Scanning electron microscopy evaluation of capsulorhexis in femtosecond laser-assisted cataract surgery

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.

Modified Technique of Setting Capsulotomy Thickness in Reducing Capsulotomy-Related Complications During Femtosecond Laser-Assisted Cataract Surgery: A Prospective, Comparative Cohort Study

INTRODUCTION

Although uncommon, incomplete capsulotomy, anterior capsule tags and anterior capsule tears are still encountered during femtosecond laser-assisted cataract surgery (FLACS), resulting in surgical complications. This highlights the need to improve femtosecond laser-assisted capsulotomy technique to reduce capsulotomy-related complications. Therefore, the purpose of this study was to investigate the efficacy of a newly developed, modified technique of setting capsulotomy irradiation thickness in lowering the incidence of capsulotomy-related complications in FLACS.

METHODS

This open-label prospective, comparative cohort study included 440 eyes (220 patients) treated with FLACS using the LenSx laser system (Alcon Laboratories, Inc. Fort Worth, TX, USA). Varying capsulotomy irradiation thicknesses were applied in each eye of the same patient. In Group 1, capsulotomy irradiation thickness was set between the upper edge of the highest point of the anterior capsule and the lower edge of the lowest point of the anterior capsule (modified technique). In Group 2, this was set between the center of the highest point of the anterior capsule and the center of the lowest part of the anterior capsule (conventional technique). Incidence rates of incomplete capsulotomy, anterior capsule tags and tears, and posterior capsule tears were compared.

RESULTS

Preoperative baseline characteristics showed no significant differences. Mean total of the irradiation thicknesses was 877.1 ± 81.9 µm in Group 1 and 808.9 ± 80.0 in Group 2, with a statistically significant difference (P < 0.001). Incidences of incomplete capsulotomy were 1.8% and 7.7%, anterior capsule tags were 2.3% and 8.6%, and anterior capsule tears were 0% and 3.2% in Groups 1 and 2, respectively. These differences were statistically significant (P = 0.006, 0.005, and 0.015, respectively). No posterior capsule tears were reported in either group.

CONCLUSION

The modified technique for capsulotomy in FLACS may significantly reduce the occurrence of capsulotomy-related complications, maximizing the benefits of FLACS.

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.

Lens capsule-related complications in femtosecond laser-assisted cataract surgery: a study based on video analysis

PURPOSE

To analyse the occurrence and potential causes of lens capsule-related complications during femtosecond laser-assisted cataract surgery (FLACS).

METHODS

This prospective consecutive cohort study included the first 1600 eyes (from 1140 consecutive patients) who received FLACS performed by the same surgeon from May 2015 to December 2018. The potential causes and characteristic signs of capsulotomy-related complications, including incomplete capsulotomies and radial anterior capsule (AC) tears, were summarised based on the agreement of two ophthalmologists after they analysed the surgical videos. Subgroup analysis was conducted to characterise the capsulotomy learning curve.

RESULTS

Of the 1600 eyes, 52 (3.25%) had incomplete capsulotomies and 22 (1.38%) had radial AC tears. The most common causes of incomplete capsulotomies were eye tilt (16 eyes, 30.77%), air bubbles or ocular secretions at the interface (14 eyes, 26.92%) and white cataracts (7 eyes, 13.46%). Additionally, 54.55% (12/22) of AC tears were due to incomplete capsulotomy and secondary capsulorhexis. A significant difference was noted between the first 200 eyes and subsequent groups in terms of the incidence of incomplete capsulotomies. No difference was observed in the incidence of AC tears after the initial 100 procedures.

CONCLUSION

The most common causes of incomplete capsulotomies were eye tilt and air bubbles or ocular secretions at the interface. Secondary capsulorhexis after incomplete capsulotomy is the main risk factor for AC tears. There was a steep learning curve for laser capsulotomy in the first 100 operated eyes, as evidenced by the higher complication rate, but this stabilised after 200 procedures.

Electron microscopy analysis of femtosecond laser-assisted capsulotomy before and after lens fragmentation

Studying anterior lens capsule cutting edge profiles from femtosecond laser-assisted capsulotomy procedures performed before and after lens fragmentation. Twenty eyes (10 patients) with age-related cataract underwent femtosecond laser-assisted surgery (FLACS) using the Ziemer Z8 platform. First step of laser surgery was either capsulotomy (group first) or fragmentation (group second). One eye of each patient was assigned randomly, the second eye treated with the different sequence of procedures. After anterior capsule removal, tissue was fixed in cacodylate-buffered solution and cutting-edge profiles were analysed using scanning electron microscopy (SEM). All cases had cataract grade 2 and 3 based on LOCS III grading. SEM analysis showed more smooth edges in the first group, especially in cases with pseudoexfoliation (P = 0.037); more tags and bridges and a significant number of staggered cutting patterns (7 out of 10 cases) in the second group. All cases evolved the same microgroves with "valleys and mountains " as signs of the photodisruption process. Femtosecond laser capsulotomy should be performed before lens fragmentation minimizing the rate of cutting errors. Especially in eyes with advanced cataract, as intracapsular pressure may increase due to lens fragmentation without anterior capsular opening.

Electron microscopy analysis of femtosecond laser-assisted capsulotomy before and after lens fragmentation

Studying anterior lens capsule cutting edge profiles from femtosecond laser-assisted capsulotomy procedures performed before and after lens fragmentation. Twenty eyes (10 patients) with age-related cataract underwent femtosecond laser-assisted surgery (FLACS) using the Ziemer Z8 platform. First step of laser surgery was either capsulotomy (group first) or fragmentation (group second). One eye of each patient was assigned randomly, the second eye treated with the different sequence of procedures. After anterior capsule removal, tissue was fixed in cacodylate-buffered solution and cutting-edge profiles were analysed using scanning electron microscopy (SEM). All cases had cataract grade 2 and 3 based on LOCS III grading. SEM analysis showed more smooth edges in the first group, especially in cases with pseudoexfoliation (P = 0.037); more tags and bridges and a significant number of staggered cutting patterns (7 out of 10 cases) in the second group. All cases evolved the same microgroves with "valleys and mountains " as signs of the photodisruption process. Femtosecond laser capsulotomy should be performed before lens fragmentation minimizing the rate of cutting errors. Especially in eyes with advanced cataract, as intracapsular pressure may increase due to lens fragmentation without anterior capsular opening.

Surgical outcomes with high and low pulse energy femtosecond laser systems for cataract surgery

Currently, there is no clear consensus in cataract surgery if low compared to high energy femto-lasers may enable better capsulotomy quality and induce lower inflammatory response. Therefore, the aim of this study was to compare the intra-operative outcomes achieved with high and low pulse energy femtosecond laser systems for cataract surgery. The charts of 200 eyes of 200 patients aged 68.3 ± 10.3 years who had undergone femtosecond laser-assisted cataract surgery using either group 1 high pulse energy: LenSx (Alcon Laboratories) (N = 100) or group 2 low pulse energy: FEMTO LDV Z8 (Ziemer) (N = 100) laser were reviewed retrospectively. Integrity of anterior capsulotomy, classified as (1) complete (free-floating or with minor microadhesions), (2) incomplete and (3) with capsular tears, intraoperative completeness of the clear corneal incisions (CCI, main incision and side port), incidences of intraoperative miosis and incidence of subconjunctival hemorrhage were evaluated and compared between the two groups. The proportion of complete capsulotomies was significantly higher in the group 2 than the group 1 (100% vs 94%; p = 0.03). The incidences of intraoperative miosis (0% vs 19%) and subconjunctival hemorrhage (1% vs 63%) were significantly lower in the group 2 than the group 1 (p < 0.001). Completeness of the main incision was comparable (97% vs 95%; p = 0.721) between the two groups. Although not statistically significant, the completeness of side-port incision was slightly better in the group 2 than the group 1 (91% vs 86%). Low energy laser system performed significantly better in terms of completeness of capsulotomy, intraoperative miosis and sub-conjunctival hemorrhage, compared with high energy laser; the CCI outcomes were comparable.

Comparison of cumulative dispersed energy between conventional phacoemulsification and femtosecond laser-assisted cataract surgery with two different lens fragmentation patterns

The purpose of the study is to compare the total ultrasound power used between eyes undergoing different lens fragmentation patterns of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification surgery (CPS). A total of 506 patient eyes underwent preoperative grading of lens opacity using the Lens Opacity Classification System III (LOCSIII). The eyes were divided into two subgroups: subgroup 1 had a LOCSIII grade of 1-3, and subgroup 2 had a LOCSIII grade of 4-6. The eyes underwent FLACS (LenSx) for clear corneal wound, capsulotomy, and lens fragmentation. Either a grid pattern or radial pattern was used for lens fragmentation. The eyes received one of the following three treatments: (1) CPS without femtosecond laser assistant, (2) FLACS with a grid pattern (FGP) lens fragment, or (3) FLACS with a quadrant pattern (FQP) lens fragment. The mean cumulative dispersed energy (CDE) for each subgroup and treatment was evaluated. The mean CDE was lower in the two FLACS groups (1.21±1.91 in FGP and 1.22±1.92 in FQP) than that in the CPG group (2.67±2.84). In subgroup 1, CDE was higher in the CPG group (1.54±1.18) as compared with the FLACS groups (0.16±0.31 in FGP and 0.74±1.17 in FQP; P<0.001). In subgroup 2, CDE was higher in the CPG (6.47±3.46) as compared with the FLACS groups (2.74±2.21 in FGP and 5.34±2.17 in FQP; P<0.001). CDE was lower in the two FLACS groups than that in the CPS group, and CDE was the lowest with FGP in both subgroups 1 and 2.

Outcomes of resident-performed laser-assisted vs traditional phacoemulsification

PURPOSE

To compare the effectiveness of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPS) by resident surgeons.

SETTING

Parkland Memorial Health and Hospital System, Dallas, Texas, USA.

DESIGN

Prospective randomized study.

METHODS

All surgeries to be performed by postgraduate year 3 and year 4 residents from October 2015 through June 2017 were eligible for inclusion. Patients were required to complete postoperative day 1, week 1, month 1, and month 3 visits. Specular microscopy was performed preoperatively and postoperatively. Surgeries were filmed, and each step was timed and compared. Surgeon and patient surveys were filled out postoperatively.

RESULTS

Of the 135 eyes of 96 subjects enrolled in the study, 64 eyes received FLACS and 71 eyes received CPS. There was no significant difference in corrected distance visual acuity (CDVA), either preoperatively or at the postoperative day 1, week 1, month 1, or month 3 visits (P = .469, .539, .701, .777, and .777, respectively). Cumulated dissipated energy and irrigation fluid usage were not different between FLACS and CPS (P = .521 and .368, respectively), nor was there a difference in the reduction of endothelial cell counts postoperatively (P = .881). Wound creation (P = .014), cortical cleanup (P = .009), and IOL implantation (P = .031) were faster in the CPS group. Survey results indicated that the overall patient experience was similar for FLACS and CPS.

CONCLUSIONS

This first prospective randomized trial evaluating resident-performed FLACS shows that, in resident hands, FLACS provides similar results to CPS regarding visual acuity, endothelial cell loss, operative time, patient satisfaction, and surgical complication rate.

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

INTRODUCTION

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

The benefits and drawbacks of femtosecond laser-assisted cataract surgery

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Femtosecond laser-assisted cataract surgery: A review

PURPOSE

Review scientific literature concerning femtosecond laser-assisted cataract surgery.

METHODS

Following databases were searched: CENTRAL (Cochrane Eyes and Vision Trials Register; Cochrane Library: Issue 2 of 12, June 2019), Ovid MEDLINE^® without Revisions (1996 to June 2019), Ovid MEDLINE^® (1946 to June 2019), Ovid MEDLINE^® Daily Update June 2019, MEDLINE and MEDLINE Non-Indexed Items, Embase (1980-2019), Embase (1974 to June 2019), Ovid MEDLINE^® and Epub Ahead of Print, in-Process & Other Non-Indexed Citations and Daily (1946 to June 2019), Web of Science (all years), the metaRegister of Controlled Trials ( www.controlled-trials.com ), ClinicalTrials.gov ( www.clinicaltrial.gov ) and World Health Organization International Clinical Trials Registry Platform ( www.who.int/ictrp/search/en ). Search terms/keywords included 'Femtosecond laser' combined with 'cataract', 'cataract surgery'.

RESULTS

Based on quality of their methodology and their originality, 121 articles were reviewed, including randomised controlled trials, cohort studies, case-controlled studies, case series, case reports and laboratory studies. Each step of the femtosecond laser-assisted cataract surgery procedure (corneal incisions, arcuate keratotomies, capsulotomy and lens fragmentation) has been discussed with relevance to published outcomes, as well as complication rates of femtosecond laser-assisted cataract surgery, and what we can learn from the larger studies/meta-analyses and the economics of femtosecond laser-assisted cataract surgery within different healthcare settings.

CONCLUSION

Studies suggest that the current clinical outcomes of femtosecond laser-assisted cataract surgery are not different to conventional phacoemulsification surgery and it is not cost effective when compared with conventional phacoemulsification surgery. In its current technological form, it is a useful surgical tool in specific complex cataract scenarios, but its usage has not been shown to translate into better clinical outcomes.

Effect of manual capsulorhexis size and position on intraocular lens tilt, centration, and axial position

PURPOSE

To evaluate the influence of a manual capsulorhexis size, shape, and position on postoperative axial position, tilt, and centration of intraocular lenses (IOLs).

SETTING

Hanusch Hospital, Vienna, Austria.

DESIGN

Prospective cases series.

METHODS

Patients had cataract surgery and had follow-ups 1 hour and 3 months after surgery. Postoperatively, patients were divided into 3 groups according to the capsulorhexis shape and size as follows: control, symmetrical capsulorhexis between 4.5 mm and 5.5 mm; small group, capsulorhexis smaller than 4.5 mm; and eccentric, all other capsulorhexes. At both follow-ups, a retroillumination image, partial coherence interferometry measurements, and Purkinje meter measurements were performed.

RESULTS

This study comprised 255 eyes. The mean postoperative absolute anterior chamber depth shift in the control, eccentric capsulorhexis, and small capsulorhexis groups was 0.31 mm ± 0.27 (SD), 0.36 ± 0.24 mm, and 0.26 ± 0.24 mm, respectively (P = .419). The mean tilt in the control, eccentric capsulorhexis, and small capsulorhexis groups was 4.08 ± 2.13 degrees, 3.66 ± 2.04 degrees, and 2.82 ± 1.67 degrees, respectively (P = .370), and the mean decentration was 0.38 ± 0.23 mm, 0.40 ± 0.21 mm, and 0.17 ± 0.08 mm, respectively (P = .027).

CONCLUSIONS

Capsulorhexis size and shape had little effect on the capsular bag performance of modern IOLs. Only eyes with a severely malformed capsulorhexis had a slightly decentered IOL.

Intereye comparison of femtosecond laser-assisted cataract surgery capsulotomy and manual capsulorhexis edge strength

PURPOSE

To compare the breaking force required to tear the explanted capsule after femtosecond laser-assisted cataract surgery in the worse eye and manual cataract surgery in the contralateral eye.

SETTING

Personaleyes, Sydney, Australia.

DESIGN

Prospective nonrandomized case study.

METHOD

Patients with bilateral cataract had femtosecond laser-assisted cataract surgery with the Lensx laser in the eye with worse vision and manual cataract surgery in the contralateral eye. Each explanted capsule was stretched mechanically, and the breaking force and strain in grams (g) were compared. When a large contralateral difference in capsule strength was found, scanning electron microscopy (SEM) was applied to determine whether morphologic imperfections were present in a case with a weak capsule.

RESULTS

Paired samples of 78 eyes of 39 patients were tested. The mean breaking force was not significantly different between manual capsulorhexes (2.3 g ± 2.0 [SD]) and femtosecond laser capsulotomies (2.0 ± 2.2 g, P = .52). The breaking strain for the manual samples (33.8% ± 18.3%) and for the femtosecond laser samples (34.6% ± 18.6%) were also not significantly different (P = .81). In 5 patients, in the femtosecond group, the capsules required considerably less force to break than the capsules in the manual group. However, the SEM images of these samples did not show specific laser imperfections.

CONCLUSION

In paired human eyes, the capsulotomies created by a femtosecond laser with a contact lens interface were as strong as manual capsulorhexes.

Comparison of the selected parameters of the anterior segment of the eye between femtosecond laser-assisted cataract surgery, microincision cataract surgery, and conventional phacoemulsification: A case-control study

The purpose of our study was to compare the selected parameters of the anterior segment of the eye in patients after femtosecond laser-assisted cataract surgery (FLACS) with the results of microincision cataract surgery (MICS) and conventional phacoemulsification surgery (CPS). This single-center prospective randomized comparative observational study included 87 patients. Patients were randomly selected into group A (FLACS), group B (MICS) and group C (control group). All the surgeries were performed by the same experienced surgeon. Preoperative and postoperative parameters were evaluated: best-corrected visual acuity (BCVA), endothelial cell density (ECD), endothelial cell loss percentage (ECL%), central corneal thickness (CCT), central anterior and posterior corneal astigmatism induction, posterior corneal elevation map were measured. Intraoperative parameters: effective phacoemulsification time (EPT), balanced salt solution use (BSS use), total surgical time and suction time were analyzed. Examination was performed preoperatively and on the first, seventh day, one and six months postoperatively. The follow up period was 6 months. There was no statistically significant difference in BCVA, central anterior and posterior astigmatism induction between studied groups. The ECL% was statistically significant lower in the group A on the 7th day, 1 month and 6-months postoperatively (P < .05). The CCT was statistically significant lower in the group A and in the group B than in the group C on the 7th postoperative day (P = .002). However, in the 6 months follow-up there was no statistically significant difference in the CCT between studied groups (P = .133). We observed statistically significant difference in change of the posterior corneal elevation map at the periphery assessed within the 90° to 120°meridian range between group A, group B and group C at every timepoint postoperatively (P < .05). The EPT and BSS use were statistically significant lower whilst total surgery time was statistically significant higher in the FLACS group (P < .05). To conclude in the 6 months follow-up there was statistically significant difference found between eyes undergoing FLACS, MICS and CPS with respect to the posterior corneal elevation map assessed within the studied range, ECL%, EPT, BSS use and total surgery time. Postoperative BCVA, central anterior and posterior astigmatism induction, CCT were comparable between studied groups.

The Clinical Relationship of Anterior Capsular Tears and Vertical Spacing in the Femtosecond Laser Capsulotomy Procedure

PURPOSE

To evaluate the frequency of anterior capsule tears and capsule edge irregularities in femtosecond laser anterior capsulotomy, including the effect of optimized vertical spacing settings.

METHODS

Three thousand eight hundred thirty-four cases were examined and grouped according to the femtosecond laser capsulotomy settings using manufacturer default settings with a vertical spacing of 10, 15, and 20 µm. Capsulotomy edge irregularities and anterior capsule tears were recorded intraoperatively.

RESULTS

The anterior capsule tear rates for the 10, 15, and 20 µm groups were 0.79%, 0.35%, and 0.09%, respectively. The capsule edge irregularity rates for the 10, 15, and 20 µm groups were 6.25%, 1.13%, and 1.15%, respectively. The treatment times for the 10, 15, and 20 µm groups were 1.6, 0.7, and 0.8 second, respectively. The risk reduction of anterior capsule tears positively correlated with the 15 and 20 µm group settings. The anterior capsule tear rate difference between the 10 and 20 µm group settings was statistically significant. Capsule edge irregularity rates were reduced in the 15 and 20 µm group settings. Eye movement was monitored in the 20 µm group and was observed in 9 of 13 patients with capsule edge irregularities.

CONCLUSIONS

Anterior capsule tear rates are low with femtosecond laser cataract surgery. The rate can be further reduced with optimization of the settings, including an increase in vertical spacing. [J Refract Surg. 2019;35(5):280-284.].

Comparison of anterior capsulotomy techniques: continuous curvilinear capsulorhexis, femtosecond laser-assisted capsulotomy and selective laser capsulotomy

Purpose

To compare the anterior capsulotomy edge tear strength created by manual continuous curvilinear capsulorhexis (CCC), femtosecond laser-assisted capsulotomy (FLACS), and selective laser capsulotomy (SLC).

Setting

Singapore National Eye Centre, Singapore and Excel-Lens, Livermore, California, USA.

Design

Three armed study in paired human eyes.

Methods

Capsulotomies were performed in 60 cadaver eyes of 30 donors using CCC, Victus Femtosecond Laser, (Bausch & Lomb, Rochester, New York, USA) or CAPSULaser, (Excel-Lens, Los Gatos, California, USA). Three pairwise study groups each involved 10 pairs of eyes. Study group 1: SLC eyes compared with fellow eyes with CCC. Study group 2: CCC eyes compared with fellow eyes with FLACS. Study group 3: FLACS eyes compared with fellow eyes with SLC.

A shoe-tree method was used to apply load to the capsulotomy edge, and Instron tensile stress instrument measured distension and threshold load applied to initiate capsule fracture. Relative fracture strengths and distension of CCC, FLACS and SLC were determined. Scanning electron microscopy (SEM) of capsule edges were reviewed

Results

Anterior capsulotomies behave as non-linear elastic (elastomeric) systems when exposed to an external load. The pairwise study demonstrated that the SLC fracture strength was superior to that of CCC by a factor of 1.46-fold with SLC 277±38 mN versus CCC with 190±37 mN. Furthermore, CCC fracture strength was superior to that of FLACS by a factor of 1.28-fold with CCC 186 + 37 mN versus FLACS 145 ± 35 mN (p < 0.001). This was determined by statistical analysis utilising the Wilcoxon matched-pairs signed-ranks test and in accordance with the Consolidated Standards of Reporting Trials guidelines. The capsule edge of SLC on SEM demonstrated a rolled over edge anteriorly and an alteration of collagen.

Conclusions

The strength of the capsulotomy edge for SLC was significantly stronger than that of CCC which and both were significantly stronger than FLACS. The relative strengths can be explained by SEM of each type of capsulotomy.

[Biomechanical properties of the anterior lens capsule after manual and femtolaser capsulotomy]

PURPOSE

To comparatively evaluate the mechanical stability of the edge of central fragment of anterior lens capsule after manual and femtolaser capsulotomy.

MATERIAL AND METHODS

The mechanical tests were performed on the central fragments of the anterior lens capsules obtained intraoperatively after manual and femtolaser capsulotomy (15 and 13 samples, respectively). The conditions of the developed method of mechanical testing are as close to in vivo as possible. The method allows evaluation of the mechanical response mainly from the edge of the sample, reception of the averaged response from the four edges of the capsule, and almost eliminates the effect of additional edge notches in samples obtained by manual capsulotomy.

RESULTS

After manual capsulotomy, the maximum force and elongation of the anterior capsule sample at maximum tensile strength were significantly higher than similar characteristics of the samples after femtolaser capsulotomy.

CONCLUSION

The obtained results correspond with the morphological studies of capsule edge structure after manual and femtolaser capsulotomy. The edge of the anterior capsule after femtolaser capsulotomy has form, in rough approximation, close to one of a postage stamp perforation, which is the consequence of micro-irregularities (microfractures) in the areas irradiated by pulsed laser, and wider area of deepithelization compared to the manual technique.

[Comparison of clinical and functional results of conventional and femtosecond laser-assisted cataract phacoemulsification]

PURPOSE

To perform a comparative analysis of ultrasound and hydrodynamic parameters, and the outcomes of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS).

MATERIAL AND METHODS

This prospective cohort study included 246 eyes. The first group consisted of 138 patients who underwent FLACS, second group - 108 patients after CPCS.

RESULTS

Total ultrasound time was 95.36±47.93 and 113.3±97.71 seconds (p=0.04) in the 1^st and the 2^nd groups, respectively. The duration of torsional ultrasound was 84.72±50.03 seconds in 1^st group (p=0.04) and 113.3±97.71 seconds in the 2^nd group (p=0.04). Aspiration time was 208.3±95.86 seconds in the 1^st group (p=0.04) and 258.43±158.81 seconds in the 2nd group (p=0.04). On the 3-4^th day after the surgery, uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were significantly better in the 1^st group - 0.62±0.21 (LogMAR 0.20±0.19) and 0.53±0.15 (LogMAR 0.30±0.21) (p=0.01), respectively, compared to the 2^nd group with UDVA of 0.75±0.18 (LogMAR 0.10±0.16) and CDVA of 0.69±0.19 (LogMAR 0.20±0.15) (p=0.04). Central corneal thickness (CCT) was 573.41±33.12 and 632.43±58.30 μm in the 1^st and 2^nd groups, respectively (p=0.020). At 1 month post-op there were no statistically significant differences in UDVA (p=0.17), CDVA (p=0.40) or CCT (p=0.50) between the groups.

CONCLUSION

Compared with CPCS, total ultrasound time (p=0.04), torsional ultrasound time (p=0.04) and aspiration time (p=0.04) were significantly lower in the FLACS group. CCT was significantly lower (p=0.02), while UDVA (p=0.04) and CDVA (p=0.01) were significantly higher in the FLACS group in the early post-operative period (3-4 days after surgery). There were no statistically significant differences in the parameters between the groups 1 month after the surgery.

Scanning Electron Microscopy Analysis of the Anterior Capsulotomy Edge: A Comparative Study between Femtosecond Laser-Assisted Capsulotomy and Manual Capsulorhexis

Purpose

To compare the capsule edges ultrastructure obtained by two femtosecond laser-assisted cataract surgery (FLACS) platforms and manual continuous curvilinear capsulorhexis (CCC) using scanning electron microscopy (SEM).

Setting

Eye Clinic, University of Trieste, Italy.

Design

Experimental comparative study.

Methods

150 anterior capsules were collected and divided into three groups as follows: Group 1 (50 capsules) obtained with manual CCC, Groups 2 and 3 (each with 50 capsules) obtained with the Catalys Laser and the LenSx Laser, respectively. All samples were imaged by means of SEM and regularity of the cut surface, and thickness of the capsule edge were evaluated and compared.

Results

All femtosecond laser (FSL) capsules were perfectly circular, whereas some alteration of the circular shape was observed in the manual ones. Group 1 showed a smooth and regular capsule edge without any surface irregularity, conversely Groups 2 and 3 showed postage-stamp perforations on the capsule edge. The cut surface irregularity value in Group 2 was 1.4 ± 0.63, while it was 0.7 ± 0.49 in Group 3 (p < 0.05). Group 1 had a significantly lower thickness of the capsule edge than the FSL groups (p < 0.05). No statistically significant difference in the capsule edge thickness between the FSL groups was found (p=0.244).

Conclusions

Despite the presence of slight cut surface irregularities, both FSL capsulotomies showed a better geometry and circularity than the manual ones. Capsulotomy specimens obtained using both FSL capsulotomies showed laser-induced alterations of the capsule edge when compared with smooth and regular edges obtained using manual CCC.

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

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

Femtosecond laser-assisted cataract surgery versus standard phacoemulsification cataract surgery: Study from the European Registry of Quality Outcomes for Cataract and Refractive Surgery

PURPOSE

To compare the visual, refractive, and adverse outcomes of femtosecond laser-assisted cataract surgery and conventional phacoemulsification cataract surgery.

SETTING

Cataract surgery clinics in 9 European countries and Australia (femtosecond-assisted) and 18 European countries and Australia (conventional).

DESIGN

Multicenter case-control study.

METHODS

Eyes having femtosecond laser-assisted cataract surgery were matched to eyes from the European Registry of Quality Outcomes for Cataract and Refractive Surgery phacoemulsification cataract surgery database for preoperative corrected distance visual acuity (CDVA), age, and preoperative risk factors. Intraoperative and postoperative complications, postoperative CDVA, and refractive outcome were compared. The follow-up was 7 to 60 days.

RESULTS

The study matched 2814 femtosecond-assisted cases to 4987 conventional phacoemulsification cases. Femtosecond-assisted surgery compared as follows to conventional phacoemulsification: posterior capsule complications, 0.7% versus 0.4%; postoperative logMAR CDVA, 0.05 (6/6^-3) versus 0.03 (6/6^-2); worse postoperative CDVA at follow-up (by 5 letters or more), 1.0% versus 0.4%; CDVA 0.3 (6/12) or better, 96.3% versus 97.1%; absolute biometry prediction error, 0.43 diopter (D) versus 0.40 D; within ±0.5 D of target, 72% versus 74.3%; and postoperative complications, 3.4% versus 2.3%.

CONCLUSIONS

Femtosecond laser-assisted cataract surgery did not yield better visual or refractive outcomes than conventional phacoemulsification cataract surgery. Intraoperative complications were similar and low in both groups. Postoperative complications were lower in conventional phacoemulsification cataract surgery.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Differences in energy and corneal endothelium between femtosecond laser-assisted and conventional cataract surgeries: prospective, intraindividual, randomized controlled trial

AIM

To compare intraoperative phacoemulsification parameters and its effect on the corneal endothelium of eyes undergoing femtosecond laser-assisted cataract surgery (FLACS) versus conventional phacoemulsification (CP) cataract surgery.

METHODS

Two hundred eyes from one hundred patients were included in a prospective, non-blinded, randomized, controlled, intraindividual clinical study. One hundred eyes underwent FLACS while their one hundred fellow eyes underwent CP. All surgeries were performed using the Victus^® femtosecond laser platform and Infinity^® Vision System phacoemulsification machine. Primary outcome measure was endothelial cell density 6mo after surgery. Secondary outcome measures included central corneal thickness (CCT), average cell area, standard deviation, coefficient of variation and hexagonality before surgery and 6mo after surgery and endothelial cell density loss during this period were also evaluated. Intraoperative efficiency parameters [cumulative dissipated energy (CDE), total intraocular surgery time, total ultrasound time, total phacoemulsification time, total torsional energy time, total aspiration time, ultrasound energy, torsional amplitude and fluid required during surgery] were also collated.

RESULTS

Data from these patients was not considered for analysis. Data from 92 patients were analysed. Postoperative endothelial cell density (cells/mm²) between groups (2211.88±392.49 CP; 2246.31±403.48 FLACS) was not statistically significant (P=0.869). Total ultrasound time, torsional energy time, CDE and fluid requirements were significantly lower the FLACS group (P<0.05). Other parameters did not show statistically significant difference between FLACS and CP.

CONCLUSION

FLACS displays significant improvements in phacoemulsification parameters in comparison to CP. There are no significant differences in corneal endothelium measures between FLACS and CP.

Comparison of clinical outcomes between femtosecond laser-assisted versus conventional phacoemulsification

Background

To compare femtosecond laser-assisted versus conventional phacoemulsification in terms of visual and refractive outcomes, cumulative dissipated energy, anterior chamber inflammation and endothelial cell loss.

Methods

In this retrospective cohort study, records of eyes that underwent femtosecond laser-assisted cataract surgery (FLACS) or conventional phacoemulsification (CP) were reviewed. The Victus femtosecond laser (Bausch and Lomb, Germany) was used to carry out corneal incisions, anterior capsulotomy, and lens fragmentation in FLACS procedures. Manifest refraction spherical equivalence (MRSE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), cumulative dissipated energy (CDE), postoperative cells and flare and endothelial cell count data were collected. Subgroup analysis of the visual acuity tests was performed based on the type of intraocular lens implanted (monofocal, monofocal toric, multifocal, multifocal toric, accommodating).

Results

A total of 735 eyes were included in the study (296 eyes for the FLACS group and 439 eyes for the CP group). At one year follow-up, 120 eyes comprised the FLACS group and 265 eyes for the CP group. MRSE in the FLACS group was - 0.16 ± 0.58 D and - 0.20 ± 0.52 D in the CP group (P = 0.50). UDVA in the FLACS group was 20/25 (mean logMAR 0.12 ± 0.13) and 20/25 (mean logMAR 0.11 ± 0.13) in the CP group (P = 0.48). CDVA was 20/20 (mean logMAR 0.03 ± 0.07) in the FLACS group and 20/20 (mean logMAR 0.02 ± 0.06) in the CP group (P = 0.15). No statistically significant trend was seen for FLACS versus CP by intraocular type for visual acuity. CDE for the different cataract grades ranged from 6.97 ± 5.74 to 29.02 ± 16.07 in the FLACS group and 7.59 ± 6.42 to 35.69 ± 18.30 in the CP group. The FLACS group was significantly lower for post-operative central corneal edema (P = 0.05), cells and flare (P = 0.01), and endothelial cell loss (P = 0.04).

Conclusions

Femtosecond laser-assisted cataract surgery and conventional phacoemulsification had similar refractive and visual outcomes. Phacoemulsification energy, anterior chamber inflammation and corneal endothelial cell loss were less in the femtosecond laser group.

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

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

[n.s.i.n.i.V. Biomechanical aspects of anterior capsulotomy in cataract surgery]

This paper reviews studies on biomechanical properties of the anterior lens capsule. Early experiments in this field were more fundamental. Later studies were aimed mainly at assessing the mechanical stability of the capsule edge after manual or femtosecond laser capsulorhexis (capsulotomy) - an important step in modern minimally invasive phaco surgery. For biomechanical tests, ex vivo samples of human and animal anterior capsules were used. The results of the studies presented here are quite heterogeneous, which suggests the necessity of gaining further insight into the issue.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Ideal parameters for femto-second laser-assisted anterior capsulotomy: Animal studies

In femtosecond laser-assisted cataract surgery, the parameter such as horizontal spot spacing and energy level can be adjusted. Although there have been several studies reported on various laser systems, showing the effects of varying energy levels and horizontal spot spacing on lens capsulotomy cut edges, none have been reported on the Catalys laser system (Abbott Medical Optics, Inc., Santa Ana, CA). The aim of this study is to evaluate, using scanning electron microscopy (SEM), the quality of the cut edges of the laser lens capsulotomy obtained using the Catalys Laser System, using different horizontal spot spacing and energy levels, and to determine the ideal parameters based on SEM results. Fifty rabbit capsulorhexis specimens from a femtosecond laser with different spot spacing and energy settings were divided into five groups randomly. Spot spacing was 3 um and laser pulse energy was 4 uJ in group 1. The respective values were 5 um and 2 uJ in group 2, 5 um and 4 uJ in group 3, 5 um and 6 uJ in group 4, and 7 um and 4 uJ in group 5. All samples were evaluated using SEM to compare the number of tags per capsulotomy and the laser emission time. Group 1 had a significantly lower tag formation than groups 3 and 5 (P = 0.042 and 0.021, respectively). Although the laser emission time increased about 1.5 sec as the spot spacing increased from 3 to 7 um, the quality of the cut was smoother in group 1 because of overlapping effect of photodisruption cavities. There was no significant difference between groups 2, 3 and 4 at different laser energy settings. In an ex-vivo study, samples from an energy setting of 10 uJ showed increased irregularity and damage. The degree of irregularity was higher at increasing spot spacing and laser energy settings, with abundant tag formation. Dense spot spacing with low-energy settings provide a better cut quality, which is probably correlated with the reduction in anterior capsular tear complications.

Learning curve of femtosecond laser-assisted cataract surgery: Experience of surgeons new to femtosecond laser platform

PURPOSE

The purpose of this study is to assess the learning curve in the initial 100 cases of cataract surgery performed using femtosecond laser-assisted cataract surgery (FLACS) by experienced cataract surgeons without prior experience in femtosecond laser platform.

METHODS

This study was conducted at tertiary care eye hospital, South India. This was a prospective interventional study. The first 100 consecutive eyes undergoing FLACS were studied to understand docking time, number of docking attempts, problems encountered during docking, and complications attributable to docking. Phacoemulsification performed after femtosecond laser was also studied for complications, need for additional instrumentation, and total time required for surgery. Comparison was also made between two operating surgeons.

RESULTS

Successful docking was recorded in 70% eyes at the first attempt. Mean time taken for successful docking was 9.3 ± 6.4 min (median = 6 min, interquartile range (IQR) = 5-10 min, range = 4-35 min). When surgeries were divided into quartiles, docking time reduced significantly from 16.2 ± 7.9 min in the first quartile to 6.2 ± 2.7 min in the fourth quartile (P < 0.001). Phacoemulsification postdocking required 12.9 ± 6.2 min (median = 10 min, IQR = 9-17.5 min). Six eyes showed anterior capsular tags, one had radial extension of capsulorhexis, and two eyes showed pupillary miosis after femtosecond laser application. At 6 weeks, 79% eyes attained uncorrected vision of 20/20, and all eyes had best-corrected vision of 20/20.

CONCLUSION

Approximately 25-30 cases were required before obtaining reproducible results with FLACS, irrespective of cataract surgical experience, suggesting that training programs must offer a minimum 25 surgeries. Very few complications occurred during the learning curve, making it patient friendly.

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

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

Femtosecond laser-assisted cataract surgery after penetrating keratoplasty: a case report

BACKGROUND

Cataract surgery after penetratingkeratoplasty (PKP) is often challenging due to changes in the integrity of the cornea caused by PKP. For example, corneal endothelial cell (CEC) loss and corneal edema commonly occur after traditional phacoemulsification cataract surgery in patients that previously had successful PKP. Recent studies have reported that femtosecond laser-assisted cataract surgery (FLACS) significantly reduces the need for ultrasound energy minimizing mechanical damage to the cornea and results in a reduction of CEC loss and corneal edema.

CASE PRESENTATION

We report a case in which FLACS was used in a patient with previous PKP.

CONCLUSION

This case supports the suggestion that the use of the femtosecond laser improves the surgical outcome of cataract surgery after PKP. This improvement may be result of the precise incision, controlled capsulorhexis, and reduced lens fragmentation experienced with the femtosecond laser which helps to reduce potential complications of cataract surgery after PKP.

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.

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

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

Comparative analysis of the performance of two different platforms for femtosecond laser-assisted cataract surgery

Purpose

To analyze and compare the intraoperative and postoperative outcomes of cataract surgery performed with two different femtosecond laser platforms.

Methods

Randomized controlled prospective intraindividual comparative study including 90 eyes of 45 patients aged between 61 and 86 years. All eyes underwent bilateral cataract surgery assisted with femtosecond laser technology. Eyes were randomized to one of two different femtosecond laser platforms: Catalys Precision system (Abbott Medical Optics Inc., Santa Ana, CA, USA) (Catalys group), and LenSx system (Alcon-LenSx Inc., Aliso Viejo, CA, USA) (LenSx group). Several intraoperative parameters and changes in corrected distance visual acuity and corneal endothelial density were evaluated and compared.

Results

The LenSx group showed a significantly higher cumulative dissipated energy and phacoemulsification power needed compared to the Catalys group (P≤0.043). Likewise, a longer patient interface preparation time, more severe perception of pressure by patient, and more cases of subconjunctival hemorrhage were found in the LenSx group (P≤0.014). A complete capsulotomy was achieved in more cases in the Catalys group compared to the LenSx group (P=0.002). Regarding corneal incisions, no statistically significant differences were found between groups (P≥0.071). The same occurred for postoperative corrected distance visual acuity (P≥0.48), endothelial cell density changes (P≥0.14), and the incidence of corneal edema or flare (P≥0.399).

Conclusion

Cataract surgery with the two evaluated femtosecond laser platforms is a safe procedure, with reduced phaco time and energy, and preservation of corneal endothelium integrity. However, both systems differ in the performance of capsulotomy and the procedure of docking, with an advantage of the Catalys over the LenSx system.

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.

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.

Initial experience using a femtosecond laser cataract surgery system at a UK National Health Service cataract surgery day care centre

OBJECTIVES

To describe the initial outcomes following installation of a cataract surgery laser system.

SETTING

National Health Service cataract surgery day care unit in North London, UK.

PARTICIPANTS

158 eyes of 150 patients undergoing laser-assisted cataract surgery.

INTERVENTIONS

Laser cataract surgery using the AMO Catalys femtosecond laser platform.

PRIMARY OUTCOME MEASURE

intraoperative complications including anterior and posterior capsule tears.

SECONDARY OUTCOME MEASURES

docking to the laser platform, successful treatment delivery, postoperative visual acuities.

RESULTS

Mean case age was 67.7±10.8 years (range 29-88 years). Docking was successful in 94% (148/158 cases), and in 4% (6/148 cases) of these, the laser delivery was aborted part way during delivery due to patient movement. A total of 32 surgeons, of grades from junior trainee to consultant, performed the surgeries. Median case number per surgeon was 3 (range from 1-20). The anterior capsulotomy was complete in 99.3% of cases, there were no anterior capsule tears (0%). There were 3 cases with posterior capsule rupture requiring anterior vitrectomy, and 1 with zonular dialysis requiring anterior vitrectomy (4/148 eyes, 2.7%). These 4 cases were performed by trainee surgeons, and were either their first laser cataract surgery (2 surgeons) or their first and second laser cataract surgeries (1 surgeon).

CONCLUSIONS

Despite the learning curve, docking and laser delivery were successfully performed in almost all cases, and surgical complication rates and visual outcomes were similar to those expected based on national data. Complications were predominately confined to trainee surgeons, and with the exception of intraoperative pupil constriction appeared unrelated to the laser-performed steps.

[Light and scanning electron microscopy of anterior lens capsule following different capsulorhexis techniques]

Aim - to assess the morphology of anterior lens capsules following circular capsulorhexis, for which capsulotomy was either manual or femtosecond (FS) laser produced.

MATERIAL AND METHODS

A total of 30 capsular samples obtained during phacoemulsification surgery were studied by light and scanning electron microscopy. All the samples were divided into 3 groups of 10 according to the type of capsulotomy: group 1 - manual, groups 2 and 3 - FS laser produced (with the laser set at high or low energy level, respectively).

RESULTS

In manual capsulorhexis, capsular disk edges were rather smooth all the way round. Rare notches and dents as well as fine burrs up to 4 µm long could only be seen under high magnification. In FS laser capsulotomy groups, under low magnification already, capsular disk edges appeared stepped, stratified, and notched (some notches were up to 20 µm deep). The said changes were more significant following low-energy laser treatment, while high-energy levels were notable for 'melted' disk edges. Regardless of the technique used, all the disks carried a zone of de-epithelization of different width along the free edge.

CONCLUSION

The differences revealed may result from several factors: 1) less accurate focusing of the laser due to fine torsional eye movements and minimal shape changes of the applanated cornea; 2) peculiarities of FS laser-tissue interaction, particularly, cavitation bubbles that are formed during tissue evaporation and tend to merge, subsequently producing the incision and demarcation line. Moreover, photothermal effects of laser radiation on epithelial cells within the anterior lens capsule cannot be excluded.

Postoperative IOL Axial Movements and Refractive Changes After Femtosecond Laser-assisted Cataract Surgery Versus Conventional Phacoemulsification

PURPOSE

To evaluate intraocular lens (IOL) axial movements and refractive changes during a 6-month follow-up period after femtosecond laser-assisted cataract surgery and conventional cataract surgery, investigate the influence of capsulorhexis features on postoperative IOL axial changes, and assess the prediction error for both techniques.

METHODS

Eighty eyes of 80 candidates for cataract extraction were randomized into two groups: femtosecond laser (40 eyes) and manual (40 eyes).

RESULTS

The overall anterior chamber depth variation was significantly lower in the femtosecond laser group compared to the manual group during follow-up (P<.001). At 30 and 180 days postoperatively, the mean spherical equivalent showed a hyperopic shift (0.09±0.28 diopters [D]) in the femtosecond laser group and a myopic shift in the manual group (-0.25±0.18 D). Median absolute error was not significantly different between the two groups with standard formulas ranging between 0.29 and 0.64 (Hoffer Q) in the femtosecond laser group and between 0.24 (SRK-T) and 0.55 D (Hoffer Q) in the manual group. There was a significant lower deviation from intended versus achieved capsulotomy/capsulorhexis area in the femtosecond laser group (P<.001) compared to the manual group. The femtosecond laser group showed better IOL centration compared to the manual group at all time periods (P<.001).

CONCLUSIONS

Femtosecond laser-assisted cataract surgery was related to a lower overall variability of anterior chamber depth compared to conventional cataract surgery with more stable postoperative refraction. The two techniques did not show significant differences of prediction error.

[Modified technique of hybrid phacoemulsification]

AIM

to develop a modification to hybrid phacoemulsification (PE) that would involve the use of femtosecond laser.

MATERIAL AND METHODS

Modified hybrid PE was performed in 225 patients (267 eyes) with grade II-IV lens nuclei in terms of their density. Conventional PE was performed in 237 patients (278 eyes).

RESULTS

By utilizing the suggested technique of PE, one can avoid certain problems of conventional surgery and optimize the steps of nucleus fragmentation and emulsification.

CONCLUSIONS

The suggested modification to hybrid PE enables effective removal of grade II-V cataract lenses at minimum ultrasonic load.

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 in Alport Syndrome with Anterior Lenticonus

Purpose

To report the surgical treatment of 3 eyes of 2 patients with bilateral anterior lenticonus due to Alport syndrome using femtosecond laser-assisted cataract surgery (FLACS).

Methods

Two patients with Alport syndrome presented to our department due to anterior lenticonus in both eyes. We performed FLACS with posterior chamber lens implantation in both eyes of one patient and in one eye of the other patient. Anterior segment morphologic changes were visualized with a Scheimpflug camera, and anterior segment optical coherence tomography preoperatively and 3 months after surgery. Ultrastructure of the cut capsule edges was observed with scanning electron microscopy and compared to the edge of femtosecond laser capsulotomy performed on an otherwise healthy patient with cataract (control).

Results

The intraocular lens (IOL) postoperative positioning parameters met the international requirements of aspherical and wavefront customized IOLs (tilt <10 degree, decentration <800 μm). Scanning electron microscopy revealed the same characteristics of the cut capsule edges in the Alport and in the control eyes.

Conclusions

Femtosecond laser cataract surgery can be a safe and successful method for optical rehabilitation of anterior lenticonus in patients with Alport syndrome.

The use of femtosecond lasers in cataract surgery: review of the published results with the LenSx system

PURPOSE

To review the published literature describing the use of the LenSx femtosecond laser technology (Alcon Laboratories, Inc., Fort Worth, TX) in cataract surgery.

METHODS

Literature review.

RESULTS

The LenSx system has been used in more than 200,000 cataract surgery procedures to date. Pre-clinical evaluations have shown that this system produces accurate and reproducible capsulorhexes, and that both the energy required for phacoemulsification and total phacoemulsification time are less than with conventional phacoemulsification. In comparative studies, femtosecond lasers have been shown to produce more precise and reproducible capsulorhexes than manual procedures, and better intraocular lens placement; capsule overlap, circularity of capsulotomy, and centration of the intraocular lens are consistently better with femtosecond lasers than with manual procedures. The improved quality of capsulorhexis and intraocular lens positioning are reflected in favorable visual and refractive outcomes. As with any new technology, there is a significant learning curve: prospective cohort studies have shown that the incidence of intraoperative complications such as suction breaks or anterior capsular tears or tags decreases with experience. In general, the incidence of such complications is within the range (< 2%) considered in recent evidence-based guidelines to be feasible and desirable.

CONCLUSIONS

Although femtosecond laser cataract surgery is in its infancy, the technology is evolving rapidly and offers the potential for more consistent and predictable results after cataract surgery.