The journey to femtosecond laser-assisted cataract surgery: new beginnings or a false dawn?

Application of Femtosecond Laser in Challenging Cataract Cases

Femtosecond laser can provide precise and customized incision of ocular tissue with excellent accuracy and predictability. Thus, femtosecond laser-assisted cataract surgery (FLACS) can theoretically enhance the safety and efficacy of cataract surgery by providing reproducible and reliable clear corneal incision, limbal relaxing incision, anterior capsulotomy, and lens fragmentation. However, thus far, the superiority of the anatomical and visual outcomes of FLACS over those of conventional cataract surgery have been unclear. Nevertheless, studies have indicated that FLACS can potentially be helpful in improving the safety of cataract surgery in challenging situations, such as zonular weakness, preexisting capsular tear, white cataract, shallow anterior chamber, and pediatric cataracts, which may contribute to enhanced visual and anatomical outcomes. In this review, we provide a summary of the application of femtosecond laser in general cataract cases. In addition, we introduce the application of FLACS in the abovementioned challenging situations and discuss the results of studies regarding the safety and outcome of FLACS in these challenging cases.

Semi-Supervised Medical Image Segmentation with Co-Distribution Alignment

Medical image segmentation has made significant progress when a large amount of labeled data are available. However, annotating medical image segmentation datasets is expensive due to the requirement of professional skills. Additionally, classes are often unevenly distributed in medical images, which severely affects the classification performance on minority classes. To address these problems, this paper proposes Co-Distribution Alignment (Co-DA) for semi-supervised medical image segmentation. Specifically, Co-DA aligns marginal predictions on unlabeled data to marginal predictions on labeled data in a class-wise manner with two differently initialized models before using the pseudo-labels generated by one model to supervise the other. Besides, we design an over-expectation cross-entropy loss for filtering the unlabeled pixels to reduce noise in their pseudo-labels. Quantitative and qualitative experiments on three public datasets demonstrate that the proposed approach outperforms existing state-of-the-art semi-supervised medical image segmentation methods on both the 2D CaDIS dataset and the 3D LGE-MRI and ACDC datasets, achieving an mIoU of 0.8515 with only 24% labeled data on CaDIS, and a Dice score of 0.8824 and 0.8773 with only 20% data on LGE-MRI and ACDC, respectively.

Optimization of femtosecond laser-constructed clear corneal wound sealability for cataract surgery

PURPOSE

To compare the sealability of femtosecond laser (FSL)-assisted corneal incisions (CIs) with that of triplanar manual (M)-CIs and to determine FSL wound parameters minimizing leakage.

SETTING

Private practice.

DESIGN

Phase IV, single-surgeon, retrospective cohort study.

METHODS

One eye per patient was included. Two groups defined by the main wound (FSL-CI or M-CI) were compared for leakage, inferred by placement of a suture at the end of surgery. Leakage in FSL-CIs was analyzed as a function of customizable wound parameters: anterior plane depth (APD), posterior plane depth (PPD), anterior side-cut angle (ASCA), and posterior side-cut angle (PSCA). The risk of leakage of FSL-CIs with optimal and nonoptimal parameters was further compared with that of M-CIs.

RESULTS

A total of 1100 eyes (757 [68.8%] FSL-CI; 343 [31.2%] M-CI) were included. Wound leakage occurred in 133 FSL-CI (17.6%) and 30 M-CI eyes (8.7%) (P < .001). FSL wound parameters associated with the lowest risk of leakage were 60% APD, 70% PPD, 120 degrees ASCA, and 70 degrees PSCA. FSL-CIs constructed with at least 3 optimal parameters (60% APD, 70% PPD, and 120 degrees ASCA) had a similar risk of leakage to M-CIs (odds ratio [OR], 1.1; 95% CI, 0.5-2.3). FSL-CIs with suboptimal parameters had twice the risk of leakage of M-CIs (OR, 2.0; 95% CI, 1.1-3.8).

CONCLUSIONS

Overall, FSL-CIs leaked more than M-CIs. However, FSL-CIs with optimized wound profiles had an equivalent risk of leakage to M-CIs. Wound parameter customization is an asset of FSL technology that allows optimization of FSL-CI sealability.

Intraocular Pressure Reduction after Femtolaser Assisted Cataract Surgery and Its Association with the Use of Ultrasound

Background and Objectives: To quantify the change in intraocular pressure (IOP) after phacoemulsification in patients having undergone femtolaser assisted cataract surgery (FLACS), and study the influence of the use of ultrasound on this change. Setting: Jules-Gonin Eye Hospital, University Department of Ophthalmology, Lausanne, Switzerland. Materials and Methods: Interventional study. Methods: All consecutive cases operated with FLACS and with complete data for the studied parameters were selected for inclusion in the study. Data had been prospectively collected and was analysed retrospectively. Linear regression was performed to explore the association of change in IOP with time of measure, ultrasound use, sex, age, and duration of surgery. Results: There was a mean decrease in intraocular pressure of 2.5 mmHg (CI 95% −3.6; −1.4, p < 0.001) postoperatively. No association between the change in intraocular pressure and ultrasound time or effective phaco time was observed when the data were analyzed one at a time or in a multiple linear regression model. There was no association with sex, age, nuclear density, presence of pseudoexfoliation, duration of surgery, and time of ocular pressure measurement. Eyes with preoperative IOP ≥ 21 mmHg had a more significant IOP reduction after surgery (p < 0.0001) as did eyes with an anterior chamber depth <2.5 mm (p = 0.01). Conclusion: There was a decrease in intraocular pressure six months after FLACS in our study similar to that in the published literature for standard phacoemulsification. The use of ultrasound may not influence the size of the decrease, whereas the preoperative IOP and anterior chamber depth do. FLACS may be as valuable as standard phacoemulsification for cases where IOP reduction is needed postoperatively.

Femtosecond laser-assisted cataract surgery compared with phacoemulsification: the FACT non-inferiority RCT

BACKGROUND

Cataract surgery is one of the most common operations. Femtosecond laser-assisted cataract surgery (FLACS) is a technique that automates a number of operative steps.

OBJECTIVES

To compare FLACS with phacoemulsification cataract surgery (PCS).

DESIGN

Multicentre, outcome-masked, randomised controlled non-inferiority trial.

SETTING

Three collaborating NHS hospitals.

PARTICIPANTS

A total of 785 patients with age-related cataract in one or both eyes were randomised between May 2015 and September 2017.

INTERVENTION

FLACS (n = 392 participants) or PCS (n = 393 participants).

MAIN OUTCOME MEASURES

The primary outcome was uncorrected distance visual acuity in the study eye after 3 months, expressed as the logarithm of the minimum angle of resolution (logMAR): 0.00 logMAR (or 6/6 if expressed in Snellen) is normal (good visual acuity). Secondary outcomes included corrected distance visual acuity, refractive outcomes (within 0.5 dioptre and 1.0 dioptre of target), safety and patient-reported outcome measures at 3 and 12 months, and resource use. All trial follow-ups were performed by optometrists who were masked to the trial intervention.

RESULTS

A total of 353 (90%) participants allocated to the FLACS arm and 317 (81%) participants allocated to the PCS arm attended follow-up at 3 months. The mean uncorrected distance visual acuity was similar in both treatment arms [0.13 logMAR, standard deviation 0.23 logMAR, for FLACS, vs. 0.14 logMAR, standard deviation 0.27 logMAR, for PCS, with a difference of -0.01 logMAR (95% confidence interval -0.05 to 0.03 logMAR; p = 0.63)]. The mean corrected distance visual acuity values were again similar in both treatment arms (-0.01 logMAR, standard deviation 0.19 logMAR FLACS vs. 0.01 logMAR, standard deviation 0.21 logMAR PCS; p = 0.34). There were two posterior capsule tears in the PCS arm. There were no significant differences between the treatment arms for any secondary outcome at 3 months. At 12 months, the mean uncorrected distance visual acuity was 0.14 logMAR (standard deviation 0.22 logMAR) for FLACS and 0.17 logMAR (standard deviation 0.25 logMAR) for PCS, with a difference between the treatment arms of -0.03 logMAR (95% confidence interval -0.06 to 0.01 logMAR; p = 0.17). The mean corrected distance visual acuity was 0.003 logMAR (standard deviation 0.18 logMAR) for FLACS and 0.03 logMAR (standard deviation 0.23 logMAR) for PCS, with a difference of -0.03 logMAR (95% confidence interval -0.06 to 0.01 logMAR; p = 0.11). There were no significant differences between the arms for any other outcomes, with the exception of the mean binocular corrected distance visual acuity with a difference of -0.02 logMAR (95% confidence interval -0.05 to 0.00 logMAR) (p = 0.036), which favoured FLACS. There were no significant differences between the arms for any health, social care or societal costs. For the economic evaluation, the mean cost difference was £167.62 per patient higher for FLACS (95% of iterations between -£14.12 and £341.67) than for PCS. The mean QALY difference (FLACS minus PCS) was 0.001 (95% of iterations between -0.011 and 0.015), which equates to an incremental cost-effectiveness ratio (cost difference divided by QALY difference) of £167,620.

LIMITATIONS

Although the measurement of outcomes was carried out by optometrists who were masked to the treatment arm, the participants were not masked.

CONCLUSIONS

The evidence suggests that FLACS is not inferior to PCS in terms of vision after 3 months' follow-up, and there were no significant differences in patient-reported health and safety outcomes after 12 months' follow-up. In addition, the statistically significant difference in binocular corrected distance visual acuity was not clinically significant. FLACS is not cost-effective.

FUTURE WORK

To explore the possible differences in vision in patients without ocular co-pathology.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN77602616.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 6. See the NIHR Journals Library website for further project information. Moorfields Eye Charity (grant references GR000233 and GR000449 for the endothelial cell counter and femtosecond laser used).

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.

Ultrasound-Energy Consumption During Phases of Phacoemulsification of Nuclear Cataracts Using Femtosecond Laser: A Comparative Study

Purpose

To compare ultrasound (US) energy utilized in different phases of nuclear cataract removal in femtosecond laser-assisted cataract surgery (FLACS) with conventional phacoemulsification surgery (CPS) in relation to different nuclear densities.

Methods

A prospective nonrandomized comparative study was conducted at Ain Shams University and Al Watany Eye Hospital, Cairo, Egypt on 250 eyes with senile nuclear cataracts (NCs) of different nuclear densities (1-6). Eyes were divided into two groups - FLACS and CPS - and each group was subdivided according to cataract density into subgroups A (NC 1-2), B (NC 3-4) and C (NC 5-6). sextant-softened fragmentation patterns were assessed in the FLACS group and the quick-chop technique used in the CPS group. US energy required for nucleus cracking (EFX split) and for quadrant removal (EFX quadrant) was recorded.

Results

Total eyes included in the FLACS and CPS groups were 117 and 133, respectively. No significant differences between the groups for EFX quadrant and EFX split groups were observed (P=0.18 and P=0.49, respectively). For subgroup A, no significant difference was found between FLACS and CPS on EFX split (P=0.08) and EFX quadrant (P=0.49). For subgroup B, significantly lower values of EFX split (P=0.0001) and EFX quadrant (P<0.0001) were obtained with FLACS than CPS. For subgroup C, no significant difference was found for EFX split (P=0.86); however, EFX quadrant was significantly lower in the FLACS group (P=0.05).

Conclusion

FLACS lowers US energy utilized during quadrant removal at different nuclear densities, with highest significance in medium-density nuclear cataracts. Nucleus cracking by femtosecond laser is less effective in very hard cataracts. However, femtosecond-laser softening of hard nuclei is capable of of US-energy reduction during quadrant removal.

Clinical and Surgical Outcomes of Femtosecond Laser-Assisted Cataract Surgery (FLACS) on Hard Cataracts in the Egyptian Population

Objective

To evaluate the clinical and surgical outcomes of femtosecond laser-assisted cataract surgery (FLACS) in hard cataract of Egyptian population.

Setting

ICare Center, Alexandria, Egypt.

Design

Retrospective observational.

Methods

The study included 50 FLACS cases of 40 patients who had cataract; NO4 NC4 or more according to Lens Opacities Classification System III (LOCS III), performed between October 2018 and May 2019. The cases underwent anterior capsulotomy, lens fragmentation, and corneal incisions with the femtosecond laser. Arcuate keratotomy was performed in selected cases. Phacoemulsification and implantation of an intraocular lens are then performed.

Results

Patients mean age was 63.06 ± 7.75 yr, mean femtosecond laser energy was 12.92 ± 0.72 mJ, mean docking time was 3.00 ± 0.83 min and overall mean laser treatment time was 92.00 ± 25.01 sec. Mean laser treatment time was lower in cases that did not get astigmatic keratectomy (87.7 ± 18.97 vs 89.47 ± 13.43 sec; p < 0.73). Attempted refraction was -0.09 ± 0.52 D and achieved 12 months postoperative manifest sphere equivalent refraction (SER) was -0.19 ± 1.11 D (r = 0.8 and P˂0.001). Mean error (ME) was -0.2 ± 1.11 (range: -2.5-1.5) while mean absolute error (MAE) was 0.97 ± 0.57 (range: 0-2.5). Eighty percent and 92% of cases had 1 month postoperative SER within 1.0 D and 1.5 D, respectively. One eye (2%) had incomplete capsulotomy, 7 eyes (14%) had incomplete corneal incision and lens fragmentation was complete in all cases except 1 eye (2%). Thirty-four eyes (68%) showed postdocking conjunctival ecchymosis and 35 eyes (70%) had intraoperative miosis.

Conclusion

FLACS has low complication rate with effective results. High cost of technology is still the main barrier against its popularity.

Stability of a non-applanating handheld liquid patient interface for femtosecond laser-assisted cataract surgery

PURPOSE

A stable and reliable vacuum is crucial for the correct planning and performance of femtosecond laser-assisted cataract surgery (FLACS) in order to avoid complications such as suction loss and cyclorotation. This study investigates, for the first time, the impact of different vacuum levels on the stability of the application of a liquid patient interface for FLACS in view of break-away forces.

METHODS

Break-away forces were measured using a multifunctional material testing machine with a mounted digital manometer. Sixteen porcine eyes were docked to the patient interface of a femtosecond laser platform (FEMTO LDV Z8), and the impact of different vacuum levels between 300 and 500 mbar investigated.

RESULTS

Mean break-away forces for each vacuum level were as follows: 1.78 N (± 0.58 N) for 300 mbar; 2.24 N (± 0.68 N) for 350 mbar; 2.66 N (± 0.68 N) for 400 mbar; 2.86 N (± 0.77 N) for 420 mbar; and 3.49 N (± 0.86 N) for 500 mbar.

CONCLUSION

The stability increases with the vacuum in a nearly linear manner. Vacuum levels higher than 500 mmHg and lower than 350 mmHg are not recommended for FLACS.

Application of Femtosecond Laser in Anterior Segment Surgery

Femtosecond laser (FSL) is a near-infrared laser that can create reliable and reproducible tissue cutting with minimal damage to adjacent tissue. As the laser can also create incisions with various orientations, depths, and shapes, it is expected to be a useful tool for anterior segment surgery, such as cornea, refractive, and cataract surgery. In this review, the authors will introduce the application of FSL in various anterior segment surgeries and discuss the results of studies regarding the efficacy and safety of FSL in cornea, refractive, and cataract surgery. Experimental studies regarding the potential use of FSL will also be introduced. The studies discussed in this review suggest that FSL may be a useful tool for improving the prognosis and safety of surgeries of the anterior segment.

Incidence and characteristics of cataract surgery in South Korea from 2011 to 2015: A nationwide population-based study

IMPORTANCE

Detailed incidence data for cataract surgery in the general population are limited, yet important for determining the surgical needs of the community and formulation of healthcare policies.

BACKGROUND

To report incidence rates of cataract surgery in South Korea.

DESIGN

Nationwide, retrospective population-based study.

PARTICIPANTS

This study involved the entire population of South Korea (n = 47 990 761); 2 236 107 eyes of 1 591 176 patients confirmed as having cataract surgery from 1 January 2011 to 31 December 2015 were included.

METHODS

Data for all patients who underwent primary cataract surgery in South Korea were retrieved using Korean Electronic Data Interchange and Korean Standard Classification of Diseases-7 codes. Annual incidence rates were calculated and adjusted to the national population data for the corresponding year.

MAIN OUTCOME MEASURES

The average incidence of cataract surgery during the 5-year study period was estimated using population data from the 2010 Korean census.

RESULTS

The incidence of cataract surgery increased from 8.54/1000 person-years in 2011 to 9.67/1000 person-years in 2015. The probability of second-eye surgery within 12 months after the first-eye surgery increased from 42.98% in 2011 to 48.01% in 2015. In total, 85.72% of surgeries were performed in non-rural areas: 43.18% in individuals with a higher household income and 76.65% in primary healthcare centres. The rate of vitrectomy for posterior capsular rupture was 0.72%.

CONCLUSIONS AND RELEVANCE

The incidence of cataract surgery in South Korea is increasing over time. Our findings are expected to aid in the formulation of future healthcare policies concerning cataract surgery in South Korea.

Intraocular Pressure Changes during Femtosecond Laser-Assisted Cataract Surgery: A Comparison between Two Different Patient Interfaces

Purpose

The aim of this retrospective cohort study was to evaluate intraocular pressure (IOP) changes during femtosecond laser-assisted cataract surgery (FLACS) using two different patient interface systems.

Methods

116 eyes of 116 patients scheduled for cataract surgery were divided into 2 groups: group 1 (61 eyes) and group 2 (55 eyes) underwent FLACS using Catalys Laser with fluid interface (liquid optics interface, LOI) and LenSx Laser with curved interface and soft contact lens (SoftFit), respectively. IOP was assessed using a portable rebound tonometer (Icare®) preoperatively, after docking, immediately after surgery, at one and seven days postoperatively.

Results

In group 1, the mean IOP (±SD) was 14.1 ± 0.4 mmHg before surgery, 33.2 ± 1.1 mmHg after docking, and 21.4 ± 0.9 mmHg immediately after surgery. In group 2, the mean IOP was 13.8 ± 0.4 mmHg before surgery, 24.2 ± 1.4 mmHg after docking, and 20.2 ± 1.2 mmHg immediately after surgery. After the docking procedure, a statistically significant increase in IOP from the baseline was found in both groups (p < 0.001). Moreover, no statistically significant difference in IOP measured at 1 and 7 days postoperatively was observed compared with the preoperative values (p > 0.05) using both laser platforms. No intraoperative and postoperative complications were observed.

Conclusions

FLACS suction phase resulted in a transient increase of IOP in both groups, especially with the LOI system, and it is probably related to the greater pressure of a suction ring and suction generated through the vacuum, independently from the effect of femtosecond laser itself.

Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms

Every part of the human body is subject to aging, including the eye. An increased prevalence of dry eye disease with age is widely acknowledged. Aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Additional age-related processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. Correction strategies for presbyopia and cataracts may directly or indirectly challenge the ocular surface. Contact lenses disturb the normal structure of the tear film and can interact negatively with the ocular surface, further deteriorating an already unbalanced tear film in presbyopes, however, newer contact lens designs can overcome some of these issues. Moreover, cataract and corneal refractive surgeries sever corneal nerves and disrupt the corneal epithelium and ocular surface, which can influence surgical outcomes and aggravate dryness symptoms in older age groups. This review summarises the current understanding of how the invasive nature of contact lens wear and cataract and refractive surgery influence signs and symptoms of ocular dryness in an aging population.

Effect of lens thickness and nuclear density on the amount of laser fragmentation energy delivered during femtosecond laser-assisted cataract surgery

PURPOSE

To study the influence of lens thickness and nuclear density on the amount of laser fragmentation energy delivered during femtosecond laser-assisted cataract surgery.

SETTING

Ain Shams University and Al-Watany Eye Hospital, Cairo, Egypt.

DESIGN

Retrospective case series.

METHODS

This study included eyes of patients with primary cataract of different nuclear densities that had femtosecond laser-assisted cataract surgery using the Catalys Precision system. Variables studied included preoperative lens thickness measured by spectral-domain optical coherence tomography, nuclear density using the Lens Opacities Classification System III, pupil size, laser fragmentation energy, total laser energy, and transversal ultrasound time (Ellips FX). Patients were divided according to the preoperative lens thickness as follows: lens thickness more than 4.8 mm (Group 1) and lens thickness 4.8 mm or less (Group 2).

RESULTS

The study included 192 eyes of 120 patients. The amount of laser energy for fragmentation was statistically significantly higher in Group 1 than in Group 2 (5.9 J ± 1.5 [SD] versus 4.5 ± 1.8 J) (P < .001). Laser fragmentation energy and total laser time had a strong positive correlation with lens thickness (r = 0.53, P < .001) but not with nuclear density or pupil size. Lens thickness was positively correlated with age (r = 0.42, P < .001) but not with nuclear density.

CONCLUSIONS

The preoperative lens thickness, not density, determined the amount of laser energy delivered. The laser might deliver unnecessary energy for softer and thicker nuclei while delivering less energy for thinner but harder nuclei.

Consensus on the management of astigmatism in cataract surgery

This project was aimed at achieving consensus on the management of astigmatism during cataract surgery by ophthalmologists from Latin America using modified Delphi technique. Relevant peer-reviewed literature was identified, and 21 clinical research questions associated with the definition, classification, measurement, and treatment of astigmatism during cataract surgery were formulated. Twenty participants were divided into seven groups, and each group was assigned three questions to which they had to respond in written form, after thoroughly reviewing the literature. The assigned questions with corresponding responses by each group were discussed with other participants in round 4 – presentation of findings. The consensus was achieved if approval was obtained from at least 80% of participants. The present paper provides several agreements and recommendations for management of astigmatism during cataract surgery, which could potentially minimize the variability in practice patterns and help ophthalmologists adopt optimal practices for cataract patients with astigmatism and improve patient satisfaction.

Cataract surgery and lens implantation

PURPOSE OF REVIEW

This review aims to introduce recent updates in cataract surgery and lens implantation.

RECENT FINDINGS

Compared to phacoemulsification, femtosecond laser-assisted cataract surgery (FLACS) may offer benefit for cataract patients with other complicated ocular diseases, such as corneal disease and vitreous abnormalities. Meanwhile, several types of novel intraocular lenses (IOLs) have been introduced to the market, and each of them has particular features in improving patients' visual acuity. In addition, based on a series of studies, multifocal IOL is superior to monofocal IOL when it comes to providing a better visual correction at different distances. Furthermore, a research group has introduced a new approach for cataract surgery - all laser surgery (FLACS band with nanolaser emulsification), which can effectively reduce iatrogenic trauma to the cornea. Also, a novel technique designed for children can lessen damage from cataract surgery.

SUMMARY

Based on previous studies, we summarize the new proceedings in FLACS and the indications for applying multifocal or toric IOL. In addition, we briefly introduce a new approach to cataract surgery - all laser surgery (FLACS band with nanolaser emulsification), and a less invasive surgical procedure used in pediatric cataract patients.

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.

Comparison of clinical outcomes between cystotome-assisted prechop phacoemulsification surgery and conventional phacoemulsification surgery for hard nucleus cataracts: A CONSORT-compliant article

BACKGROUND

This study aimed to investigate the safety and efficacy of the cystotome-assisted prechop phacoemulsification surgery (CAPPS) and conventional phacoemulsification surgery (CPS) in patients with IV degree nucleus cataract.

METHODS

The prospective, randomized, consecutive, comparative cohort study consecutively recruited Chinese age-related cataract patients, CAPPS and CPS were performed by a seasoned surgeon. Postoperative follow-up was at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year, and the outcome measures comprised ultrasound power, effective phacoemulsification time (EPT), corrected distance visual acuity (CDVA), endothelial cell density (ECD), corneal endothelium loss rate (ECL), central corneal thickness (CCT), and intraoperative and postoperative complications.

RESULTS

Patients in both groups gained a better CDVA postoperatively. The ultrasound power and EPT in the CAPPS group were lower than the CPS group (P < .001). ECD value decreased at each follow-up visit and did not return to the preoperative level; CPS resulted in greater endothelial cell loss than CAPPS did, which was significant. CCT increased immediately after the surgery, and decreased thereafter. The mean CCT values returned to preoperative levels at 3 months after surgery in the CAPPS group while it took 6 months in the CPS group. The differences in cornea edema and anterior chamber flare between the 2 groups were not significant at 1 day postoperatively (P = .070 and .094, respectively), while at the 1-week time point, the differences were statistically significant (P = .002 and .001, respectively).

CONCLUSION

CAPPS appears to be an excellent method for treating hard nucleus cataract.

Clinical results of the open ring PMMA guider assisted capsulorrhexis in cataract surgery

Background

To compare the results of continuous curvilinear capsulorrhexis(CCC) after application of an open ring-shaped guider compared with a free-hand procedure in eyes with cataracts.

Methods

This study comprised patients undergoing cataract surgery in Seoul St.Mary’s Hospital, The Catholic University of Korea. Eyes were grouped depending on the capsulotomy method; CCC was performed by free-hand procedure on 94 eyes (free-hand group), and it was performed under the guidance after introduction of an open ring-shaped guider on consecutive 89 eyes (guided group). Horizontal and vertical diameter, area and circularity of capsulotomy were measured postoperatively at one day, two months and six months. Differences in parameters and the percentage of ideal capsulorrhexis were analyzed between the two groups.

Results

On the first postoperative day, the vertical diameter in the guided group (5.24 ± 0.16 mm) was significantly longer than that of the free-hand group (5.01 ± 0.65 mm, P = 0.019). The area of capsulotomy was larger in the guided group (21.55 ± 0.87 mm²) than that of the free-hand group (20.34 ± 2.96 mm², P < 0.001). Circularity in the guided group (0.84 ± 0.03), was significantly greater than that of the free-hand group (0.69 ± 0.17, P = 0.036). Ideal capsulorrhexis was obtained in 60 eyes (67%) in the free-hand group and 81 eyes (86%) in the guided group.

Conclusions

After introduction of an open ring-shaped guider, CCC became larger and more circular with less anterior capsular contracture. The rate of acquiring ideal capsulorrhexis was higher in the guided group than it was in the free-hand group for six months after surgery.

Monitoring tool usage in surgery videos using boosted convolutional and recurrent neural networks

This paper investigates the automatic monitoring of tool usage during a surgery, with potential applications in report generation, surgical training and real-time decision support. Two surgeries are considered: cataract surgery, the most common surgical procedure, and cholecystectomy, one of the most common digestive surgeries. Tool usage is monitored in videos recorded either through a microscope (cataract surgery) or an endoscope (cholecystectomy). Following state-of-the-art video analysis solutions, each frame of the video is analyzed by convolutional neural networks (CNNs) whose outputs are fed to recurrent neural networks (RNNs) in order to take temporal relationships between events into account. Novelty lies in the way those CNNs and RNNs are trained. Computational complexity prevents the end-to-end training of "CNN+RNN" systems. Therefore, CNNs are usually trained first, independently from the RNNs. This approach is clearly suboptimal for surgical tool analysis: many tools are very similar to one another, but they can generally be differentiated based on past events. CNNs should be trained to extract the most useful visual features in combination with the temporal context. A novel boosting strategy is proposed to achieve this goal: the CNN and RNN parts of the system are simultaneously enriched by progressively adding weak classifiers (either CNNs or RNNs) trained to improve the overall classification accuracy. Experiments were performed in a dataset of 50 cataract surgery videos, where the usage of 21 surgical tools was manually annotated, and a dataset of 80 cholecystectomy videos, where the usage of 7 tools was manually annotated. Very good classification performance are achieved in both datasets: tool usage could be labeled with an average area under the ROC curve of A_z=0.9961 and A_z=0.9939, respectively, in offline mode (using past, present and future information), and A_z=0.9957 and A_z=0.9936, respectively, in online mode (using past and present information only).

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparison of clinical outcomes, patient, and surgeon satisfaction following topical versus peribulbar anesthesia for phacoemulsification and intraocular lens implantation: a randomized, controlled trial

Background:

Both cataract surgery and anesthesia techniques are rapidly evolving to become more patient friendly. However, comparison of topical anesthesia (TA) and peribulbar anesthesia (PA) for phacoemulsification and cataract surgery is limited. We evaluated the clinical outcomes and patient and surgeon satisfaction between anesthetic techniques.

Materials and Methods:

This randomized clinical trial was conducted between January and June 2012. Patients were randomly assigned to TA and PA groups for surgery. Visual acuity at 4 weeks postoperatively, status of the cornea and the wound and intraoperative complications were compared between groups at day 1, and 1 and 4 weeks after surgery. Patients and the surgeon completed a close-ended questionnaire on satisfaction with analgesia and comfort. The relative risk (RR) with 95% confidence intervals (CI) was calculated.

Result:

There were 500 patients in each group. There were no significant differences between groups preoperatively. Complications at 1-day postoperatively were significantly greater in the TA group (RR = 1.36, 95% CI: 1.17–1.58). Satisfaction with the mitigation of pain was statistically significantly greater in the PA group compared to the TA group (χ² = 10.9, df = 3, P = 0.001). Surgeons were more satisfied with PA compared to TA (RR = 1.4, 95% CI: 1.34–1.63). There were more anesthesia-related complications in the PA group compared to the TA group.

Conclusions:

Patients who underwent surgery with topical anesthetic experienced lower complications by more pain compared to patients who underwent PA. Topical anesthetic supplemented with analgesic medications could help the patient and surgeon during cataract surgery.

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.

The effects of a low-energy, high frequency liquid optic interface femtosecond laser system on lens capsulotomy

The introduction of femtosecond laser assisted cataract surgery (FLACS) is a paradigm changing approach in cataract surgery, the most commonly performed surgical procedure. FLACS has the potential to optimize the creation of an anterior lens capsulotomy, a critical step in accessing the cataractous lens. The merits of using a laser instead of a manual approach include a potentially more circular, consistent, and stronger aperture. In this study we demonstrated for the first time in both a porcine and human experimental setting that with a low energy, high repetition FLACS system, that a circular, smooth and strong capsulotomy was achievable. While there was no demonstrable difference in the resistance to rupture before or after the removal of the nucleus, larger capsulotomies had an increase in tensile strength. The LDV Z8 system appeared to create circular, rupture-resistant and smooth capsulotomies in both porcine and more importantly human globes.

Femtosecond laser capsulotomy versus manual capsulotomy: a Meta-analysis

AIM

To perform a Meta-analysis on the precision and safety of femtosecond laser (FSL) capsulotomy compared with manual continuous curvilinear capsulotomy (CCC).

METHODS

We searched PubMed, EMBASE, Web of Science, the Cochrane Library databases, and Clinical Trials.gov that maintained our inclusion criteria. Reference lists of retrieved articles were also reviewed. The effects of morphology of capsulorhexis and the tears of anterior capsule were calculated by using random-effect models.

RESULTS

We identified 4 randomized and 7 nonrandomized studies involving 2941 eyes. The diameter of capsulotomy and the rates of anterior capsule tear showed no statistically difference between FSL group and manual group (MD=0.03; 95%CI, -0.03 to 0.09, P=0.31), and (OR=1.40; 95%CI, 0.28 to 6.97, P=0.68) respectively. In terms of the circularity of capsulotomy, FSL group had a more significant advantage than the manual CCC group (MD=0.09; 95%CI, 0.05 to 0.12, P<0.0001).

CONCLUSION

Our Meta-analysis shows that FSL can perform a capsulotomy with more precision and higher reliability than manual CCC. The results in diameter of capsulotomy and the rate of anterior capsule tears was no significant difference between FSL and manual CCC groups. However in terms of circularity, the FSL was superior to the manual procedure.

Femtosecond laser assisted cataract surgery, beginning of a new era in cataract surgery

The purpose of this article is to analyze and understand the mechanism of action, effectiveness, cost and time benefits, advantages and disadvantages of the femtosecond laser (FSL) assisted cataract surgery. A PubMed search was done using the topic and the keywords. Research shows considerable improvements in corneal incisions, anterior capsulotomy, and phacofragmentation using FSL. We will also discuss and compare FSL with conventional cataract extraction techniques in terms of both short-term and long-term advantages and disadvantages. Limitations of the studies reviewed include small sample size and short-term follow-up. The major dilemma is still considered to be its heavy financial feasibility to date.

Randomised, single-masked non-inferiority trial of femtosecond laser-assisted versus manual phacoemulsification cataract surgery for adults with visually significant cataract: the FACT trial protocol

INTRODUCTION

Cataract is one of the leading causes of low vision in the westernised world, and cataract surgery is one of the most commonly performed operations. Laser platforms for cataract surgery are now available, the anticipated advantages of which are broad and may include better visual outcomes through greater precision and reproducibility, and improved safety. FACT is a randomised single masked non-inferiority trial to establish whether laser-assisted cataract surgery is as good as or better than standard manual phacoemulsification.

METHODS AND ANALYSIS

808 patients aged 18 years and over with visually significant cataract will be randomised to manual phacoemulsification cataract surgery (standard care) or laser-assisted cataract surgery (intervention arm). Outcomes will be measured at 3 and 12 months after surgery. The primary clinical outcome is uncorrected distance visual acuity (UDVA, logMAR) at 3 months in the study eye recorded by an observer masked to the trial group. Secondary outcomes include UDVA at 12 months, corrected distance visual acuity at 3 and 12 months, complications, endothelial cell loss, patient-reported outcome measures and a health economic analysis conforming to National Institute for Health and Care Excellence standards.

ETHICS AND DISSEMINATION

Research Ethics Committee Approval was obtained on 6 February 2015, ref: 14/LO/1937. Current protocol: v2.0 (08/04/2015). Study findings will be published in peer-reviewed journals.

ISRCTN

77602616.

Investigating the ocular temperature rise during femtosecond laser lens fragmentation: an in vitro study

PURPOSE

To investigate the trend of temperature variation during lens fragmentation simulated by a femtosecond laser on an in vitro eye model.

METHODS

In our experimental study, a convex cylinder of gelatinous material, usually employed in femtosecond laser calibration, was used to simulate both an anterior segment and a crystalline lens during fragmentation performed with the Victus femtosecond laser (Technolas Perfect Vision GmbH, Germany; Bausch + Lomb Incorporated, USA). Two radiated energies (7000 nJ and 9000 nJ) and three cutting patterns (crosses, circles and cross + circle) were applied. Trends of temperature variation as a function of time were obtained using a T-type thermocouple.

RESULTS

The maximum value of temperature rise during lens fragmentation ranged from 3.53 to 5.13 °C; the rise was directly proportional to the intensity of the radiated energy (7000 nJ or 9000 nJ) and the cutting pattern performed. This behavior was experimentally represented by an asymmetric function with a characteristic bell curve shape, whereas it was mathematically described by a transport diffusive model.

CONCLUSIONS

Since the temperature rise at the fragmentation volume base resulted to be around 5 °C in our in vitro study, lens fragmentation performed using the Victus femtosecond laser might be considered safe form a thermal point of view.

Comparison of intra-ocular pressure changes with liquid or flat applanation interfaces in a femtosecond laser platform

Cataract surgery is the most common surgical procedure and femtosecond laser assisted cataract surgery (FLACS) has gained increased popularity. FLACS requires the application of a suction device to stabilize the laser head and focus the laser beam accurately. This may cause a significant escalation in intra-ocular pressure (IOP), which poses potential risks for patients undergoing cataract surgery. In this study we aimed to assess the effect of the Ziemer LDV Z8 femtosecond cataract machine on IOP. We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum. Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg. A pilot series in patients showed comparable pressure rises with the porcine model (30 mmHg). These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

New device for creating a continuous curvilinear capsulorhexis

PURPOSE

To describe the evolution of a new device to facilitate continuous curvilinear capsulorhexis (CCC) creation.

SETTING

Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.

DESIGN

Experimental study.

METHODS

Bench-side ex vivo testing of unique prototypes for guidance and assistance of CCC in bovine and human eyes was performed. Five designs were sequentially tested as follows: a flexible circular blade of nickel-titanium alloy (nitinol), a flexible nitinol guide wire, a flexible elastomeric suction device, a combination approach of a nitinol guide wire and flexible silicone ring, and a freestanding micropatterned silicone ring.

RESULTS

The first 3 designs were not amenable to insertion through a sub-2.4 mm corneal incision and failed to maintain adequate downward force to cut the capsule and/or prevent radial tears. The fourth design was successfully inserted through a 2.4 mm incision and maintained adequate downward pressure and contact to guide a manual CCC without radial tears. The final design was insertable through a 2.4 mm incision and exhibited self-adhesive characteristics after placement on the anterior capsule of an ophthalmic viscosurgical device-filled anterior chamber.

CONCLUSIONS

Given the steep learning curve of manual capsulorhexis and the high cost of capsulotomy-assistive devices, such as the femtosecond laser, an alternative approach for creating a CCC is desirable. Performance of a highly precise manual CCC through a small incision using a medical-grade silicone device with an adhesive micropatterned design is a viable and cost-effective option for use in cataract surgery across a wide range of user experience.

FINANCIAL DISCLOSURE

All authors are named as the inventors in a patent filed by the University of Colorado covering the details in this report.

A Comparison of Different Operating Systems for Femtosecond Lasers in Cataract Surgery

The introduction of femtosecond lasers is potentially a major shift in the way we approach cataract surgery. The development of increasingly sophisticated intraocular lenses (IOLs), coupled with heightened patient expectation of high quality postsurgical visual outcomes, has generated the need for a more precise, highly reproducible and standardized method to carry out cataract operations. As femtosecond laser-assisted cataract surgery (FLACS) becomes more commonplace in surgical centers, further evaluation of the potential risks and benefits needs to be established, particularly in the medium/long term effects. Healthcare administrators will also have to weigh and balance out the financial costs of these lasers relative to the advantages they put forth. In this review, we provide an operational overview of three of five femtosecond laser platforms that are currently commercially available: the Catalys (USA), the Victus (USA), and the LDV Z8 (Switzerland).

Laser-Assisted Cataract Surgery: Soft Lens Assisted Interface (SoftFit) versus Direct Contact Interface

Purpose

To determine the safety of the Laser SoftFit™ patient interface by comparing intraoperative results with the contact interface of the LenSx® femtosecond laser platform (FSL).

Methods

In this nonrandomized, consecutive case series, 50 eyes underwent femtosecond laser-assisted cataract surgery (FLACS) using the LenSx® laser platform (group 1); FLACS was performed in another 50 eyes, using the Laser SoftFit™ patient interface (group 2). Intraoperative complications (corneal folds) and surgical results (incomplete and free capsulotomies, incomplete phacofragmentation, and unopened incisions) were compared.

Results

Corneal folds and incomplete capsulotomies were less common (p = 0.0001 for both) and free-floating capsulotomies were more frequent (p = 0.0001) with the Laser SoftFit™ patient interface. Incomplete phacofragmentation and unopened incision exhibited similar rates in both groups (p = 0.436 and 0.204, respectively).

Conclusions

Using the Laser SoftFit™ patient interface decreased the incidence of corneal folds, resulting in better capsulotomy outcomes during FLACS.

An Experimental Low-Cost Ultrasonic Phacoemulsifier—A Prototype Test

The structure and the features of a low-cost ultrasonic phacoemulsification prototype device are described in this paper. The phacoemulsifier was designed to comply with the techniques of modern cataract surgery. The functionality and reliability of the device were confirmed through in vitro experiments and animal studies. The device was designed to minimize surgical trauma: Reduced heat dissipation was achieved by specific power modulation, while the original design of aspiration control assured a reduced surge effect. In order to assess the suitability of the device, phacoemulsification was performed on rabbit eyes with nuclei of medium hardness. Their recovery was closely observed and only mild inflammation caused by surgical trauma was noticed. The device performed well in terms of reliability, ergonomics, and controllability throughout the experiments.

Adjustable intraocular lens power technology

We present an overview of the adjustable intraocular lens (IOL) technologies that are available or under development. This includes IOL technologies that can be adjusted using secondary surgical procedures, such as the multicomponent IOL, the mechanically adjustable IOL, and the repeatedly adjustable IOL; IOLs that can be adjusted noninvasively in the postoperative setting, such as the magnetically adjustable IOL, the liquid crystal IOLs with wireless control; and IOLs that can be adjusted using the femtosecond laser or 2-photon chemistry. Finally, we discuss the preclinical and clinical studies of the light-adjustable intraocular lens (LAL) that is available commercially in Europe and Mexico and in the final stages of clinical evaluation in the United States. The general principles of each technology, as well as their research status, are described.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Visual and refractive outcomes of laser cataract surgery

PURPOSE OF REVIEW

Femtosecond laser is a promising new technology for the field of cataract surgery. Early studies have investigated many factors including visual outcomes, complication rates, and financial overhead costs. This review analyzes the most recent clinical studies of visual and refractive outcomes in laser cataract surgery, including those that make comparisons to outcomes found in conventional phacoemulsification cataract surgery.

RECENT FINDINGS

As femtosecond laser cataract surgery has only emerged recently, there is limited literature available regarding visual outcomes. Most but not all existing studies showed no statistically significant difference in visual acuity and mean absolute refractive error between laser and conventional cataract surgery cases.

SUMMARY

The majority of studies examined found visual acuity or refractive outcomes of femtosecond laser to be statistically equivalent to those of conventional phacoemulsification cataract surgery. However, the learning curve involved with laser use may account for these early results, which could potentially improve as better technology and surgical techniques are developed. Further long-term outcomes studies are necessary to more accurately evaluate the benefits and drawbacks of femtosecond laser cataract surgery.