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At least 757 records · Page 42Linked to original sources
PubMed1998

Influence of decay of laser fibers during laser prostatectomy on clinical results.

Three types of sidefiring laser fibers (34 Urolase, 20 Ultraline, and 114 Prolase II) were visually inspected after a laser prostatectomy, and transmission measurements were performed using a power meter (Aquarius). The results were correlated with the clinical outcome. Despite differences in the amount of loss in transmission for the fibers used, we could not establish any significant effect on clinical outcome measures, such as improvement in maximal flow rate or symptom score. The visual aspect of the Urolase fibers was significantly related to the amount of transmission loss, whereas no such relation was found for the other two types of fibers. Prostate size and the total amount of energy delivered by the laser source also did not correlate with the clinical outcome. To determine the relation between the energy absorbed by the prostate and clinical outcome, a large number of patients must be evaluated, and any factor that can be controlled needs to be monitored. For the latter, the power meter as presented here is a useful complementary tool.

Diuresis↗
PubMed1988

Biostimulation of human carcinoma cells with the argon laser: a previously unreported potential iatrogenic effect of lasers.

The human squamous carcinoma cell line P3 was subjected to treatment with a single mode argon laser at 514.5 nm. The temperature and energy levels delivered to the target cells were determined by a reproducible method of dosimetry. At energy levels between 860 to 990 J/cm2 and a corresponding temperature of 39 +/- 1 degrees C, a significant delayed stimulation in DNA synthesis was noted after 24 hours, but the cells remained viable. However, at energy levels and temperatures higher or equal to 1100 J/cm2 (41 degrees C), an immediate suppression of DNA synthesis was accompanied by nonviability of the P3 carcinoma cells. These results indicate that the argon laser has potential for selective biostimulation on carcinoma cell duplication at the specific "non-thermal" range of 39 +/- 1 degrees C. Similar effects were not observed when the P3 carcinoma cells were heated to this same temperature using a standard heat bath. This phenomenon appears to represent a previously undescribed potential iatrogenic effect of the monochromatic laser beam in the treatment of cancer.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less using the Nidek EC-5000 laser.

PURPOSE: We compared the efficacy, predictability, and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the surgical correction of low and moderate myopia. METHODS: A retrospective study was performed to evaluate uncorrected and spectacle-corrected visual acuity, and manifest refraction 1 year after PRK or LASIK. All procedures were done using an automatic microkeratome (Chiron Ophthalmic) and the Nidek EC-5000 excimer laser. RESULTS: PRK was performed in 75 eyes of 45 patients and LASIK in 133 eyes of 77 patients. Mean age for PRK patients was 32.8 years (range, 18 to 52 yr) and LASIK patients was 29.6 years (range, 18 to 49 yr). Mean preoperative spherical equivalent refraction for PRK patients was -3.28 D (range, -1.00 to -6.00 D) and LASIK, -3.86 D (range, -1.00 to -6.00 D). One year after surgery, mean spherical equivalent refraction for Group 1 (baseline, -1.00 to -3.00 D) PRK eyes was -0.18 +/- 0.61 D (range, -1.50 to +0.75 D) and for LASIK eyes, -0.08 +/- 0.61 D (range, -1.50 to +1.62 D), with no statistically significant difference. For Group 2 eyes (baseline, -3.25 to -6.00 D), mean spherical equivalent refraction for PRK eyes was -0.44 +/- 0.87 D (range, -2.00 to +2.12 D) and for LASIK eyes, -0.09 +/- 0.83 D (range, -1.50 to +1.75 D), with no statistically significant difference. The antilogarithm of the mean UCVA (antilogUCVA) in Group 1 for PRK was 0.79 +/- 0.21 (20/25) and for LASIK was 0.87 +/- 0.19 (20/23), with no statistically significant difference. The antilogUCVA in Group 2 for PRK eyes was 0.70 +/- 0.24 (20/28) and for LASIK eyes was 0.83 +/- 0.18 (20/24), with a statistically significant difference (0.7 vs. 0.83, P < .005). The percentage of eyes with a postoperative UCVA >20/40 in Group 1 for PRK was 91.5% (38 eyes) and for LASIK was 95% (50 eyes) (no statistically significant difference), and in Group 2 for PRK eyes, it was 82% (27 eyes) and 97.5% (78 eyes) for LASIK (statistically significant difference, P < .05). CONCLUSION: PRK and LASIK with the Nidek EC-5000 excimer laser are effective and safe for correcting low to moderate myopia, but LASIK eyes showed better results for moderate myopia in terms of uncorrected visual acuity.

Adolescent↗
PubMedDate not supplied

Laser in situ keratomileusus for mixed and simple myopic astigmatism with the Nidek EC-5000 Laser.

PURPOSE: To evaluate the visual and refractive results of laser in situ keratomileusis (LASIK) for mixed and simple myopic astigmatism using bitoric ablation. METHODS: A retrospective study was performed in 65 eyes of 38 consecutive patients to evaluate uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA) and cyclopegic and manifest refraction, before and 3 and 6 months after LASIK (Moria LSK-ONE microkeratome, Nidek EC-5000 excimer laser). RESULTS: At 3 and 6 months after LASIK, 40 eyes of 24 patients (64.5%) were available for follow-up examination. Mean age was 25.9 +/- 6.6 years (range 18 to 43 yr). Mean preoperative manifest spherical equivalent refraction was -1.40 +/- 0.80 D (range -3.80 to +0.50 D) mean preoperative cylinder was -3.30 +/- 1.30 D (range -1.00 to -6.00 D). At 6 months follow-up, mean manifest spherical equivalent refraction was +0.30 +/- 0.46 D (range -0.38 to +1.88 D), mean cylinder was -0.73 +/- 0.61 D (range -2.25 to 0 D). There was a 77.8% decrease in astigmatism magnitude. According to vector analysis, mean achieved vector magnitude was 80% of intended. Fifty percent (20 eyes) had a cylinder within +/- 0.50 D of emmetropia. Twenty-three eyes (57.5%) had a spherical component within +/- 0.50 D. Eighty-five percent (34 eyes) had postoperative UCVA of 20/40 or better. Ten percent (four eyes) lost two lines of Snellen BSCVA, whereas 35% (14 eyes) gained one or more lines. CONCLUSIONS: Bitoric LASIK with the Moria LSK-ONE microkeratome and Nidek EC-5000 excimer laser was effective and safe for the reduction of cylinder in mixed and simple myopic astigmatism. Moderate undercorrection of the cylinder was evident.

Adolescent↗
PubMedDate not supplied

Prophylactic laser photocoagulation for retinal breaks before laser in situ keratomileusis.

PURPOSE: To determine the efficacy and safety of prophylactic laser photocoagulation for retinal breaks in myopic patients undergoing laser in situ keratomileusis (LASIK). METHODS: Between August 1998 and August 2002, a total of 1931 eyes in 1006 patients requesting LASIK received a fundus examination with indirect ophthalmoscopy before surgery. For analysis, patients were divided into two groups according to the presence or absence of retinal breaks. All patients with retinal breaks underwent prophylactic laser photocoagulation to seal the breaks, even though they were asymptomatic. RESULTS: Patient age ranged from 18 to 68 years (30.8 +/- 7.4 yr). Mean preoperative spherical equivalent refraction was -7.55 +/- 3.72 D (range -1.87 to -34.50 D). Retinal breaks were identified and treated in 39 eyes (2.02%) of 32 patients (3.2%); 1892 eyes of 974 patients had no retinal breaks. No statistically significant difference was found in age (P=.87) or gender (P=.91) between the two groups. However, a significantly higher preoperative spherical equivalent refraction was noted in patients with retinal breaks (-9.41 +/- 4.15 D) compared with those without (-7.52 +/- 3.71 D) (P=.017). During a mean 19-month follow-up, none of the patients developed retinal detachment except for one in a patient without retinal breaks who sustained ocular trauma 19 months after LASIK. This patient was treated with scleral buckle and the retina was attached after surgery. CONCLUSIONS: Retinal breaks were identified and treated by photocoagulation in 2% of 1931 eyes before LASIK for myopia.

Adolescent↗
PubMed1992

Evaluation of port wine stain perfusion by laser Doppler imaging and thermography before and after argon laser treatment.

Thirteen patients with port wine stains (PWS) were treated with argon laser therapy. Before and at different points in time following treatment, skin blood perfusion and temperature were mapped with laser Doppler imaging and thermography. In nine patients no elevation in blood perfusion was observed in the PWS in comparison with the surrounding normal skin before treatment. In the remaining four patients a significantly (p less than 0.01) higher blood flow was recorded within the PWS. Immediately after treatment nine patients showed elevated perfusion within the PWS. During the first two days following treatment, all patients showed a gradually decreasing hyperperfusion in the borderline between the PWS lesion and surrounding skin. Immediately after treatment 10 patients had a significantly (p less than 0.01) higher temperature in the PWS than in normal skin. During the first 24 h following treatment, an elevated perfusion was in general accompanied by a tissue temperature increase. Three and a half months after argon laser treatment, three patients showed excellent clinical results with no remaining PWS spots or scarring. Two of these patients had had both elevated perfusion and temperature in the PWS prior to treatment.

Adolescent↗
PubMed1990

Laser lithotripsy of ureteral calculi: initial experience with a new pulsed dye laser.

Thirty-two patients with ureteral calculi ranging in size from 5 x 5 to 12 x 18 mm underwent lithotripsy with a new pulsed dye laser (Pulsolith, TMI). In 24 cases, the patients were entirely free of stones following laser lithotripsy alone, or with adjunctive stone basket removal. There were three instances of equipment failure and five calcium oxalate monohydrate stones that did not respond to laser energy.

Calcium Oxalate↗
PubMed1976

[Laser-treatment of the anterior segment of the eye with the new glaucoma research laser (author's transl)].

The possibilities for treatment of the anterior segment of the eye with the new glaucoma research laser, model 152, constructed by Britt-Corp. are reported on, along with the possibilities of vasodesolation, pupilplastics, iridontomies and iridectomies. Especially mentioned is the technic and possibility of laser-trabeculopuncture. This laser archieves remarkable success also in open-angle glaucoma and closed-angle glaucoma provided the technic is suitable. It is shown that all operations can be carried out by an ambulant patients and practicly without any complications. There are no problems during the aftertreatment for the doctor or for the patient.

Anterior Chamber↗
PubMed2002

[Lasers in dentistry 6. The soft laser].

A soft laser is a low-power laser emitting in the red and near-infrared part of the spectrum. Studies with cell cultures have shown that radiation from a soft laser, when used under proper conditions, promotes cell function and cell proliferation. However, wavelength and dose should be carefully adjusted to an optimum value: too low a dose does not work and neither does a high dose. The dose should be adjusted within an interval of about 10%. In a few animal studies a positive effect on wound healing has been demonstrated, although other studies did not show such an effect. Of the human studies done in the dental field, many do not meet scientific standards because there was no control group or the study was not double-blind. A few studies showed a positive effect but most did not. Perhaps the large variation in results may be explained by the required accuracy of adjustment of the dose, combined with the complicated processes that relate the incident dose to the dose to cells lying on or in tissue. More research, in particular studies in which the dose and wave length are varied systematically, are needed before responsible clinical use can be recommended.

Animals↗
PubMed1986

Q-switched neodymium-YAG laser iridotomy. A field trial with a portable laser system.

The efficacy of a small, portable, battery-operated, Q-switched neodymium-YAG laser with a slit-lamp delivery system was evaluated in a short-term pilot study. Iridotomies were created in 44 Eskimo eyes (23 patients) with occludable angles in Alaska's Kotzebue region. The laser was transported as regular baggage, was used in three villages (utilizing available facilities), and was operational within five minutes. Patent iridotomies were achieved in all eyes and with one pulse in 18 eyes (44%). Complications included transient bleeding from the iridotomy site in 23 eyes (52%), focal corneal opacities in 11 eyes (25%), and a transient immediate postoperative intraocular pressure elevation in nine eyes (20%). This appears to be the first portable laser system that can be used in frontier areas and underdeveloped nations to prophylactically treat pupillary-block glaucoma.

Aged↗
PubMed1987

Laser power and postoperative intraocular pressure increase in argon laser trabeculoplasty.

Argon laser trabeculoplasty was performed on 45 open angle glaucoma patients with three different laser power levels (0.5, 0.7, and 0.9 W). We evaluated the influence of the treatment variables on the postoperative intraocular pressure (IOP) increase. The only statistically significant correlation we found was with the laser power. Most (75% [6/8]) of the serious IOP increases (greater than or equal to 10 mm Hg) were in the high-power group, and the average postoperative IOP increase was also greatest in this group.

Aged↗
PubMed1996

Predictability of excimer laser treatment of myopia. Melbourne Excimer Laser Group.

OBJECTIVE: To prospectively examine the predictability of excimer laser photorefractive keratectomy and photoastigmatic refractive keratectomy for myopia that ranged from -1 to -18 diopters (D). METHODS: Patients were treated with an excimer laser and followed up prospectively for 12 months. Low myopia was treated in one ablation zone (6.0 mm), high myopia in two ablation zones (5.0 and 6.0 mm), and extreme myopia in three ablation zones (4.5, 5.0, and 6.0 mm) with a maximum treatment of 15 D. Data were analyzed to determine the distribution of the various postoperative outcomes by preoperative myopia. RESULTS: Two hundred seventy-four low myopes, 189 high myopes, and 41 extreme myopes were available for 12-month follow-up. The re-treatment rate increased with preoperative myopia. The predictability of refraction and uncorrected and best corrected visual acuity progressively decreased with increasing myopia. The likelihood of losing lines of best corrected visual acuity and corneal haze increased with increasing myopia. CONCLUSION: These data should help in the counseling of patients about the likely outcome if they have excimer laser surgery to correct myopia.

Adult↗
PubMed2000

Structural and morphological study of pulsed laser deposited calcium phosphate bioceramic coatings: influence of deposition conditions, laser parameters, and target properties.

Calcium phosphate (CaP) bioceramics, especially hydroxyapatite (HA), have been used as coatings on implants owing to their biocompatible properties. The commercial practice for applying HA coating, plasma spraying, has some disadvantages which limit the long-term stability of the implants. Pulsed laser deposition (PLD) is being investigated as an alternative technique. The purpose of this research was to systematically study the effect of various parameters of the PLD process on the properties of CaP coatings. In this study, three types of HA targets and two laser wavelengths were used to make six categories of coatings. Predominantly crystalline HA coatings were produced under all six categories at optimum conditions, although small amounts of minor phases sometimes were found. Sufficient coating/substrate bond strength was also obtained. A wide variety of coating morphologies was obtained, from rather dense and uniform to rough and porous. The important factors that affected the morphology included target properties, vacuum level, deposition temperature, and laser wavelength and energy density. PLD's ability to produce both amorphous and crystalline, and both smooth/dense and rough/porous coatings may be a unique advantage.

Biocompatible Materials↗
PubMed1991

Holmium laser angioplasty after failed coronary balloon dilation: use of a new solid-state, infrared laser system.

A new solid-state laser system was used in a case of saphenous vein graft occlusion untreatable by standard very low-profile balloon angioplasty. The 2100 nm infrared pulsed thulium/holmium: YAG laser successfully recanalized an obtuse marginal bypass graft without complications. The holmium laser has several advantages over excimer systems and may prove an effective adjunct or alternative to coronary balloon angioplasty.

Aged↗
PubMed1992

Excimer laser coronary angioplasty: results in restenosis versus de novo coronary lesions. Excimer Laser Coronary Angioplasty Investigators.

There is limited information regarding the use of excimer laser coronary angioplasty (ELCA) in patients with restenotic lesions. The purpose of this investigation was to compare the results of ELCA in patients with restenosis following prior PTCA with results obtained in de novo (no restenosis) patients. A retrospective review was obtained of all patients undergoing attempted ELCA at each of the 12 participating clinical investigative centers. There were 620 patients in the prior restenosis group and 949 in the de novo group. Both laser success (88% vs 78%) and procedural success (92% vs 88%) were higher in restenosis lesions compared with de novo lesions (P less than 0.001). Six-month follow-up was available in 40% of patients. Restenosis occurred in 49% of the prior restenosis group vs 44% of the de novo group (P nonsignificant) but death was more common in the de novo group (2.2 vs 0.4%, P = 0.01). ELCA can be performed with a high success rate in patients with restenosis following prior balloon angioplasty but recurrent restenosis following laser procedure remains a significant problem.

Adult↗
PubMed2003

Preliminary study of laser welding for aortic dissection in a porcine model using a diode laser with indocyanine green.

BACKGROUND AND OBJECTIVES: The objective of this study was to determine whether a dissected aorta could be welded by a diode laser with a solder using an in vitro porcine aortic dissection model. STUDY DESIGN/MATERIALS AND METHODS: Porcine aortic strips were dissected into two flaps and the dissected faces were immersed in a solution of indocyanine green. The two flaps were pressed at 0.2 kg/cm2 with contact between the two immersed faces. The pressed flaps were irradiated with a diode laser (810 nm) at intensities of 170-425 W/cm2 for 8 seconds. The welded flaps were studied by light microscopy and the adhesive strengths were measured. RESULTS: The irradiated flaps were successfully welded. The breaking stress, the maximum stress recorded in a stress-strain curve, increased with increase in irradiation intensity up to 396 W/cm2 (2.7 x 10(2) mmHg) and decreased when the intensity reached 425 W/cm2. In the specimen irradiated at 396 W/cm2, the welded faces showed continuous fusion of elastin layers, while some voids were seen between the welded faces in the specimen irradiated at 425 W/cm2. CONCLUSIONS: The dissected porcine aortas were successfully welded using a laser with solder. The results suggest that the welded aorta can bear physiological blood pressure.

Aortic Dissection↗
PubMed2003

In vivo and in vitro effects of an Er:YAG laser, a GaAlAs diode laser, and scaling and root planing on periodontally diseased root surfaces: a comparative histologic study.

BACKGROUND AND OBJECTIVES: The aim of the present histologic study was to compare the in vivo and in vitro effects of an erbium: yttrium, aluminum, and garnet (Er:YAG) laser (ERL), combined with a fluorescent calculus detection system, a diode laser (DL) and scaling and root planing (SRP) on periodontally diseased root surfaces. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four single rooted teeth, considered for extraction due to severe periodontal destruction, were included in the study. Prior to extraction all mesial root surfaces were randomly assigned to the following treatment groups: (1) ERL combined with a calculus detection system with fluorescence induced by 655 nm InGaAsP DL radiation (160 mJ/pulse and 10 pulses/second under water irrigation) (ERL), or (2) GaAlAs DL (1.8 W, pulse/pause relation 1:10), or (3) SRP using hand instruments. Immediately after extraction, all distal root surfaces were treated with the same instruments under standardized conditions. For light microscopic investigation, a plastic embedding technique was used to cut the undecalcified roots into 30 microm thick crossections. The following parameters were recorded by on blind examiner: remaining debris, root surface morphology, and thermal side effects. RESULTS: Root surfaces instrumented with both, ERL in vivo and DL in vitro exhibited no detectable surface alterations. In contrast, ERL scaling in vitro and SRP in vivo/in vitro produced superficial microchanges in root cementum. However, irradiation with DL in vivo caused severe damages to the root surface (i.e., crater formation). There were no signs of thermal side effects in all laser treated groups. ERL provided subgingival calculus removal on a level equivalent to that provided by SRP. DL was unsuitable for calculus removal, since macroscopic inspection revealed the presence of large amounts of subgingival calculus. CONCLUSIONS: The present in vivo results showed that (i) ERL, combined with a fluorescent calculus detection system, provided a selective subgingival calculus removal on a level equivalent to that provided by SRP, and (ii) DL, using this power output, was unsuitable for calculus removal and altered the root surface in an undesirable manner.

Dental Calculus↗
PubMed2003

Evaluation of myocardial perfusion and left ventricular function six months after percutaneous transmyocardial laser revascularization: comparison of two Ho-YAG laser systems with the same wavelength, but different energy delivery and navigation systems.

BACKGROUND AND OBJECTIVES: Myocardial perfusion and left ventricular function (LVF) were assessed after percutaneous transmyocardial laser revascularization (PTMR) in patients not amenable to conventional revascularization, with a comparison of two laser systems. STUDY DESIGN/MATERIALS AND METHODS: PTMR was performed with an Eclipse laser in 15 patients, and with a Biosense DMR in 10 patients. (201)Thallium scintigraphy, coronary angiography, and ventriculography were performed at baseline and at the 7.5+/-4.3-month follow-up. All patients in the Biosense DMR group and 10 in the Eclipse group underwent NOGA mapping before PTMR and after follow-up. RESULTS: The event-free survival rates were comparable, and the angina scores of all patients improved significantly, but more so in the Biosense DMR group than in the Eclipse group (1.2+/-1.1 vs. 2.3+/-0.9, P < 0.05). Both, the electrical activity assessed by NOGA mapping and the normalized (201)thallium uptake at redistribution improved significantly in the treated segments after Biosense DMR, while the global LVF decreased insignificantly in the Eclipse group. CONCLUSIONS: PTMR resulted in significant improvements in the clinical symptoms, but the electrical activity improved only in the Biosense DMR group, without transforming to a better LVF.

Aged↗