Femtosecond Laser Group Research Articles

Effects of various laser applications on surface roughness and bond strength to veneering composites of polyether ether ketone (PEEK) and polyether ketone ketone (PEKK) materials.

The aim of this study was to investigate the bond strength between PEEK/PEKK and composite resins after various laser treatments and to compare the effectiveness of lasers on these polymers. 130 disc-shaped PEEK and PEKK blocks were obtained (10mm diameter-4mm height). One sample from each group (10 in total) was selected for scanning electron microscopy (SEM) analysis. The samples were randomly divided into 5 different surface treatment groups for each material (PEEK and PEKK): Er: YAG laser, Nd: YAG laser, diode laser, femtosecond laser and control (no surface treatment) (n = 12). Baseline and post-treatment surface roughness measurements were performed using a profilometer. The composite resin was bonded and SBS was measured. Comparisons among the groups were conducted via Kruskal-Wallis, one-way ANOVA; Tukey and Dunn tests were used as a post hoc test (p ≤ 0.05). All lasers significantly increased the roughness values of the PEEK and PEKK samples. In terms of shear bond strength; the Er: YAG and femtosecond laser groups had the highest values and the Nd: YAG, diode and control groups had the lowest values of the PEEK samples (p ≤ 0.05). The control group had the highest bond strength values and the femtosecond group had the lowest values for PEKK samples (p ≤ 0.05). All laser treatments increased the surface roughness of the PEEK and PEKK. Lasers increased the bond strength of PEEK to the veneering composite resin and decreased the bond strength values of PEKK. This shows that lasers behave differently in PEEK and PEKK materials.

The Effect of Femtosecond Laser Surface Patterns on the Effectiveness of Resin Composite to Zirconia Bonding.

This laboratory study aimed to evaluate the effect of different surface patterns using femtosecond laser treatment on the enclosed mold shear bond strength (EM-SBS) of resin composite to zirconia (ZrO2) surfaces and to contrast it with the widely used tribochemical silica coating (TBC) surface conditioning method. A set of fifteen rectangular ZrO2 blocks were randomly divided into five groups according to surface pretreatment: Control G0-no treatment; G1-TBC with silane application; G2-femtosecond laser irradiation with horizontal lines 30 µm apart; G3-femtosecond laser irradiation with horizontal lines 15 µm apart; and G4-femtosecond laser irradiation with cross lines 30 µm apart. The pretreated surfaces were characterized by a surface profilometer, tensiometer and scanning electron microscope. The EM-SBS of resin composite stubs to ZrO2 was measured followed by fractographic analysis. The surface roughness and water contact angle were observed to be statistically higher among the femtosecond laser groups compared to the TBC and control groups. The G4 group exhibited the highest EM-SBS among all the groups, irrespective of the ageing conditions used. At the end of 5000 thermocycles, G4 exhibited EM-SBS of 14.05 ± 4.21 MPa compared to 13.80 ± 3.01 MPa in G1 and 5.47 ± 0.97 MPa in G0. The two-way ANOVA revealed a significant effect of both study groups and ageing conditions on the EM-SBS (p < 0.001). Utilization of femtosecond laser technology holds promise as a potential and alternative mechanical retention approach for enhancing the bonding strength of the resin composite to ZrO2.

Composite-veneering of polyether-ether-ketone (PEEK): evaluating the effects of different surface modification methods on surface roughness, wettability, and bond strength.

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.

Measurement of tear resistance after manual capsulorhexis and femtosecond laser\u2013assisted capsulotomy of crystalline lenses

BackgroundIn this study, the tear resistance of porcine lens capsules after continuous curvilinear capsulorhexis (CCC) and femtosecond (fs)-laser-assisted capsulotomy for cataract surgery (FLC) with different laser parameters is measured with a custom-made testing setup.MethodsForty-five fresh porcine lenses were randomly chosen for CCC (n = 15) or FLC 1 (n = 15) and FLC 2 (n = 15). The FLC 1-group was treated with smaller spot distances than the FLC 2-group. The force necessary to break the opening of the anterior capsule and the maximum displacement were measured.ResultsThe mean tear resistance of the CCC-group (150 ± 70 mN) was higher than that of the FLC 1-group (60 ± 20 mN) and the FLC 2-group (30 ± 20 mN).ConclusionIt could be shown that CCC leads to a significantly higher tear resistance of the opening than FLC in porcine lenses. The femtosecond laser group demonstrated that smaller spot distances lead to a higher tear resistance.

Thin-Flap Laser In Situ Keratomileusis-Associated Dry Eye: A Comparative Study Between Femtosecond Laser and Mechanical Microkeratome-Assisted Laser In Situ Keratomileusis.

To assess and compare postlaser in situ keratomileusis (LASIK) dry eye after LASIK with planned thin flaps created by a femtosecond laser (FS) and mechanical microkeratome (MK). Patients were stratified according to the flap creation technique into FS and MK groups with planned 100 μm flap thickness in all eyes. Dry eye parameters including tear film break-up time (TBUT), Schirmer I test, ocular surface disease index (OSDI), and lower tear meniscus height and area (tear meniscus height [TMH] and tear meniscus area [TMA]) were assessed before surgery and at 3 and 6 months after surgery. The study included 102 eyes of 55 patients (52 eyes underwent FS-LASIK/50 eyes underwent MK-LASIK). The preoperative characteristics including age, gender, and spherical equivalents were similar in both groups (P>0.05). The difference in postoperative flap thickness was statistically significant (P<0.05). In each group, dry eye parameters showed a statistically significant worsening (P value<0.001) at 3 months with later significant improvement at 6 months but did not return to baseline. The mean TBUT, Schirmer I, and lower TMH and TMA were statistically higher, and the mean OSDI was statistically lower in FS-LASIK than the MK-LASIK group at both 3 and 6 months (P value<0.001). The depth of ablation had a statistically significant correlation with Schirmer I at 6 months and OSDI at both 3 and 6 months post-LASIK (P<0.05). The use of femtosecond laser technology in performing thin-Flap LASIK eye surgeries has improved the outcome of post-LASIK dry eye when compared with the mechanical microkeratome.

Comparative study on incidence of posterior vitreous detachment (PVD) between conventional and femtosecond laser-assisted laser in situ keratomileusis (LASIK)

To compare incidence of posterior vitreous detachment (PVD) in patients after microkeratome and femtosecond laser-assisted laser in situ keratomileusis (LASIK) using ultrasound B-scan. Prospective, non-randomised, comparative and interventional hospital based study. This study was performed on 138 eyes of 69 patients, 64 eyes in microkeratome group and 74 eyes in femtosecond laser group for a period of 10 months from December 2017 to October 2018. The mean age of patients in microkeratome group was 23.34 years and in femtosecond laser group was 23.19 years. All patients in both the groups underwent one of the two procedure. Patients were assessed for subjective and objective refraction, presence of PVD, subjective complaints of floaters and axial length changes at each visit. At 1 week and 1 month postoperative period there was no PVD in either of the groups and none of the patients complained about disturbing floaters. At one week postoperative period, 17 eyes (26.5%) in microkeratome group and 22 eyes (29.6%) in femtosecond laser group had residual refraction ranging from -0.25D to -0.75D. The changes in axial length following surgery was 0.08 ± 0.08mm in microkeratome group and 0.1 ± 0.07mm in femtosecond laser group at one month. Our study did not demonstrate any difference between both the procedures with respect to posterior segment complications. Patients in our study are relatively younger compared to other studies and hence, age of the patient undergoing LASIK may affect the incidence of PVD.Both microkeratome assisted LASIK and femtosecond assisted LASIK were comparable with respect to posterior segment complications. The mean age of patients in this study is assumed to have an effect on outcome. Whereas axial length, power of the eye, procedure opted did not significantly have any impact on outcome. A larger population with longer follow up is needed in Indian population to conclude our results.

Femtosecond laser-assisted big bubble for deep anterior lamellar keratoplasty.

To assess the utility of a femtosecond laser-assisted stromal channel to assist the creation of a big bubble (BB) for deep anterior lamellar keratoplasty (DALK) surgery in cadaveric corneas. L V Prasad Eye Institute, Hyderabad, India. Experimental study. An attempt to create a BB was made on 10 donor pairs of human cadaveric corneoscleral tissues. The 20 corneas were split into 2 groups: Group A underwent femtosecond laser pretreatment and Group B had conventional manual deep lamellar technique. Laser pretreatment was performed using the VisuMax femtosecond laser system to create a stromal channel using the intracorneal ring segment treatment module for direct insertion of the 27-gauge air cannula for pneumodissection at a predetermined depth. Of the 20 corneas studied, type 1 BB was achieved in 9 of 10 corneas in Group A and in 7 of 10 corneas in Group B. One cornea from Group A had a combined type 1 and 2 BB, whereas no BB was achieved in 1 cornea. Creation of an intrastromal channel using a femtosecond laser at a predetermined depth seemed to be a promising option to increase the chances of achieving a BB when compared with the conventional air injection technique of BB DALK.

Laser-assisted in-situ keratomileusis (LASIK) with a mechanical microkeratome compared to LASIK with a femtosecond laser for LASIK in adults with myopia or myopic astigmatism.

Laser-assisted in-situ keratomileusis (LASIK) is a surgical procedure that corrects refractive errors. This technique creates a flap of the outermost parts of the cornea (epithelium, bowman layer, and anterior stroma) to expose the middle part of the cornea (stromal bed) and reshape it with excimer laser using photoablation. The flaps can be created by a mechanical microkeratome or a femtosecond laser. To compare the effectiveness and safety of mechanical microkeratome versus femtosecond laser in LASIK for adults with myopia. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 2); Ovid MEDLINE; Embase; PubMed; LILACS; ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We used no date or language restrictions. We searched the reference lists of included trials. We searched the electronic databases on 22 February 2019. We included randomized controlled trials (RCTs) of LASIK with a mechanical microkeratome compared to a femtosecond laser in people aged 18 years or older with more than 0.5 diopters of myopia or myopic astigmatism. We used standard methodological procedures expected by Cochrane. We included 16 records from 11 trials enrolling 943 adults (1691 eyes) with spherical or spherocylindrical myopia, who were suitable candidates for LASIK. Five hundred and forty-seven participants (824 eyes) received LASIK with a mechanical microkeratome and 588 participants (867 eyes) with a femtosecond laser. Each trial included between nine and 360 participants. In six trials, the same participants received both interventions. Overall, the trials were at an uncertain risk of bias for most domains. At 12 months, data from one trial (42 eyes) indicates no difference in the mean uncorrected visual acuity (logMAR scale) between LASIK with a mechanical microkeratome and LASIK with a femtosecond laser (mean difference (MD) -0.01, 95% confidence interval (CI) -0.06 to 0.04; low-certainty evidence). Similar findings were observed at 12 months after surgery, regarding participants achieving 0.5 diopters within target refraction (risk ratio (RR) 0.97, 95% CI 0.85 to 1.11; 1 trial, 79 eyes; low-certainty evidence) as well as mean spherical equivalent of the refractive error 12 months after surgery (MD 0.09, 95% CI -0.01 to 0.19; 3 trials, 168 eyes [92 participants]; low-certainty evidence). Based on data from three trials (134 eyes, 66 participants), mechanical microkeratome was associated with lower risk of diffuse lamellar keratitis compared with femtosecond laser (RR 0.27, 95% CI 0.10 to 0.78; low-certainty evidence). Thus, diffuse lamellar keratitis was a more common adverse event with femtosecond laser than with mechanical microkeratome, decreasing from an assumed rate of 209 per 1000 people in the femtosecond laser group to 56 per 1000 people in the mechanical microkeratome group. Data from one trial (183 eyes, 183 participants) indicates that dry eye as an adverse event may be more common with mechanical microkeratome than with femtosecond laser, increasing from an assumed rate of 80 per 1000 people in the femtosecond laser group to 457 per 1000 people in the mechanical microkeratome group (RR 5.74, 95% CI 2.92 to 11.29; low-certainty evidence). There was no evidence of a difference between the two groups for corneal haze (RR 0.33, 95% CI 0.01 to 7.96; 1 trial, 43 eyes) and epithelial ingrowth (RR 1.04, 95% CI 0.11 to 9.42; 2 trials, 102 eyes [50 participants]). The certainty of evidence for both outcomes was very low. Regarding the visual acuity outcomes, there may be no difference between LASIK with mechanical microkeratome and LASIK with femtosecond laser. Dry eye and diffuse lamellar keratitis are likely adverse events with mechanical microkeratome and femtosecond laser, respectively. The evidence is uncertain regarding corneal haze and epithelial ingrowth as adverse events of each intervention. The limited number of outcomes reported in the included trials, some with potentially significant risk of bias, makes it difficult to draw a firm conclusion regarding the effectiveness and safety of the interventions investigated in this review.

Surface quality and endothelial cell viability after femtosecond laser-assisted donor lenticule preparation for endothelial keratoplasty - An in-vitro study.

Purpose:To compare surface quality and endothelial cell viability of descemet stripping automated endothelial keratoplasty (DSAEK) donor lenticules prepared with femtosecond laser (FSL) or microkeratome (MK).Methods:Experimental ex-vivo evaluation of 15 DSAEK donor lenticules prepared from optical quality donor corneas using 200 KHz FSL (9 eyes) or MK (6 eyes). Surface quality and smoothness of the cut were assessed using atomic force microscopy and endothelial cell viability was assessed using transmission electron microscopy.Results:Mean lenticule thickness was 121.89 ± 17.13 μm in FSL group and 112.67 ± 5.89 μm in MK group (P = 0.33). Average roughness of stromal surface (RMSavg) [FSL- 30.51 ± 4.55 nm, MK-22.37 ± 1.83 nm; P = 0.02] and root mean square roughness (RMSrough) [FSL-31.39 ± 5.75 nm, MK-23.08 ± 0.40 nm; P = 0.012] was significantly more in FSL group. Increased granular and linear irregularities were observed in the FSL group. Endothelial cell disruption was more in FSL group (FSL- 29.49 ± 6.91% MK-13.28 ± 3.62%; P < 0.001) with decreased mean nucleus length (FSL-5.56 ± 0.17 μm, MK-7.52 ± 0.65 μm; P < 0.001).Conclusion:Automated MKs are still the standard of care for donor lenticule preparation and MK-assisted donor lenticules have smoother surface with less endothelial cell disruption than FSL. Further research is mandatory before FSL platforms can be considered a viable alternative to the MK.

Comparison of lens anterior capsular changes between femtosecond laser-assisted phacoemulsification and conventional phacoemulsification for cataract patients with diabetes

Objective To compare the anterior capsule opacification and contraction of lens following femtosecond laser-assisted cataract surgery versus conventional phacoemulsification for cataract patients with diabetes. Methods A non-randomized control study was carried out.Eighty-five eyes of 85 cataract patients with diabetes were included from March 2015 to August 2016 in Xiamen Eye Center.The patients were divided into 2 groups based on the different surgeries.Forty-three eyes of 43 patients in the femtosecond laser group received femtosecond laser-assisted phacoemulsification and completed the 5.3 mm capsulorhexis using the Alcon LenSx femtosecond laser platform.Forty-two eyes of 42 patients in the conventional surgery group underwent conventional phacoemulsification group and performed 5.3 mm continuous circular capsulorhexis under the guidance of Alcon VERION.Anterior capsule opacification (ACO) was graded according to Werner's method.The area of anterior capsular opening was calculated by using Image Pro Plus 6 software.The number of eyes in different grades of ACO and anterior capsule opening area between two groups were compared at 1 month, 3 months and 6 months after operation. Results Initial anterior capsular opening area was not significantly different between the femtosecond laser group and the conventional phacoemulsification group (t=0.003, P=0.958). The anterior capsule opening area in the two groups among different time-points after operations was significantly different (Fgroup=73.602, P<0.001; Ftime=378.895, P<0.001), and anterior capsule opening areas were smaller in the conventional phacoemulsification group than those in the femtosecond laser group at various time points after operation (all at P<0.001). At 1 month after suigery, grade Ⅰ of the ACO was found in 29 eyes (67.4%) in the femtosecond laser group and 26 eyes (61.9%) in the conventional phacoemulsification group, and there was no significant difference between two groups (P=0.133). At 3 months after surgery, the incidence rate of grade Ⅱ of ACO was 11.6% (5/43) in the femtosecond laser group, which was lower than than that in the conventional phacoemulsification group(66.7%, 28/42), showing a significant difference between them (P<0.001). At the 6th month after operation, the incidence rate of grade Ⅲ of ACO in the femtosecond laser group was 14.0%(6/43), which was lower than that in the conventional phacoemulsification group(73.8%, 31/42), with a significant difference between them (P<0.001). Conclusions Femtosecond laser-assisted cataract surgery for cataract is a good choose patients with diabetes mellitus because of reducing the occurrence of ACO and the contraction of anterior capsule. Key words: Cataract/surgery; Diabetic mellitus; Laser/therapy use; femtosecond laser-assisted phacoemulsification; Anterior capsular membrane, lens

Comparison of Complication Rates between Manual and Femtosecond Laser-Assisted Techniques for Intrastromal Corneal Ring Segments Implantation in Keratoconus

ABSTRACTPurpose: To compare the incidence of complications between manual and femtosecond-laser assisted surgery for intrastromal corneal ring segments (ICRS) implantation.Material and methods: This study included keratoconus patients who had ICRS implantation using manual dissection and using the femtosecond laser with a minimum follow-up of 12 months. Uncorrected (UDVA) corrected (CDVA) distance visual acuity (CDVA), refraction, corneal topography and aberrometry, pachymetry map and slit-lamp microscopy were assessed before and after surgery.Results: The study included 265 eyes in the manual group and 111 in the femtosecond laser group. In the manual group, there were complications in 48 eyes (18.11%); while in the femtosecond laser 4 eyes had a complication (3.6%). In the manual group, the most frequent complications were ICRS exchange/adjustment for visual and refractive enhancement (25 eyes; 9.43%) and late ICRS spontaneous extrusion (15 eyes; 5.66%). In the manual group, 81.25% of complications were observed during the first 3 years of surgeon’s experience. Eyes who suffered a complication had preoperatively higher mean refractive (p = .002) and topographic cylinder (p = .003) and lower UDVA (p = .005) and CDVA (p = .002). After a second surgical procedure for complication management visual, refractive and topographic outcomes significantly improved.Conclusion: Manual mechanical ICRS surgery shows a higher rate of intra- and postoperative mechanical and refractive complications when compared to femtosecond laser assisted technique. The incidence is specially higher during the surgeon’s first years of implementation of the technique.

Effect of age on visual and refractive results after LASIK: mechanical microkeratome versus femtosecond laser.

To evaluate the effect of age on visual and refractive results after laser in situ keratomileusis (LASIK) obtained with a mechanical microkeratome or a femtosecond laser. Retrospective, nonrandomized, cohort study. A total of 3826 eyes were included in the study (1725 eyes treated with mechanical LASIK and 2101 eyes treated with femtosecond LASIK). The relationship between patient age and the 3-month postoperative visual and refractive results of both procedures were analyzed by linear regression analysis. Three months postoperatively, we found a significant correlation between age and the postoperative spherical equivalent (SE; r 2=0.004, P=0.006), efficacy (r 2=0.006, P=0.001), and safety indexes (r 2=0.05, P=0.0001) in the mechanical LASIK group. On the other hand, we found a significant correlation between age and the postoperative SE (r 2=0.02, P=0.0001) and the efficacy index (r 2=0.01, P=0.0001) but not the safety index in the femtosecond laser group. Mechanical LASIK provided slightly but significantly better efficacy and predictability in patients 18 to 40 years of age and femtosecond LASIK did so in patients older than 40 years of age. The femtosecond laser provided better safety results than the mechanical microkeratome in both age groups. A tendency toward undercorrection and less predictability is found with aging after myopic LASIK regardless of whether the flap was created with a mechanical microkeratome or a femtosecond laser. However, femtosecond laser provides significantly better outcomes in terms of efficacy, safety and predictability compared to mechanical microkeratome for the correction of myopia in patients over 40y.

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

Purpose To compare the capsule edges ultrastructure obtained by two femtosecond laser-assisted cataract surgery (FLACS) platforms and manual continuous curvilinear capsulorhexis (CCC) using scanning electron microscopy (SEM). Setting Eye Clinic, University of Trieste, Italy. Design Experimental comparative study. Methods 150 anterior capsules were collected and divided into three groups as follows: Group 1 (50 capsules) obtained with manual CCC, Groups 2 and 3 (each with 50 capsules) obtained with the Catalys Laser and the LenSx Laser, respectively. All samples were imaged by means of SEM and regularity of the cut surface, and thickness of the capsule edge were evaluated and compared. Results All femtosecond laser (FSL) capsules were perfectly circular, whereas some alteration of the circular shape was observed in the manual ones. Group 1 showed a smooth and regular capsule edge without any surface irregularity, conversely Groups 2 and 3 showed postage-stamp perforations on the capsule edge. The cut surface irregularity value in Group 2 was 1.4 ± 0.63, while it was 0.7 ± 0.49 in Group 3 (p < 0.05). Group 1 had a significantly lower thickness of the capsule edge than the FSL groups (p < 0.05). No statistically significant difference in the capsule edge thickness between the FSL groups was found (p=0.244). Conclusions Despite the presence of slight cut surface irregularities, both FSL capsulotomies showed a better geometry and circularity than the manual ones. Capsulotomy specimens obtained using both FSL capsulotomies showed laser-induced alterations of the capsule edge when compared with smooth and regular edges obtained using manual CCC.

Femtosecond laser–assisted cataract surgery versus conventional phacoemulsification: Refractive and aberrometric outcomes with a diffractive multifocal intraocular lens

To compare the outcomes of conventional phacoemulsification and femtosecond laser-assisted cataract surgery followed by multifocal intraocular lens (IOL) implantation. Asan Medical Center, Seoul, South Korea. Retrospective case series. Depending on their preference, patients had femtosecond laser-assisted cataract surgery or conventional phacoemulsification. Patients in the femtosecond group with corneal astigmatism greater than 0.75 diopter also had arcuate keratotomy. All eyes had multifocal IOL implantation. One month after treatment, the uncorrected distance and near visual acuities, spherical equivalent, corneal and refractive astigmatism, aberrometry results, and questionnaire results were compared between groups. Correlations between target-induced astigmatism (TIA) and surgically induced astigmatism (SIA) were also compared between the groups. The femtosecond group comprised 17 patients (23 eyes), with arcuate keratotomy performed in 14 eyes. The conventional phacoemulsification group comprised 22 patients(26 eyes). In the femtosecond group, the difference in corneal astigmatism between preoperatively and postoperatively was statistically significant. The correlation between TIA and SIA was greater in the femtosecond group. Corneal root-mean-square higher-order aberrations (RMS HOAs) (P<.01) and total trefoil (P=.043) were significantly higherin the femtosecond laser group. However, internal totalRMS (P=.05), tilt (P=.041), and RMS HOAs (P=.047) were significantly lower in the femtosecond group.Satisfaction scores were significantly higher in the femtosecond group. Astigmatic change was more predictable in the femtosecond laser-assisted cataract surgery group. Internal aberrations, including total RMS, tilt, and RMS HOAs, were lower in the femtosecond group, and patients in that group were more satisfied.

Surface Roughness of Ceramic-Resin Composites After Femtosecond Laser Irradiation, Sandblasting or Acid Etching and Their Bond Strength With and Without Silanization to a Resin Cement.

The aim of this study was to investigate the effects of femtosecond laser irradiation, sandblasting, or acid etching treatments on the surface roughness of ceramic-resin composites and also shear bond strength (SBS) with and without silanization to a resin cement. Samples of Vita Enamic (VE; Vita Zahnfabrik, Bad Säckingen, Germany) and Lava Ultimate (LU; 3M ESPE, Seefeld, Germany) were classified into control (no treatment), sandblasting, hydrofluoric acid, and femtosecond laser groups (n=30). Surface roughness was determined using two-dimensional contact profilometry. Surface topography was evaluated using a three-dimensional contact profilometer and a scanning electron microscope. Then groups were divided into two subgroups with similar surface roughness values, including control (C), control + silane (C-S), sandblasting (SB), sandblasting + silane (SB-S), hydrofluoric acid (HF), hydrofluoric acid + silane (HF-S), femtosecond laser (FS), and femtosecond laser + silane (FS-S) groups (n=15). Panavia F 2.0 resin cement was applied to the sample surfaces using an SDI SBS rig (SDI Limited, Bayswater, Australia). The SBS test was performed after water storage (24 h, 37°C) and thermocycles (2000 cycles, 5°C to 55°C), and failure modes were evaluated. The highest surface roughness was observed in the FS group, and the highest SBS was observed in the FS-S group for both VE and LU ( p<0.001). Silanization improved the SBS of VE significantly ( p<0.001) in all surface treatments but did not improve that of LU except in the FS group ( p=0.004). There was a significantly moderate negative correlation in the VE/SB group ( p=0.012) and a moderate positive correlation in the VE/HF group ( p=0.049). Femtosecond laser irradiation was found to be more effective than sandblasting or acid etching in increasing the surface roughness, and it was also the most effective surface treatment with silanization on the SBS of a resin cement to the ceramic-resin composites.

Femtosecond laser-assisted deep anterior lamellar keratoplasty in phototherapeutic keratectomy versus the big-bubble technique in keratoconus

To compare the functional and anatomic results of femtosecond laser (FSL)-assisted deep anterior lamellar keratoplasty (DALK) associated with phototherapeutic keratectomy (PTK) and FSL-assisted DALK performed using the big-bubble technique in keratoconus. During the first phase of the study, an electron microscopy histopathology pilot study was conducted that included four unsuitable donor corneas divided into two groups: in FSL group, FSL lamellar cuts were performed on two corneas and in FSL+PTK group, PTK was performed at the stromal beds of two corneas after FSL lamellar cuts were made. During the second phase of the study, a randomized clinical trial was conducted that included two treatment groups of patients with keratoconus: group 1 (n=14 eyes) underwent FSL-assisted DALK associated with PTK and group 2 (n=12 eyes) underwent FSL-assisted DALK associated with the big-bubble technique. The main outcome measures were the postoperative visual acuity (VA) and optical coherence tomography (OCT) measurements, confocal microscopic findings, and contrast sensitivity. In the pilot study, histopathology showed a more regular stromal bed in the FSL+PTK group. In the clinical trial, group 1 had significantly worse best spectacle-corrected VA and contrast sensitivity (P<0.05 for both comparisons). The residual stromal bed measured by OCT was significantly (P<0.05) thicker in group 1. Confocal microscopy detected opacities only at the donor-receptor interface in group 1. Patients with keratoconus treated with FSL-assisted DALK performed using the big-bubble technique fare better than treated with FSL-assisted DALK associated with PTK.

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

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

Changes of tear film and corneal sensitivity after femtosecond laser-assisted cataract extraction surgery

Objective To compare the changes of tear film and corneal sensitivity between femtosecond laser-assisted cataract surgery and microincisional phacoemulsification surgery. Methods A prospective cohort study was performed.Fifty-three eyes of 53 patients with age-related cataract were included in Wuhan Aier Eye Hospital from March to July 2015.The patients were divided into femtosecond laser group and microincisional group.The 26 eyes in the femtosecond laser group received femtosecond laser-assisted cataract surgery, and 27 eyes in the microincisional group received 2.2 mm microincisional phacoemulsification surgery.The patients were followed-up for 3 months.The data of corneal sensitivity, Schirmer test values, non-invasive tear film break-up time (NIBUT) and subjective score for dryness were collected in 7 days, 1 month and 3 months after surgery, and these results were compared between the two groups.This study was approved by Ethic Committee of Wuhan Aier Ophthalmology Hospital, and written informed consent was obtained from each patient prior to surgery. Results The operations were finished smoothly in all the eyes.In preoperative and 7 days, 1 month, 3 months after operation, the upper corneal sensitivity threshold and NIBUT between the two groups appeared a first reduction and a subsequent rise, the same phenomenon occurred in Schirmer test of the microincisional group and the subjective scores for dryness of the femtosecond laser group with statistically significant differences in the overall comparison (all at P 0.05). The dry eye scores increased gradually with the time expand after operation in the microincisional group, the difference was statistically significant (P<0.05). In postoperative 3 months, these parameters were restored preoperative values.However, the dry eye scores in the microincisional group were still higher than that before operation, and the difference was statistically significant (P<0.05). Conclusions Compared with the 2.2 mm microincisional phacoemulsification surgery, femtosecond laser-assisted cataract surgery brings less disturbance to lacrimal secretion, slight symptoms of dry eye and more comfortable sensation. Key words: Femtosecond laser/therapy use; Cataract/surgery; Tear film; Dry eye; Corneal sensuousness; Prospective study

Comparison of macular parameters after femtosecond laser–assisted and conventional cataract surgery in age-related macular degeneration

To evaluate differences in postoperative central macular thickness, central macular volume, corrected distance visual acuity (CDVA), and number of intravitreal anti-vascular endothelial growth factor (VEGF) injections between conventional and femtosecond laser-assisted cataract surgery in wet age-related macular degeneration (AMD). Tertiary referral center, Lucerne, Switzerland. Retrospective case series. Consecutive patients with AMD and cataract were enrolled between January 2010 and December 2015. Associations between postoperative changes in central macular thickness, central macular volume, CDVA, and number of anti-VEGF injections with type of surgery were assessed statistically. The study comprised 140 eyes (110 patients). No differences in postoperative central macular thickness (-9.20μm; 95% confidence interval [CI], -41.68 to 23.28; P=.576), central macular volume (-0.08mm2; 95% CI, -0.36 to 0.19; P=.553), visual acuity (0.03 logarithm of the minimum angle of resolution; 95% CI, -0.09 to 0.15; P=.647) or postoperative number of anti-VEGF injections (0.30; 95% CI, -0.45 to 1.05; P=.427) were found between the femtosecond laser group and the conventional group over a mean follow-up of 619days±473 (SD). In the 33 eyes that had optical coherence tomography measurement within a postoperative period of 2weeks, the central macular volume was significantly lower in femtosecond laser-treated eyes (-0.71mm2; 95% CI, -1.19 to -0.23; P=.005). Overall, the postoperative course between wet AMD after femtosecond laser and conventional cataract surgery was equal. During the early follow-up, femtosecond laser-treated eyes had less subclinical macular edema, indicating a possible benefit for patients with macular vulnerability.

Effects of Postsurface Treatments Including Femtosecond Laser and Aluminum-oxide Airborne-particle Abrasion on the Bond Strength of the Fiber Posts.

Bond strength of fiber posts. The purpose of this study was to evaluate the effect of different Post Surface treatment techniques on the push-out bond strength of the quartz fiber posts. A total of 30 maxillary central incisors were decoronated at cementoenamel junction. Root canals were filled and postspaces were prepared. The specimens were classified into three groups according to the surface treatment performed to the postsurface (n = 10) as no surface treatment (control group) (Group 1), A 50-μm aluminum-oxide airborne-particle abrasion group (Group 2), femtosecond laser (FS) group (Group 3). A self-curing adhesive cement was used for cementation of posts. Six sections (two coronal, two middle, and two apical) of 1-mm thickness specimens were prepared with a slow speed diamond saw. Specimens were stored in distilled water at 37°C for 24 h. Then, push-out test was performed on a universal testing machine. The data were analyzed by one-way ANOVA (α = 0.05). The test results indicated that push-out test values significantly different according to surface treatments among groups (P < 0.05). There were no significant differences between root sections of each group for bond strength (P > 0.05). All dislodged Group 3 posts were free of cement, indicating adhesive failure, Group 1 and 2 were partially coated with cement, indicating a mixed failure at the cement/postsurface. Based on the results, aluminum-oxide airborne-particle abrasion group showed higher and FS irradiation group showed lower bond strength values. Push-out bond strength values of the root segments were the same in all groups.