Neodymium-doped Yttrium Aluminum Garnet Laser Research Articles

The Influence of Neodymium-Doped Yttrium Aluminum Garnet Laser Pulse Repetition Rate on Cytokine Secretion from Peripheral Blood Mononuclear Cells in Vitro

Objective: Biological effects of infrared laser energy at various exposure parameters have been characterized in previous in vitro and animal studies. However, the impact of pulse repetition rate (PRR) has not been evaluated in this context. The purpose of this investigation was to assess the influence of PRR on cytokine secretion from peripheral blood mononuclear cells (PBMCs) subjected to pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser energy. Materials and Methods: Rat PBMCs were cultured in vitro then stimulated using a lipopolysaccharide concentration of 0 or 100 ng/ml. Cultures received Nd:YAG laser radiation (1064 nm, 5 W, 30 s) at PRR of 0 (untreated controls), 20, 30, 40, or 60 Hz. Concentrations of tumor necrosis factor-α (TNF-α), macrophage inflammatory protein (MIP)-1α, macrophage inflammatory protein (MIP)-2, monocyte chemoattractant protein-1 (MCP-1), interferon-gamma-induced protein (IP)-10, interleukin (IL)-6, and IL-10 were recorded using a magnetic microsphere immunoassay. The main effects of PRR and LPS stimulation on cytokine concentrations, and the interaction between PRR and LPS stimulation, were assessed using two-way analysis of variance. Bonferroni post hoc tests were used to identify pairwise differences between groups. Results: The main effect of PRR was statistically significant for MIP-1α (P = 0.018), TNF-α (P = 0.025), MCP-1 (P < 0.001), MIP-2 (P = 0.013), and IL-6 (P = 0.031). Five of six pro-inflammatory cytokines exhibited significantly lower mean concentrations in laser-exposed compared with control cultures at one or more PRR. However, no statistically significant differences were found between PRR groups. Conclusions: Under the described conditions, statistically significant differences in cytokine secretion were observed between laser-exposed and control cultures, consistent with prior reports. However, PRR appears to be an irrelevant factor in immunomodulation of PBMCs.

Retinal injury from a laser skin resurfacing device during medical tourism: a public health concern

BackgroundLaser skin resurfacing is a popular cosmetic procedure for noninvasive skin rejuvenation. Since health insurance plans often do not cover these types of procedures, patients often pay out of pocket. Consequently, there is an incentive to go abroad, where prices are more affordable. However, practitioners in destination countries may lack rigorous training on laser safety, regulatory oversight, or licensing, especially on devices used for “cosmetic” procedures. In certain cases, this can lead to tragic outcomes, especially when underqualified practitioners operate medical-grade laser devices.Case presentationA 29-year-old woman suffered a retinal burn from a handheld Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulse device used to perform skin resurfacing treatment at a medical spa in Vietnam. The patient was not adequately informed about the potential risk to her vision and was not provided with any eye protection. A momentary, unintended laser exposure to the patient’s right eye led to irreversible vision loss due to a macular burn. This incident caused immediate pain, followed by the sudden appearance of floaters, along with a retinal and vitreous hemorrhage. Despite treatment with off-label bevacizumab for the development of a choroidal neovascular membrane, vision remained at the level of counting fingers because of the presence of the macular scar.ConclusionWhen utilizing laser-based devices, it is crucial to employ safety measures, such as the wearing of safety goggles or the use of eye shields to protect ocular tissues from potential damage. The growing availability of cosmetic laser devices presents a substantial public health risk, because numerous operators lack adequate training in essential safety standards, or they neglect to follow them. Furthermore, patients seeking services abroad are subject to the regulatory practices of the destination country, which may not always enforce the requisite safety standards. Further research is needed to determine regional and global incidence of laser-related injuries to help direct educational and regulatory efforts.

Pilot Study to Demonstrate Improvement in Skin Tone and Texture by Treatment with a 1064 nm Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser.

The 1064 nm Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser was developed to treat unwanted pigmentation in the skin such as lentigines caused by photoaging, and tattoos from dye/ink insertion. This laser has also been used for non-ablative epidermal rejuvenation (skin toning). To evaluate changes in skin tone, skin texture and overall improvement after a series of treatments with the QS Nd:YAG laser. Participants received seven full-face treatments with M22 or Stellar M22, a 1064 nm QS Nd:YAG laser, at 2-week intervals. The investigators and participants evaluated the improvement in skin tone and texture at 1, 3 and 6 months after the last treatment. Patient satisfaction, patient discomfort, downtime and adverse events were recorded. Histological changes in the treated area were also evaluated. Thirteen women with a median age of 45 years (range, 34-61 years) were included in the study. The majority of the participants (53.9%) had skin type VI. One month after the last treatment session, 38% of participants reported good to very good improvement. This value increased to 100% participant improvement at both the 3-month and 6-month follow-up visits. The reduction in melanin index and the histological analysis demonstrated that the laser procedure contributed to a reduction in epidermal melanin content. Treatments were not associated with high levels of pain or discomfort. The most common immediate post-treatment response was erythema and edema. Most participants were satisfied with the resulting treatment outcome. Skin treatment with the 1064 nm QS Nd:YAG laser module on the M22 and Stellar M22 devices, using a large spot size, low fluence, moderately high repetition rate, improves skin tone and texture in patients with skin types II-VI.

Novel 532-nm Q-switched Nd: YAG laser for the treatment of melasma and rejuvenation: a prospective, randomized controlled comparison with 1,064-nm Q-switched Nd: YAG laser.

Melasma is a common pigmentary and photoaging disorder. Although various treatments, including 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (QS-Nd: YAG) laser toning, are available for melasma, results are often unsatisfactory. We aimed to determine the efficacy and safety of 532-nm QS-Nd: YAG laser (shortwave toning) in patients with melasma and facial rejuvenation. Fifty-two patients were recruited to receive either 1,064-nm QS-Nd: YAG laser or 532-nm QS-Nd: YAG laser every 2 weeks for 8 sessions and a 2-month follow-up visit in a randomized controlled double-blinded study. The primary outcome measure was the Melasma Area and Severity Index (MASI) score. Dermoscope and high-frequency ultrasound (HFUS) were used to assess the improvement of melasma and photoaging. 532-nm QS-Nd: YAG laser achieved significantly higher improvement in the MASI score (P = 0.000). The Dermoscopic melasma score (DMS) displayed significant change and confirmed the improvement. HFUS showed a significant decrease in the thickness of the subepidermal low-echogenic band (SLEB) and increases in dermal thickness and dermal density in both groups (P = 0.000 for all). The rate of very satisfied responses was significantly higher in the 532-nm laser group (P = 0.001). There was no significant difference in the visual analog scale pain assessment score (P = 0.248) and recurrence rate (P = 0.734) between the two groups. 532-nm QS-Nd: YAG laser (shortwave toning) proved to be an effective and safe treatment for melasma and rejuvenation. Shortwave toning was significantly better for pigmentation clearance, while 1,064-nm laser showed better improvement in skin rejuvenation.

Analysis of the interaction-length dependence of frequency stability in an iodine-stabilized Nd:YAG laser.

We report a numerical simulation and an experimental study on the interaction-length dependence of frequency stability in an iodine-stabilized neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A saturation spectroscopy model was used in the simulation to calculate the interaction-length dependence of the linewidth and signal-to-noise ratio of the iodine saturation spectrum. We determined that 2m was the optimal interaction length for laser-frequency stabilization. We confirmed the simulation results by performing modulation transfer spectroscopy and laser-frequency stabilization using 45-cm- and 2-m-long iodine cells and multipass configurations. The results of this study are useful for designing compact and highly stable iodine-stabilized lasers.

Effects of Nd: YAG LASER irradiation and O2 plasma on the adhesive performance of poly-ether-ether-ketone (PEEK)

PurposeTo evaluate the effects of neodymium-doped yttrium aluminum garnet (Nd: YAG) LASER irradiation and oxygen (O2) plasma on the adhesive performance of polyether ether ketone (PEEK) and resin adhesive. MethodsNd: YAG LASERs of varying powers and O2 plasma for different durations were used to modify PEEK. A total of 168 PEEK specimens were randomly divided into seven groups (n = 24/group): (A) Control group: untreated PEEK, (B) L0.75 group: PEEK modified with 0.75 W Nd: YAG LASER, (C) L1 group: PEEK modified with 1.0 W Nd: YAG LASER, (D) L1.25 group: PEEK modified with 1.25 W Nd: YAG LASER, (E) P15 group: PEEK modified with 15 min of O2 plasma, (F) P25 group: PEEK modified with 25 min of O2 plasma, and (G) P35 group: PEEK modified with 35 min of O2 plasma. The surface characteristics of the materials were comprehensively analyzed using a scanning electron microscope (SEM), profilometer, energy-dispersive spectrometer (EDS), and contact angle tester. The adhesive specimens were bonded with Variolink N resin adhesive in all groups and each group was further divided into two subgroups (n = 12/group): (a) water storage for 56 h at 37 °C and (b) thermal cycling 5000 times. Shear bond strength (SBS) was tested using a universal testing machine, and the fracture modes were observed using an automated chemiluminescence analysis system to assess the effects of Nd: YAG LASER and O2 plasma on the bond strength of PEEK to resin adhesive. ResultsBoth Nd: YAG LASER and O2 plasma treatments altered the surface characteristics of PEEK and significantly increased the SBS between PEEK and Variolink N resin adhesive. The L0.75 group (Nd: YAG LASER) and the P35 group (O2 plasma) achieved the highest SBS, respectively. Furthermore, the SBS of the L0.75 group was higher than that of the P35 group. Following thermal cycling, SBS values decreased compared to the water storage subgroups. The fracture modes of the specimens in each group were predominantly interfacial and mixed, with no cohesive fractures observed. ConclusionsNd: YAG LASER irradiation and O2 plasma treatments can improve the SBS between PEEK and resin adhesive, with the 0.75 W Nd: YAG LASER being the preferred treatment method.

Are there sex-based disparities in cataract surgery?

To investigate sex-based differences in the occurrence of intra-operative and post-operative complications and associated visual outcomes following cataract surgery. This was a retrospective study of patients who had phacoemulsification cataract surgery at the University of Colorado School of Medicine. Data collected included the patient's health history, ocular comorbidities, operative and post-operative complications, and the post-operative best corrected visual acuity (BCVA). The data were analyzed using univariate and multivariable logistic regression with generalized estimating equations to account for the correlation of some patients having two eyes included in the study. A total of 11 977 eyes from 7253 patients were included in the study. Ocular comorbidities differed by sex, with males having significantly higher percentages of traumatic cataracts (males 0.7% vs females 0.1%), prior ocular surgery (6.7% vs 5.5%), and mature cataracts (2.8% vs 1.9%). Conversely, females had significantly higher rates of pseudoexfoliation (2.0% vs 3.2%). In unadjusted analysis, males had higher rates of posterior capsular rupture (0.8% vs 0.4%) and vitreous loss (1.0% vs 0.6%), but this difference was not significant after adjustment for confounders. Males had a significantly increased risk of post-operative retinal detachment, but in multivariable analysis this was no longer significant. Males were significantly less likely to undergo post-operative neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy for posterior capsule opacification (OR=0.8, 95%CI=0.7-0.9, P=0.0005). The BCVA was slightly worse for males pre-operatively; but post-operatively, both sexes exhibited similar visual acuity of Snellen equivalent 20/25. The study finds that in a cohort of patients presenting for cataract surgery, sex differences exist in pre-operative comorbidities and surgical characteristics that contribute to higher rates of some complications for males. However, observed surgical complication rates exhibit almost no difference by sex after adjusting for pre-operative differences and post-operative BCVA is similar between sexes.

Prediction of quality characteristics of micro-channels by deep learning algorithm during laser transmission ablation of PMMA

Underwater laser transmission micro-channelling of thick transparent polymethyl methacrylate (PMMA) using a neodymium-doped yttrium aluminium garnet (Nd: YAG) laser is the focus of this study. Experiments are conducted to determine the effect of three significant variables, namely pulse frequency, lamp current, and cutting speed, on heat-affected zone (HAZ) width, cut depth, and kerf width. Experiments are designed systematically utilising the full factorial design method. The purpose of constructing empirical models, specifically non-linear ones, is to establish and clarify the relationship between control factors and corresponding responses. A feed forward backpropagation neural network (FF-BPNN) is employed for predicting the measured response. Additionally, an assessment is made between the FF-BPNN results and the values predicted by the model. On the basis of the anticipated results, it can be concluded that the FF-BPNN model is preferable in predicting both the depth of cut and kerf width. In contrast, when specifically contemplating the measurement of HAZ width, the application of a non-linear model is more advantageous. As a measure of accuracy, the mean absolute error is computed for both the feedforward backpropagation neural network (FF-BPNN) and the nonlinear modelling technique.

An experimental investigation of the dynamic response of a liquid metal jet subjected to nanosecond laser ablation

The dynamic response of a micrometer-sized gallium–indium (Ga-In) jet in nitrogen subjected to intense Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser pulses with energy ranging from 0.35 to 5.0 mJ per pulse is investigated experimentally. The rapid deformation of the jet was visualized using timed-delayed stroboscopic shadowgraphy. The laser pulse disrupts the jet to form a gap, and the length of the gap grows according to a logarithm relationship with respect to the dimensionless time normalized a characteristic timescale τ, which is determined by the pulse energy Ep. The ablation impulse bends and flattens the jet into a thin curved film that resembles a wind-blown sail. The area of the sail increases with t6/5Ep13/15, where t is time. The sail eventually breaks up into fine mist. Additionally, we found that the laser-blast-induced initial bending velocity of the jet could be predicted using the semi-empirical laser-ablated propulsion model for an In-Sn droplet of tens of micrometers.

Conditioning of PEEK Implant Abutment Surfaces Using Photodynamic Therapy, Nd:YAG Laser, and Conventional Methods to Evaluate Shear Bond Strength.

Objective: This study was done to evaluate shear bond strength (SBS) and modes of failures after different surface treatment modalities on polyetheretherketone (PEEK) implant abutments. Materials and methods: Seventy-five PEEK implant abutment specimens were randomly distributed into five groups based on surface treatment methods: Group I: No treatment, Group II: methylene blue-mediated photodynamic therapy (MB-PDT), Group III: neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, Group IV: Sulfuric acid (H2SO4), and Group V: Sandblasting (Sb). The measurements for SBS and failure modes for PEEK implant abutment specimens were evaluated via Universal Testing Machine and Stereomicroscope, respectively. Two-way analysis of variance and Tukey's post-hoc test (p > 0.05) were used for the statistical analysis. Moreover, the Shapiro-Wilk normality test was also performed for normality. Results: The SBS mean values and standard deviations in megapascals (MPa) for PEEK abutment specimens with different surface pretreatment groups are shown in Table 1 and Fig. 1. The control group had the lowest SBS (9.67 ± 2.1 MPa), while the highest SBS was observed in Group II (MB-PDT; 17.21 ± 1.32 MPa). SBS values for Group IV (H2SO4; 15.83 ± 0.63 MPa) and Group III (Nd:YAG laser; 16.91 ± 2.10 MPa) were similar to Group II (MB-PDT; p > 0.05). The SBS values for the sandblasted specimens (13.90 ± 1.87 MPa) were not significantly different from the control group (p > 0.05). Conclusions: The PEEK implant abutment surfaces treated with MB-PDT and Nd:YAG laser expressed significantly improved SBS.

Efficacy and safety of a novel 785 nm picosecond neodymium-doped yttrium aluminum garnet laser for the treatment of facial benign pigmented lesions in Asian skin: a pilot study

Background and Objectives Benign pigmented lesions and a general uneven tone in people with skin of color are growing issues that have been presented to dermatologists. To the best of our knowledge, this is the first controlled study to examine the efficacy and safety of using the newly introduced 785 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) picosecond laser to treat facial benign pigmented lesions in Asian patients with diffractive lens array. Materials and Methods A 785 nm Nd:YAG picosecond laser was used to treat 15 healthy female volunteers older than 18 years who had Fitzpatrick skin types II–IV and facial benign pigmented lesions. Each volunteer received five weekly treatments in dual modes. The clinical improvement was assessed by independent investigators and by objectively measuring the melanin index. Results After the treatment, the melanin and erythema indices decreased, and the pigmented lesions showed clinical improvements. No serious adverse effects were observed during the study period. Conclusions A 785 nm Nd:YAG picosecond laser may be safe and effective in treating facial benign pigmented lesions in Asian skin.

Comparison of the Incidence of Nd:YAG Laser Capsulotomy Based on the Type of Intraocular Lens.

Background and Objectives: Posterior capsular opacification (PCO) is the most common long-term complication of successful cataract surgery and can cause visual impairment. We aimed to investigate the effects of intraocular lens (IOL) characteristics on PCO by comparing the incidence of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy for different types of intraocular lenses. Materials and Methods: A retrospective analysis was performed on 2866 eyes that underwent cataract surgery between January 2010 and December 2017, with at least 5 years of follow-up. The IOLs used for surgery were the hydrophobic lenses SN60WF (Alcon, Fort Worth, TX, USA), ZCB00 (Johnson & Johnson Vision, Santa Ana, CA, USA), and MX60 (Bausch & Lomb, Rochester, NY, USA), and the hydrophilic lens MI60 (Bausch & Lomb, Rochester, NY, USA). We analyzed the incidence of Nd:YAG laser capsulotomy according to the type of IOL used. Results: The incidence of Nd:YAG laser capsulotomy was significantly higher with MI60 lenses (31.70%, 175/552 eyes) compared to SN60WF (7.90%, 113/1431 eyes), ZCB00 (10.06%, 64/636 eyes), and MX60 (10.57%, 13/123 eyes; p < 0.001) lenses. The incidence of Nd:YAG laser capsulotomy was significantly lower with the hydrophobic IOLs (8.68%, 190/2190 eyes) than with the hydrophilic IOL (31.70%, 175/552 eyes; p < 0.001). Over time, the rate of increase in the cumulative number of Nd:YAG laser capsulotomy cases was the highest with MI60. The cumulative rate of Nd:YAG laser capsulotomy during the first 3 years was 4.90% with SN60WF (70/1431 eyes), 6.76% with ZCB00 (43/636 eyes), 8.94% with MX60 (11/123 eyes), and 26.10% with MI60 (144/552 eyes) lenses. Conclusions: The incidence of PCO is influenced by the material of the IOLs. The hydrophilic IOL was associated with a higher rate of Nd:YAG laser capsulotomy than the hydrophobic IOLs, with a shorter time to Nd:YAG laser capsulotomy.

Comparison of visual improvement based on the Potential Visual Test "Retinometry" in patients with Posterior Capsular Opacity Fibrotic and Regenerative types before and after Nd YAG Laser Capsulotomy

Background: Posterior Capsular Opacity (PCO) can disrupt a patient's vision and is a prevalent challenge medical professionals face in restoring visual clarity after cataract surgery. Various evaluation methods can be employed to measure visual improvement and the efficacy of Nd: YAG Laser Capsulotomy. One such method is Retinometry, which harnesses interference patterns of light on the retina as light passes through the pupil to provide patients with relevant information regarding the potential outcomes of Nd: YAG Laser Capsulotomy. This study aims to review the efficacy of the potential vision test "Retinometry" in patients with posterior capsular opacity before and after Nd: YAG Laser Capsulotomy. Methods: Literature searching was conducted using six online databases (PubMed, Scopus, Science Direct, Clinical Key, and Google Scholar). Search terms included a combination of main keywords: "Retinometer", "Posterior Capsulotomy", "Nd: YAG laser", and "Visual Acuity". Results: A total of 5 articles were included in this review. It’s found that the retinometer visual potential test has a function in evaluating the effects that occur and visual function after Nd: YAG laser capsulotomy. Due to the increasing incidence of cataract surgery, the rise of IOL placement will increase the risk of PCO formation and the need for Nd: YAG capsulotomy. Conclusion: Posterior Capsular Opacity (PCO) management remains a significant concern in patients post-cataract surgery, given its potential to disrupt visual acuity. Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser capsulotomy is a practical approach for addressing PCO-related visual impairment. Still, its impact on visual improvement may be modest, especially regarding refractive measurements. The type of lens used does not significantly influence the procedure outcomes. As the incidence of cataract surgery continues to rise, the prevalence of PCO and the need for Nd: YAG capsulotomy are likely to increase.

Viability of bacteria associated with root caries after Nd:YAG laser application in combination with various antimicrobial agents: An in vitro study.

The neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has various therapeutic applications in dentistry, including the treatment of dentin hypersensitivity and the bacterial reduction therapy in periodontology. The addition of antimicrobial agents may enhance the impact of the laser on bacterial viability. This in vitro study aimed to assess the effect of Nd:YAG laser application in combination with various chemical antimicrobial agents, including hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl), chlorhexidine (CHX), and sodium fluoride (NaF), on the viability of bacteria implicated in the etiology of root caries. Three oral bacterial species were examined: Streptococcus mutans (S. mutans); Streptococcus sanguinis (S. sanguinis); and Enterococcus faecalis (E. faecalis). The bacteria were grown in broth at 37°C, and then treated with the chemical agents and/or irradiated with an Nd:YAG laser for 30 s. Each treatment modality was repeated 3 times: group 1 - no treatment; group 2 - 0.5% H2O2; group 3 - 0.5% NaOCl; group 4 - 0.12% CHX; group 5 - 2% NaF; group 6 - Nd:YAG laser irradiation; group 7 - laser and 0.5% H2O2; group 8 - laser and 0.5% NaOCl; group 9 - laser and 0.12% CHX; and group 10 - laser and 2% NaF. The viability of the bacteria was determined by plating them, counting viable colonies, converting the data into colony-forming units (CFUs)/mL, and transforming them into the log form. Statistical analysis was performed using the two-tailed paired t test. Irradiation with an Nd:YAG laser alone did not show a statistically significant effect against any of the bacterial species. The only effective antimicrobial used alone was CHX for S. mutans. Chlorhexidine with Nd:YAG resulted in a greater reduction in S. mutans and E. faecalis than either treatment alone. Meanwhile, H2O2 with Nd:YAG also showed an enhanced S. mutans reduction. Treatment with 0.5% NaOCl in conjunction with Nd:YAG brought the most significant reduction in viability for all bacteria in comparison with other treatment modalities. The Nd:YAG laser combined with 0.5% NaOCl resulted in the most substantial reduction in bacterial survival as compared to the antimicrobials or the Nd:YAG laser used alone.

Management of recurrent aphthous ulcers with therapeutic Nd:YAG laser, using two different methods.

Low-level laser therapy (LLLT) has been applied for the management of craniomaxillofacial disorders, including intraoral wounds, as well as recurrent aphthous stomatitis (RAS) lesions. However, the proper combination of laser features and tissue characteristics remains the major challenge in the realm of photobiomodulation (PBM). The aim of the present study was to assess the feasibility of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser therapy in treating RAS lesions, and to compare 2 techniques, different with regard to the distance between the fiber tip and the ulcer. A total of 138 patients (94 males and 44 females) with untreated RAS were divided into 3 groups: focused laser (energy density: 48 J/cm2; power density: 0.797 W/cm2; spot size: 0.1256 cm2); defocused laser (energy density: 21 J/cm2; power density: 0.354 W/cm2; spot size: 0.2826 cm2); and placebo. In the focused group, laser irradiation was performed with the laser tip kept 1 mm away from the lesion. Acrylic cylinders were prepared to precisely fit the handpiece tip and hold it in the proper position. In the defocused group, acrylic cylinders were prepared to set the laser tip 6 mm away from the lesion to obtain defocused irradiation. Finally, in the placebo group, a routine laser therapy procedure was carried out with a helium-neon (He-Ne) red light laser. The lesion size, and pain intensity and duration were recorded. Photobiomodulation showed a significantly more efficient pain relief as compared to the placebo group (p < 0.001) and also significantly better results in decreasing pain duration (p < 0.001). Besides, the diameter of the lesions in the exposed cases decreased during the 3 consecutive days of the study, while an increase in the diameter of the lesions was noticed in the placebo group. The Nd:YAG laser therapy, with the conditions and adjustments of the present study, may be successfully applied to manage RAS lesions, using either focused and defocused scanning techniques.

Outcome and safety of secondary pars plana capsulotomy in patients with posterior capsular opacity following extracapsular cataract extraction

Objectives: Posterior capsular opacity is a major delayed complication seen in patients following cataract extraction. Neodymium-doped Yttrium Aluminium Garnet laser capsulotomy is the standard procedure for capsulotomy; however, its high cost and unavailability in the developing countries makes it important for us to find an alternative, effective and safe method that will help reduce the burden of severe visual impairment and blindness in individuals who have had cataract extraction. The aim of the study was to showcase the effectiveness, outcome and safety of pars plana capsulotomy in reducing the burden of visual impairment and blindness occurring after cataract extraction due to posterior capsular opacity amongst patients. Materials and Methods: This is a hospital-based retrospective study, where the clinic, ward and theatre registers of patients who had secondary pars plana capsulotomy in the past 3 years (2019–2022) due to posterior capsular opacity were reviewed. Patient’s folders who had pars plana capsulotomy with incomplete records were excluded as well as patients who had diabetes, glaucoma, corneal opacity and age-related macular degenerations. The frequency, age distribution, duration from cataract extraction to presentation with posterior capsule opacification (PCO), the grading and morphology of PCO were all noted. The pre- and post-operative visual acuity (VA) was also recorded alongside the pre- and post-operative intraocular pressure (IOP). We also documented intra- and post-operative complications that were seen in these patients. Data were analysed using SPSS package version 23 (SPSS Inc. Illinois, Chicago), and values were expressed as simple frequencies and proportions. Paired t-test was used to test the statistical significance with P &lt; 0.05. Results: A total of 36 patients records were reviewed; capsulotomy was performed in all age groups with the majority done in individuals 60–69 years – 11 eyes (26.8%). A total of 41 eyes of 36 patients had undergone secondary pars plana capsulotomy. Five (13.9%) patients had bilateral pars plana capsulotomy on different occasions. The mean age was 45.3 ± 26.9 years. There were 22 (53.7%) females and 19 (46.3%) males. Female-to-male ratio was 1.2:1. About 75.6% presented between 1 and 5 years after cataract surgery; mean duration for presentation with posterior capsular opacity after cataract extraction was 2.0 years ± 1.6 months. The majority 31 (75.6%) had their pars plana capsulotomy done under topical anaesthesia. VA at presentation was found to be below 3/60 in 17 (41.5%) eyes. After pars plana capsulotomy, VA improvement was seen – 6/6–6/12 in 23 (56.1%) eyes. Grade of PCO revealed that 15 (36.6%) eyes had Grade 2 PCO and the Elschnig pearls were the most common morphological form seen in 30 (73.2%) eyes. Most eyes had normal IOP post-operatively 38 (92.7%); there was a transient increase in IOP in 3 (7.3%) eyes. There were no complications recorded in most eyes 27 (66%). The most common of the few complications seen was subconjunctival haemorrhages in 6 (14.6%) eyes which resolved within a week of follow-up. Conclusion: Pars plana capsulotomy is a safe, easy and effective alternative for posterior capsulotomy and will be useful in resource-poor settings.

Laser ignition and flame propagation of methanol-air mixture in a constant volume combustion chamber

ABSTRACT The combustion performance of laser-ignited methanol-air mixture in a constant volume combustion chamber was investigated using the Schlieren photography technique. The experimentation was conducted at 5, 7, 9, and 11 MPa fuel injection pressure and 363 K initial chamber temperature using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser of 1064 nm wavelength. The gasoline direct injection (GDI) system was used for injecting the fuel at different pressures inside the chamber. The laser beam is focused into the chamber using a 150 mm focal length lens, and laser energy of 200 mJ was used for all experimentation. The Schlieren system was used for capturing flame propagation of methanol-air mixture for different equivalence ratios. The pressure-time history for equivalence ratio (ϕ) of 0.8, 0.9, and 1.0 was plotted and analyzed at different chamber filling pressures. Flame propagation was found faster for ϕ of 1.0 due to higher laminar velocity than 0.8 and 0.9. Flame visualization showed that the flame attains the ellipsoid shape during the early stage of ignition. It generates two lobes in the vertical direction and then again expands in a horizontal direction toward the ignition source. For all equivalence ratios, the flame propagation toward the incoming laser source (X-) was observed faster compared to the flame propagation in the direction and perpendicular to the laser beam direction. For all equivalence ratios, higher laminar flame speed was observed at 5 MPa injection pressure; however, it decreases as the injection pressure increases. At ϕ of 1.0 and 11 MPa injection pressure, the maximum peak pressure of 0.67 MPa and combustion duration of 19.3 ms were noted. At 9 MPa injection pressure and ϕ of 1.0, the peak pressure and combustion duration was found as 0.61 MPa and 19.4 ms, respectively. At ϕ of 0.8, the peak pressure and combustion duration were observed 0.27 MPa with 34.6 ms duration and 0.47 MPa with 36.9 ms duration at 5 MPa and 11 MPa injection pressures, respectively.

PEEK Surface Treatment Using Nd: YAG, Riboflavin Activated by PDT, and Alumina Particles on Surface Roughness, Bond Failure, and Bond Integrity to Composite Resin

Aims: Conditioning protocols, Airborne Particles of Alumina (ABP), Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser, and Riboflavin (RF), were tested on PEEK disc bonded to composite restorations for surface roughness (Ra) and shear bond strength (SBS). Method and Material: Random sampling was used to divide 80 PEEK discs into four groups for surface conditioning. (n = 20). Group 1: Sulfuric acid (SA); Group 2: PDT (RF); Group 3: Alumina particle ABP; Group 4: NYL. Pretreated PEEK discs were measured for Ra using a surface profilometer. They were luted and bonded to composite resin discs. On Universal testing equipment, SBS was tested. Stereomicroscopes analyzed failure type. Data was analyzed using one-way ANOVA and Tukey’s test. Results: The SA-treated group had the highest Ra (1.411 ±0.043 μm). However, PDT (RF) treated tissues had the lowest mean Ra score (1.299 ± 0.019 μm). Regarding SBS, the SA-treated group (11.83±0.82 MPa) had the highest mean score. PDT (RF) (10.23±0.64 MPa) treated specimens showed the lowest bond integrity values. The most common fracture type in all investigated groups is cohesive failure. Conclusion: Airborne alumina, riboflavin, and Nd: YAG laser could replace PEEK sulfuric acid to improve composite cement bond integrity and surface roughness.

Effect of Er, Cr: YSGG, Nd: YAG, and diode laser against different photosensitizers on tensile and shear bond strength of bonded composite to caries affected dentin.

This study aimed to assess the impact of various cavity disinfection methods on the adhesive bond integrity of composite resin to caries-affected dentin (CAD). Additionally, it will evaluate the micro tensile bond strength (µTBS) of different dentin substrates [CAD and sound dentin (SD)] using various adhesive agents. The sample consisted of twenty human mandibular molars with sound dentin (SD) and eighty with CAD. All samples were positioned in a group of polyvinyl pipes with an internal diameter of 3 mm and were positioned perpendicularly up against the cementoenamel junction (CEJ). A total of 60 CAD samples (n=10) were used for shear bond strength (SBS) testing. CAD samples were disinfected with erbium chromium-doped yttrium, scandium, gallium and garnet (Er, Cr: YSGG) laser in group 1, Diode laser in group 2, neodymium-doped yttrium aluminum garnet (Nd: YAG) laser in group 3, riboflavin in group 4, curcumin in group 5, and chlorhexidine in group 6. Sixty CAD samples were treated with Scotchbond™ Etchant and Scotchbond™ multi-purpose primer and bonded with composite for SBS testing. On the twenty remaining CAD samples that did not undergo any type of disinfection, as well as the twenty samples that had sound dentin (SD), two different types of adhesive systems were used for micro tensile testing. For ten of each CAD and SD sample, 3c™ Adper™ Scotchbond™ multi-purpose adhesive was applied to the dentin surfaces. For the remaining ten CAD and SD samples, the All-Bond 2 adhesive system was used. The samples were prepared for µTBS testing. In all specimens, bond failure was assessed using a stereomicroscope. Analysis of variance (ANOVA) and Tukey Honestly Significant Difference (HSD) tests were used to compare the means of multiple groups, at a significance level of p<0.05. CAD disinfected with chlorhexidine (CHX) (17.19±1.02 MPa) exhibited the highest SBS values. Samples in group 5 disinfected with curcumin activated by photodynamic therapy (PDT) showed the lowest SBS (12.49±1.11 MPa). Scotchbond adhesive displayed comparable µTBS (p>0.05) when applied on CAD and SD. Moreover, All-Bond 2 adhesive, when applied on CAD, exhibited µTBS significantly lower than All-Bond 2 adhesive on SD (p<0.05). Analysis of debonded CAD surface after SBS showed that a cohesive type of failure was dominant in different experimental groups, followed by adhesive CONCLUSIONS: CAD disinfection with Er:Cr: YSGG, Diode Laser, and Riboflavin activated by photodynamic therapy have the potential to be used as an alternative to CHX for acceptable shear bond strength. The use of Adper™ Scotchbond™ multi-purpose adhesive on CAD and SD did not significantly compromise µTBS.

Response to query and additional considerations regarding the article "The complication rate following neodymium-doped yttrium aluminum garnet laser posterior capsulotomy for posterior capsular opacification in patients with and without comorbidities".

Response to query and additional considerations regarding the article "The complication rate following neodymium-doped yttrium aluminum garnet laser posterior capsulotomy for posterior capsular opacification in patients with and without comorbidities".