Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Lasers”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed1992

Comparison of laser trabeculostimulation with laser trabeculoplasty in open-angle glaucoma.

We compared a new method, laser trabeculostimulation (LTS), with laser trabeculoplasty (LTP). The technique LTS stimulates trabecular meshwork tissue and thereby increases the outflow facility. The method LTP causes shrinkage and cicatrization of the meshwork tissue, thus limiting the reduction in postoperative intraocular pressure (IOP). The mean preoperative IOP of 40 eyes was 24.9 +/- 6.8 mmHg (mean +/- standard deviation). The LTS was applied with a 50-microns spot size, a power setting of 50mW, and an exposure time of 1 sec. With LTS, the IOP decreased and then increased afterward. Low power (50mW) was effective if used for a longer duration. The LTS can be applied repeatedly and used in addition to conventional LTP. The overall effect achieved with LTS was less than that with LTP, but it is possible to reduce IOP by selecting more reasonable parameters, e.g., a laser setting of 200mW, a 50 microns spot size and a 0.5 to 1-sec duration.

Adult↗
PubMed2004

[Effect of laser irradiation power on the mechanical properties of Co-Cr and Ni-Cr laser-welded joints.].

PURPOSE: To investigate the effect of different irradiation power on the mechanical properties of laser-welded joints. METHODS: The standard tensile test and three-point bending test rods made from Co-Cr and Ni-Cr alloy were laser-welded with different irradiation powers. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis and microhardness test were also performed on polished longitudinal sectioned samples. RESULTS: For Co-Cr alloy, greater irradiation power resulted in greater UTS, minor UBS. For Ni-Cr alloy, there was no significant difference of UTS and UBS between the four groups. SEM and metallurgical examination showed that the welded zone exhibited more gas pores and cracks as the irradiation power increased. Microhardness test showed that hardness increased toward the center of the welded zone and as the irradiation power increased, the range of hardness increased was expanded. CONCLUSION: The optimal laser irradiation power was the key to achieved superior mechanical properties joints.

Chromium Alloys↗
PubMed1992

Corneal laser photocoagulation for treatment of neovascularization. Efficacy of 577 nm yellow dye laser.

The authors treated corneal neovascularization in 25 eyes of 23 patients with corneal laser photocoagulation using 577 nm yellow light. Four groups of patients were treated: patients with corneal neovascularization and active graft rejection (group 1); patients with neovascularization before penetrating keratoplasty (PK) (group 2); lipid keratopathy patients with opacification and/or focal edema threatening the visual axis (group 3); and patients with extensive corneal neovascularization, who were not candidates for PK (group 4). Area of neovascularization and clinical outcome were monitored. After corneal laser photocoagulation, there was a statistically significant reduction in the neovascularized area in group 1 from 32% of corneal area to 10%, and in group 3 from 46% to 27%. All five patients in group 1 had resolution of their graft rejection. In group 3, there was a reduction in the area of corneal opacification from 59% of corneal area to 52%. This difference was not statistically significant. Seven of nine patients in group 3 had stabilization or improvement in their vision over a mean of 9.3 months follow-up. There was no significant change in neovascularized area in groups 2 and 4. In group 2, no rejection reactions occurred over a mean of 5.6 months follow-up after PK. In group 4, corneal laser photocoagulation was disappointing.

Corneal Diseases↗
PubMedDate not supplied

Scanning laser polarimetry and retinal thickness analysis before and after laser in situ keratomileusis.

PURPOSE: To evaluate changes in retinal nerve fiber layer (RNFL) thickness after laser in situ keratomileusis (LASIK) using a scanning laser polarimeter with fixed corneal compensation (GDx) and the retinal thickness analyzer (RTA). METHODS: Thirty-eight eyes of 19 healthy subjects (10 female and 9 male; mean age 37.0-/+8.8 years) underwent GDx and RTA measurements before and after LASIK. All subjects revealed mild to high myopia (mean spherical refraction: -4.0-/+2.75 D). Measurements using GDx were followed by RTA measurements after pupil dilation. All measurements were performed the day before LASIK and 1 week postoperatively. RESULTS: GDx revealed a decrease in nerve fiber layer thickness measurements after LASIK, but did not reach statistical significance (p>0.05). Using RTA, mean RNFL thickness (MRNFL) and RNFL cross sectional area decreased significantly after LASIK (p=0.03 and p=0.02, respectively). CONCLUSIONS: Scanning laser polarimetry revealed a slight decrease in RNFL thickness measurements after LASIK. MRNFL and RNFL cross section were significantly lower after LASIK using RTA. The changes might be artifacts in a small group of myopic subjects.

Adult↗
PubMed2005

[Free versus non-free treatments with laser and intense pulsed light in dermatology: distinguishing medical laser treatments to be provided free of charge from cosmetic self-payment treatments].

Lasers and light sources are increasingly used in dermatology. Due to the limited financial resources of the public health care system, the Danish Dermatological Society has developed recommendations for distinguishing medical laser treatments to be provided free of charge from cosmetic self-payment treatments. Several considerations underlie the recommendations: present legislation; the diagnosis, etiology, severity, and anatomical location of the disease; and the availability of evidence-based treatments. It is suggested that the recommendations constitute the basis for referring patients to dermatological treatment involving laser and intense pulsed light in Denmark.

Cosmetic Techniques↗
PubMedDate not supplied

A new translaparoscopic approach in endometriosis treatment: a. CO2 laser endometriosis excision and/or vaporization. b. CO2 laser uterine nerve ablation. c. Uterine suspension with Falope Rings. d. Intraperitoneally 32% Dextran-70 installation.

During a period of 18 months with a history of chronic pelvic pain symptomatology (severe dysmenorrhea, severe dyspareunia, extramenstrual pain) retroverted or retroflexed uterus, and infertility were subjected to laparoscopy for diagnostic and therapeutic purposes as well. These women were able to follow up this protocol. After informed consent had been presented patient decided, in a case of endometriosis being verified by the tissue pathology intraoperatively, which one mode of therapy (Group I or Group II) would be administered in her case. All women failed to respond to non-steroidal, antiinflammatory medication, as well as to oral contraceptive treatment. Proposed intraoperative staging of pelvic endometriosis that has not yet been published, was utilized by the author. Group I twenty women were subjected to a translaparoscopic CO2 laser excision and (or vaporization of endometriosis implants, CO2 laser uterine nerve ablation, uterine suspension with Falope Rings and intraperitoneally 32% Dextran was installed. Group II twenty women were subjected only to a translaparoscopic CO2 laser endometriosis excision and/or vaporization and intraperitoneally 32% Dextran-70 was installed. In Group I extramenstrually pain was 90%, severe dysmenorrhea 85%, and infertility 90% were cured. Ten per cent of extramenstrual pain, 5% of severe dysmenorrhea, and 15% of severe dyspareunia were improved. Infertility in this group was unchanged in 10%. Patients' symptoms were not worsened during the 18 months of observation. In Group II only 60% infertility was curred. In 60% extramenstrual pain, in 35% severe dysmenorrhea, in 5% severe dyspareunia were improved. Symptoms were noted to worsen in 5% extramenstrual pain, in 5% severe dysmenorrhea, in 10% severe dyspareunia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Laser in periodontology: theoretical-experimental approach. 3. Experimental study of the effects of He-Ne (638 nm) and infrared diodic (904 nm) lasers on the gingival mucosa of rats].

Medical and surgical laser-therapy is becoming more and more important in various branches of Medicine, however independently from clinical results still very little is known about physical-biological interaction between laser beam and living matter. The aim of this study is of finding tissutal and cellular effects of stimulation with soft and mid laser. The study started from an original work carried out at the Institute of Biology of the 1st Faculty of Medicine and Surgery of Naples University from which appears the possibility of visualizing the stage of nuclear active synthesis of the cell, simply by Maloory tricromic colouring. By this method the cellular nucleuses take, usually, a red colour, however in presence of an increase of the RNA nuclear synthesis the nucleuses take a typical blue colour. The importance of the study induced us to research the presence in the oral mucose of the rat after radiation as an effect of biostimulation. The results of this study showed and increase of the epithelial cheratine and a variation of the disposition and of the number of the precheratine grains in treated site. The blue nucleuses have been found at the basal level without any difference between treated and control site. On the other hand their presence is the normal consequence of the epithelial evolution which starts from the basal level which is the most active in the stage of nuclear synthesis.

Animals↗
PubMed1990

High-speed photography of Er: YAG laser ablation in fluid. Implication for laser vitreous surgery.

The mechanism of Er:YAG laser-induced long-range damage in intraocular surgery was investigated using high-speed photography. A short pulse of 2.94-microns radiation delivered by an optical fiber into an aqueous medium causes rapid localized heating and vaporization and creates a bubble at the tip of the fiber. The size of the bubble depends on the pulse energy and is about 1 mm at 1 mJ. The shape of the bubble has multiple lobes, which can be attributed to the spiky output of the laser pulse. The expanding bubble can cause thermal and mechanical damage to tissues. In addition, laser spikes propagating through the bubble can strike and damage tissue on the distal side of the bubble. In both mechanisms the damage zone approximates the bubble size and can be greater than 1 mm, ie, 1000 times the steady-state absorption length of water at 2.94 microns. The authors discuss ways to reduce the damage zone by bubble confinement.

Hot Temperature↗
PubMed1989

Laser vaporization versus laser excision conization in the treatment of cervical intraepithelial neoplasia.

One hundred patients with histologically confirmed cervical intraepithelial neoplasia suitable for ablative therapy were randomly allocated to treatment by either laser vaporization or laser excision conization under local anesthesia in the outpatient colposcopy clinic. The two methods were compared with respect to the immediate surgical complications, ease of performance, and long-term complications. They were comparable in most respects, and both were well accepted by the patients. Laser excision had the added advantage of providing further material for histologic examination to confirm the absence of invasion and the completeness of excision of the lesion.

Adolescent↗
PubMed1988

[Conservative treatment of grade 3 intra-epithelial cervical neoplasms. Comparative study of CO2 laser vaporization, laser conization and cold scalpel conization].

Carbon dioxide laser was used in 79% of the 141 conservative treatments carried out for grade 3 cervical intra-epithelial neoplasia (CIN III) between the years 1982 and 1986 (41% vaporized and 38% coned out by using the laser as against 21% that were treated by scalpel conisation. The mean age of the women treated in this way by the laser was low (28.5 years of age and 32.5 years as against 38.1). Their parity was also low (0.8 and 1.2 as against 2.2). The lesions were very often spread out on the ectocervix and sometimes going into the vagina (26 and 9% as against 26%) or associated with koilocytosis (65.5 and 47.2% as against 41.3%). In one out of two cases vaporisation of the lesion is contra-indicated and the three diagnostic methods that are used (an ecto and endocervical smear, colposcopy and multiple directed small biopsies) do not make it certain that there is no underlying invasion of the tissues. Vaporisation and conisation are easily carried out under colposcopic control and are associated with widespread lesions at the squamo-columnar junction. These treatments sometimes have to be repeated; then they give a cure rate of 92-96% as against 96%. They are more reliable than conventional surgery for widespread lesions and they do make it possible to keep to the morphology of the cervix and thus make it possible for the cervix that is treated to behave more physiologically. It is also much easier and more reliable in these cases to carry out follow-up for carcinoma. This follow-up should be carried out on two occasions. The triple diagnostic method should be carried out again at the third month (2 smears, colposcopy and colposcopically directed small biopsies). This makes it possible to diagnose and treat early the cases where there has been failure of the original treatment. Then ecto and endocervical smears should be repeated at 3-monthly intervals, then at 6-monthly intervals and finally annually to screen for recurrences of these neoplastic conditions, and for koilocytosis which sometimes repeat themselves in an extensive manner.

Adult↗
PubMedDate not supplied

[Current possibilities and prospects of using gas lasers in medicine. Laser therapy].

Local laser radiation of human organism for therapeutical purposes can be looked upon as an efficient and controlled method of normalization of functioning of a number of organs. Laser units designed on the basis of industrial gas lasers are used on a large scale for treatment of vascular diseases and related ischemias in various parts of the human body.

Humans↗
PubMed1986

[Laser angioplasty: effect of laser energy on human coronary arteries].

An experimental study of rationed action of laser emission energy (LEE) on human coronary arteries (autopsy specimens) identified major aspects of LEE interaction with biological tissues of atherosclerotically-affected vessels under "dry" and "wet" conditions. An impulse laser with a 1.06 micron wave-length was used as the LEE source. The results suggest that controlled LEE action on atherosclerotically-affected vessels for recanalization purposes (laser angioplasty) may prove a promising approach to the treatment of cardiovascular occlusions.

Adult↗
PubMed1979

CO2 laser in vitreoretinal surgery: 1. Quantitative investigation of the effects of CO2 laser radiation on ocular tissue.

Scleral, lens, and vitreoretinal tissue was incised using CO2 laser radiation in a controlled and predictable fashion without producing untoward effects on neighboring ocular tissue. The penetration depth of infrared radiation into normal human vitreous was measured and was found to be exceedingly small. A quantitative correlation was observed between the CO2 laser power and the depth of penetration in scleral-chorio-retinal wall incisions and in lens tissue from human eyebank eyes. The results of this investigation suggest that the CO2 laser may be useful in intravitreal surgery, full-thickness scleral-chorio-retinal wall resections, transvitreal chorioretinal biopsy, and even dissolution of cataracts.

Animals↗
PubMed1994

[The CO2 laser in ophthalmology. II. Use of the CO2 laser in facial skin disorders].

The authors present an account on results of CO2 laser therapy in facial skin and conjunctival affections during the period between 1990 and 1993. In the evaluated group, comprising 60 patients with an observation period of 18 months, this method was used 82 times, incl. four where it was used repeatedly. In the technique of the procedure simple vaporization markedly predominates over combined operations or laser incisions (continual regime). The defect after vaporization heals by tissue which has the same colour as surrounding skin, in a very small minority with slight local depigmentation without a tendency of major scarring and with a satisfactory cosmetic effect. The authors discuss indications of CO2 lasers in ophthalmology. The method is recommended in strictly defined affections of the skin and conjunctivae.

Adolescent↗
PubMed1994

[Laser coagulation treatment of urothelial tumors of the upper urogenital tract with the Nd:-YAG laser].

Six patients with upper urinary tract tumors were treated in our department with the Nd:-YAG laser between 1989 and 1993. The average follow-up was 23.8 months. The mean age of the patients was 65.7 years. The patients were selected for organ-conserving treatment because of bilateral synchronous tumors (2 cases), a solitary renal unit (2 cases), renal insufficiency with high surgical risk (1 case) and high surgical risk alone (1 case). Two patients were treated with open tumor excision and laser, two patients with ureteroscopic and percutaneous procedures one patient with percutaneous treatment and one patient with ureteroscopy. Two patients underwent nephroureterectomy; one of them died of metastatic bladder cancer 9 months later. Local relapses were observed in one patient who had been treated endoscopically. In a follow-up period of 6-36 months there were three patients who had no relapses. Three patients received intracavitary therapy. Kidney conserving procedures with the Nd:-YAG laser in patients with upper urinary tract tumors should be reserved for highly selected cases.

Aged↗
PubMed1994

[An experimental study of diode laser photocoagulation and indocyanine green dye-enhanced diode laser photocoagulation in the primate retina].

A diode laser, emitting light in the near-infrared range (803 nm), was used for photocoagulation at mild, moderate, and strong intensities with or without intravenous administration of indocyanine green (ICG) in 7 eyes of 4 rhesus monkeys. The retinochoroidal lesions were studied histopathologically from 24 hours to 3 months after treatment, and choroidal vascular casts were studied by electron microscopy. Mild diode laser burns caused occlusion of the choriocapillaris and slight outer retinal damage. Moderate and severe burns caused more marked occlusion of the choriocapillaris, deep choroidal vessels, and choroidal nerves. There was little difference between ICG-enhanced and non-enhanced mild burns, but ICG-enhanced moderate and severe burns showed larger retinochoroidal lesions and more complete obstruction of the choriocapillaris than did burns without ICG enhancement. It seems that at moderate and strong levels, ICG-enhanced diode laser burns have more apparent effect on the retina and choroid, particularly on the choroidal vessels.

Animals↗
PubMed1994

Laser sclerostomy ab externo using the erbium: YAG laser. First results of a clinical study.

A new approach to fistulating glaucoma surgery, laser sclerostomy ab externo, was investigated in a clinical study. A pulsed (200 microseconds) erbium-YAG laser was used, as its wavelength (2940 nm) is very well absorbed by tissue water. The laser energy was transmitted via a fiber to an application probe with a cannula particularly designed to guide another fiber into the subconjunctival space. Nine patients with advanced open-angle or neovascular glaucoma were treated. In all cases a functioning fistula with a prominent filtering bleb and a reduction of the intraocular pressure (from up to 50 mmHg to 8-18 mmHg) could be achieved. The total energy was 60 mJ on average. No complication occurred intraoperatively. Postoperatively, all fistulas in patients with neovascular glaucoma (n = 6) were impatent after approx. 7 days due to iris adherence to the internal ostium and episcleral scarring. In cases of open-angle glaucoma (n = 3) a patent fistula persisted for several months. Variation of the exposure parameters, the use of antiproliferative drugs, and a less restrictive selection of patients could further improve the success rate.

Fiber Optic Technology↗