Initial Clinical Evaluation of an Intraocular Femtosecond Laser in Cataract Surgery

Incidence and analysis of intraoperative complications in femtosecond laser-assisted cataract surgery: a large-scale cohort study to establish the learning curve

AIMS

To assess the safety of femtosecond laser-assisted cataract surgery (FLACS) based on surgical parameters and intraoperative complications analysis and to determine the length of the learning curve for FLACS.

METHODS

A prospective consecutive cohort study was conducted on Chinese patients who underwent either FLACS (3289 cases) or contemporaneous conventional phacoemulsification cataract surgery (2130 cases). The laser group was divided into four subgroups in chronological order. We recorded intraoperative complication incidences and compared with surgical parameters between groups. Subgroup analysis was conducted to explore the learning curve of FLACS.

RESULTS

The laser group had a 4.93% incidence of incomplete capsulotomies and a 1.22% incidence of anterior capsule tears. Subgroup analysis showed significant differences in 8 aspects between the first 250 cases (50 cases per surgeon) and the last 2539 cases, but only 2 aspects differed between the second 250 cases (50 cases per surgeon) and the last 2539 cases. There were no significant differences between the third 250 cases (50 cases per surgeon) and the last 2539 cases.

CONCLUSIONS

The intraoperative complications of FLACS were reported, and the learning curve is associated with a significant reduction in the incidence of intraoperative complications. The length of the basic learning curve of FLACS is 100 cases, and the length of the advanced learning curve was 150 cases. This study demonstrated that FLACS is characterised by a relatively straightforward and secure operative technique.

Utilization of Ophthalmic Technology and Advances in Endothelial Keratoplasty: A Case Report

INTRODUCTION AND IMPORTANCE

The authors report a case of a 65-year-old male with corneal decompensation associated with poor vision with a recent history of cataract surgery.

CASE PRESENTATION

A patient presented with complaints of poor vision in the left eye. The patient had undergone phacoemulsification surgery 4 months prior to presentation. The presenting best corrected vision was 20/400 in the left eye with the presence of corneal edema and central Descemet's membrane detachment (DMD) extending to the inferior two-thirds of the cornea with a fibrotic demarcation line separating detached Descemet's from intact, attached Descemet's.

CLINICAL DISCUSSION

Anterior segment optical coherence tomography (AS-OCT) confirmed the diagnosis of Type 1 DMD. The patient was managed with femtosecond laser-assisted descematorrhexis with intraoperative AS-OCT, and a ready preloaded Descemet stripping endothelial keratoplasty graft.

CONCLUSIONS

This report emphasizes that many technological advancements in the field can be employed to improve the outcomes of endothelial keratoplasty, especially when fibrosis is associated with the combined PDL and DMD.

Comparison of low-energy FLACS and conventional cataract surgery: meta-analysis and systematic review

TOPIC

To systematically compare the effectiveness of conventional phacoemulsification surgery (CPS) and low-energy femtosecond laser-assisted cataract surgery (FLACS) in patients with cataract.

CLINICAL RELEVANCE

Cataract surgery is a common procedure, and comparing different techniques such as CPS and low-energy FLACS is crucial for optimizing patient outcomes.

METHODS

The PubMed, Web of Science, MEDLINE, EMBASE, and Cochrane library databases were searched for clinical trials. Outcomes of procedure time, effective phacoemulsification time, balanced salt solution usage, cumulative dissipated energy, mean change of corrected distance visual acuity, endothelial cells reduction, central corneal thickness (CCT), and aqueous cytokine level were evaluated. The effect measures were weighted mean differences with 95% CI. The protocol was registered at the Prospective Register for Systematic Reviews (registration number CRD42023420173).

RESULTS

11 studies were included in this meta-analysis, of which 1680 eyes were analyzed (637 eyes in the low-energy FLACS group and 1043 eyes in the CPS group). Low-energy FLACS demonstrated significantly fewer reductions in endothelial cell count at 6 months ( P < .001) compared with CPS. It also exhibited a shorter effective phacoemulsification time ( P < .001) and less balanced salt solution usage ( P < .001). However, there were no differences in cumulative dissipated energy, corrected distance visual acuity, CCT changes, or aqueous cytokine levels between the 2 groups.

CONCLUSIONS

Both low-energy FLACS and CPS are effective in treating cataracts, but low-energy FLACS may offer advantages such as reduced phacoemulsification time and less endothelial cell loss.

Dr. Sohel Khan's prechopper and prechopping technique

The quest of every dedicated phaco surgeon is to develop skills to emulsify all forms of hard nuclei efficiently with minimal damage to the endothelium and reducing the risk of wound burn. Obtaining a pristine cornea the very next day in a hard cataract is a dream far from reality. Prechop means nuclear division without the use of phaco energy. In this article, we describe a prechopping technique using a new sickle-shaped (saber tooth curvature and tip) novel prechopper that has a slender, sleek, and elegant design well suited for nuclear disassembly. The novel prechopper has proved to be a wonder device for hard, soft, white, posterior polar, and exfoliation cataracts. All maneuvers of prechop are performed in the bag away from the endothelium to be easily emulsified, subsequently making phacoemulsification easier, faster, and safer.

Lens Fragmentation with Picosecond Laser Pulses After Artificial Cataract Induction with Microwaves

Objectives: In this work we demonstrate the first laboratory study results of lens fragmentation with low-energy picosecond ultrashort laser pulses after artificial induction of cataract with microwave radiation on an ex vivo animal model. Background: This method will be evaluated with regard to the further development of lens fragmentation with novel ultrashort picosecond laser systems instead of ultrasonic phacoemulsification or the significantly more complex femtosecond laser fragmentation. Methods: As samples we used postmortem porcine eyes. The lenses were dissected and then irradiated in a microwave oven for artificial cataract induction. Subsequent computer-driven lens fragmentation was performed with a 12 ps, 1064 nm pulsed laser source with 100 µJ pulse energy, and 10 kHz pulse repetition rate. Results: Both the artificial cataract induction and the lens fragmentation were demonstrated. When inducing cataract, different degrees/stages of opaqueness and hardness could be achieved with different irradiation times and methods. The fragmentation with 12 ps pulses led to good results with regard to ablation depth and rate, especially for the softer lenses. Conclusions: As could be shown, low-energy picosecond ultrashort laser pulses are feasible for cataractous lens fragmentation on an ex vivo animal model with artificial cataract induction. Thus, this technique may influence future cataract surgeries by possibly being an alternative or extension to state-of-the-art methods. This will be evaluated with further tests and studies.

Long-term impact of low-energy femtosecond laser and manual cataract surgery on macular layer thickness: A prospective randomized study

PURPOSE

To evaluate change in retinal layers 18 months after femtosecond laser-assisted cataract surgery (LCS) and manual cataract surgery (MCS) in a representative age-related cataract population using artificial intelligence (AI)-based automated retinal layer segmentation.

METHODS

This was a prospective, randomized and intraindividual-controlled study including 60 patients at the Medical University of Vienna, Austria. Bilateral same-day LCS and MCS were performed in a randomized sequence. To provide insight into the development of cystoid macular oedema (CME), retinal layer thickness was measured pre-operatively and up to 18 months post-operatively in the central 1 mm, 3 mm and 6 mm.

RESULTS

Fifty-six patients completed all follow-up visits. LCS compared to MCS did not impact any of the investigated retinal layers at any follow-up visit (p > 0.05). For the central 1 mm, a significant increase in total retinal thickness (TRT) was seen after 1 week followed by an elevated plateau thereafter. For the 3 mm and 6 mm, TRT increased only after 3 weeks and 6 weeks and decreased again until 18 months. TRT remained significantly increased compared to pre-operative thickness (p < 0.001). Visual acuity remained unaffected by the macular thickening and no case of CME was observed. Inner nuclear layer (INL) and outer nuclear layer (ONL) were the main causative layers for the total TRT increase. Photoreceptors (PR) declined 1 week after surgery but regained pre-operative values 18 months after surgery.

CONCLUSION

Low-energy femtosecond laser pre-treatment did not influence thickness of the retinal layers in any topographic zone compared to manual high fluidic phacoemulsification. TRT did not return to pre-operative values 18 months after surgery. The causative layers for subclinical development of CME were successfully identified.

Comparing the efficacy and safety between femtosecond laser-assisted cataract surgery and conventional phacoemulsification cataract surgery: systematic review and meta-analysis

OBJECTIVE

To investigate the efficacy and safety of femtosecond laser-assisted cataract surgery (FLACS) compared with conventional phacoemulsification cataract surgery (CPCS).

METHODS

Randomized controlled trials (RCTs) were systematically searched in PubMed, Embase, Cochrane Library, ClinicalTrials.gov, CNKI, and Wanfang. Main outcomes were visual acuity, capsulotomy parameters, effective lens position, and complications. Secondary outcomes included refractive outcomes, intraoperative parameters, and corneal parameters.

RESULTS

In total, 41 RCTs involving 9310 eyes were included. There was a statistically significant difference in favour of FLACS over CPCS for uncorrected distance visual acuity at 12 months (mean difference [MD] -0.03; 95% CI -0.05 to -0.01); corrected distance visual acuity at 1 week (MD -0.05; 95% CI -0.07 to -0.02) and 12 months (MD -0.02; 95% CI -0.04 to -0.00); area of capsulotomy at 1 month (MD 4.04 mm2; 95% CI 3.45-4.64) and 6 months (MD 5.02 mm2; 95% CI 3.28-6.77); and intraocular lens centroid-pupil centroid distance at 1 week (MD -0.06 mm; 95% CI -0.08 to -0.05), 1 month (MD -0.07 mm; 95% CI -0.09 to -0.06), and 6 months (MD -0.06 mm; 95% CI -0.07 to -0.04). With regard to surgical complications, FLACS was less than CPCS for the incidence of decentred IOL (odds ratio 0.06; 95% CI 0.01-0.24). However, FLACS did not increase the incidence of other intraoperative or postoperative complications except subconjunctival hemorrhage.

CONCLUSIONS

Both FLACS and CPCS are effective and safe. FLACS achieves better visual outcomes in the early postoperative period and long-term follow-up, accompanied by more accurate capsulotomy and more optimized effective lens position than CPCS. However, no difference of visual outcomes was found after middle-term follow-up.

Comparative analysis of changes in retinal layer thickness following femtosecond laser-assisted cataract surgery and conventional cataract surgery

BACKGROUND

To investigate the influence of femtosecond laser-assisted cataract surgery (FLACS) on macula by examining changes in retinal layers after FLACS and to compare these changes with those after conventional cataract surgery (CCS).

METHODS

This study included 113 unrelated Korean patients with age-related cataract who underwent CCS or FLACS in Severance Hospital between September 2019 and July 2021. Optical coherence tomography was performed before and 1 month after surgery. The total retinal layer (TRL) was separated into the inner retinal layer (IRL) and outer retinal layer (ORL); moreover, the IRL was subdivided into the retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer (INL), outer plexiform layer, and outer nuclear layer. We performed between-group comparisons of the postoperative thickness in each retinal layer and the postoperative differences in retinal thickness. The average retinal thickness of the four inner macular ring quadrants was used for comparative analysis.

RESULTS

Compared with the CCS group, the FLACS group exhibited a thicker ORL (P = 0.004) and a thinner INL (P = 0.007) after surgery. All retinal layer thickness values showed significant postoperative changes regardless of the type of surgery (P < 0.05). The postoperative increase in TRL and IRL thickness was significantly smaller in the FLACS group than in the CCS group (P = 0.027, P = 0.012).

CONCLUSIONS

The 1-month postoperative retinal changes were less pronounced in the FLACS group than in the CCS group.

Comparative study of FLACS vs conventional phacoemulsification for cataract patients with high myopia

PURPOSE

To compare the short-term changes in cornea, retina, and choroid of femtosecond laser-assisted cataract surgery (FLACS) with conventional phacoemulsification (CPS) in high myopia patients with cataract.

SETTING

Affiliated Hospital of Nantong University, Jiangsu Province, China.

DESIGN

Prospective single-center study.

METHODS

Demographics, ocular clinical features, ultrasound power, absolute phacoemulsification time, and effective phacoemulsification time were recorded for each patient. Endothelial cell density (ECD), central corneal thickness (CCT), corrected distance visual acuity (CDVA), intraocular pressure (IOP), center foveal thickness (CFT), subfoveal choroidal thickness (SFCT), and choroidal vascularity index (CVI) were evaluated preoperatively and at 1 week, 1 month, and 3 months postoperatively. Intraoperative parameters and intraoperative/postoperative complications were recorded.

RESULTS

97 eyes (46 eyes and 51 eyes in the FLACS and CPS groups, respectively) were included and analyzed. Effective phacoemulsification time was lower in the FLACS group compared with the CPS group ( P < .05). The increase in CCT was significantly lower in the FLACS group compared with the CPS group at 1 week and 1 month ( P < .05). CDVA and IOP were similar in both groups at the final visit ( P > .05). The ECD decreased was lower among CPS patients compared with FLACS patients. CFT, SFCT, and CVI increase in both groups but were increased more in the CPS group with high myopia patients. No serious complications occurred in either group.

CONCLUSIONS

FLACS is a more safety and effective in cataract patients with high myopia. It has advantages in effectively reducing EPT and promoting faster recovery of the cornea, macular, and choroidal thickness.

Intraoperative trypan blue central landmark and its use in capsulotomy and capsulorhexis centration

PURPOSE

To compare 3 capsulotomy centration methods.

SETTING

Private clinic, Zlin, Czech Republic.

DESIGN

Prospective, consecutive case series.

METHODS

180 eyes undergoing cataract surgery had anterior capsule staining with microfiltered 0.4% trypan blue solution before selective laser capsulotomy. The first 60 eyes (Group 1) had mydriatic dilated pupil centered capsulotomies. The next 60 eyes (Group 2) were centered on the trypan blue central landmark (TCL). The final 60 capsulotomies (Group 3) were centered on the patient fixated coaxial Purkinje reflex (CPR). Measurements between key anatomical landmarks and the TCL, CPR capsulotomies, and implanted intraocular lens (IOL) center were made.

RESULTS

The TCL, observed in >94% of eyes in the study, coincided with the CPR with a displacement of <0.1 ± 0.1 mm. Group 1 capsulotomies were noticeably decentered on the IOLs by 0.3 ± 0.2 mm. The Group 2 symmetrical IOL relationship was maintained with a decentration of 0.15 ± 0.1 mm. Group 3 had a similar decentration with the IOLs with 0.15 ± 0.1 mm. Verification with IOLMaster 700 data and CALLISTO Eye System showed that the CPR and the TCL were coincident with the measured visual axis.

CONCLUSIONS

The clearly visible TCL served as an alternate landmark to the patient fixated CPR, and being on the anterior capsule was not sensitive to tilt. Further patient compliance was not required. Both were superior to dilated pupil centration, to achieve symmetric IOL coverage. This has application for both capsulotomies and capsulorhexes.

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.

Preventing the Argentinian flag sign and managing anterior capsular tears: A review

The Argentinian flag sign (AFS) is a feared complication during cataract extraction. Intralenticular pressures, especially excessive posterior pressure, have been identified as potential mechanisms for capsular stress and tearing associated with AFS. Capsular tension is created by positive intralenticular pressures, which cause the irido-lens diaphragm to move anteriorly once the manual capsulorhexis has been initiated. This tension can cause inadvertent tears that self-propagate to the lens equator, causing an AFS, among other intraoperative complications. Thus, this review highlights the importance of identifying intumescent cataracts as well as a combination of techniques to relieve intracapsular pressures needed to prevent AFS. However, some instances of anterior capsular tears are unavoidable. Therefore, focus will also be placed on techniques during cataract extraction used to manage anterior capsular tears, mitigating extension to the posterior capsule.

[Surgical technique for aspiration of soft lens nucleus with preoperative femtosecond laser-assisted fragmentation]

Fragmentation and aspiration of soft cataracts require different surgical techniques and approaches compared to the removal of dense nuclei, including when using a femtosecond laser.

PURPOSE

This study was conducted to develop a non-ultrasound technique for aspiration of a soft lens nucleus after its preliminary femtosecond laser-assisted fragmentation.

MATERIAL AND METHODS

The study included 63 patients (63 eyes) aged 23 to 40 years who underwent surgery. In 27 cases, early or immature cataract was observed, and in 36 cases, cataract removal was performed for refractive purposes in high myopia and complex myopic astigmatism. The VICTUS femtosecond laser surgical system (Technolas Perfect Vision GmbH, Germany) was used for preliminary fragmentation of the lens nucleus. Surgeries were performed using the Centurion Vision System phacoemulsifier (Alcon Laboratories, Inc., USA). The volume of the required irrigation solution was evaluated during the surgery. Intraoperative and postoperative complications were assessed.

RESULTS

The surgery was performed without complications in all cases. Capsulorhexis edge was completely preserved along its entire circumference. The study showed the fundamental possibility of aspirating a cataract with a nucleus of grade I-II density without low-frequency ultrasound after preliminary femtosecond laser-assisted fragmentation of the nucleus with a "grid" pattern, which ensures minimal fragment size in the central zone of the nucleus. The volume of irrigation solution required for aspiration of the nucleus was 36.0 (27.0; 44.0) ml, which does not significantly differ from the volume of solution during ultrasound phacoemulsification of a nucleus of such density.

CONCLUSIONS

Femtosecond laser-assisted fragmentation of the lens nucleus with a "grid" pattern and phacoemulsifier systems with a high vacuum level allow effective aspiration of a soft lens without using low-frequency ultrasound.

[Influence of the pattern of femtosecond laser-assisted lens nucleus fragmentation on the energy and hydrodynamic parameters of phacoemulsification]

The influence of various patterns of preliminary femtosecond laser-assisted fragmentation of the lens nucleus on the energy and hydrodynamic parameters of phacoemulsification remains insufficiently studied.

PURPOSE

This study evaluates the influence of various patterns of preliminary femtosecond laser-assisted fragmentation of the lens nucleus on the energy, hydrodynamic parameters of phacoemulsification, and the degree of corneal endothelial cell loss.

MATERIAL AND METHODS

Hybrid phacoemulsification was performed in 336 patients (336 eyes) with grade IV immature cataract according to the Buratto classification in three age-matched groups. Group 1 included 103 patients (103 eyes) who underwent hybrid phacoemulsification with preliminary femtosecond laser-assisted fragmentation of the nucleus with a «pizza» pattern (division of the nucleus with 10 radial cuts). Group 2 included 112 patients (112 eyes) who underwent femtosecond laser-assisted fragmentation of the nucleus with a «cylinders» pattern (division of the nucleus with 8 radial cuts in combination with 5 circular cuts). Group 3 included 121 patients (121 eyes) who underwent femtosecond laser-assisted fragmentation of the nucleus with a «grid» pattern (division of the nucleus with 8 radial cuts in combination with multiple mutually perpendicular cuts in the central zone in the form of a grid with a 0.5 mm cell). Effective ultrasound time and the volume of irrigation solution for emulsification of the lens nucleus fragments were determined during the operation. The loss of corneal endothelial cells was assessed 3 months after surgery.

RESULTS

The minimum effective ultrasound time was noted after using the "grid" pattern - 4.05 (2.88; 4.74) s, which was significantly less than with the "cylinders" pattern - 4.97 (3.78; 5.88) s and the "pizza" pattern - 6.15 (4.52; 7.75) s (p<0.05). The effective ultrasound time when using the "cylinders" pattern was significantly less than with the "pizza" pattern (p<0.05). The volume of irrigation solution used for emulsification of the lens nucleus fragments was significantly less in the "grid" pattern - 41.5 (33.5; 49.5) ml compared to the "cylinders" patterns 58.5 (51.0; 66.0), p<0.05 and "pizza" pattern 75.0 (66.0; 83.5), p<0.01. The volume of irrigation solution when using the "cylinders" pattern was significantly less than when using the "pizza" pattern (p<0.05). The loss of corneal endothelial cells after using the "grid" pattern was 8.82 (7.59; 9.87)%, which was significantly less than after the "cylinders" patterns - 9.97 (8.81; 10.83)%, p<0.05 and "pizza" - 11.70 (10.62; 12.97)%, p<0.05. At the same time, the loss of endothelial cells after using the "cylinders" pattern was significantly less than after the "pizza" pattern (p<0.05).

CONCLUSIONS

The choice of the optimal pattern of preliminary femtosecond laser-assisted fragmentation of the lens nucleus provides a significant decrease in the energy and hydrodynamic parameters of phacoemulsification and, accordingly, the loss of corneal endothelial cells.

Ultrafast Laser Microlaryngeal Surgery for In Vivo Subepithelial Void Creation in Canine Vocal Folds

BACKGROUND/OBJECTIVES

Tightly-focused ultrafast laser pulses (pulse widths of 100 fs-10 ps) provide high peak intensities to produce a spatially confined tissue ablation effect. The creation of sub-epithelial voids within scarred vocal folds (VFs) via ultrafast laser ablation may help to localize injectable biomaterials to treat VF scarring. Here, we demonstrate the feasibility of this technique in an animal model using a custom-designed endolaryngeal laser surgery probe.

METHODS

Unilateral VF mucosal injuries were created in two canines. Four months later, ultrashort laser pulses (5 ps pulses at 500 kHz) were delivered via the custom laser probe to create sub-epithelial voids of ~3 × 3-mm2 in both healthy and scarred VFs. PEG-rhodamine was injected into these voids. Ex vivo optical imaging and histology were used to assess void morphology and biomaterial localization.

RESULTS

Large sub-epithelial voids were observed in both healthy and scarred VFs immediately following in vivo laser treatment. Two-photon imaging and histology confirmed ~3-mm wide subsurface voids in healthy and scarred VFs of canine #2. Biomaterial localization within a void created in the scarred VF of canine #2 was confirmed with fluorescence imaging but was not visualized during follow-up two-photon imaging. As an alternative, the biomaterial was injected into the excised VF and could be observed to localize within the void.

CONCLUSIONS

We demonstrated sub-epithelial void formation and the ability to inject biomaterials into voids in a chronic VF scarring model. This proof-of-concept study provides preliminary evidence towards the clinical feasibility of such an approach to treating VF scarring using injectable biomaterials.

LEVEL OF EVIDENCES

N/A Laryngoscope, 133:3042-3048, 2023.

The necessity of pretreatment with 0.1% pranoprofen for femtosecond-assisted cataract surgery: A single-center, randomized controlled trial

Purpose

To explore the effect of the variation of pupil diameter (PD) and intraocular pressure (IOP) induced by femtosecond laser treatment on the subsequent phacoemulsfication and intraocular lens implantation. And whether the application of 0.1% pranoprofen could significantly reduce the miosis and increased IOP caused by femtosecond laser treatment in femtosecond laser-assisted cataract surgery (FLACS).

Methods

In this study, patients were pretreated with (trial group) or without (control group) topical 0.1% pranoprofen. The PD and IOP were measured at different time points within 30 ​min after the completion of the femtosecond laser treatment.

Results

The comparisons of the two groups showed the PD of patients pretreated with 0.1% pranoprofen was significantly larger than that of the control only at 15 ​min after FLACS (P ​= ​0.046), and there was no significant difference in IOP at any time point (P ​> ​0.05). Neither the ratio of significant miosis (PD ​≤ ​5 ​mm) nor intraocular hypertension (IOP ≥30 ​mmHg) was significantly different between the control group (1.72%, 6.67%) and the trial group (1%, 4.17%) (P ​> ​0.05).

Conclusions

The PD and IOP of patients undergoing FLACS showed fluctuations within a small range. The rates of significant miosis and intraocular hypertension are very low, it is safe for surgeons to complete the follow-up procedures within 30 ​min after femtosecond laser treatment. Pretreatment with 0.1% pranoprofen exerted a slight, albeit significant prophylactic effect preventing pupil miosis. However, it provided only a limited benefit in patients undergoing FLACS without other complications.

Combined Femtosecond Laser-Assisted Keratotomy and Cataract Surgery for Enhancing Refractive Outcomes. An Indonesian Case Study

Purpose

We evaluate the reduction of corneal astigmatism and the improvement of visual outcomes of this surgical method in the Indonesian population. We also assess the accuracy and predictability of using femtosecond laser astigmatic keratotomy (FLAK) combined with cataract surgery.

Patients and Methods

In a retrospective study, a total of 275 subjects (78 with against-the-rule (ATR) astigmatism, 178 with with-the-rule (WTR) astigmatism, and 19 with oblique (OBL) astigmatism) with preexisting corneal astigmatism ranging from 0.75D to 3.00D underwent FLAK. All subjects completed a 3-month follow-up. The femtosecond laser used for creating paired AK 2.2 mm, primary incision, and paracentesis incision was the FEMTO Z8 NEO from Ziemer Ophthalmic System, Switzerland. The surgical approach was guided by the "NAPA" nomogram.

Results

The reduction in postoperative astigmatism was 56.90% for the WTR group, 49.46% for the ATR group, and 47.33% for the oblique group. A significant reduction in astigmatism was observed at the 1-week, 1-month, and 3-month follow-up intervals in both the WTR and ATR groups. The reduction in astigmatism was more favorable in cases of moderate astigmatism within the WTR group, as compared to the ATR and oblique groups. Postoperative astigmatism reduction was found to be more predictable in the right eye than in the left eye.

Conclusion

The combination of FLAK can be considered as a potential method for reducing corneal astigmatism ranging from 1.00D to <3.00D. The highest reduction was observed in the WTR group, along with a higher rate of intended correction without astigmatism meridian shift in the right eye for the WTR group. However, factors such as cyclotorsion resulting from the surgical technique, alignment of docking, incision length, and preoperative astigmatism need to be taken into account for further enhancement and predictability of astigmatism reduction with this method.

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.

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.

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

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

Posterior capsule dynamics during femtosecond laser lens fragmentation

PURPOSE

The dynamics of the posterior capsule during femtosecond laser lens fragmentation has received little attention in the literature. We analysed the movements of the posterior capsule to identify the rupture risk factors, if any, and to suggest possible modification of the laser spot energy pattern during fragmentation.

MATERIALS AND METHODS

Posterior capsule ruptures during fragmentation were identified over a 10-year period of femtosecond laser use. In addition, the dynamics of the posterior capsule were identified through the real-time swept-source OCT lateral view available during the surgeries.

RESULTS

Out of the 1465 laser cataract procedures performed, we recorded 1 case of posterior capsule rupture during lens fragmentation, which was caused by eye movement that was detected but ignored by the surgeon. Three types of posterior capsule dynamics were identified, all related to a gas bubble formation during the first part of the lens fragmentation. In eyes with a hard nucleus, the concussion of the posterior capsule was evident, however, with no capsule rupture.

DISCUSSION

Maintaining good docking throughout the whole procedure seems important in avoiding a posterior capsule cut by the femtosecond laser. In addition, a Gaussian pattern of spot energy is suggested when fragmenting hard cataracts.

Mechanical protective effect of lens anterior capsule disc on corneal endothelial cells during femtosecond laser-assisted cataract surgery in a rabbit model

PURPOSE

To evaluate the effects of a novel technique using an isolated lens anterior capsule disc (LACD) to protect corneal endothelial cells in rabbit eyes during femtosecond laser-assisted cataract surgery.

METHODS

Experimental study. 40 rabbits were divided into endothelium-protected (experimental) and control groups, with 20 rabbits in each group. In the experimental group, after femtosecond laser capsulotomy, the isolated capsule disc was lifted to the corneal endothelium by an ophthalmic viscosurgical device. The endothelium was damaged for 1 min with an ultrasonic probe. The control group underwent the same surgery, except that the disc was removed immediately after capsulorhexis. Corneal endothelioscopy was performed preoperatively and on postoperative days (PODs) 3 and 7 to observe endothelial cell counts (ECC) and endothelial cell loss rate. Central corneal thickness (CCT) was measured before and at PODs 1, 3 and 7.

RESULTS

There were 3.59%±1.88% (p < 0.001) and 2.92%±2.14% (p < 0.001) loss of ECC in experimental group at POD3 and POD7, respectively, while those in the control group were 11.62%±7.43% and 10.34%±5.77%, respectively. On POD 1, the difference in central corneal thickness was significant(P = 0.019) between the two groups. At POD 3 and POD 7, CCT was not significantly different (P = 0.597;0.913) between the two groups.

CONCLUSIONS

The isolated LACD technique significantly reduced damage to the endothelium caused by ultrasonic energy and protects corneal endothelial cells during phacoemulsification.

Comparison of femtosecond laser-assisted cataract surgery and conventional phacoemulsification on corneal impact: A meta-analysis and systematic review

This meta-analysis aims to compare corneal injuries and function after femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification surgery (CPS). A comprehensive literature search of PubMed, EMBASE, and the Cochrane Controlled Trials Register was conducted to identify randomized controlled trials (RCT) and high-quality prospective comparative cohort studies comparing FLACS with CPS. Endothelial cell loss percentage (ECL%), central corneal thickness (CCT), endothelial cell density (ECD), endothelial cell loss (ECL), percentage of the hexagonal cell (6A), and coefficient of variance (CoV) were used as an indicator of corneal injury and function. Totally 42 trials (23 RCTs and 19 prospective cohort studies), including 3916 eyes, underwent FLACS, and a total of 3736 eyes underwent CPS. ECL% is significantly lower in the FLACS group at 1-3 days (P = 0.005), 1 week (P = 0.004), 1 month (P<0.0001), 3 months (P = 0.001), and 6 months (P = 0.004) after surgery compared to CPS. ECD and ECL appeared no statistically significant difference between the two groups, except for the significant reduction of ECD at 3 months in the CPS group (P = 0.002). CCT was significantly lower in the FLACS group at 1 week (P = 0.05) and 1 month (P = 0.002) early postoperatively. While at 1-3 days (P = 0.50), 3 months (P = 0.18), and 6 months (P = 0.11), there was no difference between the FLACS group and the CPS group. No significant difference was found in the percentage of hexagonal cells and the coefficient of variance. FLACS, compared with CPS, reduces corneal injury in the early postoperative period. Corneal edema recovered faster in the FLACS group in the early postoperative period. In addition, FLACS may be a better option for patients with corneal dysfunction.

Femtosecond Laser-Assisted Cataract Surgery versus Conventional Phacoemulsification Surgery: Clinical Outcomes with EDOF IOLs

In this study, we evaluate and compare the outcomes of conventional phacoemulsification cataract surgery (CPS) and femtosecond laser-assisted cataract surgery (FLACS) with the implantation of an extended depth of field (EDOF) intraocular lens (IOL). A prospective, consecutive cohort study was conducted. Patients were given the option to choose FLACS or CPS and were implanted with an EDOF IOL. Refractive data, visual acuity data, ocular aberration measured with a wavefront aberrometer, and optical quality measured with an optical quality analysis system II were collected at one month postoperatively. A total of 92 eyes of 64 patients were enrolled in this study; 35 eyes of 26 patients were treated with FLACS, whereas 57 eyes of 38 patients were treated with CPS. Uncorrected visual acuity at far, intermediate, and near distance and best-spectacle-corrected visual acuity were not statistically significantly different between the groups (all p > 0.05), nor were the mean cylinder and mean spherical equivalent refraction (both p > 0.05). The FLACS group had a lower ocular trefoil than the CPS group (p = 0.033), and there was no significant difference between the two groups considering other aberration parameters, whether ocular or internal (all p > 0.05). Optical-quality-related parameters showed also no significant difference between the two groups (all p > 0.05). In conclusion, there was no significant difference between FLACS and CPS with implantation of EDOF IOLs in postoperative ocular parameters, refractive outcomes, ocular aberration, optical quality, and aberration parameters, except a lower ocular trefoil in the FLACS group. In terms of these indicators, FLACS does not provide an additional clinical benefit for patients over CPS.

Efficacy of a new fragmentation pattern in femtosecond laser-assisted cataract surgery with the Ziemer FEMTO LDV Z8

PURPOSE

To determine the efficacy of different fragmentation patterns in femtosecond laser-assisted cataract surgery (FLACS) using Ziemer FEMTO LDV Z8.

METHODS

We compared three different types of surgery: conventional cataract surgery (CCS), FLACS with conventional radial slices (named No-Spiderweb), and FLACS with a novel fragmentation pattern (radial slices combined with one or two rings) called "Spiderweb." Visual acuity (VA), nuclear opacity (NO) according to the Lens Opacities Classification System (LOCS lll), effective phacoemulsification time (EPT) and vacuum time were obtained for 845 eyes.

RESULTS

Using FLACS (Spiderweb + No-Spiderweb), EPT was significantly reduced by 26% compared to CCS (FLACS: 2.46 ± 2.60 s; CCS: 3.34 ± 2.89 s; ΔM = - 0.88 s, p < .001). Furthermore, EPT as a function of progression of lens opacity was found to be not only lower in Spiderweb compared to CCS, but also in comparison with No-Spiderweb. At NO3, a significant reduction of 65% in EPT was observed by using Spiderweb compared to CCS (Spiderweb: 0.68 ± 1.23 s; CCS: 1.96 ± 1.53 s; ΔM = - 1.28 s, p <.001). Interestingly, EPT at NO3 was also significantly reduced by 57% in Spiderweb compared to No-Spiderweb (Spiderweb: 0.68 ± 1.23 s; No-Spiderweb: 1.57 ± 1 .59 s; ΔM  = - 0.90 s, p <.001). The use of Spiderweb only marginally extends the vacuum time compared to No-Spiderweb by 11 s (Spiderweb: 209.13 ± 35.83 s; No-Spiderweb: 198.35 ± 36.84 s; p = .003) and the postoperative improved VA showed no significant difference among the different types of surgery (all ps ≥ .05).

CONCLUSION

FLACS significantly reduces EPT compared to CCS. Furthermore, the novel Spiderweb pattern significantly reduces EPT in patients with a cataract of NO3 compared to CCS, but also to FLACS with the existing radial pattern (No-Spiderweb).

Cataracts

94 million people are blind or visually impaired globally, and cataract is the most common cause of blindness worldwide. However, most cases of blindness are avoidable. Cataract is associated with decreased quality of life and reduced life expectancy. Most cases of cataract occur after birth and share ageing and oxidative stress as primary causes, although several non-modifiable and modifiable risk factors can accelerate cataract formation. In most patients, phacoemulsification with intraocular lens implantation is the preferred treatment and is highly cost-effective. There has been an increase in the use of comprehensive cataract surgical services, including diagnoses, treatment referrals, and rehabilitation. However, global inequity in surgical service quality is still a limitation. Implementation of preoperative risk assessment, risk reduction strategies, and new surgical technologies have made cataract surgery possible at an earlier stage of cataract severity with the expectation of good refractive outcomes. The main challenge is making the service that is currently available to some patients accessible to all by use of universal health coverage.

Comparison of clinical outcomes between cystotome-assisted prechop phacoemulsification surgery and femtosecond laser-assisted cataract surgery for hard nucleus cataracts

BACKGROUND/OBJECTIVES

To compare the safety and efficacy of cystotome-assisted prechop phacoemulsification surgery (CAPPS) and femtosecond laser-assisted cataract surgery (FLACS) in patients with hard nucleus cataract.

SUBJECTS/METHODS

Ninety-six eyes of 64 patients with grade IV hard nucleus cataract were assigned to 1 of the 2 groups (49 CAPPS and 47 FLACS). Follow-up visits were performed 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 cell loss rate (ECL), central corneal thickness (CCT), and intraoperative and postoperative complications.

RESULTS

The ultrasound power and EPT were lower in the CAPPS group (p = 0.03 and <0.0001, respectively). Patients in both groups gained better CDVA postoperatively. The ECD value decreased at each follow-up visit and did not return to the preoperative level; FLACS resulted in greater endothelial cell loss compared to CAPPS. CCT increased immediately after the surgery and decreased thereafter. The mean CCT value returned to the preoperative level 3 months postoperatively in the CAPPS group, while in the FLACS group, CCT value took 6 months to return to the preoperative level. Miosis was more likely to occur in the FLACS group.

CONCLUSIONS

Due to its efficacy and cost-effectiveness, CAPPS is worth promoting and applying to clinical work in the future.

Pupil Status with Low-Energy Femtosecond Laser-Assisted Cataract Surgery versus Conventional Phacoemulsification: An Intraindividual Comparative Study

Purpose

To compare the pupil changes in low-energy femtosecond laser-assisted cataract surgery (FLACS) with conventional phacoemulsification (CP) intraindividually.

Patients and Methods

A retrospective review of registered surgical data from patients that undergone uncomplicated cataract surgery in a single centre, with randomly assigned femtosecond laser-assisted cataract surgery (FLACS) to one eye and conventional phacoemulsification (CP) to the other, was performed. The recorded pupil images were evaluated at pre and post laser treatment (after suction release) and at several surgical timepoints for both techniques (FLACS and CP). Pupil areas were calculated and compared in the same eye undergone FLACS (pre vs post laser treatment), between eyes (CP vs FLACS) in the same patient and between groups. Subgroups were built regarding age and ocular comorbidity.

Results

This study involved a total of 164 eyes of 82 patients (55 female, 27 male). No statistical differences regarding the total duration of surgery (p=0.805) between FLACS and CP. Pupil measurements between pre and post laser treatment in the FLACS group showed no statistically significant differences (p=0.107). The mean change in pupil area from the beginning until the end of surgery (total variation) was 6.59±2.08 mm² in the FLACS group and 6.67±2.13 mm² in the CP group, associated to less narrowing of pupil area with FLACS, although not statistically significant (p=0.080). Comorbidity group analysis revealed less, but not significant, pupil narrowing with the FLACS technique (p=0.071). No statistically significant differences between FLACS and CP concerning age subgroups were registered.

Conclusion

This study shows no significant pupil changes, namely myosis, after low-energy FLACS pre-treatment. Comparison between techniques showed less pupil variation in FLACS as compared to CP, more markedly in eyes with comorbidities (particularly with shallow anterior chamber), although non-statistically significant.

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.

Femtosecond Laser-Assisted Cataract Surgery: Analysis of Surgical Phases and Comparison with Standard Phacoemulsification in Uncomplicated Cataracts

The aim of this work is to compare the time of surgical phases and the cumulative dissipated energy (CDE) of the phacoemulsification phase in femtosecond laser-assisted cataract surgery (FLACS) and in standard surgical procedures of phacoemulsification (PCS). This prospective, non-randomized study analyzed the data of 100 cataract surgeries, 66 using FLACS and 34 with standard PCS. The time of surgical phases was recorded by a digital chronometer; an additional parameter recorded was the CDE of the phacoemulsification phase. The mean time of femtosecond laser phase was 121.7 ± 27.3 s with minimal fluctuations in duration; the mean opening time of the corneal tunnel and the service incisions was 60.5 ± 20.4 s in the PCS, and 48.8 ± 17.4 s in FLACS (p = 0.04); the mean time of capsulorhexis was 39.6 ± 12.9 s in the PCS and 7.0 ± 5.2 s in FLACS (p < 0.0001); the mean time of phacoemulsification was 180.1 ± 45.6 s in the PCS and 163.0 ± 38.2 s in FLACS (p = 0.12); the mean aspiration time of the residual cortical was 66.3 ± 27.5 s in the PCS and 91.5 ± 35.7 s in FLACS (p = 0.02). Overall, the total surgical time of the cataract surgery was 742.3 ± 185.8 s in PCS and 985.1 ± 118.6 s in FLACS (p = 0.03). The mean CDE was 11.35 in the PCS and 8.3 in FLACS (p = 0.01). In conclusion, the greatest advantage obtained from the use of the femtosecond laser was the reduction of the duration of the phacoemulsification time and of the CDE parameter.

Clinical outcomes of femtosecond laser-assisted cataract surgery versus conventional phacoemulsification: A retrospective study in a tertiary eye care center in South India

Purpose

To compare the clinical outcomes of femtosecond laser-assisted cataract surgery (FLACS) versus conventional phacoemulsification (CP) in terms of refractive outcomes, cumulative dissipated energy, and intraoperative complications.

Methods

In this retrospective study performed in a tertiary care ophthalmic hospital, we reviewed 2124 eyes that underwent FLACS or CP. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), cumulative dissipated energy (CDE), and intraoperative complications were analyzed in the study.

Results

Out of 2124 eyes, 873 underwent FLACS and 1251 underwent CP. The postoperative mean UCVA after one month was 0.05 ± 0.11 logMAR and 0.14 ± 0.23 logMAR for FLACS and CP, respectively (P < 0.00001). Mean CDVA one month post operation was 0.02 ± 0.07 logMAR and 0.06 ± 0.19 logMAR for FLACS and CP, respectively (P < 0.0001). The CDE for the FLACS group was 6.17 ± 3.86 (P < 0.00001) and it was 9.74 ± 6.02 for the CP group. The intraoperative complication for the FLACS group was 1.60% and the CP group was 2.39% (P < 0.00001).

Conclusion

The visual outcomes were better in FLACS compared to CP. The CDE was lower for the FLACS group and FLACS had significantly less intraoperative complications.

Femtosecond Laser-Assisted Ophthalmic Surgery: From Laser Fundamentals to Clinical Applications

Femtosecond laser (FSL) technology has created an evolution in ophthalmic surgery in the last few decades. With the advantage of high precision, accuracy, and safety, FSLs have helped surgeons overcome surgical limits in refractive surgery, corneal surgery, and cataract surgery. They also open new avenues in ophthalmic areas that are not yet explored. This review focuses on the fundamentals of FSLs, the advantages in interaction between FSLs and tissues, and typical clinical applications of FSLs in ophthalmology. With the rapid progress that has been made in the state of the art research on FSL technologies, their applications in ophthalmic surgery may soon undergo a booming development.

The Effects of High Energy Capsulotomy on Aqueous Cytokine Profiles and Pupil Size During Femtosecond Laser-Assisted Cataract Surgery

PURPOSE

To assess whether aqueous cytokine profiles and pupil size are altered when high capsulotomy energy is used in eyes undergoing femtosecond laser-assisted cataract surgery (FLACS), and if preoperative use of a topical non-steroidal anti-inflammatory drug (NSAID) has an effect on this.

METHODS

This prospective study recruited 83 eyes (63 patients) that were allocated to four treatment groups: conventional phacoemulsification (n = 20 eyes); FLACS with 90% capsulotomy energy without NSAID pretreatment (n = 20 eyes); FLACS with 90% capsulotomy energy with NSAID pre-treatment (n = 21 eyes); and FLACS with 150% capsulotomy energy with NSAID pretreatment (n = 22 eyes). Aqueous humor was collected before and after phacoemulsification to assess cytokine profiles. Pupil size was measured before and after laser capsulotomy.

RESULTS

FLACS increased aqueous concentrations of pros-taglandin E₂ (PGE₂), interferon γ (IFN-γ), and interleukin 6 (IL-6) compared to conventional phacoemulsification. However, when increasing capsulotomy energy from 90% to 150% (with topical NSAID pretreatment), there was no significant increase in aqueous concentrations of PGE₂ (37.7 ± 21.7 vs 33.6 ± 27.6 pg/mL, P = .99), IFN-γ (3.6 ± 1.1 vs 3.6 ± 0.8 pg/mL, P = .99), or IL-6 (7.1 ± 2.9 vs 6.3 ± 2.4 pg/mL, P = .99). For 90% and 150% capsulotomy energy, there was significant miosis following laser capsulotomy. Increased PGE₂ concentration was significantly correlated with a reduction in pupil area (r = -0.58, P < .001) and pupil diameter (r = -0.57, P < .001). However, when a topical NSAID was given preoperatively, there was no difference in the degree of miosis between the 90% and 150% capsulotomy energy groups.

CONCLUSIONS

Pretreatment with a topical NSAID prevented a rise in PGE₂, IFN-γ, and IL-6 levels and excessive miosis when a higher capsulotomy energy was used. When a topical NSAID is used preoperatively, it is safe to use higher capsulotomy energy settings (with a low pulse energy femtosecond laser system) to achieve a satisfactory capsulotomy. [J Refract Surg. 2022;38(9):587-594.].

Subfoveal Choroidal Thickness After Femtosecond Laser-Assisted Cataract Surgery for Age-Related Cataracts

Purpose

To compare the effects of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification surgery (CPS) on subfoveal choroidal thickness (SFCT) in patients with age-related cataracts.

Methods

In this prospective consecutive study, 26 patients (26 eyes) with age-related cataracts without previous ocular surgery or other ocular diseases who had FLACS were included as the study group. Twenty-six age-matched patients (26 eyes) who underwent CPS in the same period were also included as the control group. The SFCT and the foveal retinal thickness (FRT) were measured at baseline and at 1 day (D1), 7 days (D7), 1 month (M1), and 3 months (M3) postoperatively by spectral-domain optical coherence tomography. Aqueous flare was also measured with a laser flare meter.

Results

The mean SFCTs of the FLACS group at baseline and at D1, D7, M1, and M3 were 185.2, 174.3, 184.2, 180.8, and 184.1 μm, respectively. A Bonferroni posttest showed that the choroid became thinner on postoperative D1 (P = 0.006). The measurements at 1 week, 1 month, and 3 months postoperatively showed no significant differences in the SFCTs compared with that at baseline (P = 0.66, P = 0.22, and P = 0.53, respectively). A different trend was observed in the CPS group. The choroid became thicker by the 3-month postoperative measurement, as follows: 1 day (P = 0.28), 1 week (P = 0.016), 1 month (P = 0.020), and 3 months (P < 0.001).

Conclusion

The mean SFCT significantly and temporarily decreased following FLACS. In contrast, an increased SFCT was observed following CPS.

[Femtolaser-assisted phacoemulsification of intumescent cataract]

PURPOSE

To optimize the technique of intumescent cataract phacoemulsification by involving the use of femtosecond lasers.

MATERIAL AND METHODS

Group 1 included 29 patients (30 eyes) with mature intumescent cataract, who underwent femtolaser-assisted phacoemulsification using a new, optimized technique. Group 2 included 20 patients (20 eyes), in whom the femtolaser stage was performed using the standard technique. Patients of groups 1 and 2 were almost identical in all preoperative parameters. The optimized femto-capsulorhexis technique included: preoperative assessment of intralenticular pressure, staining of the anterior capsule of the swelling lens with trypan blue, introduction of a viscoelastic with high molecular weight into the anterior chamber to balance intraocular and intralenticular pressures, increasing the laser energy when performing anterior capsulorhexis up to 10 mJ.

RESULTS

In group 1, there was a non-penetration of the anterior capsule in 2 eyes, in one of them in the 30° sector, in the second - in the 45° sector. Leakage of lens material into the anterior chamber and the floating anterior capsule were not observed in patients of group 1. In group 2, non-penetration of the anterior capsule was observed in 6 eyes, in the 45-60° sector - in 2 eyes, in the 90° sector - in 3 eyes, in the 180° sector - in 1 eye. Floating anterior capsule was observed in 5 cases. Leakage of lens material into the anterior chamber was observed in 9 eyes.

CONCLUSION

The optimized technique of femtolaser-assisted intumescent cataract phacoemulsification eliminates leakage of lens material into the anterior chamber and allows performing anterior capsulorhexis of given size and shape.

A Counter Prechop Technique Using a Modified Universal Prechopper in Combination with or without Using a Universal Chopper

Purpose

To introduce an alternative prechop technique without or with the use of a modified universal chopper (AE-2591, HI Kim chopper, ASICO, Inc. USA).

Methods

Patients who underwent cataract surgery using the phaco-chop technique and the modified prechop technique have been grouped and reviewed retrospectively. Endothelial cell count (ECC) and central corneal thickness (CCT) measured 7 days pre-operatively, and 1 month and 3 months post-operatively, were compared between the two groups. In modified prechop technique, a narrow 1.7 mm neck prechopper (AE-4298, HI Kim-Inamura chopper, ASICO, Inc., USA) was used with universal chopper (AE-2591, HI Kim chopper, ASICO, Inc., USA) as an additional device for grade 4 and above cataracts or without it for grade 2 to 3 cataracts. Details of the surgical technique is further described in the Method section.

Results

A total of 104 eyes in the modified prechop group and 97 eyes in the phaco-chop group were enrolled in the study. Pre-operative nuclear opacity, ECC, and CCT as well as post-operative ECC (absolute value and the loss) and CCT (absolute value and the change) throughout the follow-up between the two groups did not show statistically significant differences.

Conclusion

Counter prechop technique using the modified prechopper and universal chopper is a safe, easy, and versatile surgical technique that can be applied broadly in a wide range of cases with various complexities, including LOCS lll N1 to N6 nuclei, hypermature cataracts, small pupils, and fragile suspensory zonular ligaments, with post-operative result not inferior to that of the conventional technique.

Adverse events associated with femtosecond laser-assisted cataract surgery reported to the MAUDE database

PURPOSE

To report real-world complications associated with femtosecond laser-assisted cataract surgery (FLACS).

SETTING

Deidentified database.

DESIGN

Retrospective review.

METHODS

The U.S. Food and Drug Administration's Manufacturer and User Facility Device Experience (MAUDE) database was culled for adverse events involving ophthalmic femtosecond laser during cataract surgery from January 2010 to January 2020. Reports in which the narrative description was inadequate to determine the nature of the complication were excluded. Each report was reviewed for complications, which were subsequently assigned to a complication category as determined by these authors. The number of events per year was determined and compared.

RESULTS

Between January 2010 and January 2020, the MAUDE database search yielded 2927 reports involving femtosecond laser, of which 1927 met inclusion criteria and were included for analysis. These reports revealed 2704 complications: 1115 capsule tears (41.2%), 329 of which required vitrectomy, 372 instances of suction loss, 321 other capsulotomy-related complications, and 432 corneal or incisional complications. Rare complications included 54 reports of miosis, 16 reports of endophthalmitis, and 4 reports of toxic anterior segment syndrome. The number of events in the MAUDE database increased year over year between 2011 and 2017, peaking in 2017 at 303 events.

CONCLUSIONS

By drawing on real-world data in the MAUDE database, this study identified the complications of greatest importance in clinical practice. Surgeons should be aware of the spectrum of possible complications to best prepare for all potential outcomes and to effectively counsel patients.

[Historical development of energetic cataract surgery]

This article reviews scientific literature analyzing the history of ultrasound and laser phaco surgery of combined or isolated designs: erbium YAG laser, 1.064 μm Nd:YAG laser for dissection of the lens capsule and nucleus, exclusively-laser technique of lens destruction with 1.44 µm Nd:YAG laser without manual, vacuum or ultrasonic action, femtosecond laser assistance with automated transcorneal delivery of radiation into the eye cavity.

Efficient use of ultrasound in cataract surgery

PURPOSE OF REVIEW

Modern phacoemulsification machines apply ultrasound through a variety of settings and parameters to remove a cataract. Using these new technologies efficiently is critical for both reducing surgical times and improving postoperative outcomes. The present article reviews recent findings in phacodynamics to explore the optimum use of ultrasound in cataract surgery.

RECENT FINDINGS

In studies seeking to determine the optimum parameters in both fluidics and power, increased power and aspiration does not necessarily equate to more efficiency. New developments, such as torsional ultrasound, micropulse, and burst mode have shown increased efficiency in randomized control trials and in-vitro compared with conventional ultrasound. Regarding vacuums, the venturi pump has demonstrated greater efficiency compared with the peristaltic pump. We also explore other parameters, such as chamber pressure and tip selection. Meta-analyses on femtosecond-laser assisted cataract surgery (FLACS) have shown similar long-term visual outcomes compared to conventional cataract surgery.

SUMMARY

Though conventional cataract surgery remains highly effective, surgeons have increasing options for customizing their ultrasound settings and phacoemulsification techniques.

Study on the enlargement index of femtosecond laser-assisted capsulorhexis in 2-6-year-old patients with congenital cataract

Background

To identify the capsule enlargement index after femtosecond laser-assisted anterior capsulorhexis in 2–6-year-old children who underwent congenital cataract surgery.

Methods

In this prospective case series study, femtosecond laser-assisted anterior capsulorhexis was performed in patients with congenital cataract, aged 2–6 years. The actual achieved capsulorhexis diameters were measured with Digimizer version 4.2.6. Correlation coefficient (r) and multiple linear regression analysis were used to evaluate the variables that could potentially influence anterior capsulorhexis enlargement index (E).

Results

This prospective study enrolled 28 eyes of 22 patients with congenital cataract. The mean age of the patients at surgery was 4.67 years ±1.54 (standard deviation [SD]). “E” of the 28 cases was 1.211 ± 0.039 (SD). Correlation analysis showed that “E” correlated significantly with the anterior chamber depth (ACD) (r = − 0.469, p = 0.021) and axial length (AL) (r = 0.452, p = 0.027). The following formula was developed by using multivariable linear regression analysis: Predicted E = 1.177–0.052 × ACD + 0.009 × AL, R² = 0.346 (F = 4.396, p = 0.046).

Conclusions

The anterior capsulorhexis enlargement index and its calculation formula could help to set up an accurate programmed capsulorhexis diameter for femtosecond laser-assisted congenital cataract surgery in children aged 2–6 years. Thus, an appropriate actual capsulorhexis diameter could be achieved.

Comparison of perioperative parameters in one-handed rotational phacoemulsification versus conventional phacoemulsification and femtosecond laser-assisted cataract surgery

AIM

To compare perioperative parameters of one-handed rotational phacoemulsification technique (one-handed phaco-roll) with each of other two techniques, "Divide et Conquer" and femtosecond laser-assisted cataract surgery (FLACS).

METHODS

In this retrospective and comparative cohort study, eyes with uncomplicated cataract (nuclear density grade 2 to 3) treated routinely with one-handed phaco-roll (n=23; Group 1) or "Divide et Conquer" (n=23; Group 2) or FLACS (n=23; Group 3) were enrolled. Intraoperative parameters including effective phaco-time (EPt), ultrasound time (USt), aspiration time, surgical time, phacoemulsification (phaco)-power, balanced salt solution (BSS) use, cumulative dissipated energy (CDE) were recorded and compared. Clinical outcomes including best corrected visual acuity (BCVA), corneal endothelial cell density (ECD), endothelial cell loss (ECL), central corneal thickness (CCT) and central macular thickness (CMT), were assessed and compared pre-operatively and at 1mo after surgery.

RESULTS

Aspiration and surgical time, and BSS used were lower in Group 1 (P<0.01) than other groups. EPt, phaco-power and CDE were lower in Group 1 (P<0.05) than Group 2 but not significantly different from Group 3. In Group 1, USt was lower (P<0.05) than Group 2 but higher (P<0.05) than Group 3. BCVA improved in all groups without significant difference between Group 1 and the other ones. No significant differences regarding all post-operative morphologic outcomes (ECD, ECL, CCT, CMT) were reported. No clinical complications occurred.

CONCLUSION

One-handed phaco-roll seems to be less time-consuming than "Divide et Conquer" and FLACS and less energy-consuming than "Divide et Conquer". Furthermore, one-handed phaco-roll seems to have an equal safety profile compared to the other two techniques.

Corneal Endothelial Cell Changes After Femtosecond Laser-Assisted Cataract Surgery in Diabetic and Nondiabetic Patients

OBJECTIVE

To compare corneal endothelial cell changes after femtosecond laser-assisted cataract surgery (FLACS) in diabetic and nondiabetic patients.

METHODS

This retrospective study included patients with cataract who underwent FLACS performed by a single surgeon between August 2018 and November 2020. Changes in corneal endothelial cell density (ECD), hexagonality, coefficient of variation in cell size (CV), and central corneal thickness (CCT) at baseline and at the 1-month and 3-month postoperative follow-ups were investigated by dividing the patients into diabetic and nondiabetic groups.

RESULTS

We included 75 patients (60% men, mean age: 57.7±11.4 years, range: 27-80 years) in the analysis: 31 diabetic patients (64% men, mean age: 58.7±11.9 years, range: 27-79 years) and 44 nondiabetic patients (56% men, mean age: 57.1±11.3 years, range: 34-80 years). No differences were observed between the two groups as regards preoperative and intraoperative parameters, the mean postoperative ECD, hexagonality, and CV. At 1 month postoperatively, the CCT was significantly greater in the diabetic group (P=0.034); however, at 3 months, there was no significant difference between the two groups (P=0.927).

CONCLUSIONS

Changes in postoperative corneal endothelial cells were comparable between patients with and without diabetes after FLACS. Femtosecond laser-assisted cataract surgery seems to cause less damage to the corneal endothelium in diabetic patients because it uses less phacoemulsification energy.

Trends in Ophthalmology Resident Operative Experience and the Early Impact of the COVID-19 Pandemic

Purpose This study aimed to evaluate trends in ophthalmology resident operative experience and the early impact of the novel coronavirus disease 2019 (COVID-19) pandemic.

Design Present study is a retrospective analysis of the Accreditation Council for Graduate Medical Education (ACGME) Case Log System.

Participants Anonymized graduating resident case logs from 2011 to 2020 academic years (AYs) were examined for this study.

Methods Regression analysis for each procedure category was performed to identify trends between 2011 and 2019 AYs. Unpaired two-tailed t-test compared 2018 to 2019 and 2019 to 2020 AY's for each category surgeon (S) and as surgeon and assistant (S + A).

Main Outcome Measures Mean and median cases as (S) and (S + A) during 2011 to 2019 AYs. Comparison between 2018 to 2019 and 2019 to 2020 AY's for each category as (S) and (S + A) to evaluate the impact of the COVID-19 pandemic.

Results Total ophthalmology procedures as (S) rose from a mean of 479.6 to 601.3 (p < 0.001; R 2 = 0.96; Δ/year = 16.9) and a median of 444 to 537 (p < 0.001; R 2 = 0.97; Δ/year = 13.1). Total procedures as (S + A) rose from a mean of 698.1 to 768 (p < 0.01; R 2 = 0.83; Δ/year = 9.07) and a median of 677 to 734 (p < 0.05; R 2 = 0.61; Δ/year = 6.64). Cataract procedures as (S) rose from a mean of 152.8 to 208 (p < 0.001; R 2 = 0.99; Δ/year = 7.98) and a median of 146 to 197 (p < 0.001; R 2 = 0.97; Δ/year = 7.87). Cataract procedures as both (S + A) rose from a mean 231.4 to 268.7 (p < 0.001; R 2 = 0.95; Δ/year = 5.5) and a median of 213 to 254 (p < 0.001; R 2 = 0.93; Δ/year = 5.33). Between 2018 to 2019 and 2019 to 2020 AYs, the first pandemic year was associated with significant reductions in total procedures (601.3–533.7 [p < 0.0001]) as (S) and 768.0 to 694.4 (p < 0.0001) as (S + A), cataract surgery (208–162.2 [p < 0.0001]) as (S) and 268.7 to 219.1 (p < 0.0001) as (S + A), and glaucoma surgery (16.3–14.2 [p = 0.0068]) as (S) and 25.6 to 22.6 (p = 0.0063) as (S + A).

Conclusion During 2011 to 2019 AYs, cataract, intravitreal injections, glaucoma, and total procedures increased significantly. During the early period of the COVID-19 pandemic (2019–2020 AY), national halting of elective procedures had a precipitous effect on resident cataract surgery experience to volumes similar to 2013 to 2014 AY where the mean was twice the current required minimum number. With few exceptions, other procedure volumes remained stable.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

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

Thermal Profile of Pulse Precision Capsulotomy: In vivo and in vitro Infrared Thermography Study

Purpose

This study aimed to elucidate the thermal safety of precision pulse capsulotomy (PPC) via in vivo and in vitro evaluation of the thermal profile using infrared thermography.

Methods

This prospective observational study enrolled 15 eyes from 15 participants who underwent cataract surgery using the Zepto PPC. All patients underwent temperature measurements of the incision site and the entire cornea using an infrared thermographer during the capsulotomy procedure. To accurately analyze the temperature change of the Zepto PPC, infrared thermography was performed with the Zepto handpiece while exposed to air and then in porcine eyes. Moreover, in each case, the difference in temperature change according to the use of an ophthalmic viscosurgical device (OVD) was also checked to determine the temperature buffering effect.

Results

In the clinical evaluations, the mean temperature elevation around the corneal incision and time duration from baseline to peak temperature during the Zepto capsulotomy were 4.0 ± 1.9℃ and 4.43 ± 1.26 s, respectively, with a mean peak temperature of 32.6 ± 2.0℃. The mean peak temperature and rise time of the naïve Zepto nitinol ring, as measured from the bottom side, were 109.0 ± 22.9℃ and 43.40 ± 11.06 s in the experimental procedures, respectively. In the porcine eyes, the mean elevation of temperature and rise time of the Zepto nitinol ring were 6.2 ± 1.6℃ and 11.67 ± 2.08 s with the use of OVDs, and 10.5 ± 3.3℃ and 14.00 ± 3.61 s without OVDs, respectively.

Conclusions

Zepto PPC has the potential to generate extremely high thermal energy, according to an in vitro study. However, the temperature rise of the Zepto capsulotomy can be minimized by using OVDs.

Relationship Between Postoperative Intraocular Lens Shift and Postoperative Refraction Change in Cataract Surgery Using Three Different Types of Intraocular Lenses

Introduction

Understanding the relationship between postoperative intraocular lens (IOL) shift and refractive change is crucial for the accuracy of predicted postoperative refraction (PPR). We assessed the relationships between different IOL fixation methods, haptic designs, and several metrics.

Methods

Single-center, open-label study which included 69 eyes. We preoperatively measured the anterior chamber depth (ACD), lens thickness (LT), axial length (AL), and PPR. AcrySof IQ (n = 27) and FineVision (n = 24) were fixed in the bag, and FEMTIS (n = 18) was fixed in capsulorhexis. At 1 day, 1 week, and 1 month postoperatively, we checked the IOL position and refraction and compared the IOL shift, refraction change, and the margin of error of the predicted PPR (PR-PPR difference). We also analyzed the correlation between postoperative and preoperative variables.

Results

FEMTIS showed the highest stability in terms of IOL shift and refraction. The in-the-bag-fixated IOLs showed a significant forward shift between 1 day and 1 week postoperatively. There were significant differences in the PR-PPR difference between the IOLs. ACD and AL showed significant positive correlations, and LT showed a significant negative correlation with IOL shift and change in PR between 1 day and 1 week, but not between 1 week and 1 month postoperatively.

Conclusion

The relationship between postoperative IOL shift and refraction change varied according to IOLs with different haptic types. Capsulorhexis fixation may be more stable than in-the-bag fixation. Furthermore, preoperative ACD, LT, and AL may be useful factors to predict IOL shift, change in PR, and to a lesser extent the degree of the margin of error in clinical practice. Our findings may improve the accuracy of PPR and refractive outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-021-00390-x.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Evaluating newer generation intraocular lens calculation formulas in manual versus femtosecond laser-assisted cataract surgery

AIM

To determine the refractive accuracy of the Haigis, Barrett Universal II (Barrett), and Hill-radial basis function 2.0 (Hill-RBF) intraocular lens (IOL) power calculations formulas in eyes undergoing manual cataract surgery (MCS) and refractive femtosecond laser-assisted cataract surgery (ReLACS).

METHODS

This was a REB-approved, retrospective interventional comparative case series of 158 eyes of 158 patients who had preoperative biometry completed using the IOL Master 700 and underwent implantation of a Tecnis IOL following uncomplicated cataract surgery using either MCS or ReLACS. Target spherical equivalence (SE) was predicted using the Haigis, Barrett, and Hill-RBF formulas. An older generation formula (Hoffer Q) was included in the analysis. Mean refractive error (ME) was calculated one month postoperatively. The lens factors of all formulas were retrospectively optimized to set the ME to 0 for each formula across all eyes. The median absolute errors (MedAE) and the proportion of eyes achieving an absolute error (AE) within 0.5 diopters (D) were compared between the two formulas among MCS and ReLACS eyes, respectively.

RESULTS

Of the 158 eyes studied, 64 eyes underwent MCS and 94 eyes underwent ReLACS. Among MCS eyes, the MedAE did not differ between the formulas (P=0.59), however among ReLACS eyes, Barrett and Hill-RBF were more accurate (P=0.001). Barrett and Hill-RBF were both more likely to yield AE<0.5 D among both groups (P<0.001).

CONCLUSION

The Barrett and Hill-RBF formula lead to greater refractive accuracy and likelihood of refractive success when compare to Haigis in eyes undergoing ReLACS.