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

Comparison of short-term clinical outcomes of a diffractive trifocal intraocular lens with phacoemulsification and femtosecond laser assisted cataract surgery

PURPOSE

To evaluate short-term visual and refractive outcomes after implantation of a diffractive trifocal intraocular lens (IOL) in cataract patients with phacoemulsification (PHACO) and femtosecond laser assisted cataract surgery (FLACS).

SETTING

Department of Ophthalmology, Shanghai Aier Eye Hospital, China.

DESIGN

A retrospective, observational study.

METHODS

Patients who underwent cataract surgery combined with Acrysoft IQ PanOptix trifocal IOL implantation were enrolled and divided into three groups: PHACO group, LAstig-FLACS group (astigmatism less then 1D) and HAstig-FLACS group (astigmatism more than 1D). Logarithm of the minimum angle of resolution (logMAR) visual acuity of uncorrected distance (UDVA), intermediate (UIVA), near visual (UNVA), defocus curve, surgically induced astigmatism (SIA) were evaluated in 1 months postoperatively and wavefront aberrations were evaluated in 6 months.

RESULTS

101 eyes of 60 patients were included with 31 eyes in PHACO group, 45 eyes in LAstig-FLACS group and 25 eyes in HAstig-FLACS group. Significant difference was found of internal Strehl Ratio (SR) between PHACO and LAstig-FLACS group (P = 0.026). In PHACO group, 79.31%, 86.21%, 72.41% of eyes gain visual acuity LogMAR 0.1 or more in UDVA, UIVA and UNVA, while 83.72%, 93.02%, 93.02% of those in LAstig-FLACS group and 92.00%, 84.00%, 76.00% in HAstig-FLACS group.

CONCLUSIONS

Panoptix diffractive trifocal IOL provides satisfied visual outcome in no matter FLACS or PHACO. Besides, trifocal IOL implantation via FLACS can provide a better accumulative visual acuity outcome at all distance than PHACO in 1 month. Femtosecond laser assisted limbal relaxing incisions (FLLRIs) is an excellent way to reduce a patient's corneal astigmatism.

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.

Femtosecond laser-assisted cataract surgery versus conventional phacoemulsification: A meta-analysis of randomized controlled trials

PURPOSE

The main purpose of our study is to compare the adverse events occurrence, complications, and postoperative outcomes of Femtosecond Laser-Assisted Cataract Surgery (FLACS) versus conventional phacoemulsification surgery (CPS) in adult patients undergoing cataract surgery.

METHODS

We conducted our research using PubMed, Scopus, and MEDLINE through EBSCOhost from 2012 to July 2022 with English and Spanish language restriction, including only Randomized Controlled Trials (RCTs). The PRISMA guidelines were observed for data abstraction, including a random-effects model for each outcome.

RESULTS

We analyzed 4844 eyes from 23 RCTs with some low risk of bias according to RoB 2 tool. We found statistically significant differences between the FLACS and CPS groups for the mean absolute error (MD = -0.12, 95% CI:-0.22-[-0.02], p = 0.01), the circularity of capsulorhexis (MD = 0.04, 95% CI: 0.04-0.05, p ≤ 0.00001), IOL centration (D = -0.07, 95% CI:-0.09-[-0.05], p ≤ 0.00001), CDE count (MD = -1.75, 95% CI: -2.75-[-0.74], p = 0.0006), mean phacoemulsification time (MD = -12.90, 95% CI:-20.89-[-4.92], p = 0.002), EPT (MD = -0.93, 95% CI: -1.68-[-0.019], p = 0.01) and endothelial cell density loss ((MD = -0.6, 95% CI: -1-[-0.19], p = 0.004). Also, the safety analysis showed a lower incidence of posterior capsule tear (PCT) in the FLACS group (OR =0.29, 95% CI: 0.09-1, p = 0.05).

CONCLUSIONS

Our results suggest that FLACS might be helpful for patients with relatively dense cataracts and low preoperative endothelial cell values.

Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery

BACKGROUND

Cataract is the leading cause of blindness in the world and, as such, cataract surgery is one of the most commonly performed operations globally. Surgical techniques have changed dramatically over the past half century with associated improvements in outcomes and safety. Femtosecond lasers can be used to perform the key steps in cataract surgery, such as corneal incisions, lens capsulotomy and fragmentation. The potential advantage of femtosecond laser-assisted cataract surgery (FLACS) is greater precision and reproducibility of these steps compared to manual techniques. The disadvantages are the costs associated with FLACS technology.

OBJECTIVES

To compare the effectiveness and safety of FLACS with standard ultrasound phacoemulsification cataract surgery (PCS) by gathering evidence from randomised controlled trials (RCTs).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 5); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov; the WHO ICTRP and the US Food and Drug Administration (FDA) website. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 10 May 2022.

SELECTION CRITERIA

We included RCTs where FLACS was compared to PCS.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened the search results, assessed risk of bias and extracted data using the standard methodological procedures expected by Cochrane. The primary outcome for this review was intraoperative complications in the operated eye, namely anterior capsule, and posterior capsule tears. The secondary outcomes included corrected distance visual acuity (CDVA), quality of vision (as measured by any validated patient-reported outcome measure (PROM)), postoperative cystoid macular oedema complications, endothelial cell loss and cost-effectiveness. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 42 RCTs conducted in Europe, North America, South America and Asia, which enrolled a total of 7298 eyes of 5831 adult participants. Overall, the studies were at unclear or high risk of bias. In 16 studies the authors reported financial links with the manufacturer of the laser platform evaluated in their studies. Thirteen of the studies were within-person (paired-eye) studies with one eye allocated to one procedure and the other eye allocated to the other procedure. These studies were reported ignoring the paired nature of the data. There was low-certainty evidence of little or no difference in the odds of developing anterior capsular tears when comparing FLACS and PCS (Peto odds ratio (OR) 0.83, 95% confidence interval (CI) 0.40 to 1.72; 5835 eyes, 27 studies) There was one fewer anterior capsule tear per 1000 operations in the FLACS group compared with the PCS group (95% CI 4 fewer to 3 more).  There was low-certainty evidence of lower odds of developing posterior capsular tears with FLACS compared to PCS (Peto OR 0.50, 95% CI 0.25 to 1.00; 5767 eyes, 26 studies). There were four fewer posterior capsule tears per 1000 operations in the FLACS group compared with the PCS group (95% CI 6 fewer to same).  There was moderate-certainty evidence of a very small advantage for the FLACS arm with regard to CDVA at six months or more follow-up, (mean difference (MD) -0.01 logMAR, 95% CI -0.02 to 0.00; 1323 eyes, 7 studies). This difference is equivalent to 1 logMAR letter between groups and is not thought to be clinically important. From the three studies (1205 participants) reporting a variety of PROMs (Cat-PROMS, EQ-5D, EQ-SD-3L, Catquest9-SF and patient survey) up to three months following surgery, there was moderate-certainty evidence of little or no difference in the various parameters between the two treatment arms. There was low-certainty evidence of little or no difference in the odds of developing cystoid macular oedema when comparing FLACS and PCS (Peto OR 0.84, 95% CI 0.56 to 1.28; 4441 eyes, 18 studies). There were three fewer cystoid macular oedema cases per 1000 operations in the FLACS group compared with the PCS group (95% CI 10 fewer to 6 more).  In one study the incremental cost-effectiveness ratio (ICER) (cost difference divided by quality-adjusted life year (QALY) difference) was GBP £167,620 when comparing FLACS to PCS. In another study, the ICER was EUR €10,703 saved per additional patient who had treatment success with PCS compared to FLACS. Duration ranged from three minutes in favour of FLACS to eight minutes in favour of PCS (I2 = 100%, 11 studies) (low-certainty evidence).  There was low-certainty evidence of little or no important difference in endothelial cell loss when comparing FLACS with PCS (MD 12 cells per mm2 in favour of FLACS, 95% CI -40 to 64; 1512 eyes, 10 studies).  AUTHORS' CONCLUSIONS: This review of 42 studies provides evidence that there is probably little or no difference between FLACS and PCS in terms of intraoperative and postoperative complications, postoperative visual acuity and quality of life. Evidence from two studies suggests that FLACS may be the less cost-effective option. Many of the included studies only investigated very specific outcome measures such as effective phacoemulsification time, endothelial cell count change or aqueous flare, rather than those directly related to patient outcomes. Standardised reporting of complications and visual and refractive outcomes for cataract surgery would facilitate future synthesis, and guidance on this has been recently published.

Managing low corneal astigmatism in patients with presbyopia correcting intraocular lenses: a narrative review

Cataract surgery has become a refractive procedure in which emmetropia is the goal, with the implantation of extended depth-of-focus or multifocal intraocular lenses (IOLs) being the commonly selected option to restore vision beyond the far distance. The selection criteria for implanting these lenses can differ from those for monofocal IOLs and even between technologies, as eye characteristics can affect postoperative visual performance. Corneal astigmatism is an eye characteristic that can affect visual performance differently, depending on the implanted IOL. The magnitude of corneal astigmatism, the tolerance of the IOL to this astigmatism, economic aspects, comorbidities, and the efficacy of astigmatism treatment are factors that can make surgeons' doubt as to what astigmatism treatment should be applied to each patient. This review aims to summarize the current evidence related to low astigmatism tolerance in presbyopia-correcting lenses, the efficacy achieved through corneal incisions, and their comparison with the implantation of toric IOLs.

Predictors of Femtosecond Laser-Assisted Arcuate Keratotomy Efficacy for Astigmatism Correction in Cataract Surgery

PURPOSE

To evaluate the predictors related to the efficacy of epithelium- and Bowman membrane-penetrating femtosecond laser-assisted arcuate keratotomy (FSAK) in the treatment of preoperative astigmatism in patients with cataracts and to clarify the predictive role of the incision-to-limbus distance.

METHODS

This retrospective study included patients who underwent femtosecond laser-assisted cataract surgery combined with FSAK using the LenSX platform (Alcon Laboratories, Inc) at Beijing Aier-Intech Eye Hospital from March 2017 to December 2021. The Lenstar LS900 (Haag-Streit, Inc) was used to measure the horizontal corneal diameter, and ImageJ software (National Institutes of Health) was used to measure the vertical corneal diameter and incision-to-limbus distance. Finally, the measured values were converted. Changes in corneal astigmatism before and 3 months after surgery were analyzed using Alpins vector analysis. Correlation analysis and regression analysis were used to evaluate the factors associated with surgically induced astigmatism (SIA) in preoperative ocular biometric parameters.

RESULTS

The study included 94 eyes of 94 patients. The mean target induced astigmatism was 1.36 ± 0.44 diopters (D), SIA was 0.82 ± 0.43 D, and mean difference vector was 0.70 ± 0.40 D. Pearson correlation analysis and univariate regression analysis showed that preoperative corneal astigmatism, arcuate keratotomy arc length, incision-to-limbus distance, and astigmatism type were significant predictors of SIA. Multiple variable regression analysis included parameters such as age, arcuate keratotomy arc length, and incision-to-limbus distance and established a multiple regression model of SIA (all P < .01).

CONCLUSIONS

The incision-to-limbus distance was a significant independent predictor of SIA, and inclusion of this parameter may further improve the accuracy of the nomogram. [J Refract Surg. 2022;38(8):480-486.].

Endothelial Cell Loss, Cumulative Dissipated Energy, and Surgically Induced Astigmatism in Sutureless Scleral Tunnel Phaco-Assisted Cataract Extraction in Advanced Cataracts

Purpose

To evaluate sutureless scleral tunnel phaco-assisted cataract extraction in regards to the cumulative dissipated energy (CDE) used, the resulting endothelial cell loss (ECL), and the surgically induced astigmatism (SIA) in advanced cataracts.

Methods

A prospective interventional uncontrolled case series was performed. Patients with advanced cataracts according to the Lens Opacities Classification System III (LOCS III) had sutureless scleral tunnel phaco-assisted cataract extraction. They were followed up one week, one month, and 3 months postoperatively for SIA and ECL. The used CDE was recorded.

Results

The study included 198 eyes: 36 eyes (18.2%) with LOCS III grade nuclear opalescence (NO4) cataracts, 102 eyes (51.5%) with LOCS III grade NO5, and 60 eyes (30.3%) with LOCS III grade NO6. Three months postoperatively, the mean SIA was 0.94 ± 0.71D. The endothelial cell density (ECD) was reduced significantly to 2341.31 ± 471 cells/mm² (p=0.0001) with a mean ECL of 5.39%. The mean CDE and ECL% were 0.174 ± 0.46 U/S (2.07%), 0.859 ± 0.42 U/S (5.01%), and 2.306 ± 0.89 U/S (8.01%) in LOCS III grade NO4, NO5, and NO6, respectively. The overall mean CDE was 1.17 ± 0.99 U/S, which was significantly correlated with the ECL (p=0.0001).

Conclusion

Sutureless scleral tunnel phaco-assisted cataract extraction in advanced cataracts enabled reduction in CDE with good preservation of the ECD and acceptable SIA.

Effect of Central Corneal Thickness on Corneal Higher Order Aberrations After Cataract Surgery

PURPOSE

To investigate the changes of corneal higher order aberrations (HOAs) before and after phacoemulsification in patients with different central corneal thickness (CCT).

METHODS

In this retrospective non-randomized, non- comparative cases series, 51 eyes of 51 patients who underwent phacoemulsification were enrolled. The corneal total HOAs and Zernike coefficients (3rd and 4th order) over the 3- and 4-mm zones were measured by the iTrace aberrometer (Tracey Technologies). Participants were divided into three groups (528 µm or less, 529 to 550 µm, and greater than 550 µm) depending on the CCT tested by the LenStar LS900 (Haag Streit AG). The corneal aberrations between groups were compared with analysis of variance, the variation of corneal aberrations before and after phacoemulsification was analyzed by the paired-samples t test, and generalized linear models were used to compare postoperative aberrations between groups.

RESULTS

Significant differences were found in oblique trefoil at 3 mm and vertical trefoil, oblique trefoil, and HOAs at 4 mm in the 528 µm or less group; vertical trefoil, oblique trefoil, oblique quadrafoil, and oblique secondary astigmatism at 3 mm and oblique trefoil and oblique secondary astigmatism at 4 mm in the 529 to 550 µm group; and vertical quadrafoil at 3 mm in the greater than 550 µm group. After corrected deviation of preoperative aberrations, there were significant differences in postoperative vertical coma and oblique secondary astigmatism at 4 mm when compared to the 528 µm or less and greater than 550 µm groups.

CONCLUSIONS

The lower the CCT, the greater the change in corneal aberrations in patients with cataract after phacoemulsification. Surgeons should be aware of the potential for worse visual quality related to surgically induced aberrations in patients with thin corneas. [J Refract Surg. 2021;37(12):842-847.].

Femtosecond laser-assisted cataract surgery versus conventional phacoemulsification: comparison of internal aberrations and visual quality

PURPOSE

To compare the internal aberrations and optical quality after femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS).

METHODS

This study included patients who received FLACS or CPCS from January 2016 to July 2019. Postoperative examinations included wavefront measurements under pupil diameters of 3.0 mm and 5.0 mm, intraocular lens (IOL) decentration, visual acuity (VA), and refractive outcomes. Visual quality was measured with Strehl ratio and modulation transfer function (MTF). Subgroup analyses were conducted based on monofocal or multifocal-extended depth of focus (EDOF) IOL.

RESULTS

The study consisted of 221 eyes (105 eyes in FLACS and 116 eyes in CPCS). With a pupil diameter of 5.0 mm, FLACS demonstrated a significantly lower root mean square of total internal aberration (P = 0.004), higher order aberrations (HOAs) (P = 0.034), tilt (P = 0.049), coma (P = 0.004), and spherical aberration (P = 0.014). IOL tilt was found to be positively correlated with total internal aberration (P < 0.001), HOAs (P < 0.001), and coma (P < 0.001). The FLACS group presented significantly smaller IOL decentration than the CPCS group (P < 0.001), but there were no significant differences in terms of VA and refractive outcomes between groups. In the multifocal-EDOF subgroup, Strehl ratio and MTF values were significantly higher in the femtosecond group with a 3.0-mm pupil.

CONCLUSION

FLACS induced significantly lower values of IOL tilt, decentration, and internal aberrations compared with the CPCS group with a pupil diameter of 5.0 mm, while no significant differences were found in the VA or optical quality over long-term observation.

TRIAL REGISTRATION

This trial was registered at www.chictr.org.cn (registration number ChiCTR2000038965).

The impact of limbus detection, arcus lipoides and limbal vessels on the primary patency of clear cornea incisions in femtosecond laser-assisted cataract surgery

PURPOSE

To analyse the factors influencing the primary patency of clear corneal incisions in femtosecond laser-assisted cataract surgery (FLACS).

METHODS

In this prospective single-centre study, the graphical user interfaces of 159 patients undergoing femtosecond laser-assisted cataract surgery were documented by video. Subsequently, the quality of limbus detection along with the incidence of vessels and an arcus lipoides were assessed by a grading system and analysed in relation to the primary patency of the incisions. In particular, the differences between a superior and a temporal main incision were analysed.

RESULTS

The designed grading system could be applied in all cases without any problems. Limbus detection was highly inhomogeneous but had no influence on the patency of the incisions (46.3% poor, 18.4% moderate, 35.1% good). The characteristics of the arcus lipoides had little influence on the patency of the main incisions. Pronounced vascular ingrowth caused more tissue bridges but did not reduce the patency of the incisions. Temporal access was generally easier to open than a superior one (97.1% versus 88.9%).

CONCLUSION

We showed a patency rate of superior FLACS incisions of over 97% with the Femto LDV Z8 in our study. Temporal main incision is preferable to superior main incision in more difficult situations. The new grading system is suitable for further studies to provide information on the quality of the incision.

Clinical outcomes and complications between FLACS and conventional phacoemulsification cataract surgery: a PRISMA-compliant Meta-analysis of 25 randomized controlled trials

AIM

To update and investigate the clinical outcomes and complications between femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS).

METHODS

A Meta-analysis was performed using databases, including Pubmed, Embase, and the Cochrane library. At least one of the clinical outcomes and/or complications data in each included randomized controlled trials (RCT) was reported. The quality of the RCT was assessed with the Cochrane risk assessments tool.

RESULTS

Overall, 25 RCTs including 3781 eyes were included. No statistically significant difference detected between FLACS and CPCS in terms of corrected distant visual acuity (CDVA), uncorrected distant visual acuity (UDVA), and central corneal thickness (CCT) at the long-term follow up, although FLACS showed better CDVA at 1wk postoperatively, and less increase in CCT at 1d and 1wk. FLACS had better postoperative endothelial cell count (ECC) at 1 and 4-6wk, while there was no significantly difference between FLACS and CPCS at 1d, 3 and 6mo [weighted mean difference (WMD): 51.54, 95% confidence interval (CI): -5.46 to 108.54, P=0.08; WMD: 48.52, 95%CI: -17.54 to 114.58, P=0.15; WMD: 12.17, 95%CI: -48.61 to 72.94, P=0.69, respectively]. Postoperative endothelial cell loss (ECL) of the FLACS was significantly lower than that of the CPCS at 1, 4-6wk, and 3mo (P=0.02, 0.008, 0.03, respectively). However, there was no significant difference between two groups at 6mo (WMD: -30.36, 95%CI: -78.84 to 18.12, P=0.22). No significant difference was discovered with respect to the macular edema [odds ratio (OR): 0.93, 95%CI: 0.42 to 2.05, P=0.85], capsular complication excluding posterior capsular tears (OR: 0.79, 95%CI: 0.42 to 1.50, P=0.47) and intraocular pressure change (OR: 0.82, 95%CI: 0.39 to 1.72, P=0.60). However, posterior capsular tears were more common in CPCS group (OR: 0.12, 95%CI: 0.01 to 0.98, P=0.05). The effective phacoemulsification times were significantly lower in the FLACS group compared to the CPCS group (WMD: -0.78, 95%CI: -1.23 to -0.34, P=0.0006).

CONCLUSION

No statistically significant difference is discovered between FLACS and CPCS in clinical outcomes at the long-term follow up. However, higher rate of posterior capsular tears is detected in patients receiving CPCS.

Morphologic features and surgically induced astigmatism of femtosecond laser versus manual clear corneal incisions

PURPOSE

To compare the morphologic features and surgically induced astigmatism (SIA) between laser and manual clear corneal incisions (CCIs) after femtosecond laser-assisted cataract surgery.

SETTING

Eye Center, 2nd Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China.

DESIGN

Prospective case series.

METHODS

Patients had femtosecond laser-assisted cataract surgery with a CCI created with the laser or manually after random allocation. The corrected distance visual acuity, corneal topography, and anterior segment optical coherence tomography were assessed at the 1-day, 1-week, 1-month, and 3-month follow-ups.

RESULTS

The laser CCI group comprised 45 eyes and the manual CCI group, 48 eyes. The SIA was significantly lower in the manual CCI group than the laser CCI group at all visits (P < .05). At the 1-day and 1-week follow-ups, the mean CCI thickness was significantly smaller in the manual CCI group (P < .05). In the laser CCI group, the perpendicular linear distance between the external wound opening and the corneal vertex central line was statistically shorter than in the manual CCI group (P < .05). At 3 months, the SIA was correlated with the perpendicular linear distance with a Pearson correlation coefficient of -0.341 (P = .001).

CONCLUSIONS

Femtosecond laser-created CCIs for cataract surgery caused more SIA than manually created CCIs, which could have resulted from inaccurate or uncertain corneal incision positioning of the femtosecond machine. Manual creation of CCIs is recommended in femtosecond laser-assisted cataract surgery until the locating system for the femtosecond laser incision is updated.

Comparison of Surgically Induced Astigmatism and Corneal Morphological Features Between Femtosecond Laser and Manual Clear Corneal Incisions

PURPOSE

To assess corneal morphologic changes and surgically induced astigmatism (SIA) following clear corneal incisions (CCIs) created manually or with the Catalys femtosecond laser (Johnson & Johnson Vision, Santa Ana, CA).

METHODS

In this retrospective cohort analysis, patients undergoing femtosecond laser-assisted cataract surgery (FLACS) or manual cataract surgery between June and September 2018 from a single surgical center in Toronto, Canada, were considered for inclusion. Postoperative corneal astigmatism values were compared to preoperative astigmatism indices to determine the SIA at the postoperative 3-month (POM3) mark using the Alpins vector method. Secondary outcomes included postoperative corrected distance visual acuity (CDVA), central corneal thickness (CCT), and CCI morphology parameters.

RESULTS

Refractive outcomes from 104 eyes of 61 patients (54 eyes in the manual group and 50 eyes in the FLACS group) were included. There was no significant difference in POM3 SIA (manual: 0.45 ± 0.28 diopters [D], FLACS: 0.57 ± 0.46 D, P = .11); however, a significantly larger SIA was noted in the FLACS cohort at postoperative 1 week (P = .02) and 1 month (P = .04). FLACS led to a significantly smaller POM3 CCI thickness (P = .006), and CCI position was comparable between the two techniques (P = .44). There were no significant differences between groups in CDVA (P = .19), CCT thickness (P = .20), or phacoemulsification time (P = .59).

CONCLUSIONS

There was no significant difference in SIA between FLACS and manual cataract surgery at POM3. With a significantly smaller CCI thickness seen in FLACS cases, and a comparable CCI position, the reason for the increased SIA following laser CCIs in the early postoperative period was unclear. [J Refract Surg. 2019;35(12):796-802.].

One-year follow-up of changes in refraction and aberrations induced by corneal incision

Purpose

To evaluate the surgically induced changes in refraction (sphere and astigmatism) and higher order aberrations by corneal incision for one year.

Setting

University Hospital “Virgen de la Arrixaca”, Murcia, Spain.

Design

Retrospective interventional case series.

Methods

Corneal power, astigmatism and higher order aberrations (HOA) were calculated from corneal topography measured in 27 eyes prior to surgery and at 2 weeks, 1, 2, 3 and 6 months and 1 year following cataract surgery with 3.2-mm corneal incision. At every stage, optical changes were calculated as the difference between pre- and post-surgery data (in each follow-up) using the formulas of obliquely crossed cylinders for the refraction and Zernikes coefficients for HOA.

Results

At 2 weeks after surgery the mean corneal values of induced sphere, cylinder and the root mean square (RMS) of HOA were +0.54±0.27 D, -0.77±0.32 D and 0.15 microns respectively. These parameters decreased significantly (p-values between 0 and 0.01) at 3 months to +0.33±0.27 D sphere, -0.50±0.24 D cylinder and 0.10±0.05 microns HOA and were stable at the next follow-ups. Induced spherical equivalent was around zero at all visits. The changes in HOA were mainly due to trefoil aberration.

Conclusions

Linear corneal incisions do not change the spherical power but can induce significant values of astigmatism and trefoil aberration in the cornea. However, these changes revert fully or partially to preoperative values by the third month after surgery and remain stable with time.

Correcting astigmatism at the time of cataract surgery: Toric IOLs and corneal relaxing incisions planned with an image-guidance system and intraoperative aberrometer versus manual planning and surgery

PURPOSE

To compare the outcomes of the combination of an image-guided system and intraoperative aberrometer with the surgeon's standard of care in correcting astigmatism using toric intraocular lenses (IOLs) or corneal incisions.

SETTING

Single site in United States.

DESIGN

Prospective case series.

METHODS

Contralateral eyes of patients having uncomplicated bilateral cataract surgery and astigmatism correction were randomly assigned to Group A or Group B. Group A received the surgeon's preferred standard of care. Group B had preoperative planning using an image-guidance system (VERION), intraoperative aberrometry (ORA System with VerifEye+), and femtosecond laser-assisted cataract surgery. The primary endpoint was the residual refractive astigmatism at 3 months.

RESULTS

Thirty-eight eyes were treated with toric IOLs and 40 eyes with corneal astigmatic incisions. On average, toric IOLs resulted in almost 0.25 diopter (D) less cylinder than corneal astigmatic incisions (P < .01), with no difference between groups (P = .41). There was no statistically significant difference in the mean spherical equivalent refraction by group (P = .51). At 3 months, the IOL in 4 eyes (11%) (2 in Group A and Group B each) was more than 10 degrees of absolute orientation from the intended orientation. The mean keratometry was 0.16 D higher with the image-guided system compared with optical biometry (Lenstar). The vector difference between the 2 measurements was 0.5 D or lower in all eyes.

CONCLUSIONS

The combined use of an image-guided system and intraoperative aberrometer did not significantly improve outcomes compared with the surgeon's standard of care. Based on keratometry, there was good agreement in corneal astigmatism measurements between the image-guided system and the optical biometer.

Assessment of surgeon experience with femtosecond laser-assisted cataract surgery

PURPOSE

To evaluate the collective user experience with an image-guided femtosecond laser (FSL) for cataract surgery in a high-volume, multi-surgeon, ambulatory surgical center.

SUBJECTS AND METHODS

A detailed online survey was distributed to all surgeons in a single ambulatory surgical center who had performed cataract surgery using a FSL since its acquisition in December 2012. Information collected included the number of cases performed, typical surgical techniques and parameters, satisfaction with individual features of the laser (rated on a scale from 1=completely unsatisfied to 10=extremely satisfied) and commentary on ease of use and suggested improvements.

RESULTS

Seventeen of 30 surgeons (56.7%) completed the survey, representing a case volume of 1,967 eyes. Fourteen surgeons (82.4%) felt they required ≤10 cases with the FSL to operate with the same safety and control as in standard phacoemulsification surgery. Satisfaction was highest for capsulotomies, lens fragmentation, lens softening, arcuate incisions and the graphic user interface (mean scores 9.4, 8.7, 8.7, 7.2 and 8.9, respectively). Preferred capsulotomy diameter was 4.8-5.2 mm (64.7% of respondents). About half (52.9%) of respondents centered the capsulotomy on the pupil and the other 47.1% centered the capsulotomy using optical coherence tomography. Most respondents (81.3%) preferred transepithelial arcuate incisions compared to intrastromal incisions. Satisfaction was lowest with FSL-created, main, clear corneal incisions and paracenteses (mean scores 4.4 and 4.2, respectively).

CONCLUSION

Laser-assisted cataract surgery has a short learning curve and a high rate of user satisfaction. Further software and hardware development is warranted to improve user satisfaction with peripheral and clear corneal incisions.

Comparison of Surgically Induced Astigmatism and Morphologic Features Resulting From Femtosecond Laser and Manual Clear Corneal Incisions for Cataract Surgery

PURPOSE

To compare the surgically induced astigmatism (SIA) vector, flattening effect, torque, and wound architecture following femtosecond laser and manual clear corneal incisions (CCIs).

METHODS

In a double-armed, randomized, prospective case series, cataract surgery was performed for 600 eyes using femtosecond laser (300 eyes) or manual (300 eyes) 2.4-mm CCIs in temporal or superior oblique locations. SIA, flattening effect, torque, and the summated vector mean for SIA were calculated. Correlation with individual features was established and incision morphology was investigated by anterior segment optical coherence tomography at 3 months of follow-up.

RESULTS

The SIA, flattening effect, and torque were lower in the femtosecond laser group for both incision locations, although the differences were not significant (all P > .05). The femtosecond laser group showed less dispersion of SIA magnitude and flattening effect. Temporal and superior oblique incisions resulted in flattening effect values of -0.11 and -0.21 diopters (D), respectively, in the femtosecond laser group and -0.13 and -0.34 D, respectively, in the manual group. Significant correlations with individual features were only found in the femtosecond laser group, with preoperative astigmatism being the only significant SIA predictor by multiple regression analysis (P = .003). Femtosecond laser CCIs showed less deviation from the intended length, wound enlargement, endothelial misalignment, and Descemet membrane detachments (all P < .037).

CONCLUSIONS

Femtosecond laser CCIs were more reproducible. Although SIAs were smaller in femtosecond laser CCIs than in manual CCIs for both temporal and superior oblique incisions, the difference was not statistically significant. Association with individual features is highly variable. [J Refract Surg. 2018;34(5):322-329.].

Comparison of Wound Sealability Between Femtosecond Laser-Constructed and Manual Clear Corneal Incisions in Patients Undergoing Cataract Surgery: A Pilot Study

PURPOSE

To compare the sealability of femtosecond laser-constructed and manual clear corneal incisions (CCIs) in patients undergoing cataract surgery.

METHODS

This prospective, randomized study included 62 eyes of 62 patients with cataract grade 1 to 2 (LOCS scale). The patients were randomly assigned (1:1) for creation of either manual CCI (with a 2.4-mm keratome) or femtosecond laser-assisted CCI (LENSAR, Inc., Orlando, FL) (31 eyes in each group) before undergoing femtosecond laser-assisted cataract surgery. Wound sealability was assessed as grade 1, 2, or 3 (1: need to reform anterior chamber and hydrate wound at end of surgery; 2: need to reform anterior chamber only; 3: formed anterior chamber, no hydration or anterior chamber reformation necessary).

RESULTS

The nuclear sclerosis grade, cumulative dissipated energy and phacoemulsification time were comparable between the two groups. No complications were experienced in any of the patients. The mean wound sealability for the femtosecond laser group (2.35 ± 0.84) was statistically significantly better in comparison to the manual group (1.32 ± 0.65) (P < .001). At the end of the surgery, 22.6% (n = 7) of eyes in the femtosecond laser group needed reformation of the anterior chamber and hydration of the wound compared to 77.4% (n = 24) of eyes in the manual group. Conversely, 58.1% (n = 18) of eyes in the femtosecond laser group compared to 9.7% (n = 3) of eyes in the manual group were observed to have a formed anterior chamber.

CONCLUSIONS

Femtosecond laser-created CCIs had significantly better wound sealability compared to those created with a metal keratome. [J Refract Surg. 2017;33(11):744-748.].

Prediction of surgically induced astigmatism in manual and femtosecond laser-assisted clear corneal incisions

Purpose:

To assess the surgically induced astigmatism with femtosecond laser-assisted and manual temporal clear corneal incisions and to evaluate the performance of a model for prediction of the surgically induced astigmatism based on the preoperative corneal astigmatism.

Methods:

Clinical data of 104 right eyes and 104 left eyes undergoing cataract surgery, 52 with manual incisions and 52 with femtosecond laser-assisted incisions in each eye group, were extracted and revised retrospectively. In all cases, manual incisions were 2.2 mm width and femtosecond incisions were 2.5 mm width, both at temporal location. A predictive model of the surgically induced astigmatism was obtained by means of simple linear regression analyses.

Results:

Mean surgically induced astigmatisms for right eyes were 0.14D@65° (manual) and 0.24D@92° (femtosecond) (p > 0.05) and for left eyes, 0.15D@101° (manual) and 0.19D@104° (femtosecond) (p > 0.05). The orthogonal components of the surgically induced astigmatism (XSIA, YSIA) were significantly correlated (p < 0.05) with the preoperative orthogonal components of corneal astigmatism (Xpreop, Ypreop) (r = −0.29 for X and r = −0.1 for Y). The preoperative astigmatism explained 8% of the variability of the XSIA and 3% of the variability of YSIA. The postoperative corneal astigmatism prediction was not improved by the surgically induced astigmatism obtained from the model in comparison with the simple vector subtraction of the mean surgically induced astigmatism.

Conclusion:

Temporal incisions induce similar astigmatism either for manual or for femtosecond procedures. This can be clinically negligible for being considered for toric intraocular lens calculation due to the great standard deviation in comparison with the mean. The usefulness of the prediction model should be confirmed in patients with high preoperative corneal astigmatism.

Reviewing the visual benefits of femtosecond laser-assisted cataract surgery: Can we improve our outcomes?

Femtosecond laser-assisted cataract surgery (FLACS) was introduced in 2009 and has increasingly been incorporated into surgical practice. The automation of three key aspects of cataract surgery was expected to deliver a significant improvement in both refractive and safety outcomes. The published literature has not yet shown consistent refractive improvement above conventional techniques. The purpose of this paper is to review current FLACS refractive outcomes and explore factors that may have contributed to the current findings and whether future improvements are possible.

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.

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.

Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery

BACKGROUND

Cataract is the leading cause of blindness in the world, and cataract surgery is one of the most commonly performed operations in the Western world. Preferred surgical techniques have changed dramatically over the past half century with associated improvements in outcomes and safety. Femtosecond laser platforms that can accurately and reproducibly perform key steps in cataract surgery, including corneal incisions, capsulotomy and lens fragmentation, are now available. The potential advantages of laser-assisted surgery are broad, and include greater safety and better visual outcomes through greater precision and reproducibility.

OBJECTIVES

To compare the effectiveness of laser-assisted cataract surgery with standard ultrasound phacoemulsification cataract surgery by gathering evidence on safety from randomised controlled trials (RCTs).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 4), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to May 2016), EMBASE (January 1980 to May 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to May 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en) and the U.S. Food and Drugs Administration (FDA) website (www.fda.gov). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 10 May 2016.

SELECTION CRITERIA

We included randomised controlled trials where laser-assisted cataract surgery was compared to standard ultrasound phacoemulsification cataract surgery. We graded the certainty of the evidence using GRADE.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, assessed risk of bias and extracted data using the standard methodological procedures expected by Cochrane. The primary outcome for this review was intraoperative complications in the operated eye, namely anterior capsule and posterior capsule tears. The secondary outcomes were visual acuity (corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA)), refractive outcomes, quality of vision (as measured by any validated visual function score), postoperative complications and cost-effectiveness.

MAIN RESULTS

We included 16 RCTs conducted in Germary, Hungary, Italy, India, China and Brazil that enrolled a total of 1638 eyes of 1245 adult participants. Overall, the studies were at unclear or high risk of bias. In 11 of the studies the authors reported financial links with the manufacturer of the laser platform evaluated in their studies. Five of the studies were within-person (paired-eye) studies with one eye allocated to one procedure and the other eye allocated to the other procedure. These studies were reported ignoring the paired nature of the data.The number of anterior capsule and posterior capsule tears reported in the included studies for both laser cataract surgery and manual phacoemulsification cataract surgery were low. There were four anterior capsule tears and one posterior capsule tear in 1076 eyes reported in 10 studies (2 anterior capsule tears in laser arms, 2 anterior capsule tears and 1 posterior capsule tear in standard phacoemulsification arms). We are very uncertain as to the effect of laser-assisted surgery compared to standard phacoemulsification surgery with respect to these two outcomes. For postoperative cystoid macular oedema and elevated postoperative intraocular pressures, again the evidence was inconclusive (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.20 to 1.68; 957 eyes, 9 studies, low certainty evidence; and OR 0.57, 95% CI 0.11 to 2.86; 903 eyes, 8 studies, low certainty evidence).We found little evidence of any important difference in postoperative visual acuity between laser-assisted and standard phacoemulsification arms. There was a small advantage for laser-assisted cataract surgery at six months in CDVA. However, the mean difference (MD) was -0.03 logMAR (95% CI -0.05 to -0.00; 224 eyes, 3 studies, low certainty evidence) which is equivalent to 1.5 logMAR letters and is therefore, clinically insignificant. No studies reported patient-reported outcome measures such as visual function.There were no data reported on costs or resource use but three studies reported the time taken to do the surgery. There was little evidence of any major difference between the two procedures in this respect (MD 0.1 minutes, 95% CI -0.02 to 0.21; 274 eyes, low certainty evidence).

AUTHORS' CONCLUSIONS

The evidence from the 16 randomised controlled trials RCTs included in this review could not determine the equivalence or superiority of laser-assisted cataract surgery compared to standard manual phacoemulsification for our chosen outcomes due to the low to very low certainty of the evidence available from these studies. As complications occur rarely, large, adequately powered, well designed, independent RCTs comparing the safety and efficacy of laser-assisted cataract surgery with standard phacoemulsification cataract surgery are needed. Standardised reporting of complications and visual and refractive outcomes for cataract surgery would facilitate future synthesis. Data on patient-reported outcomes and cost-effectiveness are needed. Paired-eye studies should be analysed and reported appropriately.

Comparing the Curative Effects between Femtosecond Laser-Assisted Cataract Surgery and Conventional Phacoemulsification Surgery: A Meta-Analysis

PURPOSE

To compare the outcomes of femtosecond laser-assisted cataract surgery (FLACS) with those of conventional phacoemulsification surgery (CPS) for age-related cataracts.

METHODS

A comprehensive literature search of PubMed, EMBASE, and the Cochrane Controlled Trials Register was conducted to identify randomized controlled trials (RCT) and comparative cohort studies comparing FLACS with CPS. Endothelial cell loss percentage (ECL%), central corneal thickness (CCT), corrected and uncorrected distant visual acuity (CDVA and UDVA), and mean absolute error (MAE) of refraction were used as primary outcomes. Secondary outcomes included surgically induced astigmatism (SIA), mean effective phacoemulsification time (EPT), phacoemulsification power and circularity of the capsulorhexis.

RESULTS

Nine RCTs and fifteen cohort studies including 4,903 eyes (2,861 in the FLACS group and 2,072 in the CPS group) were identified. There were significant differences between the two groups in ECL% at one week, about one month and three months postoperatively, in CCT at one day, about one month postoperatively and at the final follow-up, in CDVA at one week postoperatively, and in UDVA at the final follow-up. Significant differences were also observed in MAE, EPT, phacoemulsification power, and the circularity of capsulorhexis. However, no significant differences were observed in CDVA at one week postoperatively or in surgically induced astigmatism.

CONCLUSIONS

Compared to CPS, FLACS is a safer and more effective method for reducing endothelial cell loss and postoperative central corneal thickening as well as achieving better and faster visual rehabilitation and refractive outcomes. However, there is no difference in final CDVA and surgically induced astigmatism between the two groups.

Comparison Between Digital and Manual Marking for Toric Intraocular Lenses: A Randomized Trial

To compare the clinical outcome of digital and manual marking for toric intraocular lens (IOL) alignment. This is a prospective clinical study that included 60 eyes of 60 patients undergoing cataract surgery with coexisting corneal astigmatism more than 1 diopter (D). The eyes were randomly assigned to either digital image guidance using VERION digital marker (Alcon Laboratories, Ft. Worth, TX) or manual slitlamp-assisted preoperative marking using pendulum-attached marker. Tecnis toric IOL (Abbott Medical Optics, Inc, Santa Ana, CA) was implanted in all cases. The mean postoperative uncorrected distance visual acuity (UCDVA) for the digital-marking group was 0.12 + 0.12 logMAR, and for the manual-marking group was 0.18 + 0.14 logMAR (P = 0.104). The mean deviation from targeted induced astigmatism (TIA) for the first group was 0.10 + 0.08 D and for the second group was 0.20 + 0.14 D (P = 0.001). The mean postoperative toric IOL misalignment measured by the slitlamp was 2.4° + 1.96° for the first group and was 4.33° + 2.72° for the second group (P = 0.003). Accurate alignment of the toric IOL is important to achieve the desired astigmatism correction. VERION system has the advantage of preoperative planning and intraoperative digital guidance of the toric IOL alignment. The use of VERION system resulted in less postoperative deviation from TIA and showed less postoperative toric IOL misalignment than using manual-marking technique.

[Results of femtosecond laser-assisted cataract surgery using the new 2.16 software and the SoftFit® Patient Interface]

INTRODUCTION

Femtosecond laser-assisted cataract surgery improved the results of cataract surgeries.

AIM

Outcome analysis of femtosecond laser-assisted cataract surgery using the novel 2.16 software and the SoftFit(®) Patient Interface.

METHOD

The novel software and the newly developed Patient Interface were used in 100 eyes of 100 patients.

RESULTS

Length of femtosecond laser pretreatment decreased to 45-60 seconds. The smaller size of the new patient interface resulted in easier docking even on pediatric eyes. Suction force used for docking decreased from 40-50 mmHg to 16-20 mmHg. Incidence rate of subconjunctival suffusion decreased from 40% to 15-20% and its clinical severity was reduced, too. No corneal microfolds evolved, thus the incidence rate of the free-floating capsulotomies increased from 30% to 97%. The total energy of femtosecond laser pretreatment was decreased by almost 50%. Corneal wounds had the desired structure, and they were easy to open and closed precisely.

CONCLUSIONS

The SoftFit(®) patient interface and the novel software widened the possible uses of the femtosecond laser-assisted cataract surgery, e.g. in pediatric ophthalmology. Innovations improved the safety and the predictability of the method.