Anterior Capsulotomy Integrity after Femtosecond Laser-Assisted Cataract Surgery

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1 Anterior Capsulotomy Integrity after Femtosecond Laser-Assisted Cataract Surgery Robin G. Abell, MBBS, 1 Peter E.J. Davies, FRANZCO, 2 David Phelan, BSc, 3 Karsten Goemann, PhD, 4 Zachary E. McPherson, BMedSci, 2 Brendan J. Vote, FRANZCO 1 Objective: To compare the incidence of anterior capsular tears after femtosecond laser-assisted cataract surgery (FLACS) versus phacoemulsification cataract surgery (PCS) and to assess the ultrastructural features of anterior capsulotomy specimens (FLACS and PCS) using electron microscopy. Design: Prospective, multicenter, comparative cohort case series. Participants: Consecutive patients undergoing FLACS or PCS. Methods: A prospective cohort study of all patients (n ¼ 1626) undergoing FLACS or PCS by 2 surgeons from centers A and B was undertaken to compare the incidence of anterior capsule tears. Anterior lens capsules were collected by 4 surgeons from centers A, B, C, and D using 3 different commercially available femtosecond platforms, each with latest version upgrades. Lens capsule tissue was prepared for scanning electron microscopy (SEM) using a total of 10 samples for patients undergoing PCS, and 40 samples for patients undergoing FLACS. Main Outcome Measures: Incidence of anterior capsule tear and comparative ultrastructural features of capsular samples from both PCS and FLACS cases. Results: There was a significantly increased rate of anterior capsule tears in the FLACS group (15/804 [1.87%]) when compared with the PCS group (1/822 [0.12%]; P ¼ , Fisher exact test). In 7 cases, the anterior capsule tear extended to the posterior capsule. Because all cases had occurred in complete capsulotomy, the integrity of the anterior capsule was questioned in the FLACS group. Subsequent SEM sampling showed irregularity at the capsule margin, as well as multiple apparently misplaced laser pits in normal parts of the tissue. Aberrant pits were approximately 2 to 4 mm apart and occurred at a range of 10 to 100 mm radially from the capsule edge. Conclusions: Laser anterior capsulotomy integrity seems to be compromised by postage-stamp perforations and additional aberrant pulses, possibly because of fixational eye movements. This can lead to an increased rate of anterior capsule tears, and extra care should be taken during surgery after femtosecond laser pretreatment has been performed. A learning curve may account for some of the increased complication rate with FLACS. However, the SEM features raise safety concerns for capsular integrity after FLACS and warrant further investigation. Ophthalmology 2014;121:17-24 ª 2014 by the American Academy of Ophthalmology. Continuous curvilinear capsulorrhexis (CCC) is one of the most integral steps of conventional phacoemulsification cataract surgery (PCS). 1 It also is one of the most difficult steps for trainees to master. 2 Variations in the size of the capsulorrhexis can result in aberrant intraocular lens (IOL) position, myopic or hyperopic shift, capsule fibrosis and contraction, or posterior capsule opacification. 3e5 The size and shape of the capsulorrhexis therefore are key determinants in both the position and performance of the IOL. 6 Inaccurate estimation of effective lens position is the largest cause of IOL power calculation error. 7,8 With the increasing prevalence of toric, multifocal, and accommodating IOLs, the importance of customized IOL formulas with predictable effective lens position is paramount to superior refractive outcomes, which the femtosecond laser may allow. The increasing use of femtosecond lasers in cataract surgery has led to numerous recent studies of its efficacy and safety in performing anterior capsulotomy. 9 Capsular complications after femtosecond laser-assisted cataract surgery (FLACS) were increased in an early study, which is thought to be the result of the initial learning curve. 10 However, complications were significantly less in the subsequent series at the same facility (both studies performed with an earlier docking system of the commercial laser platform). 9,10 Studies also have shown improved overlap, centration, size, and circularity of anterior capsulotomy with FLACS. 11e13 Currently, early data suggest that more precise laser capsulotomy results in better visual and refractive outcomes when compared with PCS. 14e16 Likewise, the strength of anterior capsulotomy after FLACS is improved in porcine eyes, 17,18 but whether this equates to human eyes, particularly in the intraoperative clinical setting, remains to be seen. In this study, we prospectively evaluated the safety of FLACS by comparing the anterior capsule tear rates between PCS and FLACS. For clinicopathologic correlation, we also evaluated the integrity of anterior capsulotomies by observing capsular edge ultrastructure from 2 different laser platforms using high-definition scanning electron microscopy (SEM). Ó 2014 by the American Academy of Ophthalmology Published by Elsevier Inc. ISSN /14/$ - see front matter 17

2 Ophthalmology Volume 121, Number 1, January 2014 Methods Study Design A prospective, nonrandomized, comparative cohort case series was carried out at 2 centers (centers A and B) in Australia using a commercially purchased femtosecond laser platform (Catalys Precision Laser; OptiMedica, Sunnyvale, CA) to evaluate the incidence of anterior capsule tear between conventional PCS and FLACS. A clinicopathologic correlation was made between anterior capsule tear rates and anterior capsular integrity by examining ultrastructural integrity of FLACS and PCS capsulotomies (from 4 centers: centers A, B, C, and D) using SEM. Data were collected prospectively on anterior capsule tear rates between FLACS and PCS at centers A and B for analysis commencing April 30, 2012, through June 7, The study was approved by the Tasmanian Human Research Ethics Committee and was conducted in accordance with the tenets of the Declaration of Helsinki and its subsequent revisions (2004). Clinical Study Intervention and Assessments Consecutive unselected patients who were older than 18 years and elected to undergo FLACS or PCS with insertion of a posterior chamber IOL were enrolled in the study. All patients were given the option to undergo FLACS, but at an extra cost. Patients who elected to undergo FLACS were placed in the FLACS group, and the remaining patients were placed in the PCS group. The primary outcome measure was incidence of anterior capsule tear between the groups (FLACS vs. PCS). The occurrence of anterior capsular complications was collected prospectively, commencing from the introduction of femtosecond laser-assisted cataract surgery into clinical practice at centers A and B. Eligible patients underwent extensive preoperative assessment; this and the laser procedure have been described elsewhere. 10,19 All patients in the FLACS group underwent a 4.0- to 5.0-mm anterior capsulotomy using the laser system (typically set at 4.7 mm, but adjusted according to pupil size). Laser system settings varied between systems, but typically spot spacing for the laser ranged from 2 to 4 mm laterally and 10 to 12 mm deep at a pulse energy of 4 to 6 mj. After the laser procedure, the patient was transferred to the operating theater for topical anesthesia or regional anesthesia via sub-tenon or peribulbar injection. Patients in the PCS group also underwent regional or topical anesthesia. Patients who underwent the laser procedure had their anterior capsulotomy removed using rhexis forceps before cautious hydrodissection. Lens segmentation was completed with a standard phacoemulsification procedure (Megatron S4 [Geuder, Heidelberg, Germany] or Alcon Constellation [Alcon, Inc., Fort Worth, TX]). Patients who underwent PCS had CCC using rhexis forceps, hydrodissection, and phacoemulsification. After successful removal of the lens cortex, both cohorts underwent IOL placement. All surgical characteristics except those related to the laser procedure were kept consistent between groups (for each surgeon). Histopathologic Study Intervention and Assessments The secondary outcome measure was ultrastructural integrity of capsule edges using SEM. Capsular specimens from patients undergoing both FLACS and PCS were collected from 4 centers (centers A, B, C, and D). Centers A and B exclusively used the Optimedica Catalys Precision Laser Platform, whereas center C exclusively used the Alcon LenSx, and center D exclusively used the LensAR Laser (LensAR, Inc., Orlando, FL). Capsulotomy specimens were removed using rhexis forceps from 50 patients. Forty consecutive laser-cut capsules and 10 consecutive phacoemulsification CCC capsules were collected for SEM. Ten laser-cut capsules were collected consecutively from each of the 4 centers using 3 commercially available femtosecond laser platforms (Catalys, Alcon LenSx, and LensAR). Capsule specimens immediately were placed in a sterile container filled with fixative and were prepared for SEM. Most samples were fixed in 2.5% glutaraldehyde in sodium cacodylate buffer and then were dehydrated using a series of ethanols. 18 Samples then were critical-point dried according to standard SEM protocol. 20 After critical-point drying, samples were sputter coated with gold and then mounted on metal stubs with double-sided carbon tape. All images were obtained under SEM within 12 hours of sample removal. The remaining samples were provided fresh either in balanced salt solution or fixed in formaldehyde only and were imaged the same day. Images of capsular edges were obtained at various magnifications. Measurements were obtained using the imaging software to prevent rotational inaccuracies that may develop using scales after image production. Electron Microscopy Technique A Hitachi SU-70 ultra-high-resolution field-emission SEM device (Hitachi High-Technologies, Tokyo, Japan) and a Zeiss Sigma VP field-emission SEM device (Carl Zeiss Microscopy GmbH, Munich, Germany) were used for analysis by 2 different university departments. Samples were examined in high vacuum mode using secondary electron detectors. The acceleration voltage varied between 1.5 and 5.0 kv, depending on magnification and optimal resolution. Magnification ranged from 20 to approximately , with a pixel resolution of down to 1 nm, but typically ranging from 50 to 100 nm. Statistical Analysis The data to be analyzed were imported into IBM SPSS software version 19 (IBM, Chicago, IL) and were examined with descriptive and frequency analyses. Categorical data were analyzed using the Fisher exact test. Differences were accepted as significant at P < Results Clinical Outcomes A total of 1626 consecutive patients undergoing cataract surgery at 2 different centers (centers A and B) were included in this prospective study of the incidence of anterior capsule tears. There were 804 eyes in the FLACS group and 822 eyes in the PCS group. There was no difference in demographics or baseline characteristics between groups (Table 1). The incidence of anterior capsule tears in the FLACS group (n ¼ 15) was significantly higher than that in the PCS group (n ¼ 1) (1.87% vs. 0.12%; P ¼ ). There was no significant difference in incidence rates between centers A and B. Cases 1 through 8 were treated at center A, whereas cases 9 through 15 were treated at center B (Table 2). All FLACS cases occurred with complete capsulotomy. When available, videos of cases were reviewed to determine when the complication occurred (Table 2). None of the patients with an anterior capsule tear were determined to have risk factors for capsular complications after review of videos and retrospective review of preoperative clinical notes (Table 2). In 7 patients, the anterior capsule tear extended to the posterior capsule and required sulcus IOL implantation. Five of these patients had no vitreous loss, whereas the remaining 2 patients underwent an anterior and posterior vitrectomy, respectively. 18

3 Abell et al Anterior Capsulotomy Integrity after FLACS Table 1. Baseline Characteristics between Groups Variable Laser Cataract Surgery (n [ 804) Phacoemulsification Cataract Surgery (n [ 822) P Value Age NS Female sex (%) NS Cataract grade NS (PNS) BCVA 6/12 6/12 NS Baseline NS keratometry (D) AC depth (mm) NS Axial length (mm) NS AC ¼ anterior chamber; BCVA ¼ best-corrected visual acuity; D ¼ diopters; NS ¼ not significant; PNS ¼ Pentacam Nuclear Staging. Data are mean standard deviation unless otherwise indicated. Histopathologic Findings A total of 50 anterior capsules from centers A, B, C, and D were examined using SEM. The integrity of the capsule edge was assessed at high magnification. Samples also were observed for anterior capsular tags and aberrant laser-induced pits or perforations internal from the capsule edge. Three laser samples, one from each laser platform (Catalys, LenSx, and LensAR), were found to have an anterior capsulotomy tag (Fig 1). All laser platforms had FLACS samples with apparently misplaced laser perforations apparent on high magnification (Fig 2). These perforations could be seen extending well inside the capsule edge on medium magnification (Fig 3). The integrity of the laser edge from all 3 platforms was compromised by postage-stamp perforations that appeared rough compared with the smooth tearing noted in the PCS group samples (Fig 4). Postage-stamp perforations were present in every FLACS sample. At medium magnification, it was apparent that edges were not perfectly circular, but instead undulating and inconsistent (Fig 5A, B). Multiplanar cuts could be seen at high magnification (Fig 3C). At low magnification (400), edges appeared flattened or contracted around the site of laser cutting. There was no difference between preservation and quality of samples with regard to preparation technique. The phacoemulsification (manual rhexis) specimens did not reveal any imperfections (Fig 5C). Discussion This prospective, multicenter study evaluated the safety of FLACS with regard to anterior capsule tears. We found a significantly higher rate of anterior capsule tears in the FLACS group beyond the initial learning curve expected with the technology. 9,10 Current published studies of FLACS technology have emphasized the benefits of FLACS. Benefits include lower phacoemulsification energy resulting in less corneal and macular edema, as well as uniform capsulotomy size and shape. 13,14,21e23 The theoretical benefits of uniform IOL position and reduced postoperative refractive error currently are being evaluated. Surgical centers worldwide are cautiously adopting current versions of this technology on the basis of early improvements and the results of early studies. Because published evidence for long-term benefits is limited, many Subject No. Anterior Chamber Depth (mm) Axial Length (mm) Pentacam Nuclear Staging Cataract Grade Table 2. Details of the Cases of Anterior Capsule Tear Effective Phacoemulsification Time (seconds) Balanced Salt Solution Volume (ml) Small Pupil Weak Zonules Comorbidities Case No. Tear Occurrence No No No 154 AC tear before hydrodissection Yes No No 186 AC/PC tear noted after final nuclear segment removal No No No 254 AC tear noted after removal of phaco probe No No No 286 AC tear during hydrodissection No No No 301 AC tear noted during nucleus removal No Yes No 350 AC tear noted during I/A No No No 389 AC tear, NR Yes No Floppy iris syndrome 420 AC tear noted during nucleus removal NR No No Previous blunt 119 AC/PC tear noted at I/A trauma NR No No HSV scarring 152 AC/PC tear noted during nucleus removal NR No No No 155 AC/PC tear during nucleus removal NR 0 NR No No No 199 AC/PC tear, NR NR No No No 229 AC/PC tear, NR NR Yes No No 250 AC/PC tear noted at IOL insertion NR No No No 302 AC tear during nucleus removal AC ¼ anterior capsule; HSV ¼ herpes simplex virus; I/A ¼ irrigation and aspiration; IOL ¼ intraocular lens; NR ¼ not recorded; PC ¼ posterior capsule. Subjects 1 through 8 were treated at center A, and subjects 9 through 15 were treated at center B. 19

4 Ophthalmology Volume 121, Number 1, January 2014 Figure 1. A, Anterior capsule tag (white arrows) extending obliquely from the capsule edge (gray arrows) from the LenSx laser (Alcon, Inc., Fort Worth, TX) (original magnification, 1500). B, Anterior capsule tag (white arrows) some distance from the capsule edge from the Catalys laser (OptiMedica, Sunnyvale, CA) (original magnification, 300). These findings may be consistent with eye movement during laser capsulotomy. cataract surgery centers are awaiting further long-term studies before adoption. 6 After initially positive results for other aspects of FLACS in our prospective comparative studies, 14,19 our early data on capsular complication rates do not mirror other published studies. 9 Evidence-based guidelines for PCS suggest that a capsule complication frequency of less than 2% should be achievable (Table 3). 24 Our anterior capsular tear rate is less than this figure but does not compare with previous benchmarks for PCS at our centers (0.06% and 0.2%, respectively, for the 2 surgeons). Our third center, center C, collected data retrospectively and also found capsular complication rates that were higher than their personal phacoemulsification benchmarks (2.9% for FLACS vs. 0% for PCS), although with only 70 FLACS cases, this may reflect greater influence of a learning curve effect, as previously identified. 9 Previous studies have not compared FLACS capsule complication rates with concurrent phacoemulsification capsule complication rates, unlike our study, which had prospective comparative cohorts. Within the FLACS group, none of the complicated cases were noted immediately before, during, or immediately after surgery to have risk factors such as weak zonules, shallow anterior chamber, small pupil, high vitreous pressure, or poor visibility during surgery. 25,26 Roberts et al 9 suggested that anterior capsule tears are more likely to result from a microtag being stretched and torn during intracapsular manipulation. They recommended switching to high magnification and inspecting the capsular edge before proceeding to phacoemulsification. Acknowledging the presence of microtags seems to be important, although if present, awareness and caution may not be sufficient to prevent capsular complications. Currently, the only solution without a proper understanding of anterior capsule force dynamics after FLACS, however, is such cautious surgical maneuvers that avoid any stress on the anterior capsule. None of our cases seemed to occur because of focal attachments or tags. Similarly, 100% of our FLACS radial tear patients underwent a complete capsulotomy, many of which were free-floating procedures. Capsule specimens consistently showed ultrastructural features that may suggest a mechanical basis for weakness in capsular integrity induced by FLACS, independent of the laser platform used. During our study, we conducted SEM studies at 2 university centers using 4 different preparation techniques. Most capsule buttons were prepared in a fashion similar to that of a previous study. 18 None of our FLACS samples resembled previously published images of femtosecond laser-cut capsules, despite identical preparation methods. 18 Figure 2. A, Irregular structure of the capsule edge from the Catalys femtosecond laser (OptiMedica, Sunnyvale, CA). Note also the apparently misplaced laser pulses (white arrows) on the smooth surface of the anterior capsule measuring less than 2 mm across (original magnification, ). B, Similar structure at the same magnification of the capsule edge from the LensAR laser (original magnification, ). 20

5 Abell et al Anterior Capsulotomy Integrity after FLACS Figure 3. A, Catalys femtosecond laser (OptiMedica, Sunnyvale, CA) capsulotomy with multiple rows of misplaced laser pulses (white arrow) on the posterior surface of the anterior capsule extending from the capsule edge (black arrows), which in this picture is folded back on itself to reveal the underside of the capsule (original magnification, 900). B, LensAR laser (LensAR, Inc., Orlando, FL) capsulotomy with a row of misplaced laser pits approximately 35 mm from the capsule edge (original magnification, 600). C, Catalys femtosecond capsule edge that appears to have been cut in 2 distinct planes, perhaps created during subsequent passes of the laser capsulotomy, but each pass is slightly misaligned (original magnification, ). Previous images revealed only slight serrations or microgrooves in the capsule and were remarkably consistent with a cleanly cut edge. Our samples showed significant microscopic postage-stamp perforations, suggesting that the capsulotomy created by FLACS is of the can-opener variety, albeit at a microscopic level. Laser-cut capsules frequently had tags and skip lesions, as well as regular lines of aberrant misfired pits, presumably from microscopic fixational movements of the eye. We observed that there was no difference in images obtained from before and after the latest software and hardware upgrades (including the Alcon LenSx SoftFit patient interface upgrade) for each of the laser platforms. A recent study used anterior segment imaging to track eye movements during the laser procedure. 27 This study revealed movements of approximately 20 mm in the time it takes to perform anterior capsulotomy. The vacuum pressure used in the study was 500 mmhg using a liquid optics interface, which has been proven to result in only a small increase in intraocular pressure, while maintaining stability of the globe. 27e29 We demonstrated that, even at this level of suction, eye movements actually may extend beyond 100 mm in the time it takes to perform the capsulotomy. This was evidenced by laser pulses creating pits in the anterior capsule at around 100 mm radially from the capsule edge. Multiple rows of these aberrant pits certainly could compromise the integrity of the capsule edge by creating a postage-stamp radial pattern for a tear to initiate with adequate force. Reasons for eye movements to this degree may include inadequate suction or a floppy conjunctiva that still allows eye movement under adequate suction. Prior studies have shown that a capsulorrhexis performed using diathermy, can-opener, or postage-stamp perforations has less resistance to capsule tears than the smooth capsule edge created using CCC. 30e34 Capsulotomy edges that are not smooth may disrupt the normal collagen microfibrillar arrangement. 32 In addition, the irregularities at the edges may act as focal points for the concentration of stress that would increase the probability of propagation and the development of capsular tear. 35 Because the CCC edge preserves collagen arrangement, the limiting distension is reached when the elastic limit of the capsule is exceeded. 32 Current studies of FLACS anterior capsulotomy have examined only porcine eyes, which are known to be more elastic than the human adult capsule and tend to resemble more closely a human pediatric anterior capsule. 30,33 In fact, the rupture load and extensibility results for manual CCC found in recent FLACS porcine strength studies (comparing manual CCC with FLACS anterior capsulotomy) are much higher than those in existing in vivo porcine and human cadaver studies. 17,36 Studies are required to assess the strength of FLACS capsulotomy in human cadaver eyes as well as the clinical setting in vivo. Most tears occurred with hydrodissection or during lens manipulations, suggesting that capsular stress Figure 4. A, Edge treated with the Catalys femtosecond laser (OptiMedica, Sunnyvale, CA) is serrated, resembling a microecan-opener structure from the laser photodisruption, each estimated here to be just less than 2 mm across (original magnification, ). B, Manually torn capsule (original magnification, ). 21

6 Ophthalmology Volume 121, Number 1, January 2014 Figure 5. A, Jagged and undulating edge of the LenSx femtosecond laser (Alcon, Inc., Fort Worth, TX) capsulotomy (original magnification, 1100). B, LensAR (LensAR, Inc., Orlando, FL) femtosecond capsulotomy showing the jagged edge at closer magnification that consists of small focal tags (circled). Outward tags would correspond to a notch in the anterior capsule in vivo (original magnification, 1400). C, Manual capsulorrhexis showing a smooth and consistent edge (black arrows), which is at the same magnification as A (Original magnification, 1100). may be more the result of expansive vector forces from gas and hydrodissection volumes rather than linear extensibility. It is unknown whether the improved circularity with FLACS is a factor dependent on equal distribution of forces after IOL implantation in the bag and resistance to tearing. Because the stress-strain and force-displacement relationships are nonlinear, it is difficult to determine the variables involved with alterations in the mechanical quality of the anterior capsule. 37,38 Capsulorrhexis strength may vary as a function of capsulotomy size, reflecting the variations in capsular thickness that occur as a function of eccentricity. 32 Hence, the stronger anterior capsulotomy found with FLACS in some studies may be a function of its centration and optimal size. The microscopic postage-stamp perforations we observed in this study, however, may have an effect on force-displacement relationships and resistance to tearing in human adult eyes that has not been tested. In addition, intraoperative fluidics and altered capsule stiffness may predispose patients to a greater risk of anterior capsular tear after FLACS because some cases were noted subincisionally on withdrawal of the phacoemulsification instrument probe after fragment removal. We believe that although femtosecond laser technology may be safer in some surgeons hands, this is not necessarily true for all surgeons and certainly depends on the benchmark against which one is measuring. We also cannot rule out individual variations in the performance of each laser platform. Deficiencies in laser output energy or disruptions to the optical path of laser pulses may affect the quality and Table 3. Summary of Anterior Capsule Tear Rates in the Current Literature Authors Year Rate, % (n) Study Type Level of Training Roberts et al (1300) Prospective (LCS) Specialist Bali et al (200) Prospective (LCS) Specialist Woodfield et al (691) Retrospective (PCS) Resident Olali et al (358) Case series (PCS) Specialist Unal et al (296) Prospective (PCS) Resident Marques et al (2646) Retrospective (PCS) Specialist Muhtaseb et al (1441) Prospective (PCS) Specialist Ng et al (1000) Prospective (PCS) Specialist PCS average 2.32% LCS ¼ laser cataract surgery; PCS ¼ phacoemulsification cataract surgery. consistency of resultant biological photodisruption resulting from laser-induced optical breakdown. Variations in pulse energy and spot spacing between company platforms, which also are adjustable by the user, also may affect the architecture of the capsulotomy edge. Optimal laser spot spacing and power settings remain to be determined. With demonstrated improvement in surgery outcomes, the small risk of complications may be acceptable; however, further studies are required to evaluate which surgical techniques, laser platforms, surgeons, and patients may benefit from the technology. Patients should be aware they belong to a learning cohort for the surgeon s initial cases. Surgeons need to take care when implementing this technology into their practice. There is a significant learning curve associated with femtosecond laser technology that may extend beyond the initial cases. Laser anterior capsulotomy integrity may be compromised when compared with phacoemulsification capsulotomy because of aberrant pits creating postage-stamp perforations during patient eye movements. In our study, this can lead to an increased rate of anterior capsule tears, and extra care needs to be taken during surgery by surgeons implementing this technology. Acknowledgment. The authors would like to acknowledge Dr. Guy Bylsma and Dr. Graham Fraenkel for the collection of additional capsulotomy samples. References 1. Gimbel HV, Neuhann T. Development, advantages, and methods of the continuous circular capsulorrhexis technique. J Cataract Refract Surg 1990;16: Dooley IJ, O Brien PD. Subjective difficulty of each stage of phacoemulsification cataract surgery performed by basic surgical trainees. J Cataract Refract Surg 2006;32: Ravalico G, Tognetto D, Palomba M, et al. Capsulorrhexis size and posterior capsule opacification. J Cataract Refract Surg 1995;22: Sanders DR, Higginbotham RW, Opatowsky IE, Confino J. Hyperopic shift in refraction associated with implantation of the single-piece Collamer intraocular lens. J Cataract Refract Surg 2006;32: Walkow T, Anders N, Pham DT, Wollensak J. Causes of severe decentration and subluxation of intraocular lenses. Graefes Arch Clin Exp Ophthalmol 1997;236: Trikha S, Turnbull AM, Morris RJ, et al. 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Intraocular pressure variation during femtosecond laser-assisted cataract surgery using a fluid-filled interface. J Cataract Refract Surg 2012;39: Trivedi RH, Wilson ME Jr, Bartholomew LR. Extensibility and scanning electron microscopy evaluation of 5 pediatric anterior capsulotomy techniques in a porcine model. J Cataract Refract Surg 2006;32: Radner G, Amon M, Stifter E, et al. Tissue damage at anterior capsule edges after continuous curvilinear capsulorrhexis, high-frequency capsulotomy, and erbium:yag laser capsulotomy. J Cataract Refract Surg 2004;30: Morgan JE, Ellingham RB, Young RD, Trmal GJ. The mechanical properties of the human lens capsule following capsulorrhexis or radiofrequency diathermy capsulotomy. Arch Ophthalmol 1996;114: Andreo LK, Wilson ME, Apple DJ. Elastic properties and scanning electron microscopic appearance of manual continuous curvilinear capsulorrhexis and vitrectorhexis in an animal model of pediatric cataract. 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8 Footnotes and Financial Disclosures Ophthalmology Volume 121, Number 1, January 2014 Originally received: April 16, Final revision: August 8, Accepted: August 8, Available online: September 30, Manuscript no Tasmanian Eye Institute, Launceston, Tasmania, Australia. 2 Newcastle Eye Hospital Research Foundation, Newcastle, New South Wales, Australia. 3 Electron Microscopy Unit, University of Newcastle, Callaghan, New South Wales, Australia. 4 Central Sciences Laboratory, University of Tasmania, Hobart, Tasmania, Australia. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Correspondence: Brendan J. Vote, FRANZCO, Launceston Eye Institute, 36 Thistle Street West, Launceston, Australia eye.vote@bigpond.net.au. 24