Displaying publications 1 - 20 of 54 in total

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  1. Khan N, Idrees A
    J Biomed Opt, 2001 Jan;6(1):86-9.
    PMID: 11178584
    The goal of this study is to assess the risk of overexposure, when DFB dye laser is used for medical treatment in pulsed mode operation. Results of experimental study showing an unexpected rise of energy in pulses of distributed feedback dye laser (DFDL) output due to temperature phase gratings in dye cell during passively Q switched and mode-locked operation is reported. This unintended increase in the number of pulses, pulse duration, per pulse energy may cause side effects, when used for selective photothermolysis. To probe this phenomenon the most commonly used Rh6G dye was excited with 10-20 pulses of second harmonic of a passively Q switched and mode-locked Nd:yttrium-aluminum-garnet(YAG) laser. The outputs of DFDL and Nd:YAG laser were recorded by an Imacon-675 streak camera. The peak of DFDL output pulses was found delayed proportionally from the peak of the Nd:YAG pulses by more than an interpulse period of excitation laser. A computer program was used to simulate the experimentally measured results to estimate the thermal decay constants and energy retained by medium. The delay between peaks of Nd:YAG (input) and DFDL (output) pulses was found to vary from 10 to 14 ns for various cavity lengths. It was interesting to note that for smaller inter-pulse periods the effect of gradual gain buildup satisfied the threshold conditions for some of the pulses that otherwise cannot lase. This may lead to unintended increase in energy fluence causing overexposure-induced bio effects.
    Matched MeSH terms: Laser Therapy*
  2. Goh WN, Mustapha M, Zakaria SZS, Bastion MC
    Indian J Ophthalmol, 2022 08;70(8):3026-3032.
    PMID: 35918966 DOI: 10.4103/ijo.IJO_3198_21
    Purpose: To determine the effectiveness of laser vitreolysis in terms of contrast sensitivity function (CSF) and vision-related quality of life (VRQol) for symptomatic floaters due to posterior vitreous detachment (PVD).

    Materials: This is an interventional study that involved 57 eyes of 45 patients with symptomatic floaters for more than 3 months. Patients underwent one to three sessions of vitreolysis via Neodymiun-doped Yttrium Aluminum Garnet (Nd:YAG) laser. We examined the CSF using the computer programs Freiburg Acuity and Contrast Test (FrACT) and VRQoL survey using the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) before, and 1 month after, vitreolysis.

    Results: Twelve patients had both eyes lasered and 33 patients had one eye lasered. The mean CSF improved from 3.20 ± 0.85%W to 2.64 ± 0.63%W 1 month after vitreolysis. Each use of the laser showed a significant mean difference in CSF (%W) as analyzed by paired t-test before and after the first laser (0.29 ± 0.49%W [P ≤ 0.001]); after the first and second laser (0.35 ± 0.53%W [P = 0.01]); and after second and third laser (0.21 ± 0.31%W [P = 0.02]). There was improvement in the median of four subscales in NEI VFQ-25 scores post treatment: general vision (z = -3.30, P = 0.001), near activity (z = 3.396, P = 0.001, distance activity (z = -2.788, P = 0.005), and mental health (z = -2.219, P = 0.026). The mean scores increased to 79.55 ± 9.45 from the baseline 75.06 ± 9.69 (P ≤ 0.001). No adverse events were recorded 1 month after the laser treatments.

    Conclusion: Vitreolysis by Nd:YAG laser improved the CFS and VRQoL in symptomatic PVD patients.

    Matched MeSH terms: Laser Therapy*
  3. Anayb Baleg SM, Bidin N, Suan LP, Sidi Ahmad MF, Krishnan G, Johari AR, et al.
    Photochem Photobiol, 2015 Jan-Feb;91(1):134-8.
    PMID: 25327511 DOI: 10.1111/php.12369
    Skin is the most important organ in our body, as it protects us from external environmental effects. Study the ability of the skin to stretch and the histological examinations of irradiated tissues have significant values in scientific and medical applications. Only a few studies have been done to study the correlation between epidermis ablation and the changes that occur at dermal levels when using dual lasers in ablative resurfacing mode. The aim of this work is to determine this correlation and to estimate the effects of multiple pulses on induced collagen remodeling and the strength of skin exposed with dual lasers in an in vivo rat model. All laser exposures led to mark improvement in the skin's strength compared to their own controls. The histological investigation indicated that there was a thickness loss in the epidermis layer with the induction of deep collagen coagulation in the dermis layer as the dual laser pulses increased. Additionally, more collagen fibers were remolded in the treated samples by dual wavelengths. We conclude that by combining dual lasers with multiple pulses targeted at not only the epidermis layer of the skin, it could also induce some heat diffusion in the dermis layer which causes more coagulation of collagen fibers. The tensile results confirmed by our histological data demonstrate that the strength of irradiated skin with dual wavelengths increased more than using both lasers separately on the skin tissue since more collagen is induced.
    Matched MeSH terms: Laser Therapy*
  4. Zamzuri AK, Al-Mansoori MH, Samsuri NM, Mahdi MA
    Appl Opt, 2010 Jun 20;49(18):3506-10.
    PMID: 20563203 DOI: 10.1364/AO.49.003506
    We demonstrate the generation of multiple Brillouin Stokes lines generation assisted by Rayleigh scattering in Raman fiber laser. The linear cavity is utilized to take advantage of the Rayleigh scattering effect, and it also produces two strong spectral peaks at 1555 and 1565nm. Under a strong pumping condition, the Rayleigh backscatters contribute to the oscillation efficiency, which increases the Brillouin Stokes lines intensity between these two wavelength ranges. The multiple Stokes lines get stronger by suppressing the buildup of free-running longitudinal modes in the laser structure.
    Matched MeSH terms: Laser Therapy
  5. Hambali NA, Mahdi MA, Al-Mansoori MH, Saripan MI, Abas AF
    Appl Opt, 2009 Sep 20;48(27):5055-60.
    PMID: 19767918 DOI: 10.1364/AO.48.005055
    The operation of a single-wavelength Brillouin-erbium fiber laser (BEFL) system with a Brillouin pump preamplified technique for different output coupling ratios in a ring cavity is experimentally demonstrated. The characteristics of Brillouin Stokes power and tunability were investigated in this research. The efficiency of the BEFL operation was obtained at an optimum output coupling ratio of 95%. By fixing the Brillouin pump wavelength at 1550 nm while its power was set at 1.6 mW and the 1480 pump power was set to its maximum value of 135 mW, the Brillioun Stokes power was found to be 28.7 mW. The Stokes signal can be tuned within a range of 60 nm from 1520 to 1580 nm without appearances of the self-lasing cavity modes in the laser system.
    Matched MeSH terms: Laser Therapy
  6. Chai CA, Inoue T, Somani BK, Yuen SKK, Ragoori D, Gadzhiev N, et al.
    Investig Clin Urol, 2024 Sep;65(5):451-458.
    PMID: 39249917 DOI: 10.4111/icu.20240185
    PURPOSE: Traditionally, bilateral urolithiasis treatment involved staged interventions due to safety concerns. Recent studies have shown that same-sitting bilateral retrograde intrarenal surgery (SSB-RIRS) is effective, with acceptable complication rates. However, there's no clear data on the optimum laser for the procedure. This study aimed to assess outcomes of SSB-RIRS comparing thulium fiber laser (TFL) and high-power holmium:yttrium-aluminum-garnet (Ho:YAG) laser in a multicenter real-world practice.

    MATERIALS AND METHODS: Retrospective analysis was conducted on patients undergoing SSB-RIRS from January 2015 to June 2022 across 21 centers worldwide. Three months perioperative and postoperative outcomes were recorded, focusing on complications and stone-free rates (SFR).

    RESULTS: A total of 733 patients were included, with 415 in group 1 (Ho:YAG) and 318 in group 2 (TFL). Both groups have similar demographic and stone characteristics. Group 1 had more incidence of symptomatic pain or hematuria (26.5% vs. 10.4%). Operation and lasing times were comparable. The use of baskets was higher in group 1 (47.2% vs. 18.9%, p<0.001). Postoperative complications and length of hospital stay were similar. Group 2 had a higher overall SFR. Multivariate regression analysis indicated that age, presence of stone at the lower pole, and stone diameter were associated with lower odds of being stone-free bilaterally, while TFL was associated with higher odds.

    CONCLUSIONS: Our study shows that urologists use both lasers equally for SSB-RIRS. Reintervention rates are low, safety profiles are comparable, and single-stage bilateral SFR may be better in certain cases. Bilateral lower pole and large-volume stones have higher chances of residual fragments.

    Matched MeSH terms: Laser Therapy/adverse effects; Laser Therapy/methods
  7. Abohabib AM, Fayed MM, Labib AH
    J Orthod, 2018 09;45(3):149-156.
    PMID: 29874972 DOI: 10.1080/14653125.2018.1481710
    OBJECTIVE: To investigate the effect of low-intensity laser therapy on mini-implant stability using resonance frequency analysis during canine retraction with fixed appliances.

    DESIGN: A split-mouth randomised clinical trial.

    SETTING: Subjects were recruited and treated in the outpatient clinic, Department of Orthodontics, Faculty of Dentistry, Cairo University.

    PARTICIPANTS: Fifteen subjects with mean age 20.9 (±3.4) years who required extraction of maxillary first premolar teeth and mini-implant-supported canine retraction.

    METHODS: Thirty orthodontic mini-implants were inserted bilaterally in the maxillary arches of recruited subjects following alignment and levelling. Mini-implants were immediately loaded with a force of 150 g using nickel titanium coil springs with split-mouth randomisation to a low-intensity laser-treated side and control side. The experimental sides were exposed to low-intensity laser therapy from a diode laser with a wavelength of 940 nm at (0, 7, 14, 21 days) after mini-implant placement. Mini-implant stability was measured using resonance frequency analysis at (0, 1, 2, 3, 4, 6, 8, 10 weeks) after implant placement.

    RESULTS: A total sample of 28 mini-implants were investigated with 14 in each group. Clinically, both mini-implant groups had the same overall success rate of 78.5%. There were no significant differences in resonance frequency scores between low-intensity laser and control sides from baseline to week 2. However, from week 3 to 10, the low-intensity laser sides showed significantly increased mean resonance frequency values compared to control (P > 0.05).

    CONCLUSIONS: Despite evidence of some significant differences in resonance frequency between mini-implants exposed to low-intensity laser light over a 10 weeks period there were no differences in mini-implant stability. Low-intensity laser light cannot be recommended as a clinically useful adjunct to promoting mini-implant stability during canine retraction.

    Matched MeSH terms: Laser Therapy*
  8. Maimunah, M., Ropilah, A.R., Othmaliza, O., Mushawiahti, M.
    Medicine & Health, 2016;11(2):199-208.
    MyJurnal
    Conventional argon laser causes transient thickening of retinal nerve fibre layer (RNFL). The effect of pattern scanning laser (PASCAL) has not been well described. We compared the immediate changes in peripapillary RNFL thickness post-panretinal photocoagulation between conventional argon lasers and PASCAL in patients with diabetic retinopathy changes. A total of 32 subjects were recruited. There were 16 patients in the argon group and 16 patients in PASCAL group. Diabetic patients were recruited from Ophthalmology Clinic, Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Complete eye examinations and fundus photographs were performed at baseline prior to laser treatment, and post-laser treatment at two and four months. RNFL thickness was measured using time domain optical coherence tomography. Both groups were comparable with respect to clinical characteristics and demographics. There was no significant difference in average RNFL thickness between the two groups prior to treatment (p= 0.323). RNFL post-laser treatment for patients receiving conventional argon laser remained unchanged with no significant differences in all quadrants at any time-point (two and four months). However, for the PASCAL group, significant thickening occurred at four months for average RNFL and the inferior quadrant (p <0.05). The other quadrants similarly demonstrated increasing thickness at four months but this did not reach statistical significance. Transient RNFL thickening occurs in both conventional and PASCAL laser patients. The PASCAL laser induces a greater increase in RNFL thickness than the argon laser group. Important events, such as laser eye treatments and even type of laser used, are worthy of consideration when evaluating RNFL.
    Keywords: diabetic retinopathy, optical coherence, photocoagulation, retinal ganglion cells, tomography
    Study site: Ophthalmology Clinic, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
    Matched MeSH terms: Laser Therapy*
  9. Mehrabi JN, Bar-Ilan E, Wasim S, Koren A, Zusmanovitch L, Salameh F, et al.
    J Cosmet Dermatol, 2022 Feb;21(2):461-472.
    PMID: 33794033 DOI: 10.1111/jocd.14110
    BACKGROUND: Melasma is an acquired disorder of hyperpigmentation, affecting a million individuals worldwide. Energy-based devices (EBDs) employed to treat melasma include various types of lasers, intense pulsed light (IPL), and radiofrequency (RF). Recent studies have attempted to address recalcitrant and recurring melasma by combining energy-based devices with topical or oral medications.

    OBJECTIVE: This article reviews EBDs-based augmented treatment for melasma and suggests practical pathogenesis-oriented treatment regimens. Treatment algorithms are proposed to address various components of melasma.

    METHODS: A systematic PubMed search was conducted acquiring information from various studies on combination treatments of melasma involving EBDs.

    RESULTS: The 286 retrieved articles were filtered by title to contain at least one type of energy-based modality such as laser, IPL, or RF along with at least one other treatment method. Based on their subject matter, combinations were further categorized into the subheadings: laser plus medication, laser plus laser, and IPL- and RF-containing treatment methods.

    CONCLUSION: There are many energy-based combination treatments that have been explored for mitigation of melasma including laser therapy with medication, multi-laser therapies, IPL, RF, and microneedling devices. Melasma is an exceedingly difficult condition to treat, however, choosing the appropriate tailor-made treatment combination can improve the final outcome.

    Matched MeSH terms: Laser Therapy*
  10. Ahmad H, Latif AA, Abdul Khudus MI, Zulkifli AZ, Zulkifli MZ, Thambiratnam K, et al.
    Appl Opt, 2013 Feb 1;52(4):818-23.
    PMID: 23385923 DOI: 10.1364/AO.52.000818
    A highly stable tunable dual-wavelength fiber laser (TDWFL) using graphene as a means to generate a highly stable output is proposed and generated. The TDWFL comprises a 1 m long, highly doped erbium-doped fiber (EDF) acting as the linear gain medium, with a 24-channel arrayed waveguide grating acting as a wavelength slicer as well as a tuning mechanism to generate different wavelength pairs. The tuned wavelength pairs can range from 0.8 to 18.2 nm. A few layers of graphene are incorporated into the laser cavity to induce the four-wave-mixing effect, which stabilizes the dual-wavelength output by suppressing the mode competition that arises as a result of homogenous broadening in the EDF.
    Matched MeSH terms: Laser Therapy
  11. Ma C, Yin P, Khan K, Tareen AK, Huang R, Du J, et al.
    Small, 2021 Jan 27.
    PMID: 33502109 DOI: 10.1002/smll.202006891
    In this paper, 2D borophene is synthesized through a liquid-phase exfoliation. The morphology and structure of as-prepared borophene are systemically analyzed, and the Z-scan is used to measure the nonlinear optical properties. It is found that the saturable absorber (SA) properties of borophene make it serve as an excellent broadband optical switch, which is strongly used for mode-locking in near- and mid-infrared laser systems. Ultrastable pulses with durations as short as 792 and 693 fs are successfully delivered at the central wavelengths of 1063 and 1560 nm, respectively. Furthermore, stable pulses at a wavelength of 1878 nm are demonstrated from a thulium mode-locked fiber laser based on the same borophene SA. This research reveals a significant potential for borophene used in lasers helping extending the frontiers of photonic technologies.
    Matched MeSH terms: Laser Therapy
  12. Tajdidzadeh M, Azmi BZ, Yunus WM, Talib ZA, Sadrolhosseini AR, Karimzadeh K, et al.
    ScientificWorldJournal, 2014;2014:324921.
    PMID: 25295298 DOI: 10.1155/2014/324921
    The particle size, morphology, and stability of Ag-NPs were investigated in the present study. A Q-Switched Nd: YAG pulsed laser (λ = 532 nm, 360 mJ/pulse) was used for ablation of a pure Ag plate for 30 min to prepare Ag-NPs in the organic compound such as ethylene glycol (EG) and biopolymer such as chitosan. The media (EG, chitosan) permitted the making of NPs with well dispersed and average size of Ag-NPs in EG is about 22 nm and in chitosan is about 10 nm in spherical form. Particle size, morphology, and stability of NPs were compared with distilled water as a reference. The stability of the samples was studied by measuring UV-visible absorption spectra of samples after one month. The result indicated that the formation efficiency of NPs in chitosan was higher than other media and NPs in chitosan solution were more stable than other media during one month storage. This method for synthesis of silver NPs could be as a green method due to its environmentally friendly nature.
    Matched MeSH terms: Laser Therapy/methods*
  13. Han PK, Rohan M, Bujang MA
    Med J Malaysia, 2013 Jun;68(3):222-6.
    PMID: 23749010 MyJurnal
    With the advent of new technology, the treatment for ureteric stricture has moved from open surgery to endoscopic procedures. Our goals were to review and determine the prognostic factors for success of laser endoureterotomy for ureteric stricture. This is a cross sectional study for all cases that underwent laser endoureterotomy in a single centre from 2002 to 2009. Standard treatment in this centre utilizes holmium laser. The fiber used was 365nm, setting as 1J and frequency 8 Hz; power output 8 W. Confirmation of adequacy of incision wss by either visualization of extra-ureteric fat or extravasations of contrast on fluoroscopic imaging. Success or recurrence of the endoureterotomy was confirmed objectively with evidence of improvement from imaging. Of these 77 patients, 42 cases (61.8%) of the strictures were from upper ureter. Eight cases (11.7%) of mid-ureteric while lower ureter had 18 cases (26.5%). Length of stricture has been grouped into two groups; Short (<1cm) and long (≥1cm) and their distributions were 47.1% and 26.5% respectively. Follow-up duration ranged from six months to 88 months with an average of 19.6 months. Success rate was 76.5% (52 patients) while 16 patients (23.5%) developed recurrence. Stone disease, positive presenting symptoms and short length of the stricture were identified as variables with good predictor. This study achieved a 76.5% of success rate for this treatment modality for benign ureteric stricture in wellselected patients. Success is more likely if patient is symptomatic (earlier treatment) and previous stone disease present as a risk factor.
    Study site: Hospital Selayang, Kuala Lumpur
    Matched MeSH terms: Laser Therapy*
  14. Baharudin A, Shahid H, Rhendra MZ
    Med J Malaysia, 2006 Aug;61(3):377-9.
    PMID: 17240597 MyJurnal
    Tonsillectomy in children is performed on a regular basis in ENT. The indications are chronic tonsillitis, sleep apnea to deeper structures. The natural history of tonsillar hyperplasia is regression when a child is six years beyond. In children with bilateral tonsillar hyperplasia we studied the use of laser as an alternative procedure to reduce the bulk of the tonsillar mass. Children with symptoms of bilateral tonsillar hyperplasia underwent laser tonsillotomy. The tonsils were dissected using carbon dioxide (CO2) laser. The tonsillar bed was left untouched. Intraoperative and postoperative conditions were noted.
    Matched MeSH terms: Laser Therapy/methods*
  15. Premsenthil M, Salowi MA, Siew CM, ak Gudom I, Kah T
    BMC Ophthalmol, 2012;12:64.
    PMID: 23241197 DOI: 10.1186/1471-2415-12-64
    To report a case of spontaneous malignant glaucoma in an Asian female. To propose the term "positive vitreous pressure glaucoma" to reflect the pathophysiology, treatment and prognosis of the condition.
    Matched MeSH terms: Laser Therapy*
  16. Chiu CL, Khanijow V, Ong G, Delilkan AE
    Med J Malaysia, 1997 Mar;52(1):82-3.
    PMID: 10968058
    We report a case of endotracheal tube fire occurring during CO2 laser surgery of the larynx. The ignition of an endotracheal tube was thought to be caused by laser penetration of an unprotected portion of the tube during resection of vocal cord tumour. Fire hazard is inevitable when a laser is used in the path of combustible gases and in the presence of flammable objects. We discuss the methods of prevention that were used.
    Matched MeSH terms: Laser Therapy/adverse effects*
  17. Abduljabbar T, Vohra F, Akram Z, Ghani SMA, Al-Hamoudi N, Javed F
    J. Photochem. Photobiol. B, Biol., 2017 Aug;173:353-359.
    PMID: 28641206 DOI: 10.1016/j.jphotobiol.2017.06.016
    BACKGROUND: Oral pigmentation, especially in the gingiva poses esthetic problems. Laser therapy has been widely used for cosmetic therapy in dentistry. The aim of the present study was to systematically review the efficacy of surgical laser therapy (SLT) in the management of oral pigmented lesions (OPL).

    MATERIALS AND METHODS: The addressed focused question was "Is SLT effective in the management of OPL?" Databases (MEDLINE via PubMed; EMBASE; Cochrane Central Register of Controlled Trials and Cochrane Oral Health Group Trials Register databases) were searched from 1970 up to and including February 2017.

    RESULTS: Ten studies were included. The reported number of OPL ranged between 8 and 140. Oral pigmented sites included, gingiva, buccal and labial mucosa, alveolar mucosa and lips. Lasers used in the studies included Q-switched alexandrite, Neodymium-doped yttrium aluminium garnet, diode, Erbium: yttrium aluminium garnet and carbon dioxide laser. Laser wavelength, power output and number of irradiations were 635-10,600nm, 1-10W and 1 to 9 times, respectively. The follow up period ranged from 6 to 24months. All studies reported SLT to be effective in the treatment of OPL. In five studies, recurrence of OPL occurred which ranged from 21.4% to 45%.

    CONCLUSIONS: Lasers are effective in the management of OPL including physiologic gingival pigmentation, smokers' melanosis and pigmentation in Laugier-Hunziker syndrome. Different laser types (CO2, Er:YAG and Diode) showed comparable outcomes in the treatment of OPL.

    Matched MeSH terms: Laser Therapy/methods*
  18. Alhajj M, Aziz MSA, Huyop F, Salim AA, Sharma S, Ghoshal SK
    Biomater Adv, 2022 Nov;142:213136.
    PMID: 36206587 DOI: 10.1016/j.bioadv.2022.213136
    This paper reports the characterization and antibacterial performance evaluation of some spherical and stable crystalline silver (Ag)/copper (Cu) nanocomposites (Ag-CuNCs) prepared in deionized water (DIW) using pulse laser ablation in liquid (PLAL) method. The influence of various laser fluences (LFs) on the structural, morphological, optical and antibacterial properties of these NCs were determined. The UV-Vis absorbance of these NCs at 403 nm and 595 nm was gradually increased accompanied by a blue shift. XRD patterns disclosed the nucleation of highly crystalline Ag-CuNCs with their face centered cubic lattice structure. TEM images showed the existence of spherical NCs with size range of 3-20 nm and lattice fringe spacing of approximately 0.145 nm. EDX profiles of Ag-CuNCs indicated their high purity. The antibacterial effectiveness of the Ag-CuNCs was evaluated by the inhibition zone diameter (IZD) and optical density (OD600) tests against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The proposed NCs revealed the IZD values in the range of 22-26 mm and 20-25 mm when tested against E. coli and S. aureus bacteria, respectively. The Ag-CuNCs prepared at LF of 14.15 J/cm2 revealed the best bactericidal activity. It is established that by controlling the laser fluence the bactericidal effectiveness of the Ag-CuNCs can be tuned.
    Matched MeSH terms: Laser Therapy*
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