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 685 records · Page 38Linked to original sources
PubMedDate not supplied

Comparison of laser in situ keratomileusis outcomes with the Nidek EC-5000 and Meditec Mel 70 excimer lasers.

PURPOSE: To report refractive outcomes of laser in situ keratomileusis (LASIK) for myopia with and without astigmatism using the Nidek EC-5000 and Meditec Mel 70 excimer laser systems. METHODS: A retrospective analysis of refractive outcomes with each laser was conducted. Approximately 5700 eyes treated for myopia and myopic astigmatism were analyzed. Preoperative sphere ranged from -0.25 to -15.50 D and cylinder ranged from -0.75 to -5.50 D. All statistical analyses were performed by Datagraph med version 2.8 refractive analysis software. RESULTS: With the Nidek EC-5000 at 6 months after LASIK, mean spherical equivalent refraction was -0.24 D with 72% of eyes within +/- 0.50 D. In the Meditec cohort, the mean spherical equivalent was -0.54 D with 55% of eyes +/- 0.50 D. CONCLUSION: Eyes treated for myopia and astigmatism with either of these lasers showed early refractive stability and similar efficacy. Higher incidences of epithelial ingrowth and haze were present in the Meditec treated eyes.

Astigmatism↗
PubMedDate not supplied

Laser in situ keratomileusis for compound myopic astigmatism using the Meditec MEL 70 G-Scan excimer laser.

PURPOSE: To determine the safety, efficacy, predictability, and stability of laser in situ keratomileusis (LASIK) in treating patients with myopic astigmatism using the Meditec MEL 70 G-Scan excimer laser. METHODS: Seventy-four eyes of 42 patients with myopia ranging from -4.50 to -9.88 D and astigmatism ranging from 0.50 to 4.00 D who underwent LASIK with the Meditec MEL 70 G-Scan excimer laser and the Summit Krumeich-Barraquer microkeratome were studied. Patients were followed for 1 year. RESULTS: Mean baseline spherical equivalent refraction was -7.12 +/- 1.70 D and cylinder was 1.62 +/- 1.72 D. At 12 months, mean postoperative spherical equivalent refraction was -0.49 +/- 0.57 D and mean refractive cylinder was 0.59 +/- 0.32 D. Mean change in spherical equivalent refraction between 1 and 12 months after surgery was -0.09 +/- 0.31 D, toward myopia. At baseline, no eyes had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, and 65% had 20/40 or better. At 12 months after surgery, 10% of eyes had BSCVA of 20/20 or better and 88% of eyes had 20/40 or better. The unusually low postoperative BSCVA results were thought to be due to amblyopia or existence of a higher percentage of some optical aberrations in this group of eyes. Mean uncorrected visual acuity was -1.38 +/- 0.42 LogMAR units (20/400) at baseline and -0.29 +/- 0.25 LogMAR units (20/40) at the 12-month postoperative examination. No eyes lost two or more lines of spectacle-corrected visual acuity. No vision threatening complications were observed. CONCLUSIONS: LASIK with the Meditec MEL 70 G-Scan excimer laser appeared to be safe, effective, reasonably predictable, and stable for correction of myopic astigmatism with a spherical component between -4.25 and -8.25 D and a cylindrical component between 0.50 and 4.00 D. However, astigmatism was slightly undercorrected with the algorithm used.

Adult↗
PubMed2003

Imaging and non-contact profile analysis of Nd:YAG laser-irradiated teeth by scanning electron microscopy and confocal laser scanning microscopy.

Two types of non-contact optical profilometers, one performing scanning electron microscopy (SEM) installed with a 3D analyzer and another performing confocal laser scanning microscopy (CLSM) were applied to evaluate imaging and surface profiles simultaneously on enamel and dentin after Nd:YAG laser irradiation. The results were correlated with a stylus profilometer. Surface roughness (Ra) was also measured. Laser was applied perpendicularly to vertical sections of human extracted caries-free molars. Analysis was done on the same spot of the same specimen by both SEM and CLSM for comparison. After irradiation, enamel produced a flake-like surface and dentin resulted in a melted globule surface. SEM and CLSM gave similar surface profiles and different image contrast. The Ra obtained by CLSM was larger than that by SEM. Both SEM and CLSM provided a non-contact evaluation of tooth structural change by laser irradiation through surface analysis in selected micro areas, which was not possible using the stylus profilometer.

Dental Enamel↗
PubMed2002

[Application of a CO₂ laser for oral soft tissue surgery in children in Sri Lanka--introduction of a laser through activities of aid to a developing country].

The objective of this study was to clarify the effect of CO2 laser irradiation on oral tissue problems in children in Sri Lanka, through the activities of aid to a developing country by the Japan International Cooperation Agency. This study took about six months, during two times periods: from November 2000 to February 2001, and from July 2001 to October 2001, in the paedodontic clinic of the Faculty of Dental Science, University of Peradeniya, in Sri Lanka. A CO2 laser was used on 48 subjects (51 cases), aged between 1 and 15 years, having main indications for labial frenectomy, frenectomy in ankyloglossia, and excision of mucocele. The results indicated that the CO2 laser had the following advantages. 1. Soft tissue cutting was efficient, with no bleeding, giving a clear operative field during operation. 2. There was no need to use sutures. 3. The surgery itself was simple and less time-consuming. Hence, there was no need for general anesthesia for such cases as tongue tie operation in small children. 4. There was no postsurgical infection. As a result, there was no need for analgesics or antibiotics, as post-surgical pain and infection were prevented. 5. Wound contraction and scarring were decreased or eliminated. Considering the above advantages, the use of a CO2 laser proved to be very safe and effective for soft tissue surgery, especially for children in developing countries such as Sri Lanka.

Adolescent↗
PubMed1999

Ruby laser irradiation (694 nm) of human skin biopsies: assessment by electron spin resonance spectroscopy of free radical production and oxidative stress during laser depilation.

Human skin biopsies (hair-bearing scalp skin and non-hair-bearing breast skin) were treated with t-butylhydroperoxide, irradiated with UV light (UVR) or irradiated with 694 nm ruby laser red light. Free-radical production and oxidative stress were assessed with electron spin resonance spectroscopy (ESR) using the ascorbate radical as a marker. In comparison with both UVR and t-butyl-hydroperoxide (which readily induce the ascorbate radical in hair-bearing and hairless skin), 694 nm red light does not result in the formation of the ascorbate radical in detectable concentrations. Spin-trapping experiments with the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) showed that while free radicals could be detected after treatment of skin with t-butylhydroperoxide, radicals could not be trapped after laser treatment. Treatment of lasered skin (containing DMPO) with t-butylhydroperoxide produced radical adducts as well as the ascorbate radical, demonstrating that the laser neither depletes endogenous ascorbate nor the preadministered spin trap. It is concluded that 694 nm red light does not induce oxidative stress in human skin in levels comparable either to t-butyl hydroperoxide or UV light.

Cyclic N-Oxides↗
PubMedDate not supplied

One-year follow-up of laser trabeculoplasty using Q-switched frequency-doubled Nd:YAG laser of 523 nm wavelength.

BACKGROUND AND OBJECTIVE: To investigate clinical efficacy and safety of a new laser treatment of open angle glaucoma that targets pigmented cells in the trabecular meshwork for disruption. MATERIALS AND METHODS: The 16 eyes of chronic open angle glaucoma patients were treated in the method similar to argon laser trabeculoplasty using Q-switched, frequency-doubled Nd:YAG laser (523 nm). The treatment results were followed and analyzed for a one-year period. RESULTS: Mean intraocular pressure reduction of 3.81 mm Hg (15%) at 3 months, 3.94 mm Hg (16.1%) at 6 months, and 4.93 mm Hg (20.2%) at 12 months from the baseline were obtained. Slightly greater reductions were seen in the responder group that consisted of eyes showing 3 mm Hg or greater reduction. Adverse reactions were minimal and not significant. CONCLUSION: This new laser trabeculoplasty has shown reasonable efficacy and safety on a limited number of eyes over a one year duration.

Aged↗
PubMedDate not supplied

[Laser extraction of brown cataracts with an Nd-YAG 1.44 mcm laser].

A total of 172 extractions of brown nucleus cataracts with maximum compactness were carried out using a RAKOT complex of devices, developed by the authors for laser extraction of compact nuclei and based on the use of Nd:YAG laser with a wavelength of 1.44 mu. Brown cataract was effectively destroyed at 200-250 mJ and pulse generation frequency 25 Hz within 9-12 min during the first 20 operations and 4-6 min during subsequent 152 operations. Five (2.9%) ruptures of the posterior capsule of the lens were detected. The cornea remained transparent on days 1-2 in 9 of 20 (45%) first operations and in 150 of 152 (98.6%) subsequent operations. A combination of common and heavy viscous elastic was used for the protection of the posterior surface of the cornea. The posterior capsule of the lens was protected by an original silicone thin plate. Loss of corneal epithelium in such a method of nucleus destruction is no more than 2-6%. Intraocular pressure is no higher than 21 mm Hg. If the coefficient of liquid discharge easiness is decreased before the intervention, intraocular pressure can increase during the early postoperative period. High visual acuity (0.7-1.0) was attained in 98% cases in the absence of concomitant retinal diseases. No complications which could be attributed to negative effect of laser on the eye were recorded during the remote period after the operation. The results indicate high efficiency and safety of laser extraction of cataracts.

Cataract Extraction↗
PubMed1992

[Laser microsurgery of meningioma. An analysis of a consecutive series of 164 cases treated surgically by using different lasers].

Over a six years period, 224 laser procedures were performed in our clinic, of these 164 (72%) involved meningiomas of various intracranial and spinal locations; 82 (50%) tumors were located in the posterior fossa, 36 (32%) were suprasellar or parasellar meningiomas: a carbon dioxide laser was used in 56 cases, a double wave length YAG laser in 101 cases, and recently a simultaneous Nd YAG and CO2 combolaser in 7 cases. Complete tumor removal was accomplished in 83% of cases and overall mortality was 3%. We think that microscope guided laser techniques represents a significant advancement in the ability to remove deep situated meningiomas that might prove difficult to extirpate by conventional microsurgery. The advantages of these methods include: 1. reduced brain retraction; 2. the ability to operate with smaller and different exposures; 3. a reduced amount of mechanical manipulation by vaporizing in first the dural attachment; 4. improved operative precision and 5. decreased intra operative blood loss.

Adult↗
PubMed1992

Determination of an appropriate laser setting for THC-YAG laser sclerostomy ab externo in rabbits.

To determine an appropriate setting for the THC-YAG laser (chromium-sensitized, thulium, and holmiumdoped YAG laser), we performed sclerostomy ab externo on 24 pigmented rabbits. The laser energy was delivered via a subconjunctivally-inserted fiberoptic probe that was placed at the limbus through a small conjunctival incision. We used four pulse-energy levels to perform the sclerostomies: 80 mJ, 120 mJ, 160 mJ, and 200 mJ. At all these levels, a new outflow pathway was easily created, a filtering bleb was formed, and intraocular pressure (IOP) was immediately reduced. Severe tissue damage around the sclerostomy site occurred with the 160-millijoule and 200-millijoule pulses. The 80-millijoule pulse created a relatively small patent sclerostomy, providing only relatively brief IOP reduction. We conclude that 120-millijoule is the most appropriate laser-pulse energy for use in pigmented rabbits.

Animals↗
PubMed2005

Laser-assisted outpatient septoplasty and laser-assisted uvulopalatoplasty for nasal obstruction and snoring.

OBJECTIVE: Nasal obstruction always occurs when the nasal passages are narrowed by a hypertrophic turbinate or a deviated nasal septum. Patients with nasal obstruction often have associated snoring. Laser-assisted outpatient septoplasty (LAOS) has a specific clinical application in chronic nasal obstruction due to moderate anterior septal deviation. Significant improvement has been reported in the measures of nasal obstruction following LAOS. The purpose of the present study was to evaluate the safety and efficacy of LAOS as an adjunctive procedure for snoring resulting from nasal obstruction. MATERIAL AND METHOD: Thirty-five patients with septal deviation and bothersome snoring were enrolled. Patients underwent a polysomnography study to rule out significant obstructive sleep apnea. Ablation of the nasal septum was undertaken with a carbon dioxide laser. No nasal packing was required. LAOS procedures were performed in conjunction with other snoring procedures (laser-assisted uvulopalatoplasty or laser turbinectomy) on an outpatient basis under local anesthesia. Data on the patients were compared from the preoperative to the postoperative assessment. Statistics used were determined by the Student's paired t test. RESULTS: All patients tolerated the procedure well. The additional surgical time needed to perform this procedure averaged 10 minutes. The mean nasal obstruction scale improved from 6.2 + 3.2 to 1.6 + 0.8 (p < 0.01) and the mean total nasal resistance decreased significantly after operation. Significant improvement was observed in the snoring scale (8.8 + 2.2 vs 2.8 + 1.7, p < 0. 05). No significant complications were noted. There were 2 cases of minor bleeding, which were easily treated. Postoperative pain was rated as minimal (VAS < 4). Follow-up of 4 to 6 months showed overall improvement of nasal obstruction and snoring symptoms in more than 90% of the patients. CONCLUSION: LAOS is a simple and well-tolerated treatment for deviated nasal septum. It appears to be a safe and effective adjunct surgical procedure for snorer with nasal obstruction on an outpatient basis.

Adult↗
PubMed2006

Laser-tissue interaction in endovenous laser treatment.

The authors present the results of recorded changes in the endothelium in rabbit's veins following photocoagulation by laser diode. This study concentrates mainly on the detailed description of individual changes in the rabbit's venous system in the area of pelvis following laser therapy. The aim of our experiments was to reach the obliteration of rabbits' lateral saphenous vein using 980 nm laser diode with 200 micron fibre. The intensity of discharge was 3, 5, 6 and 7 watts. We examined the relationship between changes and the amount of joules that affect the endothelium of the rabbit's veins. The operation was conducted under general anaesthesia. All animals survived treatment and were returned to breeders. Within the time span of one, three, six and eight weeks the laser treated veins were removed. They were fixed in formaldehyde and sent for microscopic examination. We were interested in how long it will take for fibrous changes to occur in the endothelium of the vein and thus also the subsequent occlusion of the vein depending on the amount of joules applied per one centimetre of the vein (Tab. 1, Fig. 4, Ref 6).

Animals↗
PubMed1991

CO2 laser used through the operating channel of laser laparoscopes: in vitro study of power and power density losses.

The purpose of this study was to measure the effects of several variables on energy transmission and power density through the CO2 laser laparoscope. The factors studied included the laser beam diameter, coupler optics, laparoscope lumen size, and absorption of the laser wavelength by the insufflation gas. The addition of CO2 insufflating gas to the operating channel at higher power settings not only reduced the energy transmitted to tissue by 35-58% with a 7.2-mm laparoscopic operating channel and by as much as 61% with a 5-mm operating channel, but also increased the spot size. This "blooming" of the laser beam definitely reduced power density at tissue and eliminated the pinpoint spot size needed for microdissection. Even under optimal conditions regarding lumen size and beam diameter, our data indicate a point of diminishing returns for power density above 40 W for the systems tested. Power densities obtainable at laparotomy were not possible. Clinically, this effect resulted in optimal cutting (vaporization) at low power settings and coagulation accompanying cutting at higher settings.

Carbon Dioxide↗
PubMed1990

[Thermal effects in the dental pulp caused by laser radiation from various laser types].

In this in vitro study the temperature rises occurring in the dental pulp during laser irradiation were measured. Infrared laser radiation (CO2 and Nd: YAG) had great thermal effects on the pulp tissues. At an average power output level of 5 W temperature rises of approx. 40 degrees C within 100 s were observed. The effect of a cooling system was negligible. Radiation from an ArF excimer laser (193 nm) at an average output of 5 W caused only slight thermal changes, when an airstream was used to remove the fragments of photoablative decomposition of the dental tissues. The temperature in the pulp chamber increased by approx. 5 degrees C after 6 min. This result leads to the conclusion that only ArF excimer lasers may be effectively used in the mouth without producing inacceptable thermal effects in the dental pulp.

Dental Pulp↗
PubMedDate not supplied

[Effect of absorption of laser radiation on the destruction threshold of pathologic tissue in laser angioplasty].

With laser angioplasty the hemoglobin absorbtion effect on the demolishing of the pathological objects was taken into consideration. It was stated that this effect is high for argon lasers (lambda = 0.488 = 0.514 microns) and insignificant for solid state laser (lambda = 1.064 microns). In this respect growth of laser capacity practically is not increasing the efficiency of the pathological objects destruction at a distance not more than 1 mm from the out-put of the light-guide.

Angioplasty, Balloon↗
PubMed1989

[Contribution of the argon laser in iridotomy using the Yag laser].

Yag laser iridotomy was performed immediately after argon laser application in 59 eyes with chronic angle closure glaucoma, occludable angle and secondary glaucoma. Postoperative intraocular pressure was elevated temporarily more than 5 mmHg on 86.4% of patients. Iris haemorrhages occurred in 17% of cases when laser Yag iridotomy was carried out with a power of 4 to 6 mJ. Prior argon laser seemed to prevent iris haemorrhages.

Adult↗
PubMed1989

Applications of combination wavelength (1060-nm and 530-nm) and pulsed Nd:YAG laser for contact laser surgery.

Two pulsed neodimium yittrium aluminum garnet (Nd:YAG) laser systems were evaluated for contact surgery through a fiberoptic system with a sapphire tip. Pulsed Nd:YAG laser at 1060 nm was as effective as continuous-wave Nd:YAG laser in producing tissue incisions. A combination of 1060-nm and 530-nm wavelengths achieved smooth cutting at lower energy levels. Corneal endothelial cell damage occurred at the high power level (7 watts) required for smooth underwater incisions with both continuous wave and pulsed lasers.

Animals↗
PubMed1987

[Stabilization of the laser on the target. Scanning photocoagulator: the SLC (scanning laser coagulator)].

When lasers are used to cause burns on the retina they necessitate systems of great precision especially in the posterior pole. Different possibilities are now offered. The best one is based on the intensification of the same laser beam used for the observation in the Scanning Laser Ophthalmoscope: S.L.O. when it is at a point selected from the angiogram, converting this machine into a Scanning Laser Coagulator: S.L.C.

Fluorescein Angiography↗