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PubMed1994

Comparative study of microepineural suture, microepineural suture-aided CO2 laser, and laser only anastomoses in rat sciatic nerves.

The cut sciatic nerves of 33 rats were anastomosed by three different methods under the operation microscope; microepineural suture technique, CO2 laser technique, and laser-aided microepineural suture technique. On histologic examination at the end of 3 months postoperatively, in the CO2 laser and suture-aided CO2 laser groups, the degrees of inflammation, fibrosis, and Schwann cell vacuolar degeneration were significantly higher than in the microepineural suture anastomosis group. At the end of 3 months sciatic nerve function was absent in 3 of 11 rats anastomosed by only CO2 laser, however, sciatic nerve functions were found to be normal in the other two groups.

Anastomosis, Surgical↗

PubMed1999

A randomized study of dorzolamide in the prevention of elevated intraocular pressure after anterior segment laser surgery. Dorzolamide Laser Study Group.

PURPOSE: To evaluate the efficacy of 2% dorzolamide hydrochloride opthalmic solution in preventing spikes in intraocular pressure (IOP) after anterior segment laser surgery. METHODS: This 24-hour, placebo-controlled, randomized, double-masked, multicenter evaluation was conducted to determine the efficacy of dorzolamide hydrochloride 2% in controlling IOP after neodimium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy, argon laser trabeculoplasty, or laser iridotomy. The 122 patients enrolled were assigned in randomized fashion to receive dorzolamide or placebo 1 hour before and immediately after the procedure; IOP was measured 1, 2, 3, 4, and 24 hours after the procedure. RESULTS: Of 61 patients receiving dorzolamide, only one (1.7%) had a spike in IOP of 10 mmHg or more, compared with 9 (14.8%) of the 61 patients receiving placebo. Mean IOP among patients receiving dorzolamide was significantly reduced both from baseline and compared with that among patients receiving placebo from 1 to 4 hours after administration. Only 5 (8%) of the 61 patients receiving dorzolamide experienced at least one adverse event, compared with 15 (25%) of the 61 patients receiving placebo. CONCLUSION: Dorzolamide was effective in preventing spikes in IOP after anterior segment laser surgery. Dorzolamide was generally well tolerated after short-term use.

Anterior Eye Segment↗

PubMed1999

[Clinical results of interstitial laser coagulation for benign prostatic hyperplasia using diode laser].

Interstitial laser coagulation (ILCP) is currently considered to be one of the avenues for treatment of benign prostatic hyperplasia (BPH). The efficacy and effectiveness of the treatment, however, have not been well clarified. Here we report the outcome of treatment in benign prostatic hyperplasia using ILCP. Twenty patients with BPH who underwent interstitial laser coagulation using a diode laser between March and December 1998 were investigated. Our results showed that there are significant improvements in prostate symptom score and quality of life index after the treatment. According to the efficacy criteria, 70% of the patients showed clinical improvement of both scores at 1 month, and more than 90% of the patients at 3 months. The reduction of prostate volume was observed after 1 month of treatment and continued for 6 months. The improvement on peak flow rate was observed in 50% of the patients at 3 months and in 73.3% of the patients at 6 months. The overall efficacy rates were 62.5%, 85.0% and 100% of the patients at 1, 3 and 6 months, respectively. In all 20 patients the complications were minimal. No blood transfusion was required in any patients. However, one patient experienced both epididymitis and prostatic abscess and was treated with conservative therapy. In conclusion, interstitial laser coagulation using a diode laser is a very effective means for the treatment of benign prostatic hyperplasia. Because of its less invasive nature, we strongly recommend that ILCP be the major way of treatment for benign prostatic hyperplasia.

Aged↗

PubMed2000

Erbium: YAG laser ablation of retinal tissue under perfluorodecaline: determination of laser-tissue interaction in pig eyes.

PURPOSE: To evaluate the effect of Er;YAG laser on pig retina using a perfluorodecaline/retina interphase with the goal of precisely determining the extent of retinal tissue ablation. METHODS: Free running (tau = 250 microsec) Er:YAG laser pulses were transmitted through a zirconium fluoride (ZrF4) fiber guarded by quartz rod (d = 1000 microm). Laser pulses were applied to the retinal surface of enucleated pig eyes. Eyes were mounted in a specially designed rotating sample holder. The fiber probe was elevated 1.0 +/- 0.3 mm above the retinal surface with perfluorodecaline serving as transmitting medium. The laser energy was applied in a circular pattern with a radius of 3.0 mm. Radiant exposures were set to 1, 3, 5, and 10 J/cm2. RESULTS: Tissue ablation linearly increased with radiant exposure from 3.2 +/- 3.7 microm at 1 J/cm2 up to 40.9 +/- 12.9 microm at 10 J/cm2. Thermal tissue changes extended 70 +/- 10 microm vertically into the retina and 25 +/- 5 microm horizontally. Distortion of outer photoreceptor segments was noticed when the retina was exposed to radiant exposures of 3 J/cm2 or higher. CONCLUSIONS: The Er:YAG laser in combination with perfluorodecaline produced precise ablation of the pig retina, which suggests the feasibility of this technique for safe ablation of epiretinal membranes.

Animals↗

PubMed1992

[Effects of Nd:YAG laser irradiation on ventricular myocardium in dogs using an artificial sapphire tip contact laser catheter].

To apply Nd:YAG laser irradiation through a new sapphire tip contact laser method to catheter ablation in treatment of tachy-arrhythmias, effects of laser irradiation on ventricular myocardium were investigated in 10 mongrel dogs. Nd:YAG lase (1064nm) discharges were delivered to different sites on the endomyocardium at power of 5, 10, 15, 20 or 25w with duration of 3, 5, or 10 seconds (sec.) respectively in closed beating hearts. Histopathologically, the lesion irradiated was clearly demarcated from the normal myocardium by the construction band necrosis zone. The depth of injured myocardium was less than 2mm with 3 sec. irradiations, with 5 sec. from 1 mm to 4 mm in proportion to power increase, with 10 sec. from 3mm to 8 mm in proportion to the power from 5w to 15w and could not be measured in cases of more than 20w irradiations. Although with every irradiation duration, the depth of injury increased in proportion to the power increase. With the same total energy, a longer time of irradiation produced deeper injury than a shorter time. This method makes it easier to keep the laser positioned to target than bare laser, and is suitable for use in catheter ablation.

Animals↗

PubMedDate not supplied

The role of number of treatments in laser-assisted hair removal using a 755-nm alexandrite laser.

BACKGROUND: It is generally accepted that multiple laser treatments yield more effective clinical results; however, it is not clearly known whether increasing the number of treatments would affect the incidence of adverse effect. The main objective of the study was to assess the role of the number of treatments in the efficacy and safety of laser-assisted hair removal in a relatively dark-skinned population. METHODS: A retrospective study of 313 consecutive laser-assisted hair removal treatments was conducted on a total of 23 patients (22 women, 1 man) with 58 anatomic areas by means of an alexandrite laser. Skin types of III and IV were represented. The long-pulsed alexandrite system (Aphrodite, Quanta system, Italy) was used at a 755-nm wavelength to deliver fluences ranging from 17 to 25 j/cm2 through a 10 mm spot size. The patients were divided into 4 groups according to the number of treatments (group I < or =4, group II = 5, group III = 6, and group IV > or =7 treatments). Digital photographs of the patients were used for hair counting. Adverse effects (hyperpigmentation, hypopigmentation, blister, folliculitis) were questioned. The treatment was defined as successful if there was more than 50% hair reduction and an absence of the adverse effects. RESULTS: There was a positive correlation between hair reduction and number of treatments (r = .402, p < .005). The following side effects were observed: hyperpigmentation (two patients, both in group IV); hypopigmentation (one patient in group IV) and blister (one patient in group IV); folliculitis (two patients in group III and IV). Treatment was successful in 48.3% (28 out of 58) of the treatment sites. The success rate was 25% for < or =4 treatments, and 76%, 58%, and 15% for 5, 6, and > or =7 treatments respectively (p = .002). CONCLUSION: Patients who undergo more treatment sessions achieve a higher rate of hair reduction; although this may be concomitant with an increase in the incidence of adverse effects. The benefit of more laser treatments should be balanced with the risk of occurrence of side effects in each patient.

Adult↗

PubMed1991

[Laser therapy in dental practice. What is laser?].

This article briefly discusses laser theory and medical use of different types of laser, laserphysics and laser properties. The indications for lasertherapy as claimed from laser-producers, are numerous. However, we recommend that the effect of treatment with low level laser therapy has to be more documented before general use in a dental practice.

Dental Instruments↗

PubMed1990

Superficial laser vulvectomy. IV. Extended laser vaporization and adjunctive 5-fluorouracil therapy of human papillomavirus-associated vulvar disease.

Although most human papillomavirus infections can be managed satisfactorily by office methods, extensive, refractory, and dysplastic vulvar disease poses frustrating problems. This observational cohort study evaluated the efficacy of extended laser ablation (vaporization of both clinically apparent and adjacent subclinical changes) among 160 women drawn from 1000 referrals between 1982-1987. During the final 2 years, the protocol incorporated two different 5-fluorouracil (5-FU) regimens: routine once-weekly applications as prophylaxis against postoperative recurrence, and twice-weekly dosing to avoid further laser surgery among patients with early but diffuse failures. One hundred seven patients (66.9%) were controlled by a single operation. Subsequent therapy for the remaining 53 women involved 44 additional superficial photovaporizations, 38 courses of therapeutic 5-FU, four deep laser destructions with skin grafting, and six trials of systemic alpha-interferon. Eventually, 158 patients (98.7%) entered stable clinical remission. Adjuvant 5-FU improved success rates among the 76 women with two or more adverse prognostic factors (87.5 versus 55.8%; P less than .01) but had no prophylactic value in the other 84 women. In contrast, the therapeutic 5-FU regimen was generally effective, avoiding the need for further surgery in 22 (57.9%) of 38 inevitable failures, compared with only four successes (10.3%) among 39 historic controls managed with caustic agents (chi 2 = 19.5; P less than .001). Improvements in laser technology had no impact upon outcome, but more sophisticated heat containment strategies reduced postoperative pain, healing time, and morbidity. Given adequate technique and an appropriate indication, we find extended laser ablation to be an excellent primary control method. However, the availability of an effective adjuvant regimen would be a valuable complement.

Cohort Studies↗

PubMedDate not supplied

[Current potentials and outlook for the use of gas lasers in medicine. Laser surgery].

Gas lasers are now in common use in clinical practice due to such advantages as a wide range of wavelengths, high spatial coherence, diversity of power radiations, and adequate reliability. Continuous CO2 lasers and pulse Cu and CO2 lasers recently produced on the industrial basis offer new opportunities to improve the quality of laser surgical interventions, cutting biological tissues with high blood supply and lower water content (bones, fat, burns, etc.), visceral surgery via endoscopes. Further development of fiberoptic communications with due regard to individual laser spectrum and power is beneficial for expanding the range of medical engineering.

Equipment Design↗

PubMed1987

A new valving system for removal of laser plume during pelvic CO2 laser endoscopic procedures.

The large volumes of laser plume and char created during carbon dioxide laser endoscopy of the pelvis present a common problem to the gynecologic surgeon. Laser plume not only interferes with the view of the surgical field but also reduces the efficiency of emitted laser energy. A valving system has been designed and clinically tested that allows easy removal of laser-created debris while simultaneously maintaining control of the pneumoperitoneum. The system also removes these gas and liquid products without contaminating the operating room environment or hospital vacuum handling systems.

Disposable Equipment↗

PubMed1985

[8 years' laser surgery of the inferior turbinates in vasomotor rhinopathy in the form of laser strip carbonization].

Between 1976 and 1984 more than 2000 patients with nasal obstruction due to vasomotor rhinitis were treated with the argon laser. The inferior turbinate was treated by laser-strip carbonisation over an area 3 to 5 cm long, 2 mm wide and 1 to 3 mm deep, surrounded by a 2 mm broad coagulation zone. 700 patients were invited to attend follow up and 411 turned up. The observation period was up to 5 years. 80% of the patients obtained a significantly improved or completely free nasal breathing. This result could be improved by 6% by further surgery. Advantages of the laser-strip carbonisation of the inferior turbinate are that it is a bloodless procedure which can be carried out accurately under vision, without nasal packing and it can be performed under local anesthesia without pain. Disadvantages are a longer healing period and temporary crust formation as in conchotomy, the high technical effort and cost of the laser. The end result after laser-strip carbonisation on the inferior turbinates was achieved after 1 1/2 to 2 years.

Humans↗

PubMed1995

Biodegradable self-reinforced polyglycolic acid spiral stent in prevention of postoperative urinary retention after visual laser ablation of the prostate-laser prostatectomy.

PURPOSE: The efficacy and safety of a new biodegradable (self-reinforced polyglycolic acid) spiral stent in securing free voiding despite edema after visual laser ablation of the prostate were studied. MATERIALS AND METHODS: A biodegradable spiral stent was inserted into the prostatic urethra in 22 patients immediately after visual laser ablation of the prostate. Uroflowmetry, measurement of residual urine volume, urine culture, cystoscopy and assessment of symptomatic improvement were done before, and 1, 3 and 6 months after visual laser ablation of the prostate. RESULTS: All 22 patients voided freely on day 1 or 2 after visual laser ablation of the prostate. However, 4 patients later had urinary retention due to a short spiral or too rapid spiral degradation. Half of the patients experienced a transient decrease in flow with some obstructive symptoms at 3 weeks that lasted 1 to 2 weeks. At 4 weeks all spirals were degraded and 3 patients had a positive urine culture. The maximum flow rate increased and the residual urine volume decreased significantly concomitantly with significant symptomatic improvement. CONCLUSIONS: The self-reinforced polyglycolic acid spiral stent can effectively and safely prevent postoperative urinary retention after visual laser ablation of the prostate.

Aged↗

PubMed1994

[Lasers in dentistry with special reference to internal temperature in the pulp cavity using the excimer laser with 248 nm of different frequencies].

The purpose of the present study was to examine the heat building up in the pulp cavity during superficial laser preparation, to examine the tooth surface structure at the area treated by laser and to assess the possible duration of treatment on the basis of the rate of tissue removal. Following laser application, a scanning electron microscopic examination of the tooth surface revealed a smooth structure without cracks or fissures. Although the KrF excimer laser (lambda = 248 nm) proved to be applicable in dentistry with regard to its physical properties, several reasons speak against applying it in clinical practice yet. Treatment, for example, would take too much time as sufficiant enamel may only be removed at a high frequency. Moreover, the question of a possible mutagenicity of the excimer laser with a wave-length of 248 nm has not been answered satisfactorily yet.

Body Temperature Regulation↗

PubMed1996

[Laser use in the uterine cervix. CO2 or KTP laser].

86 patients with cervical neoplasia were treated by conization. The KTP/532-laser was used in 52 cases (group 1) and the conization was performed with a carbon dioxide laser in 34 other cases (group 2). The operation took approximately 30.5 min in the KTP group and 13.5 min in the carbon dioxide group. Complications occurred in 2 cases of the KTP-laser treated patients. In group 2 no complication were observed. The time of hospitalisation was 5 days. The thermal damage of the cut-edge came up to 1 mm (group 1) and 0.1 mm (group 2), respectively. In 4 cases the histological examination was negatively effected by the heat of the KTP laser. In group 2 no affects were observed. The advantage of the KTP-laser is its styptic effect whereas the CO2-laser is better for an histological examination.

Adult↗

PubMed1997

Ablation dynamics in laser sclerostomy Ab externo by means of pulsed lasers in the mid-infrared spectral range.

BACKGROUND AND OBJECTIVE: Sclerostomy ab externo with pulsed laser systems is currently in phase II clinical trials. The authors investigated the ablation dynamics of tissue treated with pulsed laser systems in the mid-infrared range to estimate the extent of thermo-mechanical damage to the sclera and the anterior chamber. MATERIALS AND METHODS: Freshly harvested porcine eyes were used. A bare 400-micron fiber in direct contact with tissue was used for fistulization. Polarization light microscopy, fast-flash photography, as well as optical and acoustic transients were performed for analysis. RESULTS: Substantial mechanical tissue deformation and dissections were found during pulsed laser ablation. The mechanical damage range within tissue far exceeds the pure thermal damage zone. Aspheric cavitation bubbles of up to 3 mm in length penetrate the anterior chamber after perforation. The cavitation demonstrates a significantly larger time constant in tissue than in water. CONCLUSIONS: Early fistula occlusions due to iris adherences may be attributed to iris trauma caused by cavitation. In response to the findings of this study, the authors propose an automatic feedback system to control the ablation process and minimize secondary ocular tissue effects. With respect to the overall damage zones, a new continuous-wave, mid-infrared diode laser system seems to be superior to pulsed laser systems.

Animals↗

PubMed2026

Efficacy and safety of thulium fiber laser versus conventional holmium:YAG laser in anatomical endoscopic enucleation of the prostate: a systematic review and pairwise meta-analysis.

PURPOSE: Anatomical endoscopic enucleation is an established treatment for benign prostatic obstruction. Whether thulium fiber laser enucleation (ThuFLEP) improves outcomes over conventional holmium:YAG laser enucleation (HoLEP) remains uncertain. We compared the efficacy and safety of ThuFLEP versus non-MOSES-modulated HoLEP. METHODS: We performed a PRISMA-compliant systematic review and pairwise meta-analysis of randomised and comparative cohort studies comparing ThuFLEP and conventional HoLEP in adult men. Six databases were searched. Outcomes included International Prostate Symptom Score (IPSS), IPSS quality-of-life score, maximum urinary flow rate (Qmax), post-void residual volume, hospital stay, and complications. Risk of bias and certainty of evidence were assessed with RoB 2/ROBINS-I and GRADE. RESULTS: Seven non-overlapping comparative populations in eight publications included 3,509 patients. ThuFLEP was associated with a small statistically significant reduction in IPSS at 3 months (mean difference [MD] -1.04 points, 95% confidence interval [CI] -1.81 to -0.28) of uncertain clinical relevance. Qmax differences were small and directionally inconsistent across follow-up (favouring HoLEP at 3 months and ThuFLEP at 6 and 12 months) and derived mainly from retrospective cohorts, with neutral randomised subgroups. Stress and urge urinary incontinence were less frequent overall (RR 0.75, 95% CI 0.58 to 0.96, and RR 0.39, 95% CI 0.22 to 0.68), but both estimates depended on one large registry cohort and were not robust to its exclusion. Most other complications and hospital stay showed no clear between-group difference. Limitations include few studies per outcome, heterogeneity, sparse safety events, inconsistent prostate-specific antigen reporting, and mostly low/very low certainty evidence. CONCLUSION: ThuFLEP and conventional HoLEP are clinically comparable with no definitive superiority of either laser. Platform selection should be individualised according to surgeon expertise, institutional resources, and patient characteristics. Future trials should standardise cost-effectiveness outcomes and investigate whether the distinct laser-tissue interactions impact adenoma clearance, PSA reduction, enucleation completeness, and long-term durability.

Humans↗

PubMed1999

Optically Pumped FIR Laser Lines from CH3OH: New Laser Lines, Frequency Measurements, and Assignments.

We report the identification and characterization of eight new FIR laser lines from methanol (CH3OH) in the range 48.4 to 453.7 µm pumped by sequence and hot bands of a cw CO2 laser. Frequency measurements for most of the new FIR laser lines and from previously reported ones were obtained in the range 0.6-6.8 THz with a one-sigma reproducibility of two parts in 10(7). We propose an assignment of energy levels for two of the new laser lines and for five pumped by 10R(46) previously reported. The high frequency lines with absorption centers outside of the tuning range of the CO2 laser pump showed doublets. These were used to evaluate the offsets of the CO2 absorption transitions.

Journal Article↗

PubMed2003

Study of the morphology of a laser-produced aerosol plume by cavity ringdown laser absorption spectroscopy.

Cavity ring-down laser absorption spectroscopy (CRLAS) was applied for the first time to detection and characterization of laser breakdown generated aerosols. The method provided time-resolved morphological information on the aerosol plume, which is of importance in laser ablation (LA) and deposition, in laser-induced breakdown spectroscopy (LIBS) analysis, and in laser ablation inductively coupled plasma (LA-ICP) methods. This method provides sensitive detection of a variety of aerosols produced under ambient conditions. The morphological investigation revealed that the aerosol density has a reproducible pattern as a function of distance from the surface, although its details depend on time, on geometrical parameters and on the surface characteristics.

Journal Article↗