Anterior Capsulotomy Outcomes: A Comparison Between Two Femtosecond Laser Cataract Surgery Platforms

Intraocular pressure changes before and after a femtosecond laser procedure for cataract surgery

This study aimed to evaluate the changes in intraocular pressure (IOP) before and after femtosecond laser capsulorhexis and lens fragmentation for cataract surgery. We measured the IOP before, immediately, 30 min, and 1 h after the laser procedure in 47 eyes of 47 patients who underwent the femtosecond laser procedure. The mean IOP was 17.51 ± 3.28 mmHg, 30.23 ± 6.70 mmHg, 17.96 ± 3.75 mmHg, and 21.77 ± 5.88 mmHg before, immediately after, 30 min after, and 1 h after the laser procedure, respectively. The mean IOP significantly increased immediately (adjusted P < 0.001) and 1 h (adjusted P = 0.001) after the laser procedure compared with the pre-laser IOP. The mean IOP at 30 min after the laser procedure was significantly lower than that immediately after the procedure (adjusted P < 0.001). However, the IOP 1 h after the laser procedure became higher than that 30 min after the laser procedure. Additionally, the IOP 1 h after the laser procedure was positively correlated with the baseline IOP and negatively correlated with the axial length. In conclusion, this study demonstrated that cataract surgery should be commenced within 30 min after the femtosecond laser procedure to ensure a safe cataract surgery that reduces the risk of increased intraocular pressure.

Cataract surgery using two 3D visualization systems: Complication rates, surgical duration & comparison with traditional microscopes

PURPOSE

To compare the complication rates and surgical duration of cataract surgery using two 3D visualization systems and a traditional binocular microscope among experienced and inexperienced surgeons.

METHODS

This retrospective case series included 571 eyes that received cataract surgery using either heads up cataract surgery, via a 3D head mounted system (N = 148-Group 1) or a 3D display screen (N = 338 eyes-Group 2), or traditional binocular microscope (N = 85 eyes-Group 3). The surgical records of consecutive patients who underwent cataract surgery by two groups of surgeons (experienced and inexperienced) were reviewed. Patients in all groups received either femtosecond laser assisted cataract surgery (FLACS) or traditional phacoemulsification. Complication rate, as well as duration of cataract surgery were evaluated between all three visualization approaches, between experienced and inexperienced surgeons.

RESULTS

There was no statistically significant difference in duration of surgery between all 3 visualization approaches for both experienced and inexperienced surgeons (p < 0.05). Furthermore, the type of surgical technique (manual or FLACS) did not affect the surgical duration for both experienced and inexperienced surgeons (p < 0.05). No intraoperative complications were demonstrated in the current cohort.

CONCLUSIONS

The implementation of heads up-3D visualization either through a screen or a head mounted platform for cataract surgery seems to offer similar safety and efficiency as the traditional binocular microscope, and both experienced and inexperienced surgeons demonstrate the same outcomes in terms of safety and efficiency.

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.

Comparison of ultrasound energy consumption between low-energy femtosecond laser-assisted cataract surgery and conventional phacoemulsification cataract surgery in patients with different cataract densities

PURPOSE

Femtosecond laser-assisted cataract surgery (FLACS)'s effect on reducing ultrasound energy, accumulated with cumulative dispersed energy (CDE) units, still remains controversial. This study aims to evaluate the effect of low-energy FLACS on CDE with that of conventional phacoemulsification surgery (CPS) in different cataract densities from multiple surgeons.

METHODS

It was a retrospective case-control study. Total 629 eyes receiving either low-energy FLACS (performed with Ziemer LDV Z8 platform) or CPS were divided into two groups according to preoperative grading of Lens Opacity Classification System III (LOCSIII): milder and harder cataract group. The mean CDE were compared in different cataract densities and surgeons. A linear regression analysis was performed to evaluate the effect of using low-energy FLACS on CDE in harder cataract cases.

RESULTS

We found overall CDE had no significant difference between two surgeries. However, low-energy FLACS led to a significantly lower CDE in patients with harder cataracts than CPS (18.47 ± 4.32 vs. 12.96 ± 2.34; p < 0.001). Similar results were observed in the three surgeon subgroups and in linear regression analysis and no significant difference of the effect accounting for surgeons. Moreover, low-energy FLACS results in a reduction of energy consumption comparing to CPS and has endothelial sparring effect in patients with harder cataracts.

CONCLUSIONS

The reduced energy consumption was observed by using low-energy FLACS irrespective of surgeons' experience or the approaches adopted in patients with harder cataracts. Therefore, we can have more confidence to suggest this innovative platform to the patients in such cases.

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.

Inspection of the lens thickness with preoperative biometric measurements prevents an erroneous interpretation of posterior capsule during FLACS

Optical opacity reduces quality of biometry images, making it potentially difficult to find the correct location for irradiation during femtosecond laser-assisted cataract surgery (FLACS). After experiencing a case of posterior capsule (PC) rupture because of optical opacity, we started lens thickness (LT) inspection, which indicates comparison of between intra- and pre-operatively measured LT. We retrospectively investigated the effectiveness of the LT inspection. One observer reviewed all FLACS treatment summaries for 3 years by CATALYS in the Jikei University Hospital, Tokyo. Based on the lines defining the PC on intraoperative OCT images, all cases were classified into three groups: undescribed, appropriate and inappropriate PC. Among the 1070 cases, 1047 cases had appropriate PC. In 19 cases, the PC line was undescribed because of dense cataract. Among 474 cases with no inspection, 4 cases had an inappropriate PC. Whereas, in 596 cases with the LT inspection, there was no case of an inappropriate PC. LT inspection significantly reduced the cases with inappropriate PC. The safety margins normally work to prevent severe complications. However, rare outlier cases had a high risk of severe complications. We propose LT inspection could be the most practical and convenient way for safety surgery.

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.

Evaluation of femtosecond laser-assisted anterior capsulotomy in the presence of ophthalmic viscoelastic devices (OVDs)

The introduction of femtosecond laser-assisted cataract surgery is an alternative approach to conventional cataract surgery. Our study aimed to determine the effectiveness of femtosecond laser-assisted capsulotomy in the presence of different ophthalmic viscoelastic devices (OVDs) in the anterior chamber. Fresh porcine eyes (n = 96) underwent LDV Z8-assisted anterior capsulotomy, either in the presence of an OVD (Viscoat, Provisc, Healon, Healon GV or HPMC) or without, using 90% and 150% energies respectively. Following that, the capsule circularity, tag’s arc-length, tag-length, tag-area and rupture strength (mN) of the residual capsular bag were evaluated. We found that increasing energy from 90 to 150% across the OVD sub-groups improved the studied capsulotomy parameters. Amongst the 90% energy sub-groups, the circularity and tag-parameters were worse with Viscoat and Healon GV, which have higher refractive index and viscosity compared to the aqueous humour. Using 150% energy, Healon GV showed a significantly worse total arc-length (p = 0.01), total tag-length (p = 0.03) and total tag-area (p = 0.05) compared to the control group. We concluded that; an OVD with a refractive index similar to aqueous humour and lower viscosity, such as Healon or Provisc, as well as a higher energy setting, are recommended, to enhance the efficacy of laser capsulotomy.

Outcomes of toric intraocular lens implantation after femtosecond laser and traditional cataract surgery

CLINICAL RELEVANCE

Having an understanding of the refractive outcomes of different forms of cataract surgery will assist optometrists in explaining the implication of such procedures to patients being referred for such procedures.

BACKGROUND

The purpose of this study was to compare the refractive outcomes after toric intraocular lens implantation between femtosecond laser-assisted cataract surgery and traditional phacoemulsification.

METHODS

This retrospective non-randomised case series included 114 eyes of 92 consecutive patients (59 male and 55 female) aged 71.65 ± 10.46-years (range 57 to 92-years), who underwent either femtosecond laser-assisted cataract surgery (using two laser platforms) (group 1) or traditional phacoemulsification (group 2) between August 2013 and September 2015. Pre-operative keratometric values, the attempted refraction from the biometry platform and the toric intraocular lens web-based calculator, and the one month post-operative manifest refraction were assessed to evaluate the refractive outcomes of the two groups.

RESULTS

Mean pre-operative topographic corneal astigmatism was -1.94 ± 0.73 D (range 0.91 to 4.61 D) and -1.98 ± 0.60 D (range 1.07 to 3.43 D) for groups 1 and 2, respectively (p > 0.05). Mean axial length was 24.22 ± 0.73-mm (range 21.78 to 29.30-mm) and 24.60 ± 1.09-mm (range 21.82 to 25.95-mm) for groups 1 and 2, respectively (p > 0.05). Multivariate vector analysis of the remaining refractive error between the two groups (desired refraction minus achieved refraction) revealed no statistically significant difference (p > 0.05). Analysis within each group demonstrated a higher accuracy of refractive outcomes for the femtosecond laser-assisted cataract surgery eyes (p < 0.05) when compared to the traditional phacoemulsification (p > 0.05).

CONCLUSION

Femtosecond laser-assisted cataract surgery and traditional phacoemulsification demonstrate similar refractive outcomes after toric intraocular lens implantation, while femtosecond laser-assisted cataract surgery seems to provide a slightly higher accuracy.

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.

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

PURPOSE

To compare histological analyses of capsulotomies from different laser systems with regard to tissue alteration, laser spot formation, and energy settings.

METHODS

Four femtosecond laser platforms approved for cataract surgery were evaluated: LenSx (Alcon Laboratories, Inc., Fort Worth, TX), Catalys (Abbott Medical Optics, Santa Ana, CA), Victus (Tecnolas/Bausch & Lomb, Munich, Germany), and LensAR (Topcon, Gamagori, Japan). Ten human anterior lens capsulotomy disks from each laser system were analyzed: five by means of light microscopy and five by transmission electron microscopy (TEM). TEM was used especially to examine the cellular and stromal changes at the cutting edges. The cellular demarcation line was measured at 15 points along the rim and statistically compared with the findings from all laser platforms. Three capsules of each laser platform were prepared for TEM to evaluate the cellular and tissue edges of the laser cuttings.

RESULTS

All capsulotomies revealed a circular demarcation zone of different sizes along the cutting edges. Light microscopy showed a radial tissue damage of 36.0 ± 12.3 μm after Victus laser capsulotomy, 8.9 ± 2.9 μm after Catalys laser capsulotomy, 25.2 ± 5.6 μm after LensAR laser capsulotomy, and 39.8 ± 5.1 μm after LenSx laser capsulotomy. Differences between the damaged tissue zones correlated with the laser systems and their energy settings.

CONCLUSIONS

The use of less energy and larger spot separation led to smaller collateral damaged tissue areas along the cutting edges. The aberrant laser spots along the cutting edge may result in weakening of the remaining tissue, thereby enhancing the risk for capsular ruptures during surgery. [J Refract Surg. 2017;33(10):670-675.].

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.