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Abstract

Purpose: To evaluate and compare the mechanical properties of anterior capsule openings performed with the continuous curvilinear capsulorhexis (CCC) technique and femtosecond laser capsulotomy (FLC) in ex vivo porcine lens capsule specimens. Methods: Fresh porcine eyes were included in the study (CCC group, n = 50; FLC group, n = 30). The capsule openings were stretched with universal testing equipment until they ruptured. The rupture force and circumference stretching ratio were evaluated. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy (SEM). Results: The average rupture force was higher in the CCC group (median: 155 mN; interquartile range [IQR]: 129 to 201 mN; range: 71 to 294 mN) than in the FLC group (median: 119 mN; IQR: 108 to 128 mN; range: 91 to 142 mN) (P < .01, Mann-Whitney U test). The average circumference stretching ratio in the CCC group was greater (median: 150%; IQR: 146% to 156%; range: 136% to 161%) than in the FLC group (median: 148%; IQR: 145% to 150%; range: 141% to 154%) (P = .0468, Mann-Whitney U test). When less than 71 mN, no capsular tear occurred in either group. When less than 91 mN, no capsular tear occurred in the FLC group, whereas at 91 mN, the probability of capsular tears was 9% for the CCC group. SEM examination found that the CCC group had smooth edges, whereas those of the FLC group were gently serrated. Conclusions: According to the current results in a porcine eye model, FLC had less average resistance to capsule tear than CCC, but the weakest openings were seen in the CCC group.

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... The higher tear resistance of the CCC-group compared to the FLC-groups confirms the results of Sándor et al. [10]. The value of the maximum force before tear for the manual capsulorhexis (150 mN ± 70 mN) is in good agreement with the results of Sándor et al. [10] as well (155 mN). ...
... The higher tear resistance of the CCC-group compared to the FLC-groups confirms the results of Sándor et al. [10]. The value of the maximum force before tear for the manual capsulorhexis (150 mN ± 70 mN) is in good agreement with the results of Sándor et al. [10] as well (155 mN). The force value for the capsulotomy (FLC 1) measured in this study (60 mN ± 20 mN) was found to be lower than that of Sándor et al. [10] (119 mN) who used a LenSx femtosecond laser (Alcon Laboratories, Inc. Forth Worth, TX) with different parameters (pulse energy: 5 µJ, spot distance radial and lateral: 4 µm, spot distance depth: 3 µm). ...
... The value of the maximum force before tear for the manual capsulorhexis (150 mN ± 70 mN) is in good agreement with the results of Sándor et al. [10] as well (155 mN). The force value for the capsulotomy (FLC 1) measured in this study (60 mN ± 20 mN) was found to be lower than that of Sándor et al. [10] (119 mN) who used a LenSx femtosecond laser (Alcon Laboratories, Inc. Forth Worth, TX) with different parameters (pulse energy: 5 µJ, spot distance radial and lateral: 4 µm, spot distance depth: 3 µm). However, these results are hardly comparable without knowing all laser parameters (e.g. ...
Article
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Background In this study, the tear resistance of porcine lens capsules after continuous curvilinear capsulorhexis (CCC) and femtosecond (fs)-laser-assisted capsulotomy for cataract surgery (FLC) with different laser parameters is measured with a custom-made testing setup. Methods Forty-five fresh porcine lenses were randomly chosen for CCC (n = 15) or FLC 1 (n = 15) and FLC 2 (n = 15). The FLC 1-group was treated with smaller spot distances than the FLC 2-group. The force necessary to break the opening of the anterior capsule and the maximum displacement were measured. Results The mean tear resistance of the CCC-group (150 ± 70 mN) was higher than that of the FLC 1-group (60 ± 20 mN) and the FLC 2-group (30 ± 20 mN). Conclusion It could be shown that CCC leads to a significantly higher tear resistance of the opening than FLC in porcine lenses. The femtosecond laser group demonstrated that smaller spot distances lead to a higher tear resistance.
... Femtosecond laser-assisted cataract surgery (FLACS) presents numerous advantages over conventional cataract surgery, including better capsulorrhexis features (circularity, centration), [6][7][8] more precise corneal incision architecture with reduced keratometric astigmatism [9] and reduction of ultrasound energy [10]. Previous studies comparing FLACS and manual standard technique with phacoemulsification showed lower phacoemulsification time and energy with an overall reduction of cumulative dissipated energy (CDE) [10][11][12]. ...
... Before cataract surgery, patients underwent a complete ophthalmologic examination including visual acuity evaluation, manifest refraction, slit lamp examination, applanation tonometry, cataract grade/type assessment, and ophthalmoscopy through dilated pupils. In addition, the central corneal endothelial cell count (ECC) (cells/ mm 2 ) was measured by means of corneal confocal laser scanning microscope (LSM) (HRT II Rostock Cornea Module, diode-laser 670 nm, Heidelberg Engineering GmbH, Germany) as previously described [7]. Three images were selected by a masked examiner from sequential images from automatic scans and manually acquired frames based on image quality. ...
... One of the most widely reported advantages of FLACS over standard phacoemulsification was the reduced use of ultrasound energy due to crystalline lens disassembly by means of femtosecond laser. Related lower ocular inflammation and lower tissue trauma in terms of aqueous flare, corneal swelling, and corneal endothelial cell loss were also reported in FLACS compared to conventional cataract surgery [6][7][8][9][10]. Dark grey indicates same group comparisons. ...
Article
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The aim of this study was to evaluate corneal tissue trauma after femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification (femtophaco surgery) compared to FLACS and nanolaser emulsification (all laser surgery). This is a prospective nonrandomized clinical study conducted at the Ophthalmology Clinic, University “G. d’Annunzio” of Chieti-Pescara, Italy, involving forty-two eyes of 42 patients candidates to cataract surgery. Patients were enrolled in two groups: femtophaco surgery (group 1 with 21 eyes) and all laser surgery (group 2 with 21 eyes). Main outcome measures included uncorrected visual acuity and distance corrected visual acuity, corneal endothelial cell count, and corneal thickness at the tunnel site and at the center of the cornea. Best correct visual acuity was not significantly different between the two groups. Postoperatively, a significant decrement of endothelial cell count at the center of the cornea was observed in group 1 compared with preoperative values at 90 days (p < 0.001) while t remained stable in group 2. The central corneal thickness showed a statistically significant increase for both groups that reached a maximum thickness at 7 days and then returned to presurgery levels after 90 days for group 1 and after 60 days for group 2. The tunnel corneal thickness showed a statistically significant increase for both groups that reached a maximum thickness at 7 days, which did not return to presurgery level for group 1 but did return to presurgery levels after 60 days for group 2. All laser surgery induced lower central endothelial cell loss and lower increase of corneal thickness compared to femtophaco surgery.
... Для оценки биомеханической «устойчивости» края передней капсулы после разных методов капсулотомии использовали кадаверные свиные [15][16][17][18] и человеческие глаза [19][20][21][22]. Сравнительный анализ этих исследований, представленный нами в опубликованном ранее обзоре литературы, позволил сделать следующие основные выводы [23]: ...
... При применении тестов, предполагающих заполнение капсульного мешка желатином или гиалуроновой кислотой, и последующем растяжении с помощью ретракторов край капсулы после лазерного воздействия оказался достоверно прочнее, чем при мануальной технике [15,16]. При растяжении же изоли-Результаты механических испытаний образцов передней капсулы хрусталика после разных методов капсулотомии а/a б/b рованных, периферических, кольцевидных образцов передней капсулы был получен результат противоположного характера: средняя сила, регистрируемая при разрыве, оказалась достоверно выше после мануальной капсулотомии (155 мН против 119 мН), причем этот показатель снижался по мере увеличения энергии лазерного излучения (в среднем со 119 до 108 мН) [17,18]. Не исключено, что в первом случае на результаты могло повлиять применение желатина и гиалуроновой кислоты в процессе проведения механических испытаний. ...
Article
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Purpose: To comparatively evaluate the mechanical stability of the edge of central fragment of anterior lens capsule after manual and femtolaser capsulotomy. Material and methods: The mechanical tests were performed on the central fragments of the anterior lens capsules obtained intraoperatively after manual and femtolaser capsulotomy (15 and 13 samples, respectively). The conditions of the developed method of mechanical testing are as close to in vivo as possible. The method allows evaluation of the mechanical response mainly from the edge of the sample, reception of the averaged response from the four edges of the capsule, and almost eliminates the effect of additional edge notches in samples obtained by manual capsulotomy. Results: After manual capsulotomy, the maximum force and elongation of the anterior capsule sample at maximum tensile strength were significantly higher than similar characteristics of the samples after femtolaser capsulotomy. Conclusion: The obtained results correspond with the morphological studies of capsule edge structure after manual and femtolaser capsulotomy. The edge of the anterior capsule after femtolaser capsulotomy has form, in rough approximation, close to one of a postage stamp perforation, which is the consequence of micro-irregularities (microfractures) in the areas irradiated by pulsed laser, and wider area of deepithelization compared to the manual technique.
... This is important as IOLs are typically positioned in the lens bag by folding or injecting and must therefore resist forces that could lead to rupture. The morphology of FLACS capsulotomy edges, characterized by a more serrated appearance compared to manual capsulorhexis when viewed at high magnification (>×2000) may play a role in vulnerability to tags and tears [20][21][22] . It is perhaps surprising therefore that the existing literature suggest that many of the femtosecond laser platforms compare favorably to, but also exhibit high mechanical strength compared to manual rhexis (Table 1) 13,[15][16][17][18] . ...
... Judging mechanical strength across platforms and extrapolating human relevance is challenging because most studies are carried out in porcine systems, by myriad of approaches including evaluation of strength in situ, with or without lens nucleus removal and with different instrumentation (Table 1) 10,12,15,16,22,23 . The Ziemer LDV Z8, which uses a liquid optic interface to facilitate laser capsulotomy and lens fragmentation, in contrast to most systems, is a low energy high frequency system 9,24,25 . ...
Article
Full-text available
The introduction of femtosecond laser assisted cataract surgery (FLACS) is a paradigm changing approach in cataract surgery, the most commonly performed surgical procedure. FLACS has the potential to optimize the creation of an anterior lens capsulotomy, a critical step in accessing the cataractous lens. The merits of using a laser instead of a manual approach include a potentially more circular, consistent, and stronger aperture. In this study we demonstrated for the first time in both a porcine and human experimental setting that with a low energy, high repetition FLACS system, that a circular, smooth and strong capsulotomy was achievable. While there was no demonstrable difference in the resistance to rupture before or after the removal of the nucleus, larger capsulotomies had an increase in tensile strength. The LDV Z8 system appeared to create circular, rupture-resistant and smooth capsulotomies in both porcine and more importantly human globes.
... Another SEM study examined the capsulotomy edges compared with manual CCC edges using objective metrics such as arithmetic mean deviation of the surface and found increased irregularities in the FLACS groups (52) (53). However, this has not been fully borne out in mechanical testing (54,55). Indeed, a prospective inter-eye comparison tested the breaking force and breaking strain of anterior capsulotomy samples of 39 patients with bilateral cataracts having CPS in one eye and FLACS in the other and found no differences in the mean breaking force or breaking strain between the CPS and FLACS group (56). ...
... A SEM and 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 (53). However, this has not been fully borne out in mechanical testing (54,55). Indeed, a prospective inter-eye comparison tested the breaking force and breaking strain of anterior capsulotomy samples of 39 patients with bilateral cataracts having CPS in one eye and FLACS in the other and found no differences in the mean breaking force or breaking strain between the CPS and FLACS group (56). ...
Article
Purpose Review scientific literature concerning femtosecond laser–assisted cataract surgery. Methods Following databases were searched: CENTRAL (Cochrane Eyes and Vision Trials Register; Cochrane Library: Issue 2 of 12, June 2019), Ovid MEDLINE ® without Revisions (1996 to June 2019), Ovid MEDLINE ® (1946 to June 2019), Ovid MEDLINE ® Daily Update June 2019, MEDLINE and MEDLINE Non-Indexed Items, Embase (1980–2019), Embase (1974 to June 2019), Ovid MEDLINE ® and Epub Ahead of Print, in-Process & Other Non-Indexed Citations and Daily (1946 to June 2019), Web of Science (all years), the metaRegister of Controlled Trials ( www.controlled-trials.com ), ClinicalTrials.gov ( www.clinicaltrial.gov ) and World Health Organization International Clinical Trials Registry Platform ( www.who.int/ictrp/search/en ). Search terms/keywords included ‘Femtosecond laser’ combined with ‘cataract’, ‘cataract surgery’. Results Based on quality of their methodology and their originality, 121 articles were reviewed, including randomised controlled trials, cohort studies, case-controlled studies, case series, case reports and laboratory studies. Each step of the femtosecond laser–assisted cataract surgery procedure (corneal incisions, arcuate keratotomies, capsulotomy and lens fragmentation) has been discussed with relevance to published outcomes, as well as complication rates of femtosecond laser–assisted cataract surgery, and what we can learn from the larger studies/meta-analyses and the economics of femtosecond laser–assisted cataract surgery within different healthcare settings. Conclusion Studies suggest that the current clinical outcomes of femtosecond laser–assisted cataract surgery are not different to conventional phacoemulsification surgery and it is not cost effective when compared with conventional phacoemulsification surgery. In its current technological form, it is a useful surgical tool in specific complex cataract scenarios, but its usage has not been shown to translate into better clinical outcomes.
... Cystotome and forceps are two of the most commonly used instruments for a CCC, despite the rise of femtosecond laser assisted capsulorhexis [2][3][4]. According to previously published results in a porcine eye model, femtosecond laser assisted capsulorhexis had less average resistance to capsule tear than CCC because the edge of the anterior capsule opening made by femtosecond laser was not as smooth as that made manually [5]. The advantages of using a cystotome to create a capsulorhexis compared to a pair of forceps include less corneal wound distortion, better view of the capsulorhexis edge, and minimal inadvertent loss of the viscoelastic agent. ...
Article
Full-text available
We modified a 2-bend cystotome for continuous curvilinear capsulorhexis (CCC) in manual or phacoemulsification cataract surgery to improve the safety and ease of performance. A 26G needle was converted into a cystotome with 3 bends. In this retrospective study, the performance of modified 3-bend cystotome was compared with conventional 2-bend cystotome. During cataract surgery, in the 3-bend cystotome group, mean completion time of CCC was shorter, mean times of viscoelastic agent supplement were less, and CCC success rate was higher than that in 2-bend group. Complication incidence, such as postoperative transient corneal edema and irreparable V-shaped tear, was also lower in 3-bend group. No posterior capsular rupture or no other complication was observed in either group. A polymethyl methacrylate intraocular lens or a hydrogel intraocular lens was implanted in the capsular bag in all eyes. We conclude that it is safe and efficient to accomplish a CCC using the 3-bend cystotome due to its ability to sustain the anterior chamber depth (ACD) and keep the posterior lip intact. Using the 3-bend cystotome also allowed for an adequate view into the anterior chamber from lack of wound deformation.
... Young's modulus, viscoelastic parameters) are better metrics for diagnostics and treatment planning and monitoring. In particular, finite element (FE) analysis is a standard numerical tool to study mechanical behavior of structures, even soft materials [25], including ocular tissues [26][27][28]. Using temporal and spatial corneal deformation data as input, optimization algorithms allows in principle retrieving corneal biomechanical parameters. ...
Article
Full-text available
Objective To validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas. Methods Air puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters. Results The measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0–0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry. Conclusions Air puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties.
... In previous studies, there have been discrepancies between FLC and CCC in relation to the stretching forces [12][13][14]. Some investigations have shown that CCC confers higher stretch forces than FLC, suggesting that CCC creates histologically smoother capsular edges than FLC [15][16][17]. ...
Article
Full-text available
The current study reports comparing the postoperative mechanical properties of the anterior capsule between femtosecond laser capsulotomy (FLC) and continuous curvilinear capsulorhexis (CCC) of variable size and shape in porcine eyes. All CCCs were created using capsule forceps. Irregular or eccentric CCCs were also created to simulate real cataract surgery. For FLC, capsulotomies 5.3 mm in diameter were created using the LenSx® (Alcon) platform. Fresh porcine eyes were used in all experiments. The edges of the capsule openings were pulled at a constant speed using two L-shaped jigs. Stretch force and distance were recorded over time, and the maximum values in this regard were defined as those that were recorded when the capsule broke. There was no difference in maximum stretch force between CCC and FLC. There were no differences in circularity between FLC and same-sized CCC. However, same-sized CCC did show significantly higher maximum stretch forces than FLC. Teardrop-shaped CCC showed lower maximum stretch forces than same-sized CCC and FLC. Heart-shaped CCC showed lower maximum stretch forces than same-sized CCC. Conclusively, while capsule edge strength after CCC varied depending on size or irregularities, FLC had the advantage of stable maximum stretch forces.
... A sejtek meglehetősen hosszú élettartamúak, azonban a folyamatos oxidatív és egyéb károsító folyamat apoptózist okozhat, amely a cataractaképződés egyik központi elemének számít, így a lencsehámsejtek vizsgálata szürke hályog esetén kiemelt jelentőségű [23]. Kutatócsoportunk korábbi tanulmányaiban már sikeresen vizsgált lencsehámsejteket transzmissziós elektronmikroszkóppal, de azok a vizsgálatok az elülső lencsetok mechanikai tulajdonságaira irányultak [24,25]. Jelen tanulmányunkkal a szürke hályogos lencseepithelsejtek morfológiai eltéréseit kerestük. ...
Article
Inrtoduction: Caveolae are flask shaped with 50-100 nm size, non-clathrin associated invaginations of the plasmamembrane. The main membrane protein of the structures is caveolin-1. Caveolae play an important role in numerous cellular functions including vesicular transport and cell-cycle regulation, and create platforms for classical and alternative signaling pathways. According to international studies, caveolae may influence the physiology and pathology of lens epithelial cells. Aim: The aim of the study was to examine and compare the morphology of caveolae and the immunohistochemical difference of caveolin-1 in control (myopic and hyperopic) lens epithelial cells and human lens epithelial cells affected by cataract. Authors investigated whether caveolae might have a role in cataractogenesis. Method: Anterior lens capsules were obtained by capsulorhexis during surgery of senile cataract and refractive surgery of the clear lens. Ultra-fine sections have been studied by transmission electron microscopy, and semi-fine samples were labelled for immunohistochemistry with polyclonal caveolin-1 and cavin-1 antibodies. Results: By immunohistochemistry, in the control group, significant caveolin-1 label with low cavin-1 signal were measured in the lens epithelial cells. In the cataract group high cavin-1 and caveolin-1 expression was detected. In the control group, caveolae were not observed, but in the lens epithelial cells with cataract, increased number of caveolae have been detected by electron microscopy. Conclusions: For the development and maintenance of the specific caveolae shape, caveolin-1 is needed to be accompanied by cavin-1. Therefore, it is presumable that the increased expression of cavin-1 could explain the higher number of caveolae in the cataract group. These results might suggest that caveolae might play a role in cataractogenesis. Orv Hetil. 2019; 160(8): 300-308.
... Результаты противоположного характера получили G. Sandor и соавт. [20], которые провели сравнительное исследование механических свойств передней капсулы хрусталика на 80 свежеэнуклеированных свиных глазах (на 50 глазах при мануальном капсулорексисе, на 30 -при фемтолазерном). После удаления центральной части диаметром 5,0 мм по экватору выкраивали кольцевидные образцы передней капсулы. ...
Article
Full-text available
This paper reviews studies on biomechanical properties of the anterior lens capsule. Early experiments in this field were more fundamental. Later studies were aimed mainly at assessing the mechanical stability of the capsule edge after manual or femtosecond laser capsulorhexis (capsulotomy) - an important step in modern minimally invasive phaco surgery. For biomechanical tests, ex vivo samples of human and animal anterior capsules were used. The results of the studies presented here are quite heterogeneous, which suggests the necessity of gaining further insight into the issue.
... Fresh porcine eyes were used in this study, as they are readily available, inexpensive, and have been used in previous studies on femtosecond laser-assisted anterior capsulotomy 7,[29][30][31][32][33][34][35] . The porcine capsule is more elastic than an adult human capsule 30 . ...
Article
Full-text available
The introduction of femtosecond laser-assisted cataract surgery is an alternative approach to conventional cataract surgery. Our study aimed to determine the effectiveness of femtosecond laser-assisted capsulotomy in the presence of different ophthalmic viscoelastic devices (OVDs) in the anterior chamber. Fresh porcine eyes (n = 96) underwent LDV Z8-assisted anterior capsulotomy, either in the presence of an OVD (Viscoat, Provisc, Healon, Healon GV or HPMC) or without, using 90% and 150% energies respectively. Following that, the capsule circularity, tag’s arc-length, tag-length, tag-area and rupture strength (mN) of the residual capsular bag were evaluated. We found that increasing energy from 90 to 150% across the OVD sub-groups improved the studied capsulotomy parameters. Amongst the 90% energy sub-groups, the circularity and tag-parameters were worse with Viscoat and Healon GV, which have higher refractive index and viscosity compared to the aqueous humour. Using 150% energy, Healon GV showed a significantly worse total arc-length (p = 0.01), total tag-length (p = 0.03) and total tag-area (p = 0.05) compared to the control group. We concluded that; an OVD with a refractive index similar to aqueous humour and lower viscosity, such as Healon or Provisc, as well as a higher energy setting, are recommended, to enhance the efficacy of laser capsulotomy.
Article
Purpose To compare the anterior capsulotomy edge tear strength created by manual continuous curvilinear capsulorhexis (CCC), femtosecond laser-assisted capsulotomy (FLACS), and selective laser capsulotomy (SLC). Setting Singapore National Eye Centre, Singapore and Excel-Lens, Livermore, California, USA. Design Three armed study in paired human eyes. Methods Capsulotomies were performed in 60 cadaver eyes of 30 donors using CCC, Victus Femtosecond Laser, (Bausch & Lomb, Rochester, New York, USA) or CAPSULaser, (Excel-Lens, Los Gatos, California, USA). Three pairwise study groups each involved 10 pairs of eyes. Study group 1: SLC eyes compared with fellow eyes with CCC. Study group 2: CCC eyes compared with fellow eyes with FLACS. Study group 3: FLACS eyes compared with fellow eyes with SLC. A shoe-tree method was used to apply load to the capsulotomy edge, and Instron tensile stress instrument measured distension and threshold load applied to initiate capsule fracture. Relative fracture strengths and distension of CCC, FLACS and SLC were determined. Scanning electron microscopy (SEM) of capsule edges were reviewed Results Anterior capsulotomies behave as non-linear elastic (elastomeric) systems when exposed to an external load. The pairwise study demonstrated that the SLC fracture strength was superior to that of CCC by a factor of 1.46-fold with SLC 277±38 mN versus CCC with 190±37 mN. Furthermore, CCC fracture strength was superior to that of FLACS by a factor of 1.28-fold with CCC 186 + 37 mN versus FLACS 145 ± 35 mN (p < 0.001). This was determined by statistical analysis utilising the Wilcoxon matched-pairs signed-ranks test and in accordance with the Consolidated Standards of Reporting Trials guidelines. The capsule edge of SLC on SEM demonstrated a rolled over edge anteriorly and an alteration of collagen. Conclusions The strength of the capsulotomy edge for SLC was significantly stronger than that of CCC which and both were significantly stronger than FLACS. The relative strengths can be explained by SEM of each type of capsulotomy.
Article
Purpose: To evaluate and compare the mechanical resistance to tearing of the anterior lens capsule opening after staining with different concentrations of trypan blue in ex vivo porcine eyes. Setting: Semmelweis University, and Budapest University of Technology and Economics, Budapest, Hungary. Design: Experimental study. Methods: The study comprised 75 porcine eyes. The capsule was unstained in the Control Group (n = 25 eyes), 0.06% trypan blue was used to stain the capsule in Stained 1 Group (n = 25 eyes), and 0.1% trypan blue was used to stain the capsule in Stained 2 Group (n = 25 eyes). After capsulorhexis, the capsule openings were stretched with custom-designed testing equipment until they ruptured. The rupture force (RF), circumference stretching ratio (CSR), and secant modulus at 10 mN (SM10mN) and 50 mN (SM50mN) were evaluated. Results: In total, 75 eyes were enrolled. There were no statistically significant differences in the RF (P = .8924) or CSR (P = .3876) among the groups. There were no statistically significant differences in the SM10mN (P = .8215) or SM50mN (P = .4184) among the groups. Conclusions: In this porcine eye model, the trypan blue concentrations that are routinely used in cataract surgery had no effect on capsular rim stability.
Article
To report the surgical treatment of 3 eyes of 2 patients with bilateral anterior lenticonus due to Alport syndrome using femtosecond laser-assisted cataract surgery (FLACS). Two patients with Alport syndrome presented to our department due to anterior lenticonus in both eyes. We performed FLACS with posterior chamber lens implantation in both eyes of one patient and in one eye of the other patient. Anterior segment morphologic changes were visualized with a Scheimpflug camera, and anterior segment optical coherence tomography preoperatively and 3 months after surgery. Ultrastructure of the cut capsule edges was observed with scanning electron microscopy and compared to the edge of femtosecond laser capsulotomy performed on an otherwise healthy patient with cataract (control). The intraocular lens (IOL) postoperative positioning parameters met the international requirements of aspherical and wavefront customized IOLs (tilt <10 degree, decentration <800 µm). Scanning electron microscopy revealed the same characteristics of the cut capsule edges in the Alport and in the control eyes. Femtosecond laser cataract surgery can be a safe and successful method for optical rehabilitation of anterior lenticonus in patients with Alport syndrome.
Article
To evaluate cellular inflammation and apoptosis induced in the central portion of capsulorhexes/capsulotomies during cataract surgery, comparing a conventional manual technique and a femtosecond laser-assisted procedure at different energy settings using two laser systems. Fifty-six capsulorhexes/capsulotomies were divided into four groups: the manual group (14 capsulorhexes) performed with the manual technique; the 7.0-µJ group (14 capsulotomies) (LensAR laser system; Lensar, Inc., Orlando, FL); the 10-µJ group (14 capsulotomies) (LenSx laser system; Alcon Laboratories, Inc., Fort Worth, TX); and the 13.0-µJ group (14 capsulotomies) (LenSx laser system). All samples were stained for cellular apoptosis analysis (TUNEL assay) and cellular induced inflammation (NF-κB). One-way analysis of variance indicated a statistically significant difference in the percentage of NF-κB and TUNEL positive cells between the four groups, (F [3.52] = 14.717, P < .001) and (F [3.52] = 139.561, P < .001), respectively. Post-hoc analysis indicated a statistically significant difference in the percentage of NF-κB positive cells between the 13.0-µJ group and the manual, 7.0-µJ, and 10-µJ groups (P < .001, = .037, and < .001, respectively). Post-hoc analysis of differences in TUNEL positive cells indicated a significant difference between the 7.0-µJ and 10-µJ groups (P <.017) and between the 13.0-µJ group and the manual, 7.0-µJ, and 10-µJ groups (P < .001, < .001, and < .001, respectively). The results show a higher percentage of NF-κB and TUNEL positive cells in the 13.0-µJ group compared to the 7.0-µJ, 10-µJ, and manual groups. Therefore, inflammatory response and cell death increased at increasing energies. An effective capsulotomy in femtosecond laser-assisted cataract surgery with minimal detrimental apoptotic and inflammatory effects is possible if the laser system is set to use the minimum energy level. [J Refract Surg. 2015;31(5):290-294.]. Copyright 2015, SLACK Incorporated.
Article
Studies devoted to the assessment of lens capsule biomechanics can be divided into fundamental and applied. The former are oriented towards analysis of various indicators characterizing elasticity of the capsule as a basal membrane that maintains and changes the shape of the lens, and the latter deal with widespread introduction of modern microinvasive methods of phaco surgery into clinical practice. Purpose: To assess age-related changes in lens capsule biomechanics based on atomic force microscopy (AFM). Material and methods: The study included 50 central fragments of the anterior capsule of the human lens obtained intraoperatively during ultrasonic phacoemulsification by continuous circular capsulorhexis. The measurements were carried out in the Fast Force Volume (FFV) mode. The force curves were processed in the Nanoscope Analysis software (Bruker, USA) using the Hertz model that allows calculating the Young's modulus of the capsule sample based on the dependence of the force on the puncture depth. Results: There was no statistically significant difference in the «stiffness» of the inner and outer surfaces before and after removal of the subcapsular epithelium (p=0.25). In all cases, the inner surface of the capsule turned out to be «harder» than the outer one. In this case, the ratio of Young's modulus of the inner and outer surfaces has a significant dependence on age (p<0.001). With an increase in age from 50 to 90 years, this ratio decreased from ~7 to ~1.5. This was due to a simultaneous change in Young's modulus of the opposite nature: an increase in the stiffness of the outer surface and its decrease in the inner one. Conclusion: It is possible to assess lens capsule biomechanics using AFM if the subcapsular epithelium is present. In this case, the objects of study are the areas of the capsule free of epithelium, and the epithelial cells themselves can be used to identify the inner surface of the capsule. Regardless of age, the stiffness of the inner surface of the anterior lens capsule significantly exceeds that of the outer surface.
Article
Aim: This study aims to compare the efficacy and safety of femtosecond (FS) laser capsulotomy between mature and non-mature cataracts. Setting: Kaskaloglu Eye Hospital, single center study. Design: Prospective, controlled, and masked cross-sectional disease. Methods: A total of 133 eyes of 97 patients were included in this study. The Lens Opacities Classification System III grading scale was used in order to classify cataracts into two groups: mature and non-mature. The LenSx laser system (Alcon Labs Inc, Fort Worth, TX) was used. Data were extracted from patient charts, which included cataract grading, capsulotomy problems (tag, incomplete capsulotomy, and anterior capsule tears). Results: The mean age was 69.2 ± 10 years (64 males, 34 females). There were 50 eyes in Group I and 83 eyes in Group II. In 20 out of 133 eyes (15%) capsule tags occurred. Of these 20 eyes, 12 were in Group I, and 8 were in Group II. The number of tag occurrences was statistically higher in Group I when compared to Group II (P = 0.011). Incomplete capsulotomy was significantly higher in Group I when compared to Group II (P < 0.0001). Free capsulotomy was present in 36 out of 50 eyes (72%) in Group I and 75 out of 83 eyes (90%) in Group II (P = 0.03). Conclusion: The grade of cataract significantly increased the number of suboptimal capsulotomy outcomes in FS laser capsulotomy. In mature cataract cases, the surgeon should be aware of limitations of FS laser in order to prevent capsule-related complications. Further studies of the relationship between pulse energy, patient interface design, and capsule burst strength will help elucidate the optimum parameters for laser capsulotomy creation in mature cataracts. Lasers Surg. Med. © 2016 Wiley Periodicals, Inc.
Article
Purpose: To investigate the effect of femtosecond laser-assisted cataract surgery (FLACS) on aqueous humour and lens capsule. Methods: This prospective randomized comparative study enrolled 19 eyes that underwent FLACS as the trial group and 20 eyes that underwent conventional phacoemulsification as the control group. The femtosecond laser platform (LLS-fs 3D; LensAR, Orlando, FL, USA) was used to generate capsulotomy (laser energy 8 μJ) and lens fragmentation (laser energy 10 μJ). Morphology of the cutting edge and cells of anterior capsule was assessed by light microscopy. The proteins in the aqueous humour were identified by mass spectrometry (Ultraflex III TOF/TOF; Bruker Dalton, Bremen, Germany). Electrolyte in the aqueous humour was detected by a chemistry analyzer (Aeroset Clinical Chemistry Analyzer; Abbott Laboratories, Abbott Park, IL, USA). Results: The cutting edge of anterior capsule was saw-tooth-shaped under magnification of 200× and 400× in the trial group, while it was smooth in the control group. Intact cells were found in the boundary area next to the cutting edge of anterior capsule in both groups. β-Crystallin B1, γ-crystallin S and transferrin were detected in the aqueous humour in the trial group. The concentrations of K(+) , Na(+) and Cl(-) in the aqueous humour in the trial group differed significantly from those in the control group (p = 0.02, 0.03 and 0.04, respectively). Conclusion: Femtosecond laser-assisted cataract surgery (FLACS) causes release of transferrin and crystallin from lens to aqueous humour and results in significant changes in the concentrations of K(+) , Na(+) and Cl(-) in aqueous humour. However, these changes due to FLACS have no clinical significance or toxicity.
Article
The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.
Article
Purpose: To assess the role of femtosecond laser technology in the management of severely subluxated cataracts DESIGN: Retrospective, interventional case series METHODS: All eyes with subluxated cataract seen between July 2012 and June 2015 were assessed for suitability for femtosecond laser assisted cataract surgery, with the use of capsular tension devices. Participants with subluxated cataracts of at least 6 clock hours of zonular weakness were included in the study. Data collected included patient demographics, pre and post-operative best corrected visual acuity (BCVA), nuclear density, extent of zonular weakness, completeness of capsulotomy and complications. Poor visual outcome was defined as BCVA of worse than 20/40. Main outcome measure was the retention of the capsular bag. Results: Of the 72 eyes with subluxated cataracts undergoing surgery during the study period, 47 eyes of 47 patients were eligible for analysis. Mean age of the patients was 60.7 years old (standard deviation [SD] 13.2 years). The majority were male (32, 68.1%) and Chinese (38, 80.8%). The mean duration of follow up was 8 months (SD 5.6). The main identifiable cause of lens subluxation was trauma (11 eyes). Almost two-thirds (30 eyes) had more than 9 clock hours of zonular weakness. Seventy percent of cataracts (33) were nuclear sclerosis grade 3 and above. The capsular bag was preserved in 43 eyes (91.5%). The intraocular lens was stable and centered at the last follow up in all these 43 eyes. An anterior capsule tear occurred in 6 eyes, all of which had cataracts of nuclear sclerosis grade 3 and above, with posterior extension occurring in 3 eyes. Primary posterior capsule rupture occurred in one eye. At one month 37 eyes (80.4%) had a BCVA of 20/40 or better. There was significant improvement in BCVA at one month [mean of 0.92 logMAR units (SD 0.88) to 0.22 (SD 0.38) (P<0.001, paired samples T-test)] which was maintained at 1 year. Conclusions: Selected cases of severely subluxated cataracts may be managed using femtosecond laser technology to perform the capsulotomy and nuclear fragmentation, with successful preservation of the capsular bag in 90% of eligible cases especially in eyes with soft cataracts.
Article
Purpose of review: The purpose is to review the current and effective advantages of femtosecond laser-assisted cataract surgery (FLACS). Recent findings: FLACS has advantages over manual phacoemulsification in its precision, and predictability and may be especially advantageous in difficult situations such as shallow anterior chamber, subluxated cataracts, white cataracts, and so on. However, the femtosecond capsulorhexis may not be as strong as a manual rhexis. Laser-induced miosis is also a potential disadvantage. Summary: There may be increased surgeon confidence and patient satisfaction with FLACS and it may be friendlier to the internal structures of the eye. However, it is not superior to manual phacoemulsification in terms of primary outcomes such as visual and refractive outcomes or overall complications. Further refinements in technology may be needed to give it distinct advantages over manual phacoemulsification and to make it the norm in cataract surgery.
Article
Purpose of review: Continuous curvilinear manual capsulorhexis is currently the standard of cataract surgery. In the past several years, new technologies have been developed to improve the consistency and safety of capsulorhexis creation. This article reviews the most recent technologies in capsulotomy formation and their advantages and disadvantages. Recent findings: Guidance devices, femtosecond laser capsulotomy and precision pulse capsulotomy improve the centration, circularity and precision of anterior capsulorhexis and capsulotomy. These developments show particular promise for complex cataract surgeries, though clinical data on the refractive outcomes and complication rates of these technologies are currently limited and warrant additional investigation. Summary: New technological advances in capsulorhexis help surgeons achieve a more ideal capsulotomy geometry. Whether this translates into more predictable refractive outcomes and safer surgeries remains an area of future study.
Article
Laser surgery has become essential for recent clinical ophthalmic practice. Based on technological developments of precise image analyses, clinical application of femtosecond laser technology has expanded from corneal refractive surgery to cataract surgery. This technology is becoming popular in developed countries, where already over 300,000 therapeutic cases have been performed, including Japan. Cataract surgery using the femtosecond laser has allowed corneal and lens anterior capsule incisions with high reproducibility.The effectiveness of the technology is thought to be exhibited in premium intraocular lenses, including multifocal and/or toric intraocular lens.
Article
Purpose: To compare the capsulotomy rim strength with capsular marks (CMs) to the rim strength without CMs in porcine eyes, and to demonstrate the practicality of CMs for intraoperative toric intraocular lens (IOL) alignment. Setting: LENSAR facility, Orlando, Florida, USA. Design: Laboratory study. Methods: The biomechanical strength of the capsulotomy with CMs was tested under two different load orientations (orthogonal to or in-line with CMs). Thirty-six porcine eyes were randomly assigned to three treatment cohorts: (1) standard capsulotomy with no CMs, (2) capsulotomy with CMs for in-line tensile testing and (3) capsulotomy with CMs for orthogonal tensile testing. Study parameters were capsulotomy break force and maximum extensibility. The ease of using CMs for toric IOL alignment was also evaluated. Results: There was no significant difference between the mean break force for standard capsulotomy (180.57 mN ± 22 [SD]), capsulotomy with CMs with orthogonal load (178.04 ± 20 mN, P = 1.000), and with in-line load (181.05 ± 15 mN, P = 1.000). Likewise, the mean extensibility at the break point for standard capsulotomy (6.47 ± 0.33 mm) was equivalent to the mean extensibility with CMs with orthogonal load (6.49 ± 0.45 mm, P = 1.000) and with in-line load (6.3 ± 0.47 mm, P = .960). In the implanted eyes, toric IOLs were found to be easily aligned with the CMs. Conclusion: The femtosecond laser capsulotomies with CMs were equivalent in tensile strength and extensibility to standard femtosecond laser capsulotomies and showed high potential for effective alignment of toric IOLs.
Chapter
Ophthalmology always had a pioneer role in use of lasers (Light Amplification by Stimulated Emission of Radiation). A great variety of lasers have been employed since the first laser appeared within the ophthalmic armamentarium for more than 50 years. The German ophthalmologist Meyer-Schwickerath applied the first laser for photocoagulation in the retina in 1949 [1]. A laser is a special surgical device which emits specific electromagnetic light via stimulated emission. Ophthalmic lasers operate at one specific fixed wavelength, pulse pattern, energy, duration, repetition rate, spot size and causing most of the time thermal effects, but photocoagulation, evaporation and non-thermal effects also important, regarding laser-tissue interaction.
Article
Purpose To compare the breaking force required to tear the explanted capsule after femtosecond laser–assisted cataract surgery in the worse eye and manual cataract surgery in the contralateral eye. Setting Personaleyes, Sydney, Australia. Design Prospective nonrandomized case study. Method Patients with bilateral cataract had femtosecond laser–assisted cataract surgery with the Lensx laser in the eye with worse vision and manual cataract surgery in the contralateral eye. Each explanted capsule was stretched mechanically, and the breaking force and strain in grams (g) were compared. When a large contralateral difference in capsule strength was found, scanning electron microscopy (SEM) was applied to determine whether morphologic imperfections were present in a case with a weak capsule. Results Paired samples of 78 eyes of 39 patients were tested. The mean breaking force was not significantly different between manual capsulorhexes (2.3 g ± 2.0 [SD]) and femtosecond laser capsulotomies (2.0 ± 2.2 g, P = .52). The breaking strain for the manual samples (33.8% ± 18.3%) and for the femtosecond laser samples (34.6% ± 18.6%) were also not significantly different (P = .81). In 5 patients, in the femtosecond group, the capsules required considerably less force to break than the capsules in the manual group. However, the SEM images of these samples did not show specific laser imperfections. Conclusion In paired human eyes, the capsulotomies created by a femtosecond laser with a contact lens interface were as strong as manual capsulorhexes.
Article
Purpose: To compare histological analyses of capsulotomies from different laser systems with regard to tissue alteration, laser spot formation, and energy settings. Methods: Four femtosecond laser platforms approved for cataract surgery were evaluated: LenSx (Alcon Laboratories, Inc., Fort Worth, TX), Catalys (Abbott Medical Optics, Santa Ana, CA), Victus (Tecnolas/Bausch & Lomb, Munich, Germany), and LensAR (Topcon, Gamagori, Japan). Ten human anterior lens capsulotomy disks from each laser system were analyzed: five by means of light microscopy and five by transmission electron microscopy (TEM). TEM was used especially to examine the cellular and stromal changes at the cutting edges. The cellular demarcation line was measured at 15 points along the rim and statistically compared with the findings from all laser platforms. Three capsules of each laser platform were prepared for TEM to evaluate the cellular and tissue edges of the laser cuttings. Results: All capsulotomies revealed a circular demarcation zone of different sizes along the cutting edges. Light microscopy showed a radial tissue damage of 36.0 ± 12.3 μm after Victus laser capsulotomy, 8.9 ± 2.9 μm after Catalys laser capsulotomy, 25.2 ± 5.6 μm after LensAR laser capsulotomy, and 39.8 ± 5.1 μm after LenSx laser capsulotomy. Differences between the damaged tissue zones correlated with the laser systems and their energy settings. Conclusions: The use of less energy and larger spot separation led to smaller collateral damaged tissue areas along the cutting edges. The aberrant laser spots along the cutting edge may result in weakening of the remaining tissue, thereby enhancing the risk for capsular ruptures during surgery. [J Refract Surg. 2017;33(10):670-675.].
Book
This book presents the most modern and innovative techniques in ocular surgery currently utilized by experts in the field. All aspects of ocular surgery from the front to the back of the eye are covered in this resource, with all surgeries demonstrated as ‘recipes’ with first the ingredients and then the surgical techniques with step-by-step instructions. The surgeries are illustrated with photographs, drawings and videos for practical application, and the step-by-step presentation allows for quick and easy access to the most appropriate techniques in ocular surgery.
Article
Introduction: Vitrectorhexis is an alternative for manual continuous curvilinear capsulorhexis originally developed for paediatric cataract surgery. The aim of our study was the evaluation of the technique in adult patients with penetrating ocular injury and traumatic cataracts. Methods: Eight eyes of 8 patients (23-41 years, all males) had penetrating mechanical corneal trauma. Anterior lens capsule was penetrated in all cases and additional posterior capsule defect in five cases. Intraocular foreign body was detected in one case in the crystalline lens and in two cases in the posterior segment. Standard 23G infusion cannula and vitreous cutter were applied to perform anterior capsule opening, removal of lens material, anterior vitrectomy and pars plana vitrectomy if needed. No phacoemulsification or irrigation/aspiration probe was used. Results: Vitrectorhexis could be performed in 7 out of 8 cases with the preservation of peripheral anterior capsule; primary implantation of posterior chamber intraocular lens was possible in all cases (in the bag in three eyes and into the sulcus in five eyes). Anterior chamber was stable in all cases intraoperatively, and no dropped nucleus or lens fragment loss was observed. Surgery was combined with pars plana vitrectomy in three cases, with foreign body removal (when necessary). No postoperative complication occurred. Conclusion: Vitrectorhexis was found to be an effective and safe alternative method in the management of complex anterior segment trauma cases. With its use, traditional cataract surgical devices can be substituted and additional benefits of vitreous cutter can be utilized in selected cases, especially in young adults.
Article
Purpose of review: This review aims to introduce recent updates in cataract surgery and lens implantation. Recent findings: Compared to phacoemulsification, femtosecond laser-assisted cataract surgery (FLACS) may offer benefit for cataract patients with other complicated ocular diseases, such as corneal disease and vitreous abnormalities. Meanwhile, several types of novel intraocular lenses (IOLs) have been introduced to the market, and each of them has particular features in improving patients' visual acuity. In addition, based on a series of studies, multifocal IOL is superior to monofocal IOL when it comes to providing a better visual correction at different distances. Furthermore, a research group has introduced a new approach for cataract surgery - all laser surgery (FLACS band with nanolaser emulsification), which can effectively reduce iatrogenic trauma to the cornea. Also, a novel technique designed for children can lessen damage from cataract surgery. Summary: Based on previous studies, we summarize the new proceedings in FLACS and the indications for applying multifocal or toric IOL. In addition, we briefly introduce a new approach to cataract surgery - all laser surgery (FLACS band with nanolaser emulsification), and a less invasive surgical procedure used in pediatric cataract patients.
Article
To evaluate and compare the mechanical properties of anterior capsule opening performed with femtosecond laser capsulotomy at different energy settings in ex vivo porcine anterior lens capsule specimens. Twenty-five fresh porcine eyes per group were included in the study. Femtosecond laser capsulotomy was performed with three different pulse energy levels: 2 µJ (low energy group), 5 µJ (intermediate energy group), and 10 µJ (high energy group). The capsule openings were stretched with universal testing equipment until they ruptured. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy. The high energy group had significantly lower rupture force (108 ± 14 mN) compared to the intermediate energy group (118 ± 10 mN) (P < .05) and low energy group (119 ± 11 mN) (P < .05), but the difference between the intermediate energy and low energy groups was not significant (P = .9479). The high energy group had significantly lower circumference stretching ratio (144% ± 3%) compared to the intermediate energy group (148% ± 3%) (P < .05) and low energy group (148% ± 3%) (P < .05), but the difference between the intermediate energy group and low energy group was not significant (P = .9985). Scanning electron microscopy images showed that the edge was only serrated with low and intermediate energy, but additional signs of collagen melting and denaturation were observed at high energy. Anterior capsule openings created at a high energy level were slightly weaker and less extensible than those created at low or intermediate levels, possibly due to the increased thermal effect of photo-disruption. [J Refract Surg. 2015;31(3):153-157.]. Copyright 2015, SLACK Incorporated.
Article
Full-text available
The purpose of the study was to investigate the influence of age on the biomechanical properties of the human anterior lens capsule. The material comprised 67 lens capsules obtained from human donors ranging in age from 7 months to 98 years. Test specimens were prepared from the anterior lens capsule as tissue rings by means of excimer laser technique using a metal ring (mask) to shape the laser output (outer diameter = 3.2 mm, width = 100 microns). Capsular thickness was measured under microscope as the difference in focus between microspherules placed on the outer and inner surfaces of the capsule. The rings were slipped over two pins connected to a motorized micropositioner and a force transducer, respectively, and stretched at constant speed until rupture, with continuous recording of load and elongation. Capsular thickness was associated significantly with age of the donors and increased gradually (1.2% per year) until age 75, after which a slight decrease was observed. The elastic response curves showed a high degree of nonlinearity and were influenced markedly by age. Ultimate strain decreased 0.5% per year (range, 108% to 40%). Ultimate tensile strength decreased 1% per year (range, 17.5 N/mm2 to 1.5 N/mm2), and ultimate elastic stiffness (tangent modulus) decreased 0.9% per year (range, 44.8 N/mm2 to 4.4 N/mm2), whereas elastic stiffness corresponding to a specific strain level (30%) increased until age 35, after which a slight decrease was observed. Aging of the human anterior lens capsule is associated with a progressive loss of mechanical strength. The young capsule is strong, tough, and highly extensible, whereas the older, thicker capsule is less extensible and much more brittle, and it has a markedly reduced breaking strength.
Article
To ascertain the morphological changes in the edge structure of femtosecond laser-derived capsulotomy specimens using varying patient interfaces and different laser pulse energies. In this experimental clinical study femtosecond laser-assisted capsulotomies were performed in 30 eyes using the LenSx femtosecond laser (LenSx, Alcon, Fort Worth, TX, USA). Surgery was performed using either a rigid curved contact interface (group 1, 15 eyes) or a curved interface with a soft contact lens between cornea and interface (group 2, 15 eyes). The laser pulse-energy was set to 15 μJ in group 1 and to 5 μJ in group 2. After the removal of the anterior capsule, half of the specimens from each group underwent either further staining for light microscopy (LM) or scanning electron microscopy (SEM). Cell configuration, capsule shape, and edge abnormalities were analysed on a morphological basis. LM showed continuous anterior capsular incisions with a prominent demarcation line along the cutting edge, as well as tags and bridges, which were more pronounced in group 1. SEM revealed further smaller microgrooves and sawtooth patterns in both groups, and a more regular demarcation line configuration in group 2. A soft contact lens interface with a subsequent laser pulse energy of 5 μJ resulted in fewer tags and bridges, smoother edges, and a more regular and thinner demarcation line on specimens edges of femtosecond laser-performed capsulotomies compared to a rigid curved 15 μJ interface application.
Article
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. Prospective, multicenter, comparative cohort case series. Consecutive patients undergoing FLACS or PCS. A prospective cohort study of all patients (n = 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. Incidence of anterior capsule tear and comparative ultrastructural features of capsular samples from both PCS and FLACS cases. 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 = 0.0002, 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 μm apart and occurred at a range of 10 to 100 μm radially from the capsule edge. 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. The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Article
Purpose: To study the microanatomic edge structures of anterior lens capsule specimens derived from manual and femtosecond laser-assisted capsulotomies. Setting: Department of Ophthalmology, Goethe-University, Frankfurt, Germany. Design: Experimental study. Methods: Of 60 eyes with lens removal and intraocular lens implantation, 30 received a manual capsulotomy and 30 received a femtosecond laser-assisted capsulotomy (Lensx, rigid curved interface, pulse energy 15 μJ, spot separation 4 μm, layer separation 3 μm). After anterior capsule removal, tissues were immediately fixed in 4.5% formalin. Approximately 30 minutes after fixation, the tissues were removed from the fixation containers and air dried for at least 2 hours. Fifteen capsules in each group had further staining for light microscopy (LM). The surface of the capsulotomy edge was the primary focus of LM and scanning electron microscopy (SEM). Cell configuration, capsule shape, and abnormalities were evaluated. Results: Subjective LM and SEM analysis showed smooth edges at all magnifications, no cell destruction, and cells up to the cutting edge in the manual capsulotomy group. Light microscopy demonstrated almost continuous anterior capsule incisions of the femtosecond laser-assisted capsulotomy, a prominent demarcation line along the cutting edge, and several tags and bridges. Scanning electron microscopy showed microgrooves and valley- and mountain-like structures as signs of the photodisruption process. Conclusion: Compared with manual procedures, curved, rigid interface femtosecond laser-assisted capsulotomy specimens using 15 μJ pulse energy showed tags, bridges, rougher edges, and demarcation lines on the capsulotomy edges on SEM but subjectively estimated a more round shape on LM. Financial disclosures: Mr. Klaproth received travel reimbursements and/or lecture fees from Alcon Laboratories, Inc., Rayner Intraocular Lenses Ltd., and Oculus GmbH. Dr. Kohnen received travel reimbursements, grant support, and/or lecture fees from Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Bausch & Lomb, Carl Zeiss Meditec AG, Neoptics AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG; he is a consultant to Alcon Laboratories, Inc., Carl Zeiss Meditec AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG. No other author has a financial or proprietary interest in any material or method mentioned.
Article
To use scanning electron microscopy (SEM) to evaluate capsulorhexis-cut quality obtained during femtosecond laser-assisted cataract surgery at different energy settings and evaluate whether there are differences between this technique and a standard manual technique. Ophthalmology Clinic, Department of Medicine and Science of Ageing, University G. D'Annunzio Chieti-Pescara, Chieti, Italy. Prospective nonrandomized single blinded study. Sixty capsulorhexes obtained using the conventional manual technique and the femtosecond laser with different laser energy settings were divided into 5 groups as follows: Group 1 (12 capsulorhexes) obtained with the manual technique and Groups 2 to 5 (each with 12 capsulorhexes) obtained with the femtosecond laser at 7.0 μJ, 13.5 μJ, 14.0 μJ, and 15.0 μJ, respectively. All samples were evaluated using SEM to compare the thickness along the capsulorhexis edge and the overall irregularity of the cut surface. Capsulorhexes obtained with the femtosecond laser at all energy settings were perfectly circular with negligible deformation. Group 1 and Group 2 had a significantly higher thickness and lower thickness, respectively, of the capsulorhexis edge than the other 3 groups (P<.001). There was also a statistically significant correlation between the degree of irregularity and increasing energy (P<.001). The use of the femtosecond laser in cataract surgery resulted in better capsulorhexis geometry and circularity than the manual capsulorhexis. The cut surface was smoother in the manual group. In the femtosecond laser groups, the degree of irregularity was higher at increasing energy settings. No author has a financial or proprietary interest in any material or method mentioned.
Article
To objectively measure the strength of the capsulotomy performed with a femtosecond laser-assisted technique or performed manually in a pig-eye laboratory study. International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany. Experimental study. Ten fresh pig eyes were randomly assigned to femtosecond laser-assisted capsulotomy or manual capsulotomy. The capsule was immersed in hyaluronic acid, and retractors were fixed in the capsule opening with a pull-force measuring device. The force necessary to break the capsulotomy was measured in millinewtons (mN); the maximum stretching ratio was also assessed. The observed mean rupture force (ie, maximum amount of force measured immediately before tissue rupture) was 113 mN ± 12 (SD) in the laser-assisted procedure and 73 ± 22 mN in the manual procedure (P<.05). The stretching ratios were 1.60 ± 0.10 (femtosecond) and 1.35 ± 0.04 (manual) (P<.05). In this laboratory pig-eye study, femtosecond laser-assisted capsulotomy resulted in a significantly stronger anterior capsule opening than the standard manually performed capsulotomy. Drs. Auffarth, Reddy, and Holzer have received research and travel grants from Technolas Perfect Vision GmbH. Mr. Ritter is an employee of Technolas Perfect Vision GmbH, Munich, Germany.
Article
To evaluate a femtosecond laser system to create the capsulotomy. Porcine and cadaver eye studies were performed at OptiMedica Corp., Santa Clara, California, USA; the human trial was performed at the Centro Laser, Santo Domingo, Dominican Republic. Experimental and clinical study. Capsulotomies performed by an optical coherence tomography-guided femtosecond laser were evaluated in porcine and human cadaver eyes. Subsequently, the procedure was performed in 39 patients as part of a prospective randomized study of femtosecond laser-assisted cataract surgery. The accuracy of the capsulotomy size, shape, and centration were quantified and capsulotomy strength was assessed in the porcine eyes. Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 μm ± 26 (SD) for the laser technique and 337 ± 258 μm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 ± 47 μm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 ± 21 mN for 3 μJ, 121 ± 16 mN for 6 μJ, and 113 ± 23 mN for 10 μJ. The strength of the manual capsulorhexes was 65 ± 21 mN. The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique.
Article
To evaluate femtosecond laser lens fragmentation and anterior capsulotomy in cataract surgery. Anterior capsulotomy and phacofragmentation procedures performed with an intraocular femtosecond laser (LenSx Lasers Inc) were initially evaluated in ex vivo porcine eyes. These procedures were then performed in an initial series of nine patients undergoing cataract surgery. In addition to standard intraoperative assessments (including capsulotomy diameter accuracy and reproducibility), optical coherence tomography was used to evaluate human procedures. For an intended 5-mm capsulorrhexis in porcine eyes, average achieved diameters were 5.88+/-0.73 mm using a standard manual technique and 5.02+/-0.04 mm using the femtosecond laser. Scanning electron microscopy revealed equally smooth cut edges of the capsulotomy with the femtosecond laser and manual technique. Compared to control porcine eyes, femtosecond laser phacofragmentation resulted in a 43% reduction in phacoemulsification power and a 51% decrease in phacoemulsification time. In a small series of human clinical procedures, femtosecond laser capsulotomies and phacofragmentation demonstrated similarly high levels of accuracy and effectiveness, with no operative complications. Initial results with an intraocular femtosecond laser demonstrate higher precision of capsulorrhexis and reduced phacoemulsification power in porcine and human eyes.
Article
The development of the continuous circular capsulorhexis (CCC) technique has contributed significantly to the safety and effectiveness of cataract extraction and intraocular lens implantation. This technique facilitates every size of smooth, circular, capsular opening, and it produces a strong capsular rim that resists tearing even when stretched during lens material removal or lens implantation. Maintaining the general integrity of the eye and facilitating such procedures as hydrodissection, endolenticular phacoemulsification, capsule polishing, and safe lens implantation in both adults and children are some of the advantages of CCC. This procedure can be performed in several ways, and it has been proven to be consistently reproducible by experienced surgeons.
Article
We used the finite element method to evaluate different capsulotomy techniques. Nucleus expression was simulated in a computer model to visualize stress distribution in the anterior capsule. The finite element model demonstrated that the capsulorhexis edge is strong because of low and uniform stress distribution in the tissue. With can-opener and envelope capsulotomies, areas of high stress accumulation create the risk of tears during surgery.
Article
To compare the tear resistance of anterior capsulotomies using manual continuous curvilinear capsulorhexis (CCC) and vitrector-cut capsulotomy (vitrectorhexis) techniques in an animal model of the pediatric eye and in 2 pairs of human infant eyes. Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Continuous curvilinear capsulorhexis and automated vitrectorhexis capsulotomy techniques were performed in 20 pig eyes, 10 with each technique. The capsules were then stretched until they ruptured. The forces required for rupture after each technique were compared. The forces required for rupture of the pig eye lens capsule were also compared with those required for the human infant eye lens capsule. Scanning electron microscopy was performed in each group following intraocular lens (IOL) insertion. All capsules stretched adequately for IOL insertion. The percentage of stretch prior to rupture was higher in the capsulorhexis group (mean 157%, range 147% to 169%) than in the vitrectorhexis group (mean 135%, range 124% to 147%) (P < .001). The percentage of stretch in the human infant eyes was not statistically different from that in the porcine eyes (P > .05). The manual CCC offered greater resistance to capsule tearing than the vitrectorhexis and also revealed a more smooth, regular edge. It therefore remains the gold standard. However, the vitrectorhexis displayed more than adequate resistance to unwanted anterior capsule tears when used for IOL insertion through capsulotomy sizes currently used in clinical practice.
Article
To determine the incidence of anterior capsule tears, at what stage of surgery they occurred, and their intraoperative behavior. Ambulatory surgery center, Cincinnati Eye Institute, Cincinnati, Ohio, USA. This 5-year retrospective study was of patients having phacoemulsification with posterior chamber intraocular lens (IOL) implantation complicated by unplanned peripheral extension of the capsulorhexis tear or a radial anterior capsule tear. The operative notes and a videotape of the surgery were reviewed. The stage at which the tear was initially observed and when it extended were identified, as was whether the tear extended to the posterior capsule. Anterior vitrectomy and the design and location of the IOL implanted were also analyzed. A discontinuous anterior capsulorhexis or a break in the anterior capsule rim was observed in 21 eyes of 2646 cases, for an overall incidence of 0.79%. Anterior capsule tears were identified during ophthalmic viscosurgical device injection in 1 eye, capsulorhexis in 13 eyes, hydrodissection in 2 eyes, phacoemulsification in 3 eyes, irrigation/aspiration (I/A) in 1 eye, and implantation of a prosthetic iris device in 1 eye. Seven of the 13 tears identified during the capsulorhexis were managed by redirecting the second edge of the "safety" capsulorhexis to incorporate the tear. In 14 eyes, the tear in the anterior capsule extended into the zonules; 4 of these tears were limited. Ten tears extended around the equator and through the posterior capsule, occurring during the hydrodissection in 1 eye, phacoemulsification in 2 eyes, I/A in 1 eye, and IOL implantation in 6 eyes. An anterior vitrectomy was required in 4 eyes that had posterior capsule involvement. Endocapsular fixation of a 1-piece acrylic IOL was achieved in 18 eyes. Three eyes required implantation of a 3-piece acrylic IOL in the ciliary sulcus. Extension of an anterior capsule tear can complicate cataract surgery at any stage. Extension of the tear through the posterior capsule occurred in almost half the eyes with an anterior capsule tear, often requiring an anterior vitrectomy. Managing an anterior capsule tear can be challenging yet compatible with implantation of a posterior chamber IOL.
Evaluation of the mechanical properties of the crystalline lens capsule following photodisruption capsulotomy and continuous curvilinear capsulorrhexis
  • Frey RW