Update on Femtosecond Laser-Assisted Cataract Surgery: A Review

The advent of femtosecond lasers has resulted in a new standard in cataract surgery, intended to overmatch the paradigm of conventional phacoemulsification. Femtosecond laser-assisted cataract surgery (FLACS) enables a higher level of reproducibility, precision, accuracy, and customization when performing several steps of cataract (or lens) surgery. Capsulotomy, corneal incisions, lens fragmentation, and arcuate incisions are the main procedures performed using FLACS. As the demand for better refractive outcomes and spectacle independence increases, the features of FLACS are highly relevant, especially when considering the implantation of premium intraocular lenses, such as toric, enhanced depth-of-focus, or multifocal lenses. The present article reviews the state of the art of femtosecond laser-assisted cataract (lens) surgery, contemplating the advantages and limitations of the two types of femtosecond laser pulses available (high and low energy) by evaluating their reported outcomes and complications.

Safety and efficacy of cataract surgery performed with a low-energy femtosecond laser compared with conventional phacoemulsification in Chinese patients: a randomized clinical trial

BACKGROUND

To compare the safety and efficacy of femtosecond laser-assisted cataract surgery (FLACS) performed with the low-energy FEMTO LDV Z8 (Ziemer Ophthalmic Systems AG, Port, Switzerland) laser compared with conventional phacoemulsification (CP) in Chinese patients.

METHODS

This prospective, multicenter, interventional study included 126 patients who were randomized (1:1) to undergo either FLACS or CP followed by intraocular lens (IOL) implantation between January 2019 and April 2020. The primary endpoint included the comparison of the endothelial cell loss (ECL) between the two groups at 3 months. Secondary endpoints included the comparison of cumulative dissipated energy (CDE), change in central corneal thickness (CCT) from baseline, and postoperative uncorrected and corrected distance visual acuities (UDVA and CDVA) in the two groups.

RESULTS

At all postoperative time points, the FLACS group was found to be non-inferior to CP for the mean ECL (- 409.3 versus - 436.9 cells/mm² at 3 months) and mean CDE (4.1 versus 4.5 percent-seconds). The increase in CCT was significantly lower in the FLACS group compared with the CP group at Day 7 (4.9 versus 9.2 µm; P = 0.04); however, the difference was not statistically significant at 1 and 3 months. Postoperatively, mean UDVA and CDVA were comparable between the two groups. No intraoperative complications occurred.

CONCLUSIONS

Cataract surgery performed with a low-energy femtosecond laser was non-inferior to CP; however, the FLACS group had a statistically significantly lower increase in CCT at Day 7 compared with CP. Trial registration This trial is registered at ClinicalTrials.gov on May 15, 2019, with trial registration number: NCT03953053.

Solving STODS-Surgical Temporary Ocular Discomfort Syndrome

The term STODS (Surgical Temporary Ocular Discomfort Syndrome) has been coined to describe the ocular surface perturbations induced by surgery. As one of the most important refractive elements of the eye, Guided Ocular Surface and Lid Disease (GOLD) optimization is fundamental to success in achieving refractive outcomes and mitigating STODS. Effective GOLD optimization and the prevention/treatment of STODS requires an understanding of the molecular, cellular, and anatomic factors that influence ocular surface microenvironment and the associated perturbations induced by surgical intervention. By reviewing the current understanding of STODS etiologies, we will attempt to outline a rationale for a tailored GOLD optimization depending on the ocular surgical insult. With a bench-to-bedside approach, we will highlight clinical examples of effective GOLD perioperative optimization that can mitigate STODS' deleterious effect on preoperative imaging and postoperative healing.

Femtosecond laser-assisted cataract surgery: Update and perspectives

Cataract surgery is among the most frequently performed surgical procedures worldwide and has a tremendous impact on patients' quality of life. Phacoemulsification (PCS) is accepted as a standard of care; its technique has continuously evolved and already achieved good anatomical, visual, and refractive outcomes. Lasers in ophthalmology are widely used in clinical practice, femtosecond lasers (FSLs) for corneal surgery in particular. It was natural to assess the usefulness of FSL in cataract surgery as this technology was within reach. Indeed, precise and reproducible cuttings provided by FSL platforms could improve standardization of care and limit the risk associated with the human element in surgery and provide a step toward robot-assisted surgery. After docking and planning the procedure, femtosecond lasers are used to perform corneal incisions, capsulorhexis, lens fragmentation, and arcuate incisions in an automated manner. A well-constructed corneal incision is primordial as it offers safety during the procedure, self-seals afterward, and influences the refractive outcome. Capsulorhexis size, centration, and resistance to shearing influence the surgery, intraocular lens (IOL) centration and stability, and posterior capsular opacification formation. Lens fragmentation is where most of the energy is delivered into the eye, and its amount influences endothelial cell damage and potential damage to other ocular structures. The arcuate incisions offer an additional opportunity to influence postoperative astigmatism. Femtosecond laser-assisted cataract surgery (FLACS) has been a topic of research in many studies and clinical trials that attempted to assess its potential benefits and cost-effectiveness over PCS and is the subject of this mini-review.

Intraoperative complications of cataract surgery using a low-energy femtosecond laser: Results from a real-world high-volume setting

In this study, we report data on intraoperative complications occurring after cataract surgery in a high-volume single-center setting using a low-energy, mobile femtosecond laser. We retrospectively reviewed the medical records of patients who underwent femtosecond laser-assisted cataract surgery (FLACS) in our hospital between August 2015 and December 2019. Among the sample of 1,806 eyes of 1,131 patients (903 left and 903 right eyes), the mean age was 75.8 years (range, 21-99 years). The overall intraoperative complication rate was 0.28% (n = 5), with three cases of anterior capsule tear (0.17%) and two cases of posterior capsule tear (0.11%). No further complications occurred. This study underlines the safety of low-energy femtosecond-assisted cataract surgery in a real-world setting with a very low rate of intraoperative complications.

The Effects of High Energy Capsulotomy on Aqueous Cytokine Profiles and Pupil Size During Femtosecond Laser-Assisted Cataract Surgery

PURPOSE

To assess whether aqueous cytokine profiles and pupil size are altered when high capsulotomy energy is used in eyes undergoing femtosecond laser-assisted cataract surgery (FLACS), and if preoperative use of a topical non-steroidal anti-inflammatory drug (NSAID) has an effect on this.

METHODS

This prospective study recruited 83 eyes (63 patients) that were allocated to four treatment groups: conventional phacoemulsification (n = 20 eyes); FLACS with 90% capsulotomy energy without NSAID pretreatment (n = 20 eyes); FLACS with 90% capsulotomy energy with NSAID pre-treatment (n = 21 eyes); and FLACS with 150% capsulotomy energy with NSAID pretreatment (n = 22 eyes). Aqueous humor was collected before and after phacoemulsification to assess cytokine profiles. Pupil size was measured before and after laser capsulotomy.

RESULTS

FLACS increased aqueous concentrations of pros-taglandin E₂ (PGE₂), interferon γ (IFN-γ), and interleukin 6 (IL-6) compared to conventional phacoemulsification. However, when increasing capsulotomy energy from 90% to 150% (with topical NSAID pretreatment), there was no significant increase in aqueous concentrations of PGE₂ (37.7 ± 21.7 vs 33.6 ± 27.6 pg/mL, P = .99), IFN-γ (3.6 ± 1.1 vs 3.6 ± 0.8 pg/mL, P = .99), or IL-6 (7.1 ± 2.9 vs 6.3 ± 2.4 pg/mL, P = .99). For 90% and 150% capsulotomy energy, there was significant miosis following laser capsulotomy. Increased PGE₂ concentration was significantly correlated with a reduction in pupil area (r = -0.58, P < .001) and pupil diameter (r = -0.57, P < .001). However, when a topical NSAID was given preoperatively, there was no difference in the degree of miosis between the 90% and 150% capsulotomy energy groups.

CONCLUSIONS

Pretreatment with a topical NSAID prevented a rise in PGE₂, IFN-γ, and IL-6 levels and excessive miosis when a higher capsulotomy energy was used. When a topical NSAID is used preoperatively, it is safe to use higher capsulotomy energy settings (with a low pulse energy femtosecond laser system) to achieve a satisfactory capsulotomy. [J Refract Surg. 2022;38(9):587-594.].

Long-Term Evaluation of Capsulotomy Shape and Posterior Capsule Opacification after Low-Energy Bimanual Femtosecond Laser-Assisted Cataract Surgery

Purpose

To evaluate capsulotomy shape and posterior capsule opacification (PCO) during an 18-month follow-up for bimanual femtosecond laser-assisted cataract surgery (FLACS).

Methods

74 eyes operated by a well-trained surgeon with bimanual FLACS technique using low-energy LDV Z8 (Ziemer Ophthalmic Systems AG, Port, Switzerland) were included in the study. The follow-up period was 18 ± 2 months. Another 91 eyes, which underwent standard bimanual microincision cataract surgery (B-MICS), served as a control group. In all cases, a BunnyLens AF (Hanita Lenses, Israel) intraocular lens was implanted in the bag. A digital image of the capsule with slit-lamp retroillumination was performed in all patients at 18 months of follow-up. Image analysis software (ImageJ) was used to evaluate the shape of the capsulotomy in terms of diameter, area, and circularity. PCO score was evaluated using EPCO 2000 software. Best corrected visual acuity (BCVA) and endothelial cell count (ECC) were evaluated before and after surgery at 1 and 18 ± 2 months.

Results

At 18 months, mean capsulotomy diameter was 5.34 ± 0.21 mm while capsulorhexis was 5.87 ± 0.37 mm (p < 0.001) and the deviation area from baseline was 1.13 ± 1.76 mm² in FLACS and 2.67 ± 1.69 mm² in B-MICS (p < 0.001). Capsulotomy circularity was 0.94 ± 0.04 while capsulorhexis was 0.83 ± 0.07 (p < 0.001). EPCO score was 0.050 ± 0.081 in the FLACS group and 0.122 ± 0.239 in the B-MICS group (p=0.03). The mean BCVA improvement was significant in both groups, without a significant difference at 18 months. We noticed a statistically significant difference in endothelial cell loss at 18 months (FLACS 12.4% and B-MICS 18.1%; p=0.017).

Conclusions

Bimanual FLACS is a safe and effective technique, as determined in a long-term follow-up. Capsulotomy shape presented higher stability and circularity in the FLACS group over the 18-month observation period. FLACS resulted in lower PCO scores and endothelial cell loss at 18 months in comparison to B-MICS standard technique.

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.

[Prevention of intraoperative miosis in femtosecond laser-assisted phaco surgery]

INTRODUCTION

Prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification is a relevant problem of cataract surgery.

PURPOSE

Development and clinical study of an effective method for preventing intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification.

MATERIAL AND METHODS

Hybrid phacoemulsification was performed in 300 patients (300 eyes). The first group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day and 3 times in 2 hours before surgery at 30 minute intervals. The second group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day, 3 times in 2 hours before the surgery at 30 minute intervals, and 1 hour before the surgery an additional intramuscular injection of diclofenac. The third group (control, 100 eyes) 2 hours before the operation was prescribed instillations of 0.1% indomethacin, 3 times at 30 minute intervals. The diameter of the pupil was evaluated before the beginning of femtosecond laser stage and before the opening of anterior chamber during the second stage of the operation.

RESULTS

When the interval between the femtosecond laser stage and emulsification of the nucleus fragments was maintained at less than 15 minutes, pronounced decrease of the pupil (more than 2 mm) was noted in 8.2% of cases in the first group, 6.7% in the second group and 14.1% in third (control) group; mean values of pupil narrowing were 0.68±0.27 mm in the 1st group, 0.63±0.25 mm in the 2nd group, and 0.93±0.39 mm (p<0.05) in the third group.

CONCLUSION

The clinical study showed high efficiency of the proposed methods for prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phaco surgery. An important factor affecting intraoperative narrowing of the pupil is the time interval between the femtolaser stage of the operation and emulsification of the nucleus fragments, which should not exceed 15 minutes.

Acute clouding of a trifocal intraocular lens with spontaneous resolution: a case report

BACKGROUND

Opacification of hydrophobic and hydrophilic intraocular lenses (IOLs) has been reported. Herein, we report a case of spontaneous resolution of opacification following acute clouding of a trifocal IOL, which consisted of hydrophilic acrylic material (25%) with hydrophobic surface properties, occurring in a cold region in the winter season.

CASE PRESENTATION

A young adult with bilateral radiation cataract underwent phacoemulsification using a femtosecond laser and implantation of a trifocal IOL. The trifocal IOL was delivered to the operating theatre 30 min before the surgery. The outside temperature was approximately - 7 °C. The IOL package was warmed using a radiator at approximately 35 °C for 15 min. After the optical region was implanted in the eye, cloudiness was observed, which persisted throughout the operation. Complete clearing of the IOL was apparent after three postoperative hours.

CONCLUSION

In this case, rapid opacification and clearing of the IOL suggested an acute and transient process. IOLs should be stored and shipped at a constant temperature, and sudden temperature fluctuations should be avoided, especially in the colder seasons.

Cataract refractive surgery: Innovative technology provides more choices for Canadian cataract patients

Historically, cataract surgery was aimed at removing the clouded lens of the eye and replacing it with an artificial lens; this provided clear vision to patients but without regard to their refractive error-their need for spectacles or contact lenses after surgery. Modern diagnostic and surgical instrumentation now makes it possible to address these refractive errors at the time of surgery, introducing a new paradigm-cataract refractive surgery. Although not medically necessary, many patients appreciate the chance to reduce or eliminate their need for spectacles after surgery, even if some personal cost is involved.

Cell death and survival following manual and femtosecond laser-assisted capsulotomy in age-related cataract

AIM

To study molecular and morphological changes in lens epithelial cells following femtosecond laser-assisted and manually performed continuous curvilinear capsulotomy (CCC) in order to get information about these methods regarding their potential role in the induction of development of secondary cataract.

METHODS

Anterior lens capsules (ALC) were removed from 40 patients with age-related cataract by manual CCC and by femtosecond laser-assisted capsulotomy (FLAC). Samples removed by manual CCC were assorted in group 1, FLAC samples were classified in group 2. Morphology of lens epithelial cells was examined with light and electron microscopes. Following capsulotomy, expressions of p53, Bcl-2 and cyclin D1 genes were analyzed with reverse transcriptase polymerase chain reaction. Immunohistochemistry was used to detect the pro-apoptotic p53 in the epithelial cells.

RESULTS

Light and electron microscopic examination showed that ALC of group 1 contained more degenerating cells following manual CCC than after FLAC. The expression level of p53 was higher after manual than laser-assisted surgery. Immunocytochemistry indicated significantly higher number of cells containing p53 protein in the manual CCC group than following FLAC. Bcl-2 and cyclin D1 gene expression levels were slightly lower following manual CCC than after FLAC, but the difference was not significant.

CONCLUSION

Manually removed ALC shows slightly, but not significantly larger damage due to the mechanical stretching and pulling of the capsule than those removed using FLAC.

[Morphological and clinical aspects of anterior capsulotomy in femtosecond laser-assisted cataract surgery]

The review covers morphological and clinical aspects of femtosecond laser-assisted anterior capsulotomy in cataract surgery. Literature data suggests that femtosecond laser-assisted capsulotomy is more accurate in size, shape, and centration than manual. Femtosecond laser-assisted anterior capsulotomy improves the accuracy of IOL positioning within the capsular bag.

Femtosecond Laser-Assisted Capsulotomy: Histological Comparison of Four Different Laser Platforms

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.].

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.

La chirurgie réfractive de la cataracte: des technologies novatrices élargissent les choix des patients canadiens

La chirurgie de la cataracte a toujours consisté à extraire le cristallin opacifié de l'œil pour le remplacer par une lentille artificielle. Cette intervention rend la vision du patient plus nette, sans pour autant corriger l'erreur de réfraction, c'est-à-dire la nécessité de porter des lunettes ou des lentilles cornéennes après l'opération. Les instruments diagnostiques et chirurgicaux modernes permettent désormais de corriger ces erreurs de réfraction au moment de l'opération, ce qui a fait émerger une nouvelle notion, celle de la chirurgie réfractive de la cataracte. Même si cette correction n'est pas nécessaire sur le plan médical, de nombreux patients se réjouissent de la possibilité de ne plus porter de lunettes ou d'en porter moins après l'opération, même s'ils doivent engager des frais.

Update and clinical utility of the LenSx femtosecond laser in cataract surgery

The introduction of femtosecond lasers to cataract surgery has been the major disruptive technology introduced into ophthalmic surgery in the last decade. Femtosecond laser cataract surgery (FLACS) integrates high-resolution anterior segment imaging with a femtosecond laser allowing key steps of cataract surgery to be performed with computer-guided laser accuracy, precision, and reproducibility. Since the introduction of FLACS, there have been significant advances in laser software and hardware as well as surgeon experience, with over 250 articles published in the peer-reviewed literature. This review examines the published evidence relating to the LenSx platform and discusses surgical techniques, indications, safety, and clinical results.

Anterior chamber interleukin 1β, interleukin 6 and prostaglandin E2 in patients undergoing femtosecond laser-assisted cataract surgery

PURPOSE

To evaluate the interleukin (IL) 1β, IL-6 and prostaglandin E2 (PGE2) concentrations in aqueous humour in patients undergoing femtosecond laser-assisted cataract surgery.

METHODS

In 27 eyes of 27 patients undergoing femtosecond laser-assisted cataract surgery (femto group), aqueous humour of 100 μL was collected after laser treatment. In 15 eyes of 15 subjects undergoing routine cataract surgery (control group), aqueous humour of 100 μL was also collected. The IL-1β, IL-6 and Prostaglandin E2 (Human Interleukin 1β, Interleukin 6 and Prostaglandin E2 ELISA Kits, Bio-Swamp Life Science) were used to determine the concentrations of IL-1β, IL-6 and PGE2 in the aqueous humour. All patients were treated with non-steroidal anti-inflammatory drugs prior to surgery.

RESULTS

For IL-1β, IL-6 and PGE2, respectively, the mean concentration values in aqueous humour were 25.6, 24.6 and 64.2 pg/mL in the femto group, and 17.1, 15.2 and 45.7 pg/mL in the control group (table 2). Concentrations of IL-1β, IL-6 and PGE2 were significantly higher in the femto group than those in the control group (all p<0.01). There were no significant correlations between concentrations of IL-1β, IL-6 or PGE2 and age, cataract densities, suction time or laser time (all p>0.05).

CONCLUSIONS

Inflammatory cytokines IL-1β, IL-6 and PGE2 significantly increased after femtosecond laser-assisted cataract surgery, which maybe the cause of intraoperative miosis seen in these patients.

Femtosecond laser-assisted cataract surgery--current status and future directions

Femtosecond laser-assisted cataract surgery (FLACS) putatively offers several advantages over conventional phacoemulsification. We review the current status of FLACS and discuss the evolution of femtosecond lasers in cataract surgery and the currently available femtosecond laser platforms. We summarize the outcomes of FLACS for corneal wound creation, limbal relaxing incisions, capsulotomy, and lens fragmentation. We discuss surgical planning, preoperative considerations, clinical experiences including the learning curve and postoperative outcomes with FLACS, and also the cost effectiveness of FLACS. We present the intraoperative complications and management of challenging cases where FLACS offers an advantage and also speculate on the future directions with FLACS. Further advancements in laser technology to refine its efficacy, advancement in intraocular lens design to harness the potential benefits of FLACS, and a reduction in cost are needed to establish a clear superiority over conventional phacoemulsification.