Intraocular pressure during femtosecond laser pretreatment of cataract

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.

Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

We included RCTs where FLACS was compared to PCS.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

Effect of Conventional Cataract Surgery and Femtosecond Laser-Assisted Cataract Surgery on Bruch's Membrane Opening-Minimum Rim Width, Retinal Nerve Fiber Layer, and Macular Thickness

Purpose

To evaluate the effect of conventional cataract surgery (CCS) and femtosecond laser-assisted cataract surgery (FLACS) on Bruch's membrane opening-minimum rim width (BMO-MRW), peripapillary retinal nerve fiber layer thickness (RNFL), and macular thickness (MT) using spectral-domain optical coherence tomography (SD-OCT).

Methods

BMO-MRW, RNFL, and MT were measured using SD-OCT preoperatively, 1 month and 6 months after surgery in both CCS and FLACS groups. Differences between preoperative and postoperative values were evaluated in both groups. The postoperative changes were evaluated in each group and compared between groups.

Results

A total of 146 eyes of 146 patients were included in this study, 65 underwent CCS, and 81 underwent FLACS. One month after surgery, there was an increase (in microns) of 20.93 in BMO-MRW, 4.26 in RNFL, and 7.85 in MT in CCS group (P < 0.001), and 17.7, 3.73, and 5.65, respectively, in FLACS group (P < 0.001). Six months after surgery, there was an increase of 12.53 in BMO-MRW, 1.42 in RNFL, and 4.72 in MT in CCS group (P < 0.001), and 13.7, 1.88, and 4.14, respectively, in FLACS group (P < 0.001). The postoperative changes in CCS group were similar to those in FLACS group.

Conclusion

CCS as well as FLACS result in a slight increase in BMO-MRW, RNFL, and MT values one month and six months after surgery. Neither CCS nor FLACS lead to a deterioration in the parameters that define the structure of the optic nerve head and the macula. These results suggest that FLACS is as safe as CCS regarding the optic nerve head and the macula in normal eyes.

Predictors of intraocular pressure reduction after femtosecond laser-assisted cataract surgery versus conventional phacoemulsification surgery: a prospective trial

PURPOSE

To evaluate the association between postoperative intraocular pressure (IOP) reduction and phacoemulsification parameters in patients who underwent both conventional phacoemulsification surgery (CPS) and femtosecond laser-assisted cataract surgery (FLACS).

METHODS

This was a prospective multicenter comparative study that enrolled 90 participants who underwent cataract surgery at the University of Maryland Medical System and the Wilmer Eye Institute. Patients underwent FLACS in one eye and CPS in the fellow eye. IOP was measured prior to surgery and monitored through six months postoperatively. Demographic, clinical, biometric, and intraoperative variables including cumulative dissipated energy (CDE), aspiration time, and phacoemulsification time were analyzed for any significant association with postoperative IOP. Postoperative IOP reduction was the primary outcome variable. A secondary goal of the study was to determine differences in postoperative IOP reduction between CPS and FLACS cohorts.

RESULTS

In total, 157 non-glaucomatous eyes were included. Using multivariable analysis, we found preoperative IOP to be consistently associated with postoperative IOP reduction in the entire cohort. At the 6-month follow-up visit, there was a 12.4% reduction in IOP (-2.2 ± 3.4 mm Hg) seen, with no statistically significant difference between FLACS and CPS (12.3% ± 19.4% vs 12.5% ± 19.3%, respectively, p = 0.32). FLACS reduced the CDE required for phacoemulsification (6.6 ± 4.4%-seconds vs 8.6 ± 6.9%-seconds, respectively, p < 0.05). CDE was a predictor of IOP response at 6 months, but subgroup analysis revealed that this trend was driven by seven eyes requiring high CDE, and for the majority of eyes, CDE did not influence the size of the decrease. The seven eyes experiencing highest CDE were less likely to show IOP reduction at 6 months.

CONCLUSION

Both FLACS and CPS resulted in similar and significant IOP reductions through 6 months after surgery. Preoperative IOP was significantly associated with IOP reduction, and CDE generally did not influence the size of the decrease.

Femtosecond Laser-assisted Cataract Surgery in Patients With Prior Glaucoma Surgery

PRCIS

Femtosecond laser-assisted cataract surgery (FLACS) is a safe procedure in glaucomatous eyes with prior glaucoma surgery, evidenced by stable intraocular pressure (IOP) and medication use, acceptable success rate, disease stability, and low complication rates at 1-year postoperative.

PURPOSE

The purpose of this study was to assess the 1-year efficacy and safety of FLACS in glaucomatous eyes with prior glaucoma surgery.

MATERIALS AND METHODS

Retrospective case series of all consecutive glaucomatous eyes with previous glaucoma surgery that underwent FLACS using the Catalys Precision Laser System with or without concomitant glaucoma surgery at a single ophthalmology center, between 2014 and 2020. Efficacy included change in IOP, glaucoma medication use, best-corrected visual acuity, and surgical success at 12 months postoperatively (POM12). Safety included structural and functional measures of disease stability and postoperative adverse events.

RESULTS

A total of 57 eyes with an average age of 62.6±8.1 years were included. At POM12, IOP decreased from 14.5±6.6 mmHg to 13.5±3.7 mm Hg (P=0.22) and glaucoma medication use decreased from 2.1±1.5 to 1.8±1.4 with a marginal significance (P=0.089). Best-corrected visual acuity improved significantly in both groups (P<0.001) and surgical success ranged between 74% and 90% according to the study's success criteria. Safety was favorable with disease stability evidenced by lack of deterioration in cup-to-disc ratio, visual field mean deviation, retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness. One eye with prior history of trabeculectomy experienced transient bleb leak. Other adverse events were minor without sight-threatening sequelae.

CONCLUSIONS

The results of this study suggest that FLACS with or without concomitant glaucoma surgery could be a safe procedure in glaucomatous eyes-a population for which FLACS has been relatively contraindicated. Nonetheless, in those with preexisting filtering bleb, extra attention should be paid to the bleb area.

Effect of Femtosecond Laser Cataract Surgery on Peripapillary Retinal Nerve Fiber Layer Thickness

PRCIS

Femtosecond laser-assisted cataract surgery (FLACS) may cause thinning of the peripapillary retinal nerve fiber layer (pRNFL) in healthy eyes.

PURPOSE

This prospective cohort study aimed to compare changes of pRNFL after FLACS using a liquid patient interface and conventional phacoemulsification cataract surgery (CPCS).

PATIENTS AND METHODS

Included were 261 eyes (261 patients) with age-related cataracts and no ocular diseases scheduled either for FLACS (222 eyes) or CPCS (39 eyes). FLACS was performed using a Ziemer LDV Z8 laser. Average and quadrant pRNFL thickness was measured using optical coherence tomography before surgery and at 1, 3, and 6 months postoperatively. Postoperative changes in pRNFL thickness were compared within and between groups.

RESULTS

Mean quadrant and average pRNFL thicknesses significantly increased after both surgeries (P<0.001). However, pRNFL thinning occurred after FLACS and CPCS (17% vs. 5.1%, respectively, P>0.05). FLACS eyes showed a significant and stable decrease of average pRNFL thickness (P=0.057) and a gradual decrease in pRNFL thickness of all quadrants (P≤0.018). CPCS eyes showed an initial increase of pRNFL thickness, followed by a decrease only in the nasal quadrant and average pRNFL. Preoperative pRNFL thickness was associated with thinning of the temporal quadrant (P=0.04).

CONCLUSIONS

Both FLACS and CPCS demonstrated pRNFL thinning in some healthy eyes. Although the higher rate of pRNFL thinning after FLACS compared with CPCS lacked statistical significance, a consistent decrease in pRNFL thickness occurred in all quadrants and average pRNFL of FLACS eyes, suggesting that FLACS may lead to pRNFL thinning. Eyes with thinner preoperative pRNFL may be prone to temporal quadrant thinning after FLACS.

Association between Ocular Parameters and Intraocular Pressure Elevation during Femtosecond Laser-Assisted Cataract Surgery in Open-Angle Glaucoma and Nonglaucoma Individuals

In this study, we evaluate the association between biometrics and intraocular pressure (IOP) during femtosecond laser-assisted cataract surgery (FLACS) in normal patients and those with open-angle glaucoma (OAG). A retrospective cross-sectional study was conducted. A total of 103 patients who had received elective FLACS were enrolled, and those with OAG who received FLACS were further divided into a subgroup. The perioperative IOP of FLACS was measured before, during, and after the suction procedure. Demographic data and preoperative biometrics were collected from the medical records. The generalized linear model was applied to yield the adjusted odds ratio (aOR) and corresponding 95% confidence interval (CI) of each biometric for the IOP elevation in the whole group and the OAG subgroup. The mean preoperative IOP was 20.96 ± 4.79 mmHg, which rose to 55.37 ± 11.58 mmHg during suction, and decreased to 23.75 ± 6.42 mmHg after suction; the IOP both during and after suction was significantly higher than the presuction IOP (both p < 0.001). The mean IOP elevation was 34.41 ± 9.70 mmHg in the whole study population, and the difference in IOP elevation between OAG and nonglaucoma subgroups was not significant (p = 0.159). In the whole group, the presuction IOP, postdilated pupil size (PPS), and central corneal thickness (CCT) were positively corrected to higher IOP elevation (all p < 0.05), while axial length (AL) was negatively related to IOP elevation (aOR: 0.020, 95% CI: 0.008–0.699, p = 0.042). For the OAG subgroup, the longer AL was more significantly correlated to lower IOP elevation compared to those without glaucoma (aOR: 0.231, 95% CI: 0.106–0.502, p = 0.006). In conclusion, presuction IOP, PPS, and CCT are related to higher IOP during FLAC, while the AL is negatively correlated to the IOP elevation in FLACS, especially for patients with OAG. Reviewing these parameters before FLACS may enable physicians to find patients who are at risk of IOP elevation.

Real-time measurement of intraocular pressure variation during automatic intravitreal injections: An ex-vivo experimental study using porcine eyes

PURPOSE

To measure needle insertion force and change in intraocular pressure (IOP) in real-time during intravitreal injection (IVI). The effects of needle size, insertion speed, and injection rate to IOP change were investigated.

METHODS

Needle insertion and fluid injection were performed on 90 porcine eyeballs using an automatic IVI device. The IVI conditions were divided according to needle sizes of 27-gauge (G), 30G, and 33G; insertion speeds of 1, 2, and 5 mm/s; and injection rates of 0.01, 0.02, and 0.05 mL/s. Insertion force and IOP were measured in real-time using a force sensor and a pressure transducer.

RESULTS

The peak IOP was observed when the needle penetrated the sclera; the average IOP elevation was 96.3, 67.1, and 59.4 mmHg for 27G, 30G, and 33G needles, respectively. An increase in insertion speed caused IOP elevation at the moment of penetration, but this effect was reduced as needle size decreased: 109.8-85.9 mmHg in 27G for 5-1 mm/s (p = 0.0149) and 61.8-60.7 mmHg in 33G for 5-1 mm/s (p = 0.8979). Injection speed was also related to IOP elevation during the stage of drug injection: 16.65 and 11.78 mmHg for injection rates of 0.05 and 0.01 mL/s (p < 0.001).

CONCLUSION

The presented data offers an understanding of IOP changes during each step of IVI. Slow needle insertion can reduce IOP elevation when using a 27G needle. Further, the injection rate must be kept low to avoid IOP elevations during the injection stage.

Long-term visual field changes after femtosecond laser-assisted cataract surgery in glaucoma patients, case series

Purpose

To assess the short and long-term changes in Visual Field (VF) Mean Deviation (MD), Visual Field Index (VFI), and intraocular pressure (IOP) after femtosecond laser-assisted cataract surgery (FLACS) in glaucomatous eyes.

Materials and methods

Interventional, prospective case series. Patients with glaucoma, who required cataract surgery were included. All patients underwent a complete ophthalmologic assessment and Visual Fields. FLACS was performed in all patients by a single experienced surgeon. IOP was measured during surgery immediately before and after pretreatment suction docking. Changes from baseline in VF MD and VFI, IOP, visual acuity (VA), and number of glaucoma medications were evaluated up to one-year follow-up.

Results

Fourteen eyes of 11 patients were included. Eighty-five percent were female, with a mean age of 74.2 ± 7.9 years. Nine (64.3%) and 5 (35.7%) were diagnosed with primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG), respectively. We found a slight IOP reduction after the docking phase during FLACS in both glaucoma subtype groups. No significant changes in visual field mean deviation (MD) and visual field index (VFI) were found from baseline to 12 months after surgery in both groups. A significant reduction in IOP values was found in all cases from baseline up to one year follow up. No significant changes were observed in BCVA and number of topical glaucoma medications after one year in both groups.

Conclusion

In our patients, there was an IOP reduction immediately after suction docking FLACS pretreatment. Mean IOP at final follow-up showed a reduction from baseline. There was no change in VF MD and VFI from baseline to final one-year follow-up. FLACS appears to be well tolerated in early and moderate glaucoma and appears to be a safe tool for glaucoma patients undergoing cataract surgery. Similar results to traditional surgery can be obtained with the advantages of femtosecond laser precision.

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.

Protective effect of bromfenac sodium on femtosecond laser‑assisted cataract surgery via modulating cyclooxygenase‑2 expression

Cataract is a blinding‑caused disease and affects millions of individuals worldwide. Although conventional phacoemulsification (CPCS) has been widely used for treatment of cataract, the incidence of cataract‑caused blindness still increased year by year. Recently, femtosecond laser technology has been expanded to variety of clinical applications, including cataract surgery. The present study evaluated the curative effect of bromfenac sodium (BS) after femtosecond laser‑assisted cataract surgery (FLACS) and analyzed the mechanism of action. A total of 90 patients were randomly divided into five groups: Group I, conventional phacoemulsification treatment (CPCS) + dexamethasone (DEX)/tobramycin (TOB); group II, CPCS + bromfenac sodium (BS); group III, Femtosecond laser‑assisted cataract surgery (FLACS) + DEX/TOB; group IV, FLACS + BS; and group V, FLACS + pranoprofen. Aqueous humor was collected from these patients post‑surgery. For in vitro studies, SRA01/04 cells were irradiated using UV, followed by the collection of culture media and cell lysate. Prostaglandin E2 (PGE2) levels, an indicator of inflammation, were measured using ELISA both in vivo and in vitro. In addition, cyclooxygenase (COX) and cleaved caspase‑1 p20 expression levels were analyzed using western blotting. The findings suggested that BS was more effective and safer compared with glucocorticoids (GCs) after cataract surgery. BS can protect against post‑operative inflammation by inhibiting PGE2 production. Under in vitro conditions BS prevented the SRA01/04 cells from undergoing apoptosis after UV treatment and also suppressed PGE2 release from UV‑irradiated SRA01/04 cells by modulating COX‑2 expression. Furthermore, BS may have an inhibitory effect on the inflammatory form of cell death. Overall, these results indicated that BS could replace existing GCs as a reliable drug for a perioperative period of cataract surgery. It was also identified that the inhibitory effect of BS on PGE2 production was mediated via the regulation of COX‑2.

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.

Comparison of optical quality and distinct macular thickness in femtosecond laser-assisted versus phacoemulsification cataract surgery

Background

Optical quality and macular thickness changing optical quality is rarely reported after femtosecond laser-assisted cataract surgery (FLACS). In current research, we evaluated optical quality recovery and distinct macular thickness changes after FLACS and phacoemulsification cataract surgery (PCS).

Methods

A total of 100 cataract patients (100 eyes) were included (50 eyes for the FLACS group and 50 eyes for the PCS group). Modulation transfer function (MTF), point spread function (PSF) and dysfunctional lens index (DLI) were measured by a ray-tracing aberrometer (iTrace). Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were also assessed pre-operation,1 week and 1 month after surgery. The MTF values at spatial frequencies of 5, 10, 15, 20, 25 and 30 cycles/degree (c/d) were selected. We used optical coherence tomography (OCT) to assess the macular thickness of different regions pre-operatively and1month after the surgery.

Results

In PCS group, we found the statistically significant differences between pre-operation and post-operation in DLI (p < 0.0001), PSF (strehl ratio, SR) (p = 0.027) and MTF (p = 0.028), but not intraocular pressure (IOP) (p = 0.857). The differences between pre-operation and post-operation for DLI (p = 0.031), SR (p = 0.01) and IOP (p = 0.03), but not MTF (p = 0.128) were also found in FLACS group. The differences were statistically significant when the spatial frequencies were at 5, 10 and 25 (p = 0.013, 0.031 and 0.048) between pre-operation and post-operation in PCS group but not FLACS group at 1 month. In PCS group, we found the differences between pre-operation and post-operation in nasal inter macular ring thickness (NIMRT) (p = 0.03), foveal volume (FV) (p = 0.034) and average retinal thickness (ART) (p = 0.025) but not FLACS group at 1 month.

Conclusion

FLACS is safe that did not cause significant increase of macular thickness in current study. However, it also cannot produce better optical quality. In contrast, PCS can produce macular thickness changes, but better optical quality recovery. The slightly retinal change may not affect optical quality.

Impact of baseline IOP, vacuum, and different docking mechanisms, and their interaction on IOP rise in femtosecond laser-assisted refractive and cataract surgery

PURPOSE

To study the intraocular pressure (IOP) variation during vacuum and docking of femtosecond laser application.

SETTING

Department for Ophthalmology, Kepler University Hospital, Johannes Kepler University Linz, Austria.

DESIGN

Experimental study.

METHODS

Intracameral intraocular pressure (IOP) was monitored in 30 porcine ex vivo models using a dual femtosecond laser platform (VICTUS). Five different baseline IOP levels (10 to 30 mm Hg) were assessed during fluid-filled (liquid) docking, full-contact (applanating) docking, and vacuum application without docking.

RESULTS

Raising the baseline intracameral IOP from 10 to 30 mm Hg increased the IOP from 27.55 mm Hg ± 5.93 (SD) to 56.85 ± 6.10 mm Hg in the fluid-filled docking group, and from 60.91 ± 8.41 mm Hg to 90.11 ± 6.64 mm Hg in the full-contact docking group. The full-contact docking procedure per se (excluding vacuum effect) increased the IOP by 61.7% (+36.58 ± 5.84 mm Hg). In contrast, fluid-filled docking (excluding vacuum effect) raised the IOP by only 3.1% (+0.72 ± 2.71 mm Hg). Each 5 mm Hg reduction of baseline IOP resulted in a mean IOP reduction of 7.33 ± 3.05 mm Hg in the fluid-filled group, and 7.30 ± 6.88 mm Hg in the full-contact docking group (P < .001). Decreasing baseline intracameral IOP from 15 to 10 mm Hg resulted in the highest IOP reduction between all subgroups (P < .01).

CONCLUSIONS

Baseline IOP, docking procedures, and vacuum influenced IOP during femtosecond laser application in a synergistic manner. Lowering the baseline intracameral IOP resulted in a significantly lower IOP during fluid-filled docking for cataract surgery and full-contact docking for refractive surgery. Full-contact (applanating) docking resulted in a significantly higher IOP elevation compared with similar IOP values found during fluid-filled (liquid) docking and the application of the suction ring alone without docking.

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser-assisted cataract surgery

PURPOSE

To evaluate the effect of preoperative intraocular pressure (IOP) and the vacuum level on IOP during femtosecond laser-assisted cataract surgery.

METHODS

Intraocular pressure was measured in 40 enucleated porcine eyes by intracameral manometry prior, during and after vacuum application using the VICTUS femtosecond laser platform (Bausch&Lomb, Technolas Perfect Vision GmbH, Germany). Twenty combinations of different preoperative IOP levels (12, 16, 20 and 24 mmHg) and different vacuum levels (350-550 mbar) were investigated.

RESULTS

Multivariate regression analysis indicated that both the vacuum level (beta = 0.138; p < 0.001) but much stronger the preoperative IOP (beta = 0.861; p < 0.001) were predictive factors for IOP rise during vacuum application. Mean IOP was 28.23 ± 3.86, 34.23 ± 3.92, 40.35 ± 4.41 and 46.82 ± 4.11 mmHg in groups with baseline IOP of 12, 16, 20 and 24 mmHg, respectively. In the 350, 450 and 550 mbar group, and mean IOP was 35.85 ± 7.85, 37.33 ± 7.90 and 39.00 ± 8.04 mmHg, respectively. Lowering the preoperative IOP by 2 mmHg and reducing the vacuum from maximum to minimum resulted in a similar reduction in IOP during vacuum application (-3.10 ± 0.79 mmHg versus -3.15 ± 0.88 mmHg; p = 0.015). Furthermore, decreasing the baseline IOP from 20 to 12 mmHg resulted in a 30.0% reduction in intraoperative IOP.

CONCLUSION

Preoperative IOP was a stronger predictive factor for intraoperative IOP rise than the applied vacuum level. Measurements and critical interpretation of preoperative IOP in a preliminary examination could help estimating the individual risk of significant IOP rise during femtosecond laser-assisted cataract surgery and could help taking early countermeasures in selected cases. Due to the porcine ex vivo model, further studies are needed to verify these findings.

Effect of femtosecond laser-assisted lens surgery on the optic nerve head and the macula

AIM

To evaluate the effect of femtosecond laser-assisted lens surgery (FLALS; cataract surgery or refractive lens exchange) on the structure of the optic nerve head and the macula.

METHODS

This prospective longitudinal study included healthy eyes undergoing FLALS. Eyes with glaucoma or any other ocular disease that could alter optical coherence tomography results were excluded. Retinal nerve fiber layer (RNFL), Bruch's membrane opening-minimum rim width (BMO-MRW) and macular thickness (MT) were measured preoperatively, 1 and 6mo after surgery using spectral-domain optical coherence tomography (SD-OCT). Changes between preoperative and postoperative values were evaluated.

RESULTS

A total of 87 eyes of 46 patients were included in this study. Preoperative RNFL, BMO-MRW and MT in microns (µm) were 100.77±10.39, 330.31±49.99 and 276.30±33.39, respectively. Postoperative RNFL, BMO-MRW and MT were 104.74±11.55, 348.32±54.05 and 279.83±22.65 1mo after surgery and 102.93±11.17, 343.11±53.4 and 278.90±22.19 6mo after surgery, respectively; which equals an increase of 3.93%, 5.45% and 1.27%, respectively, 1mo after surgery, and 2.14%, 3.87% and 0.94% 6mo after surgery. The differences between the preoperative and the postoperative RNFL and BMO-MRW values were statistically significant (P<0.001). Regarding MT values, there were not statistically significant differences (P=0.26).

CONCLUSION

Our study suggests that FLALS does not have a negative impact on the structural status of the optic nerve head in healthy eyes, assessed by SD-OCT. There is a slight increase in the values of RNFL, BMO-MRW and MT 1mo and 6mo after surgery.

Long-term intraocular pressure changes after femtosecond laser-assisted cataract surgery in healthy eyes and glaucomatous eyes

PURPOSE

To examine the long-term effect of femtosecond laser-assisted cataract surgery on intraocular pressure (IOP) in healthy (control) and glaucomatous eyes.

SETTING

University of Colorado, Aurora, Colorado, and Vanderbilt University, Nashville, Tennessee, USA.

DESIGN

Retrospective case series.

METHODS

The study comprised patients aged 18 to 89 years meeting the inclusion criteria. Combination procedures were excluded. The main outcome measure was the change in the mean IOP from baseline to postoperatively.

RESULTS

Of the 504 eyes meeting the criteria, 278 were in the glaucoma/glaucoma suspect group and 226 in the control group. Both groups had an initial mean increase in IOP 1 day postoperatively (control: +2.0 mm Hg; 95% confidence interval [CI], 1.4-2.6; glaucoma/glaucoma suspect: +3.4 mm Hg; 95% CI, 2.5-4.2) (both P < .001). The increase was significantly higher in the glaucoma/glaucoma suspect group. The IOP returned to baseline levels at 1 week. At 1 month, both groups had a significant decrease in IOP that persisted until year 1 in the control group and through 3 years in the glaucoma group. The number of IOP medications was unchanged in the glaucoma group during follow-up. The glaucoma/glaucoma suspect group achieved significantly greater IOP lowering than the control group after 6 months.

CONCLUSIONS

Control eyes and eyes with glaucoma had an initial mean IOP rise 1 day after femtosecond laser-assisted cataract surgery. This was followed by a significant decrease starting at 1 month. The reduction was sustained through 3 years in the glaucoma group.

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

Background

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

Methods

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

Results

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

Conclusions

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

Femtosecond laser-assisted cataract surgery in a public teaching hospital setting

Background

To evaluate the efficiency and practicality of femtosecond laser assisted cataract surgery (FLACS) in a public teaching hospital setting using a mobile FLACS system compared to conventional phacoemulsification cataract surgery (CPCS).

Methods

Ninety eyes from 90 patients underwent either FLACS or CPCS (45 in each group). Cataracts were graded using the Lens Opacities Classification System III system. Outcome measures included total surgery duration, femtosecond laser treatment time, vacuum time (VT), total phacoemulsification time (TPT) and total phacoemulsification power (TPP).

Results

No differences were observed in the preoperative mean cataract grades and co-morbidities. FLACS took longer than CPCS with a mean difference of 5.2 ± 4.5 min (range: 0–18.8 min). The average femtosecond laser treatment time was 4.3 ± 3.4 min (range: 1–15.5 min). The VT was 2.51 ± 0.45 min (range: 1.59–4.10 min). Although not significant, TPT in FLACS showed a trend towards improvement (mean 1.0 ± 0.6 s; range: 0.1–2.4 s) compared to CPCS (mean 1.2 ± 0.6 min; range: 0.5–2.5 min). Whereas, TPP was significantly less in FLACS (mean 17.9 ± 5.0%; range: 5–27%) compared to CPCS (mean 20.3 ± 4.1%; range: 12.0–28.7%)(p = 0.031).

Conclusions

The mobile FLACS system housed in the same operating room increased the surgical duration by 5.2 min. The average VT was 2.51 min, which was lower in comparison to published experience using non-mobile FLACS systems.

Femtosecond laser-assisted versus phacoemulsification for cataract extraction and intraocular lens implantation: clinical outcomes review

PURPOSE OF REVIEW

Femtosecond laser-assisted cataract surgery (FLACS) has gained popularity in recent years with the new technology suggesting potential improvements in clinical and safety outcomes over conventional phacoemulsification cataract surgery (PCS). A decade since the advent of FLACS has given time and experience for laser technology to develop in maturity, and better quality evidence to become available. This review evaluates current evidence on the clinical and safety outcomes for FLACS in comparison to PCS.

RECENT FINDINGS

FLACS technology continues to improve and with it our confidence in tackling more complex patient indications. Concurrently other new technologies such as precision pulse capsulotomy also look to deliver the biomechanically ideal 5.2 mm capsulotomy, particularly as there remain suggestions from large studies and meta-analyses of raised capsular complications with FLACS compared with PCS and IOL technology responding to advantages of a consistent capsulotomy. Visual benefits of FLACS over and above PCS also remain to be conclusively demonstrated, with equivalence but not superiority. Economic modelling continues to indicate that FLACS remains 'not' cost-effective.

SUMMARY

FLACS can be considered non-inferior to conventional PCS in term of safety and clinical outcomes. However, FLACS has yet to demonstrate an overall cost-benefit to the patient.

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

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

Update and clinical utility of the LenSx femtosecond laser in cataract surgery

The introduction of femtosecond lasers to cataract surgery has been the major disruptive technology introduced into ophthalmic surgery in the last decade. Femtosecond laser cataract surgery (FLACS) integrates high-resolution anterior segment imaging with a femtosecond laser allowing key steps of cataract surgery to be performed with computer-guided laser accuracy, precision, and reproducibility. Since the introduction of FLACS, there have been significant advances in laser software and hardware as well as surgeon experience, with over 250 articles published in the peer-reviewed literature. This review examines the published evidence relating to the LenSx platform and discusses surgical techniques, indications, safety, and clinical results.

Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

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.

Femtosecond laser-assisted cataract surgery--current status and future directions

Femtosecond laser-assisted cataract surgery (FLACS) putatively offers several advantages over conventional phacoemulsification. We review the current status of FLACS and discuss the evolution of femtosecond lasers in cataract surgery and the currently available femtosecond laser platforms. We summarize the outcomes of FLACS for corneal wound creation, limbal relaxing incisions, capsulotomy, and lens fragmentation. We discuss surgical planning, preoperative considerations, clinical experiences including the learning curve and postoperative outcomes with FLACS, and also the cost effectiveness of FLACS. We present the intraoperative complications and management of challenging cases where FLACS offers an advantage and also speculate on the future directions with FLACS. Further advancements in laser technology to refine its efficacy, advancement in intraocular lens design to harness the potential benefits of FLACS, and a reduction in cost are needed to establish a clear superiority over conventional phacoemulsification.

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).

Intraocular pressure during femtosecond laser pretreatment: comparison of glaucomatous eyes and nonglaucomatous eyes

PURPOSE

To compare changes in intraocular pressure (IOP) during femtosecond laser pretreatment of cataract between glaucomatous eyes and nonglaucomatous eyes.

SETTING

Launceston Eye Institute and Launceston Eye Hospital, Launceston, Australia.

DESIGN

Nonrandomized interventional prospective case series.

METHODS

Patients with clinically stable primary open-angle glaucoma (POAG) having femtosecond laser pretreatment were compared with a concurrent cohort of patients with healthy eyes having the same procedure. Pretreatment was performed using a fluid-filled optical docking system (Liquid Optics Interface). With the patient supine, the IOP was measured at 4 time points using a rebound tonometer (Icare Pro).

RESULTS

The study comprised 143 eyes of 97 patients. Forty-three eyes (30.1%) had documented glaucoma. The mean baseline IOP was 20.2 mm Hg ± 4.2 (SD) in glaucomatous eyes and 18.9 ± 4.0 mm Hg in nonglaucomatous eyes (P = .06). The mean change in IOP values between each time frame and baseline was as follows: vacuum-on, 13.8 ± 9.9 mm Hg and 11.1 ± 6.9 mm Hg, respectively (P = .06); after treatment, 17.4 ± 7.4 mm Hg and 14.1 ± 7.2 mm Hg, respectively (P = .014); after undocking of vacuum, 9.9 ± 5.4 mm Hg and 8.7 ± 5.7 mm Hg, respectively (P = .24).

CONCLUSIONS

Femtosecond pretreatment caused a greater transient rise in IOP after treatment and a higher residual IOP after vacuum undocking in glaucomatous eyes than in nonglaucomatous eyes. This is well tolerated short term; however, long-term implications for eyes with glaucoma are unknown at present.

FINANCIAL DISCLOSURE

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

The evolution of corneal and refractive surgery with the femtosecond laser

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

Porcine Model to Evaluate Real-Time Intraocular Pressure During Femtosecond Laser Cataract Surgery

PURPOSE

To investigate the changes in intraocular pressure (IOP) in porcine eyes during femtosecond laser-assisted cataract surgery using a liquid-optic interface system.

MATERIALS AND METHODS

Femtosecond laser cataract surgery with the Catalys™ was performed on freshly enucleated porcine eyes in Oftalvist Moncloa, Madrid, Spain. Capsulorhexis and lens fragmentation were completed in all the eyes without complications. IOP was measured with a reusable blood pressure transducer connected by direct cannulation to the anterior chamber, recording data before suction (basal), at the beginning of the suction phase, every five seconds during femtosecond procedure and after the removal of the suction ring from the eye.

RESULTS

Nine porcine eyes were used in this study. Basal IOP before suction was 5.67 ± 2.39 mmHg, rising to 20.33 ± 4.18 mmHg at the beginning of the suction phase (p < 0.001). During femtosecond procedure, pressure reached a value of 19.74 ± 4.31 mmHg, remaining stable during the entire process. The IOP recorded prior to removal of the suction ring was 21.00 ± 6.93 mmHg, returning to basal values in all the eyes after the suction ring was removed, with no statistical differences between basal and post-suction IOPs. Total femtosecond procedure time was 125.9 ±  15.9 s.

CONCLUSIONS

Real-time IOP can be measured during surgery using a transducer connected to the anterior chamber. The results showed a significant increase in IOP during the procedure due to the pressure exerted by the suction ring but not by the effect of the femtosecond laser.

Femtosecond laser in refractive and cataract surgeries

In the past few years, 9 unique laser platforms have been brought to the market. As femtosecond (FS) laser-assisted ophthalmic surgery potentially improves patient safety and visual outcomes, this new technology indeed provides ophthalmologists a reliable new option. But this new technology also poses a range of new clinical and financial challenges for surgeons. We provide an overview of the evolution of FS laser technology for use in refractive and cataract surgeries. This review describes the available laser platforms and mainly focuses on discussing the development of ophthalmic surgery technologies.

Femtosecond-laser assisted cataract surgery: a review

Introduced in 2008, the femtosecond laser is a promising new technological advance which plays an ever increasing role in cataract surgery where it automates the three main surgical steps: corneal incision, capsulotomy and lens fragmentation. The proven advantages over manual surgery are: a better quality of incision with reduced induced astigmatism; increased reliability and reproducibility of the capsulotomy with increased stability of the implanted lens; a reduction in the use of ultrasound. Regarding refractive results or safety, however, no prospective randomized study to date has shown significant superiority compared with standard manual technique. The significant extra cost generated by this laser, undertaken by the patient, is a limiting factor for both its use and study. This review outlines the potential benefits of femtosecond-laser-assisted cataract surgery due to the automation of key steps and the safety of this new technology.

Intraocular pressure profiles during femtosecond laser-assisted cataract surgery

PURPOSE

To document the intraocular pressure (IOP) profiles during femtosecond laser-assisted cataract surgery.

SETTING

Refractive cataract surgery center.

DESIGN

Prospective case series.

METHODS

Intraocular pressure was measured using a handheld portable applanation tonometer (Tono-Pen Avia) during femtosecond laser-assisted cataract surgery using the Victus platform.

RESULTS

Forty-one eyes of 35 patients were recruited. The mean age of the patients was 70.5 years ± 8.2 (SD) (range 51 to 85 years). The mean IOP before, during, and after suction was 17.2 ± 3.2 mm Hg (range 10 to 23 mm Hg), 42.1 ± 10.8 mm Hg (range 20 to 55 mm Hg), and 13.8 ± 3.4 mm Hg (range 9 to 25 mm Hg), respectively. The mean difference between IOP before and during suction was 25.0 ± 11.3 mm Hg (range 5 to 43 mm Hg) (P<.01, Wilcoxon signed-rank test). The mean difference between IOP during and after suction was -28.7 ± 10.8 mm Hg (range -45 to -10 mm Hg) (P<.01, Wilcoxon signed-rank test). The mean suction duration was 216 ± 15 seconds (range 180 to 245 seconds).

CONCLUSIONS

The increase in IOP during the suction phase of femtosecond laser-assisted cataract surgery was statistically significant compared with the baseline IOP. Caution should be taken in patients with ocular conditions that are vulnerable to IOP fluctuation.

FINANCIAL DISCLOSURE

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

[Femtosecond laser-assisted cataract surgery]

Employing a femtosecond laser as an initial step in cataract surgery has the clear potential to provide more precise capsulotomies and full lens fragmentation in cases of pre-existing astigmatism in conjunction with relaxing corneal incisions. In the long run femtosecond laser-assisted cataract surgery might replace phacoemulsification which has been the standard in cataract surgery over the last 20 years. Besides precision and predictability, the low rate of complications impresses surgeons working with the technology, particularly those employing a laser with a fluid-filled interface which seems to prevent major complications including increases in intraocular pressure.

New technology update: femtosecond laser in cataract surgery

Femtosecond lasers represent a new frontier in cataract surgery. Since their introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented regarding capsulotomy, fragmentation of the crystalline lens, corneal wound creation, and refractive results. Safety issues such as endothelial and macular changes are also discussed. The most important advantage of femtolaser cataract technology at present is that all the important surgical steps of cataract surgery can be planned and customized, delivering unparalleled accuracy, repeatability, and consistency in surgical results. The advantages of premium lenses can be maximally used in visual and presbyopia restoration as well. The advantages of premium lenses can be maximally used, not only in visual, but in presbyopia restoration as well. Quality of vision can be improved with less posterior chamber lens (PCL) tilt, more centralized position of the PCL, possibly less endothelial damage, less macular edema, and less posterior capsule opacification (PCO) formation. This technological achievement should be followed by other technical developments in the lens industry. Hopefully this review article will help us to understand the technology and the results to demonstrate the differences between the use of femtolasers and phacoemulsification-based cataract surgery. The most important data of the literature are summarized to show ophthalmologists the benefits of the technology in order to provide the best refractive results to the patient.

[Femtosecond laser-assisted lens surgery depending on interface design and laser pulse energy: results of the first 200 cases]

BACKGROUND

This study was designed to evaluate the effectiveness and safety of femtosecond laser-assisted lens surgery depending on interface design and laser pulse energy settings.

METHODS

In this non-randomized, consecutive case series200 eyes underwent femtosecond laser-assisted (LenSx, Alcon) lens surgery between November 2012 and June 2013. Group 1 consisted of 85 eyes with 60 cataracts and 25 refractive lens exchanges (RLE) which were treated with a curved direct contact interface, and group 2 consisting of 115 eyes with 72 cataracts and 43 RLEs treated with a modified interface using an additional soft contact lens (SoftFit™, Alcon) between the corneal surface and the interface. The degree of opacity of the lens in cataract eyes was measured with a Scheimpflug camera. Afterwards, phacoemulsification was performed with intraocular lens (IOL) implantation in all eyes. Primary endpoints were the effective phacoemulsification time (EPT), the average laser treatment time and the occurrence of intraoperative complications.

RESULTS

The mean EPT in group 1 was 1.62 ± 1.12 s (cataract 1.94 ± 1.31 s, RLE 1.29 ± 1.01 s) and in group 2 the mean EPT was 1.66 ± 0.92 s (cataract 1.98 ± 1.28 s, RLE 1.33 ± 1.22 s, p = 0.32 between groups). The laser treatment lasted on average 48.90 ± 2.45 s (group 1) and 49.70 ± 2.87 s (group 2) with an average lens fragmentation thickness of 3401.48 ± 401.12 µm (all groups). In four cases of group 1, a second applanation of the interface was necessary. Furthermore, one anterior capsule tear, 39 cases of intraoperative wrinkling of the corneal surface and 21 cases in which the corneal incision had to be opened manually were documented in group 1. In group 2 no second applanation of the interface, no anterior capsule tears and no corneal wrinkling but 9 cases with a manual opening of corneal incisions were documented (p < 0.01 between groups).

CONCLUSION

The minor intraoperative complications of the femtosecond laser technique investigated could be significantly reduced using an optimized interface and reduced laser pulse energy.

Femtosecond laser cataract surgery: challenging cases

PURPOSE OF REVIEW

Emerging data in the peer-reviewed literature indicate that femtosecond laser-assisted cataract surgery (LCS) is a well tolerated and effective alternative to conventional phacoemulsification. Initial reports have largely been based on findings from an optimal patient selection. As confidence with the technology has grown, clinical indications have expanded and the benefit of LCS in high-risk patients with complex cataracts is increasingly being considered.

RECENT FINDINGS

We discuss challenging cataract surgery cases, citing the currently available literature alongside experience from over 3000 completed LCS cases at our centre.

SUMMARY

Current experience is limited. However, LCS platforms are continuously evolving and improving. The results collected to date would suggest that the precision and safety offered by LCS may improve outcomes in these challenging cases.

Initial evaluation of a femtosecond laser system in cataract surgery

PURPOSE

To report the early experience and complications during cataract surgery with a noncontact femtosecond laser system.

SETTING

Hong Kong Sanatorium and Hospital, Hong Kong Special Administrative Region, China.

DESIGN

Retrospective case series.

METHODS

All patients had anterior capsulotomy or combined anterior capsulotomy and lens fragmentation using a noncontact femtosecond laser system (Lensar) before phacoemulsification. Chart and video reviews were performed retrospectively to determine the intraoperative complication rate. Risk factors associated with the complications were also analyzed.

RESULTS

One hundred seventy eyes were included. Free-floating capsule buttons were found in 151 eyes (88.8%). No suction break occurred in any case. Radial anterior capsule tears occurred in 9 eyes (5.3%); they did not extend to the equator or posterior capsule. One eye (0.6%) had a posterior capsule tear. No capsular block syndrome developed, and no nuclei were dropped during irrigation/aspiration (I/A). Anterior capsule tags and miosis occurred in 4 eyes (2.4%) and 17 eyes (10.0%), respectively. Different severities of subconjunctival hemorrhages developed in 71 (43.8%) of 162 eyes after the laser procedure. The mean surgical time from the beginning to the end of suction was 6.72 minutes ± 4.57 (SD) (range 2 to 28 minutes).

CONCLUSIONS

Cataract surgery with the noncontact femtosecond laser system was safe. No eye lost vision because of complications. Caution should be taken during phacoemulsification and I/A to avoid radial anterior capsule tears and posterior capsule tears.