Femtosecond laser cataract incision morphology and corneal higher-order aberration analysis

Long Term Evaluation of Surgically Induced Astigmatism and Corneal Higher-Order Aberrations After 2.2 Mm Clear Corneal Incisions in Femtosecond Laser-Assisted Cataract Surgery: Temporal versus Superior Approach

Purpose

To assess long term changes of the surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs) after 2.2 mm clear corneal incisions (CCIs) in femtosecond laser-assisted cataract surgery and compare them between 2 types of CCIs: temporal and superior approach.

Patients and Methods

Patients received the temporal CCIs (Group A) or the superior CCIs (Group B). Outcome measures included visual acuity, manifest refraction, corneal astigmatism, SIA, flattening effect, and corneal HOAs. Correlation between postoperative corneal HOA and SIA at each follow-up were analysed.

Results

This study assessed data from 106 eyes, of which 64 in Group A and 42 in Group B. The two groups had similar postoperative visual acuity of distance, intermediate and near (all P > 0.05). SIA and corneal HOAs were significantly lower in Group A than Group B in the early postoperative period, while there was no significant difference in the late postoperative period. At 6 months after surgery, the arithmetic mean of SIA over corneal 4mm zone was 0.33 ± 0.19D for temporal incision, and 0.37 ± 0.25D for superior incision. For Group A, the correlations of HOAs and SIA persisted from 1 week to 6 months after surgery. For Group B, the changes in corneal HOAs were significantly related to the SIA at 1 week and 1 month postoperatively.

Conclusion

This study suggested the consistency of increasing and recovering process of corneal HOAs and SIA after surgery. Compared to the superior incisions, temporal incisions might induce quicker corneal recovery and less change in SIA and corneal HOAs.

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.

Functional Profile of a Customized Wound Parameter in Femtosecond Laser-Assisted Corneal Incision for Cataract Surgery

Purpose

To evaluate the performance of optimized parameters of femtosecond laser for cataract surgery corneal incisions regarding opening, patency and surgically induced astigmatism (SIA).

Patients and Methods

Patients scheduled for femtosecond laser-assisted cataract surgery between May 2018 and December 2018 were enrolled. Inclusion criteria were a healthy preoperative cornea and uneventful FLACS. Exclusion criteria were preoperative corneal astigmatism over 1.0 D, previous corneal trauma or pathologies. Clinical data were obtained from the electronic medical records. Surgical planning was based on Scheimpflug tomography images for keratometric data. At postoperative day 60, new keratometric evaluation was performed, obtained using the same device.

Results

101 eyes (61 patients) matched the criteria for SIA analysis. Overall mean SIA was 0.44 ± 0.33 D (0-1.55 D). Axis and size did not have any statistically significant effects on SIA. The overall centroid of the SIA was 0.11. For the opening analysis, was included 156 eyes (79 patients). Successful opening in 87.7% of cases (137 eyes). Temporal incisions had the highest success rate (98.36%).

Conclusion

These femtosecond laser parameters showed high opening rates with low opening times. These optimized parameters led to a low incidence of SIA and high predictability regardless of incision site and size. The association between incision opening and SIA was not statistically significant. There was, however, an association between incision opening success and site.

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.

Cataract surgery astigmatism incisional management. Manual relaxing incision versus femtosecond laser-assisted arcuate keratotomy. A systematic review

PURPOSE

This systematic review aims to compare corneal astigmatism correction in cataract surgery through corneal relaxing incision, manually and femtosecond laser assisted.

METHODS

The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations. We used PubMed, Scopus, and Web of Science (WOS) as databases from January 2010 to March 30, 2021. Patients with keratoconus, corneal ectasia, and a previous history of eye surgery were excluded because our aim was to analyze only healthy eyes.

RESULTS

A total of 1025 eyes were evaluated from 946 patients (mean age was 68.90 ± 5.12) in manual incision group articles, while 1905 eyes of 1483 patients (mean age was 65.05 ± 4.57) were evaluated in femtosecond laser arcuate keratotomy (FLAK) articles. The mean uncorrected distance visual acuity (UDVA) was 0.19 ± 0.12 and 0.15 ± 0.05 logMAR for manual incision and FLAK articles, respectively (p = 0.39). The mean correction index (CI) was similar in both groups: 0.77 ± 0.18 in manual incision and 0.79 ± 0.17 in femtosecond laser assisted incision (p = 0.70). Refractive stability was found after 3 months and no serious complications were reported during the follow-up in any group.

CONCLUSION

Both techniques are safe and moderately effective in corneal astigmatism correction in cataract surgery. FLAK represents a more precise and predictable approach. However, since visual and refractive outcomes appear to be similar in both cases, the cost-benefit analysis is controversial.

Effect of corneal incision features on anterior and posterior corneal astigmatism and higher-order aberrations after cataract surgery

PURPOSE

To evaluate the influence of 2.2 mm clear corneal incision (CCI) features in surgically induced astigmatism (SIA) and higher-order aberrations (HOAs) after cataract surgery.

METHODS

Right eyes of 92 subjects receiving 2.2 mm incision cataract surgery were involved. A total of 38 eyes were categorized as the intact incision group, and 54 eyes were the defective incision group. Pre- and postoperative (1 month and 6 months) corneal astigmatism and HOAs on anterior and posterior corneal surfaces, corneal volume, and corneal thickness (CT) were measured using Pentacam. The CCI features including incision length (IL), incision angles, distance from incision to central cornea (Dis-En/Ex), and CT at incision site were quantified using AS-OCT.

RESULTS

The defective incision group showed shorter IL and larger incision angles [false discovery rate (FDR) - p < 0.05]. Changes in CT at incision site were more pronounced for the defective incision group (FDR - p < 0.05). Some SIA parameters were related to the certain specific CCI features, especially IL (FDR - p < 0.05). Both groups exhibited significant increased 6 mm posterior corneal tHOAs at 1 month (Bonferroni corrected - p < 0.01) and the defective incision group showed increased 6 mm posterior tHOAs at 6 months (Bonferroni corrected - p = 0.023). There were characteristic correlations between Zernike terms and CCI features including IL, CT, Dis-En/Ex, and incision angles at 1 month, especially over 6 mm zone.

CONCLUSION

The CCI deformities can affect corneal recovery and induce more HOAs at 1 month postoperatively. Such effects became minor, but could persist until 6 months. The IL combined with Angle-En/Ex was important factor influencing CCI integrity and corneal optical quality.

Why Use Ultrashort Pulses in Ophthalmology and Which Factors Affect Cut Quality

The power density of femtosecond lasers and exposure time to the tissue are crucial for a successful procedure in terms of safety and precision. The reduction of the pulse duration allows reducing the quantity of the energy to be delivered to the tissue for disruption with strongly diminished mechanical and thermal collateral damage. The cutting effect of ultra-short pulses is very precise, minimally traumatic, safe, and predictable. Future developments will lead to further energy reductions to achieve optical breakdowns. However, the pulse length cannot be shortened arbitrarily because below 100 fs nonlinear effects can change the process in an unfavorable way. Compared to manual-conventional cataract surgery, femtosecond laser-assisted cataract surgery (FLACS) shows many advantages in clinical application, especially with regard to precision and tissue protection. The femtosecond laser has become particularly important and has made the overall procedure safer when we deal with complex cataract cases such as subluxated lenses. We provide an overview of the evolution of femtosecond laser technology for use in refractive and cataract surgeries. This article describes the advantages of available laser platforms with ultrashort pulses and mainly focuses on the technical and physical backgrounds of ophthalmic surgery technologies.

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.

Comparison between refractive outcomes of femtosecond laser-assisted cataract surgery and standard phacoemulsification

BACKGROUND

To compare the visual and refractive outcomes of femtosecond laser assisted cataract surgery (FLACS) using Victus platform (Technolas Bausch and Lomb (B&L), Munich, Germany) and conventional phacoemulsification cataract surgery (CPCS).

METHODS

A retrospective study of 100 eyes operated for cataract. FLACS was performed in 50 eyes and CPCS was done in another 50 eyes. Preoperative and 6 months postoperative visual and refractive evaluation (efficacy, safety, predictability, and surgically induced astigmatism) as well as higher-order aberrations were analyzed. Efficacy index which equals post-operative mean of uncorrected distance visual acuity (UDVA) divided by preoperative mean corrected distance visual acuity (CDVA) was calculated in both groups. Safety index equals post-operative mean of corrected distance visual acuity (CDVA) divided by preoperative mean CDVA.

RESULTS

Logarithm of the Minimum Angle of Resolution (LogMAR), UDVA improved in both groups after surgery (p < 0.05). It was 0.23 ± 0.20 and 0.291 ± 0.311 log MAR in FLACS and CPCS groups respectively. Safety index was 1.777 in FLACS group and 1.744 in CPCS groups showing high degree of safety of both measures. Mean surgically induced astigmatism (SIA) was 0.35 ± 0.67 D and 0.901 ± 0.882 D in FLACS and CPCS groups respectively (p = 0.015). The post-operative comparison between both groups was in favor of CPCS group vs. FLACS group regarding total aberrations (0.563 ± 0.386 vs. 0.91 ± 1.20) (p = 0.03), while low order aberrations were significantly less in FLACS group vs. CPCS group (0.64 + 0.63 vs. 2.07 + 3.15) (p = 0.027). RMS high order aberration was higher in FLACS group vs. CPCS group but of no statistical significance 0.54 ± 0.96 vs. 0.328 ± 0.360 (p = 0.082).

CONCLUSION

Femtosecond laser -assisted cataract surgery was a safe and precise procedure but enhanced visual outcomes only minimally when compared to conventional cataract surgery in experienced hands. Both FLACS and manual surgeries can achieve a high efficacy, predictability and safety with slight superior outcomes in FLACS.

TRIAL REGISTRATION NUMBER

PACTR201804003256258 (date: 27 Mar 2018) Available at: https://pactr.samrc.ac.za/.

Architecture evaluation of the main clear corneal incisions in femtosecond laser-assisted cataract surgery by optical coherence tomography imaging

Purpose

To assess the stability and reliability of femtosecond laser-assisted cataract surgery (FLACS) incisions design and dimensions using anterior segment optical coherence tomography (AS-OCT) imaging.

Setting

Renato Ambrósio Ophthalmologic Study Center from Hospital Oftalmológico de Brasília, Brasília, Brazil.

Design

Prospective nonrandomized controlled case series.

Methods

Eyes undergoing FLACS with triplanar main temporal clear corneal incision (CCI) were evaluated at the end of the case. Eyes that required any incision hydration, surgical complications or lacked follow-up were excluded. The AS-OCT was performed after femtosecond delivery; at the end of the case; at 1 day and at 30 days after surgery. Data of pachymetry, endothelial and epithelial gaps, Descemet detachment and CCI architecture were compared.

Results

Eleven eyes from 11 patients completed follow-up. Corneal thickness was statistically different between after femtosecond delivery and the end of the case (P-value <0.05), but without difference compared to 30 days evaluation. There was an increase of Descemet detachments (P-value <0.05) and endothelial gaps (P-value =0.0133) at the end of the case compared to post-femtosecond delivery. As for the architecture of the CCI, significant difference was found between the parameters of entry angle and exit angle measured with AS-OCT and the programmed.

Conclusion

The AS-OCT was capable of visualizing changes in the cornea at the CCI. Despite the stress caused by manipulation, results indicated good stability of incision and reproducibility of tunnel length.

Synopsis

Difference of corneal thickness at the CCI between after femtosecond and after phacoemulsification measurements (P-value <0.05), with increase of endothelial gaps (P-value =0.0133) and Descemet detachments (P-value <0.05).

Factors affecting corneal incision position during femtosecond laser-assisted cataract surgery

PURPOSE

To compare the expected versus actual position and dimension of corneal incisions during femtosecond laser-assisted cataract surgery.

SETTING

Private Ophthalmic Clinic, Sydney, NSW, Australia.

DESIGN

Retrospective case series.

METHODS

Video recordings of femtosecond laser-assisted cataract surgery with a Lensx laser were reviewed. The deviation of the main and 2 secondary incisions from the expected position were correlated with globe tilt, globe displacement, and biometric data. The globe tilt was inferred from anterior capsule tilt. Globe displacement was measured. The Softfit contact lens thickness used in the patient interface was measured separately.

RESULTS

The primary incision internal and external exits were within 142 μm ± 70 (SD) and 151 ± 75 μm of the planned position. The dimensions and position did not correlate with biometric variables. The superior secondary incision external exit was displaced centrally (321 ± 84 μm) and the internal exit was displaced peripherally (84 ± 102 μm). The inferior secondary incision external exit was displaced centrally (278 ± 142 μm) and the internal exit was displaced peripherally (190 ± 133 μm). Multivariate analysis showed that the external and internal exits of the superior (adjusted r² = 0.36, P < .001; r² = 0.15, P < .001) and inferior secondary incisions (r² = 0.67, P < .001; r² = 0.46, P < .001) correlated with globe tilt and displacement.

CONCLUSIONS

The primary incisions were close to the expected dimensions. The secondary incision position was affected by eye tilt and eccentric docking. These could potentially be improved with optical coherence tomography guidance.

Cataract Surgery Performed by High Frequency LDV Z8 Femtosecond Laser: Safety, Efficacy, and Its Physical Properties

Background: The aim of our study was to investigate the safety and efficacy of the LDV Z8 femtosecond laser in cataract surgery compared to the conventional procedure. Methods: This prospective study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. The study included 130 eyes from 130 patients: 68 treated with femtosecond laser-assisted cataract surgery (FLACS) using the FEMTO LDV Z8 and 62 treated with conventional phacoemulsification. Capsulotomy and lens fragmentation in the laser group were performed with the FEMTO LDV Z8 femtosecond laser system, which employs a new, low-energy, high repetition rate laser process for cataract surgery. In the conventional group, the capsulotomy was performed by a cystotome, and lens fragmentation was achieved by the stop-and-chop. Results: Ease of phacoemulsification (on a 4-point scale), the completeness of capsulotomy (on a 10-point scale), effective phacoemulsification time (seconds), uncorrected distance visual acuity (UCVA), best spectacle-corrected distance visual acuity (BSCVA), spherical equivalent (SE), and safety of the procedure were evaluated. The total follow-up time was three months. Conclusions: FLACS with the FEMTO LDV Z8 system was characterized by complete and reproducible capsulotomy and highly effective lens fragmentation. Postoperative visual outcomes were excellent, and the safety of the procedure was optimal.

A Review of Laser-Assisted Versus Traditional Phacoemulsification Cataract Surgery

The use of femtosecond laser surgery improves the precision and reproducibility of corneal incisions and the capsular opening; it also reduces the amount of ultrasound energy required for lens nucleus work-up. The rate of complications reported so far appears to be low. There are a number of contraindications such as a history of cornea and/or glaucoma surgery and certain anatomical features like deep-set eyes, kyphosis, tremor, and obesity. Visual recovery and refractive results of both techniques are excellent. Comparing laser cataract surgery (LCS) with manual cataract surgery (conventional phacoemulsification) based on meta-analysis currently reveals slight differences in refractive and visual outcome. Both methods are extremely successful and safe. LCS is a technique still on the rise, with its full potential not yet tapped.

To assess surgical outcomes of combined femtosecond laser-assisted cataract surgery with 25-gauge vitrectomy surgery at a tertiary eye care center

Background:

The aim of this study was to assess the surgical outcomes of combined femtosecond laser-assisted cataract surgery (FLACS) with 25-gauge vitrectomy surgery.

Materials and Methods:

A retrospective analysis of 45 patients who underwent combined FLACS with 25-gauge vitrectomy surgery.

Results:

A total number of 45 eyes of 45 patients were treated with a mean age of 63.27 years (range 45–75). The mean follow-up was 3 months (range 3–12 months). The mean preoperative best-corrected visual acuity was 1.47 ± 0.86. The mean postoperative vision was 0.36 ± 0.36 and 0.275 ± 0.184 at a paired t-test revealed a statistically significant improvement in visual acuity at 1 month (P < 0.001) and 3 months (P < 0.001). The most common indication for surgery was full-thickness macular hole (51.1%), vitreous hemorrhage (24.4%), followed by epiretinal membrane (17.7%) and rhegmatogenous retinal detachment (4.4%).

Conclusion:

Combining FLACS with vitrectomy may be a step toward achieving better outcomes when combined CS and vitrectomy is performed.

Comparison of surgically induced astigmatism between femtosecond laser and manual clear corneal incisions for cataract surgery

PURPOSE

To assess the surgically induced corneal astigmatism (SIA) introduced by femtosecond laser-assisted clear corneal incisions (CCIs) for cataract extraction and to compare it with the SIA of manually created CCIs.

SETTING

Bascom Palmer Eye Institute, Miller School of Medicine, Miami, Florida, USA.

DESIGN

Prospective nonrandomized comparative case series.

METHODS

Eyes received femtosecond laser-assisted CCIs (Group 1) or manual CCIs (Group 2). The surgical plan included 1 primary and 1 secondary port; the sites of the incisions were the same in both groups and were diametrically opposed between the right eye and left eye. The SIA was assessed using the preoperative and 1-month postoperative keratometric values obtained from corneal topography examinations.

RESULTS

This study included 72 eyes of 68 patients with a mean age of 69.0 years ± 9.87 (SD) (range 36 to 90 years). Thirty-six eyes received femtosecond laser-assisted CCIs (Group 1) and 36 received manual CCIs (Group 2). The mean preoperative topographic corneal astigmatism was -1.19 ± 0.68 diopters (D) (range 0 to 2.50 D) and -0.92 ± 0.63 D (range 0.10 to 2.45 D) for Group 1 and Group 2, respectively, whereas, 1 month after cataract surgery, it was -1.16 ± 0.63 D (range 0.20 to 2.57 D) and -0.95 ± 0.64 D (range 0.21 to 2.37 D), respectively. Multivariate vector analysis revealed no statistically significant difference between the 2 groups for preoperative astigmatism, postoperative astigmatism, and SIA (P > .05 for all comparisons between Group 1 and Group 2).

CONCLUSION

Femtosecond laser-assisted and manual corneal incisions for cataract surgery did not appear to significantly alter corneal astigmatism, whereas they showed comparable SIA.

FINANCIAL DISCLOSURE

Drs. Yoo and Donaldson are speakers for and consultants to Alcon Surgical, Inc., and Abbott Medical Optics, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Standard manual capsulorhexis / Ultrasound phacoemulsification compared to femtosecond laser-assisted capsulorhexis and lens fragmentation in clear cornea small incision cataract surgery

Background

Femtosecond-laser assisted clear cornea cataract surgery may hold promise in safer and more effective procedures. We decided to perform a comparative study to standard manual incision phacoemulsification surgery.

Methods

This is a single-center, single-intervention, and prospective comparative data evaluation of 133 consecutive cases subjected to cataract surgery. Group-A (Phaco), manual capsulorhexis & ultrasound phacoemulsification (n = 66); Group-B femtosecond-laser assisted capsulorhexis and lens fragmentation (n = 67), employing the LenSx laser (Alcon Surgical, Ft. Worth, TX). All cases were evaluated for refraction, visual acuity, keratometry, tomography, pachymetry, endothelial cell counts, intraocular pressure, and type of intraocular lens (IOL) implanted. The groups were matched for age, gender, pre-operative vision metrics, and cataract grade, and were followed up to 1 year.

Results

In group-A post-operative uncorrected distance visual acuity (UDVA) was 20/20 or better in 61.5 % and 20/25 or better in 78.5 % of the eyes. The femtosecond laser group-B had improved outcomes (p = 0.075 and p = 0.042, respectively): post-operative UDVA was 20/20 or better in 62.7 % of the eyes and 20/25 or better in 85.1 %.

Linear regression scatterplots of achieved versus attempted spherical equivalent had excellent regression coefficients (r² = 0.983 in group-A and 0.979 in group-B). There were 75.2 % cases in group-A and 80.6 % in group-B (p = 0.8732) within ±0.50 D of targeted refractive equivalent. Slight trend of under-correction was noted in group-A. Average residual manifest cylinder in the toric subgroup-A was -0.50 D (95 % Limit-of-Agreement (LoA) = -0.78 D), and in toric subgroup-B -0.45 D (LoA = -0.45 D).

Conclusions

Mean spherical equivalent refraction and visual acuity are comparable with laser cataract surgery compared with manual capsulorhexis & ultrasound phacoemulsification. Improved astigmatism correction may be among the benefits of femtosecond laser–assisted cataract surgery. Transient corneal edema may be a first day transient disadvantage in femtosecond laser–assisted cataract surgery.

Correlation between anterior chamber characteristics and laser flare photometry immediately after femtosecond laser treatment before phacoemulsification

PurposeTo assess the anterior chamber (AC) characteristics and its correlation to laser flare photometry immediately after femtosecond laser-assisted capsulotomy and photodisruption.Patients and methodsThe study included 97 cataract eyes (n=97, mean age 68.6 years) undergoing femtosecond laser-assisted cataract surgery (FLACS). Three cohorts were analysed relating to the flare photometry directly post femtosecond laser treatment (flare <100 n=28, 69.6±7 years; flare 100-249 n=47, 67.7±8 years; flare >249 photon counts per ms cohort n=22, 68.5±10 years). Flare photometry (KOWA FM-700), corneal topography (Oculus Pentacam, Germany: AC depth, volume, angle, pachymetry), axial length, pupil diameter, and endothelial cells were assessed before FLACS, immediately after femtosecond laser treatment and 1 day postoperative (LenSx Alcon, USA). Statistical data were analysed by SPSS v19.0, Inc.ResultsThe AC depth, AC volume, AC angle, central and thinnest corneal thickness showed a significant difference between flare <100 vs flare 100-249 10 min post femtosecond laser procedure (P=0.002, P=0.023, P=0.007, P=0.003, P=0.011, respectively). The AC depth, AC volume, and AC angle were significantly larger (P=0.001, P=0.007, P=0.003, respectively) in the flare <100 vs flare >249 cohort 10 min post femtosecond laser treatment.ConclusionsA flat AC, low AC volume, and a narrow AC angle were parameters associated with higher intraocular inflammation. These criteria could be used for patient selection in FLACS to reduce postoperative intraocular inflammation.

Comparison of visual recovery and refractive stability between femtosecond laser-assisted cataract surgery and standard phacoemulsification: six-month follow-up

PURPOSE

To compare visual recovery and refractive changes between femtosecond laser-assisted cataract surgery and standard cataract surgery.

SETTING

Center for Vision Science, Ruhr University Eye Clinic, Bochum, Germany.

DESIGN

Prospective randomized intraindividual cohort study.

METHODS

Eyes were treated with femtosecond laser-assisted cataract surgery or conventional phacoemulsification using pulsed ultrasound energy. Both groups had intraocular lens (IOL) implantation. The manifest refraction, corrected distance visual acuity, and anterior chamber depth were determined preoperatively and 2 hours, 3 to 4 days, 1 week, and 1, 2, 3, and 6 months postoperatively to determine the achieved deviation from target refraction, IOL position, and refractive stability.

RESULTS

One hundred eyes of 100 patients were treated with femtosecond laser-assisted cataract surgery; the fellow 100 eyes had conventional phacoemulsification. Six months postoperatively, 196 eyes were included and analyzed. At 6 months, 90 eyes (92%) in the femtosecond laser-assisted group and 70 eyes (71%) in the conventional group were within ±0.50 D of the target refractive outcome and 98 eyes (100%) in both groups were within ±1.00 D. The mean refractive spherical equivalent showed no significant change between 1 week and 1 month in the femtosecond laser-assisted group and between 1, 2, 3, and 6 months postoperatively in both groups.

CONCLUSION

Femtosecond laser-assisted cataract surgery yielded faster visual recovery, less deviation from the target refraction, and earlier stabilization of refraction.

FINANCIAL DISCLOSURE

Dr. Dick is a member of the medical advisory board of Abbott Medical Optics, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

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.

[Femtosecond laser-assisted cataract surgery]

Femtosecond laser-assisted cataract surgery is a major technological innovation. The femtosecond laser, during a pretreatment step, helps to prepare the patient's eye for the surgery proper by creating corneal incisions, anterior capsulotomy and lens fragmentation in an automated fashion. Thus, these steps can be performed with precision and reproducibility, and lens fragmentation reduces the amount of ultrasound required during surgery. Drawbacks of this technology are a longer operating time, a more demanding surgical procedure and a much higher cost for patients and surgical centers. New models of organization in the operating room, patient flow, and financial systems have to be designed to adapt this procedure to our practice. The benefits of this technology should make it an essential tool in the future, provided that cataract surgery can be reconsidered logistically and economically.

The evolution of corneal and refractive surgery with the femtosecond laser

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

First experience with the new high-frequency femtosecond laser system (LDV Z8) for cataract surgery

Background

The purpose of this work is to report our experience using the new Z8 laser system for femtosecond laser-assisted cataract surgery (FLACS) and to provide a sample of the performance and safety results using this new technology.

Methods

This prospective observational study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. Fourteen patients were subjected to unilateral FLACS. Capsulotomy and lens fragmentation were performed with the aid of the LDV Z8 femtosecond laser system. Ease of phacoemulsification (on a 4-point scale), completeness of capsulotomy (on a 10-point scale), time for preparation of femtosecond laser (minutes), effective phacoemulsification time (seconds), total duration of surgery (minutes), and safety of the procedure were evaluated.

Results

Ease of fragmentation and completeness of capsulotomy were estimated at 3.9 and 9.9, respectively. The preparation time for femtosecond was 3.6±0.7 minutes, effective phacoemulsification time was 2.5±3.1 seconds, and total duration of the FLACS procedure was 16.3±4.5 minutes. No major complications were observed. Approximately 42% of all patients (6/14) showed Descemet’s folds directly postoperatively.

Conclusion

FLACS with the LDV Z8 system was characterized by complete capsulotomy and highly effective and reproducible lens fragmentation. The safety of the procedure was very good as perceived by the surgeon operating in this observational case series. The cost to benefit ratio should be further debated by assessing the results of a major prospective study, which is required for valid evaluation of the efficiency and safety of the LDV Z8 laser system and of FLACS in general.

Evaluation of femtosecond laser-assisted and manual clear corneal incisions and their effect on surgically induced astigmatism and higher-order aberrations

PURPOSE

To evaluate femtosecond laser-assisted and manual clear corneal incisions and their effect on surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs).

METHODS

In a prospective randomized study, conventional phacoemulsification with a 2.8-mm clear corneal incision using a disposable keratome was performed in 20 eyes of 20 patients (manual group), and femtosecond laser-assisted cataract surgery with a 2.8-mm biplanar clear corneal tunnel created by a femtosecond laser (LenSx; Alcon Laboratories, Inc., Aliso Viejo, CA) was performed in 20 eyes of 20 patients (femtosecond laser group). Corneal topography readings and corneal wavefront aberrations (diameter: 9.0 mm) were obtained using a Scheimpflug camera (Pentacam HR; Oculus Optikgerate, Wetzlar, Germany) preoperatively and 3 months postoperatively.

RESULTS

There was no significant difference in SIA between the groups (femtosecond laser group: 0.47 ± 0.13 vs manual group: 0.41 ± 0.14; P = .218), but the axis deviation of the SIA axis from the previously planned axis was significantly smaller in the femtosecond laser group compared to the manual group (4.47°± 2.59° vs 7.38°± 4.72°, respectively; P = .048). Corneal HOAs increased significantly in both groups (femtosecond laser group: 0.13 ± 0.09 to 0.18 ± 0.12, P = .025; manual group: 0.13 ± 0.05 to 0.15 ± 0.05, P = .002), but preoperative and postoperative values did not differ significantly between them (P = .472 and .078, respectively). Lower-order and total corneal aberration values remained stable in both groups (P > .05).

CONCLUSIONS

There was no difference in SIA and induced HOAs between manual and femtosecond laser-created clear corneal incisions.

Femtosecond laser cataract surgery: updates on technologies and outcomes

PURPOSE

To describe femtosecond laser cataract surgery and discuss the published peer-reviewed articles to have a fair evaluation of this new technology and its comparisons to conventional phacoemulsification surgery.

METHODS

The technology information released in this article comes from the key individuals in each of the U.S. Food and Drug Administration-approved companies and from the available commercial information. Bibliographic research was performed in PubMed and MEDLINE for the published prospective or retrospective clinical studies.

RESULTS

The femtosecond laser has been reported to be safe intraoperatively and postoperatively, with less cornea and macula effect than conventional phacoemulsification. The incision is integrated, stable, and aberration free. Many studies reported the high precision of the capsulotomy over manual continuous curvilinear capsulorhexis, which favors less intraocular lens tilt, higher optical quality, and more accurate premium intraocular lens centration. The lens fragmentation is effective with significant reduction of the phacoemulsification power and effective phacoemulsification time. The refractive difference between femtosecond laser and standard phacoemulsification is minimal, with no difference in corrected distance visual acuity, but the optical quality and the internal aberrations results are significantly better for femtosecond laser phacoemulsification.

CONCLUSIONS

Femtosecond laser cataract surgery is a good addition to cataract surgery despite its few remarkable advantages among experienced phacoemulsification surgeons.

Histologic Evaluation of in vivo Femtosecond Laser–Generated Capsulotomies Reveals a Potential Cause for Radial Capsular Tears

Purpose

To compare histologically the size and appearance of capsule disks after femtosecond laser–assisted cataract surgery and conventional cataract surgery.

Methods

In 100 eyes of 100 patients with visually significant cataracts, a femtosecond laser capsulotomy or a capsulorhexis with an aimed diameter of 5.0 mm was performed by one experienced surgeon. The diameter, area, circularity, and cut quality was histologically examined with light microscopy and scanning electron microscopy.

Results

The mean diameter of the manual and the femtosecond laser capsule disk group were not statistically significantly different (manual 4.91 ± 0.34; femtosecond: 4.93 ± 0.03; p = 0.58). The mean area of the capsule disks was 18.85 ± 2.69 mm2 in the manual and 19.03 ± 0.26 mm2 in the femtosecond group (p = 0.64). The capsules of the femtosecond group (0.95 ± 0.02) were significantly more circular than the ones of the manual group (0.81 ± 0.07; p<0.0001). The femtosecond laser capsule disks displayed a more saw blade–like structure created through the single laser spots. The histologic examination combined with prospective video analysis revealed respiratory movement of the eye during the capsulotomy as a potential risk factor for redial tears.

Conclusions

Femtosecond laser can perform a capsulotomy with high reliability. In comparison to a highly experienced cataract surgeon, the achieved results in size are similar. In terms of circularity, the femtosecond laser was superior the manual procedure. Better refractive outcomes based on a 360°-degree optic overlap seem to be possible, especially for less experienced surgeons.

New technology update: femtosecond laser in cataract surgery

Femtosecond lasers represent a new frontier in cataract surgery. Since their introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented regarding capsulotomy, fragmentation of the crystalline lens, corneal wound creation, and refractive results. Safety issues such as endothelial and macular changes are also discussed. The most important advantage of femtolaser cataract technology at present is that all the important surgical steps of cataract surgery can be planned and customized, delivering unparalleled accuracy, repeatability, and consistency in surgical results. The advantages of premium lenses can be maximally used in visual and presbyopia restoration as well. The advantages of premium lenses can be maximally used, not only in visual, but in presbyopia restoration as well. Quality of vision can be improved with less posterior chamber lens (PCL) tilt, more centralized position of the PCL, possibly less endothelial damage, less macular edema, and less posterior capsule opacification (PCO) formation. This technological achievement should be followed by other technical developments in the lens industry. Hopefully this review article will help us to understand the technology and the results to demonstrate the differences between the use of femtolasers and phacoemulsification-based cataract surgery. The most important data of the literature are summarized to show ophthalmologists the benefits of the technology in order to provide the best refractive results to the patient.

Preliminary Investigation of Corneal Wavefront Aberration following Femtosecond Laser Clear Corneal Incision for Cataract Surgery

Purpose

To investigate the early changes of the anterior corneal wavefront aberration (WA) following femtosecond laser clear corneal incision (FS-CCI) for cataract surgery.

Methods

Twenty consecutive patients (20 eyes) with cataract underwent phacoemulsification and were divided into 2 groups: the study group received a 2.75-mm FS-CCI using an iFS Intralase; the control group received a 2.75-mm manual CCI using disposable knives. High-order corneal WA was analyzed over 3.5- and 6.0-mm pupils and corneal astigmatism was evaluated using vector analysis pre-operatively, 1 week postoperatively, and 1 month postoperatively.

Results

At 1 month postoperatively, the mean surgically induced astigmatism (D) of the anterior cornea was 1.22 ± 0.60 at 144° and 1.04 D ± 0.64 at 90° in the study and control groups (p<0.05), respectively. Over 3.5-mm pupil, there were no changes of corneal high-order aberrations (p>0.05) following FS-CCI. Trefoil increased significantly (p<0.01) following manual CCI at 1 week postoperatively. Over 6.0-mm pupil, FS-CCI did not induce any statistically significant change in corneal WA during follow-up. One week after manual CCI, total root mean square–high order aberrations (p<0.01), spherical aberration (p<0.05), and trefoil (p<0.001) were statistically significantly higher than pre-operatively.

Conclusions

The CCI method was shown to influence changes in corneal WA during the first month postoperatively. The different changes of corneal high-order WA between the study and control groups may depend on the different CCI geometry. These preliminary data are valuable to improve understanding of FS-CCI design.