Zetterstrom C (2003): Posterior capsule opacification: comparison of 3 intraocular lenses of different materials and design. J Cataract Refract Surg 29: Werner L (2010): Glistenings and surface light scattering in intraocular lenses. J Cataract Refract Surg 36: Werner L, Storsberg J, Mauger O, Brasse K, Gerl R, Muller M & Tetz M (2008): Unusual pattern of glistening formation on a 3-piece hydrophobic acrylic intraocular lens. J Cataract Refract Surg 34: Yotsukura E, Torii H, Saiki M, Negishi K & Tsubota K (2016): Effect of neodymium: YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity. J Cataract Refract Surg 42: Received on November 11th, Accepted on February 20th, Correspondence: Bj orn Johansson, MD, PhD, FEBO Department of Ophthalmology Link oping University SE58185 Link oping Sweden Tel: , Fax: bjorn.johansson@regionostergotland.se Selected data from this study have been presented previously at ESCRS congress, ASCRS congress and Nordic Congress of Ophthalmology. Research grants from the Region of Osterg otland (ALF) and Abbott Medical Optics supported this work. The author receives consultant fees from Alcon, Abbott Medical Optics, Bausch + Lomb, Thea Laboratories and Zeiss. This study was supported in part by an unrestricted grant from Abbott Medical Optics, and in part by research grants from the Region of Osterg otland (ALF). 677