Analysis of femtosecond laser assisted capsulotomy cutting edges and manual capsulorhexis using environmental scanning electron microscopy

Continuous Curvilinear Capsulorhexis - A Practical Review

BACKGROUND

Continuous curvilinear capsulorhexis (CCC) has become the gold standard technique for anterior capsulotomy, a cardinal development in modern cataract surgery. CCC enables safer and relatively convenient access to the crystalline lens, however it is more challenging to master than older methods. Understanding the physics underlying this procedure is key to achieving the desired results and avoiding complications.

PURPOSE

To review and present the established information about CCC, and to create a practical guide to this important step in cataract surgery.

METHODS

A literature review was conducted using PubMed, Embase, Cochrane and Scopus databases, with emphasis on up-to-date information. The first part of this review describes the evolution of CCC and discusses the different approaches, the various instruments available, tips and pearls and the general setup for best results. The second half covers more recent innovations and common complications, and strategies to prevent or manage them. This paper provides a practical review of all aspects of CCC.

Evaluation of femtosecond laser-assisted cataract surgery after 10 years of clinical application

INTRODUCTION

Femtosecond laser-assisted cataract surgery (FLACS) has been considered a technological advance in modern cataract surgery. After years of experience, it has been observed that clinical outcomes had more complications than expected at the beginning. The aim of this study is to compare the benefits and disadvantages of the FLACS technique with conventional cataract surgery.

METHOD

The PubMed and Web of Science platforms were used to search for scientific literature.

RESULTS

The FLACS has currently improved the surgical technique in terms of the shorter ultrasound time used and the lower loss of endothelial cells. Likewise, the centration of capsulotomy and the correction of astigmatism with arcuate incisions have also been improved. As disadvantages, are the high cost of the laser, the intraoperative capsular complications, the induction of intraoperative myosis, and the learning curve of the technique.

CONCLUSIONS

The FLACS technique is considered beneficial for specific cases, such as patients with scheduled premium surgery, or with low endothelial cell count. However, it is believed that given the technological cost it is not a cost effective technique for most standard cases in our daily clinical practice.

The benefits and drawbacks of femtosecond laser-assisted cataract surgery

INTRODUCTION

Since the introduction, femtosecond laser-assisted cataract surgery was believed to revolutionize cataract surgery. However, the judgment of clinical benefit was found to be far more complex than initially might have been thought. The aim of this review was to analyze the benefits and drawbacks of femtosecond laser-assisted cataract surgery compared with traditional phacoemulsification cataract surgery.

METHODS

PubMed and the Web of Science were used to search the medical literature. The following keywords were searched in various combinations: femtosecond laser, femtosecond laser-assisted cataract surgery, phacoemulsification cataract surgery, FLACS.

RESULTS

The benefits of femtosecond laser-assisted cataract surgery include lower cumulated phacoemulsification time and endothelial cell loss, perfect centration of the capsulotomy, and opportunity to perform precise femtosecond-assisted arcuate keratotomy incisions. The major disadvantages of femtosecond laser-assisted cataract surgery are high cost of the laser and the disposables for surgery, femtosecond laser-assisted cataract surgery-specific intraoperative capsular complications, as well as the risk of intraoperative miosis and the learning curve.

CONCLUSION

Femtosecond laser-assisted cataract surgery seems to be beneficial in some groups of patients, that is, with low baseline endothelial cell count, or those planning to receive multifocal intraocular lens. Nevertheless, having considered that the advantages of femtosecond laser-assisted cataract surgery might not be clear in every routine case, it cannot be considered as cost-effective.

Femtosecond laser-assisted cataract surgery: A review

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.

Anterior Capsule of the Lens: Comparison of Morphological Properties and Apoptosis Induction following FLACS and Standard Phacoemulsification Surgery

Purpose

Comparative evaluation of morphological features of anterior capsules and apoptosis induction in epithelial cells after femtosecond laser-assisted cataract surgery (FLACS) and standard phacoemulsification surgery.

Methods

Group 1: 30 FLACS anterior capsulotomies and Group 2: 30 manual anterior continuous curvilinear capsulorhexes. All patients were operated on by the same experienced surgeon. Morphological features of the anterior capsules and apoptosis induction in epithelial cells were evaluated.

Results

All patients revealed a significant mean best-corrected visual acuity (BCVA) improvement 3 months after surgery, and no major intraoperative nor postoperative complications occurred. The capsular epithelium appeared to be preserved in both groups. Scanning electron microscopy analysis revealed irregular saw-tooth shaped edges in capsules from Group 1 whereas capsules from Group 2 showed regular and smooth edges. A statistically significant higher expression of the downstream apoptotic effector cleaved caspase 3 was observed in Group 1.

Conclusions

The saw-tooth appearance was likely due to the progressive sequence of laser pulses on the capsule. The low energy/high frequency properties of the laser pulse, combined with an overlapped pulse pattern, resulted in highly continuous morphology of capsule edges. The higher apoptosis induction in FLACS group might be due to photodisruption-dependent plasma generation and formation of cavitation bubbles.

Mobile femtosecond laser platform for pediatric cataract surgery

PURPOSE

To describe the use of a mobile femtosecond laser platform in assisting paediatric cataract surgery.

METHODS

A mobile femtosecond laser was brought into the operating room and calibrated on the day of the surgery. After general anesthesia is induced, the femtosecond laser was docked onto the eyes with a liquid-filled interface, without any perioperative adaptations or additional surgical procedures. An anterior capsulotomy was created with the femtosecond laser, followed by conventional cataract extraction and intraocular lens implantation.

RESULTS

Five eyes of 3 children with congenital cataracts were treated with this technique. Docking and capsulorhexis were successful in all cases. No perioperative or intraoperative complications were noted in any of the cases. At median follow-up of 15 months (range 6-18 months), all patients had improved best-corrected visual acuity.

CONCLUSIONS

Using the mobile femtosecond laser platform, a perfectly sized anterior capsulotomy could be created with high precision and accuracy in paediatric cataract cases, while ensuring that perioperative care for the children undergoing the procedure was not compromised.

Femtosecond laser-assisted cataract surgery, technology, outcome, future directions and modern applications

Since its introduction in 2009 femtosecond laser-assisted cataract surgery (FLACS) has promised to revolutionize cataract surgery. Despite its promise, the assessment of FLACS's perceived benefits has proven to be far more complicated than initially might have been thought. Most studies to date have not provided validation of FLACS technology as a clinically significant advancement on our current techniques. We review FLACS technology and outcomes including detailed analysis of safety, efficacy, cost effectiveness and future prospects using data from the literature and our own published clinical experience.

Current and effective advantages of femto phacoemulsification

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.

Comparison of Maximum Stretch Forces between Femtosecond Laser-Assisted Capsulotomy and Continuous Curvilinear Capsulorhexis

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.

Comparison of the efficacy and safety of femtosecond laser capsulotomy between mature and non-mature cataracts

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. 48:590-595, 2016. © 2016 Wiley Periodicals, Inc.

Continuous Curvilinear Capsulorhexis in Cataract Surgery Using a Modified 3-Bend Cystotome

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.

Finesse of transparent tissue cutting by ultrafast lasers at various wavelengths

Transparent ocular tissues, such as the cornea and crystalline lens, can be ablated or dissected using short-pulse lasers. In refractive and cataract surgeries, the cornea, lens, and lens capsule can be cut by producing dielectric breakdown in the focus of a near-infrared (IR) femtosecond laser, which results in explosive vaporization of the interstitial water, causing mechanical rupture of the surrounding tissue. Here, we compare the texture of edges of lens capsule cut by femtosecond lasers with IR and ultraviolet (UV) wavelengths and explore differences in interactions of these lasers with biological molecules. Scanning electron microscopy indicates that a 400-nm laser is capable of producing very smooth cut edges compared to 800 or 1030 nm at a similar focusing angle. Using gel electrophoresis and liquid chromatography/mass spectrometry, we observe laser-induced nonlinear breakdown of proteins and polypeptides by 400-nm femtosecond pulses above and below the dielectric breakdown threshold. On the other hand, 800-nm femtosecond lasers do not produce significant dissociation even above the threshold of dielectric breakdown. However, despite this additional interaction of UV femtosecond laser with proteins, we determine that efficient cutting requires plasma-mediated bubble formation and that remarkably smooth edges are the result of reduced thresholds and smaller focal volume.