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At least 523 records · Page 29Linked to original sources
PubMed1999

Low-power v high-power KTP laser: improved method of laser ablation of prostate.

BACKGROUND AND OBJECTIVE: Current treatment technique for laser prostatectomy involve Nd:YAG wavelength at 60 to 80 W. Use of the KTP wavelength in addition to Nd:YAG allows for vaporization of more tissue, decreasing the amount undergoing coagulation necrosis. In this study, we compared 20 W and 40 W of KTP laser energy in conjunction with the Nd:YAG wavelength for the treatment of benign prostatic hyperplasia (BPH). PATIENTS AND MATERIALS: A total of 50 consecutive patients underwent laser ablation of the prostate, with 38 patients (Group I) receiving treatment with 20 W of the KTP and 60 W of the Nd:YAG wavelengths. The other 12 patients (Group II) underwent treatment with 40 W of KTP and 60 W of Nd:YAG laser energy. The patients had an initial evaluation consisting of American Urological Association (AUA) Symptom Score, uroflowmetry, transrectal ultrasonography for prostate volume measurement, and assay of prostate specific antigen (PSA) serum level. The patients were seen in follow-up at 1, 3, and 6 months. RESULTS: The mean symptom score decreased from 23.4 to 8.9 from Group I and from 18.2 to 3.5 for Group II at the 6-month follow-up. The mean peak urinary flow rate increased from 8.4 to 15.4 mL/sec Group I and from 8.3 to 16.5 mL/sec in Group II at the 6-month follow-up. CONCLUSIONS: The patients treated with the 40 W of KTP laser energy experienced a more rapid and sustained improvement in symptom score than those treated at 20 W. The improvement in peak urinary flow rate was approximately the same in the two groups.

Aged↗
PubMed1985

Laser flash effects on laser speckle shift visual evoked potential.

Steady-state visual evoked potentials (VEP's) were recorded from four cynomolgus monkeys in response to a sinusoidally oscillating 10 degrees helium-neon laser speckle field (632.8 nm), moving vertically 2.5 degrees at 8 shifts per second. A 5-pulse flash train at the maximum permissible exposure (MPE) dose from a collimated Q-switched frequency-doubled neodymium laser (532 nm) was superimposed on the foveal stimulus and the subsequent disruption and recovery of the VEP measured. Minimal disruption of the response signal magnitude was demonstrated (0.1 greater than p greater than 0.05) which recovered within 300 ms of the termination of the pulse train. A small but significant (p less than 0.01) disruption of phase entrainment was also noted that recovered within the same period. This is contrasted with a second experiment with three monkeys in which an argon (514 nm) laser served both as the speckle stimulus source and as the shuttered flash. Exposure to collimated MPE argon radiation for 250 ms immediately depressed the VEP (97%, p less than 0.01) and showed recovery to 70% of the pre-flash baseline only after 3 s. Phase lock was also severely degraded for several seconds. These results imply that visual processing of nonacuity-limited medium contrast stimuli with broad spatial frequency content will probably not be materially affected by ultra-short pulsed laser exposure at these energy levels and frequencies. However, even safe levels of collimated continuous laser light may have severe effects on vision that could parallel flash effects seen with Xenon discharge flash lamps.

Animals↗
PubMed2003

Distortion and size calibration of the scanning laser ophthalmoscope (SLO) laser-beam raster.

PURPOSE: The Rodenstock scanning laser ophthalmoscope (SLO) is useful for mapping retinal function and for developing and evaluating visual rehabilitation methods. It is essential to know the visual angle subtended by stimuli in the SLO laser-beam raster and to accurately measure angular distances between objects in the final SLO image. To accomplish this, the angular extent of the SLO laser-beam raster must be calibrated. METHODS: We developed a simple method and apparatus for calibrating the raster and used it for repeated calibrations during a 3-month period. RESULTS: The laser-beam raster is quite stable in shape and size, but it is trapezoidally distorted in the vertical direction. Consequently, SLO images are distorted. CONCLUSIONS: Trapezoidal distortion of the SLO laser-beam raster can cause stimulus size to change as much as 10% from the top to the bottom of the raster. Measurements of fixed horizontal retinal landmark distances in SLO images can also vary as much as 10%. We developed a straightforward mathematical method for correcting distortion in SLO image measurements.

Calibration↗
PubMed2006

Laser bleb reduction for bleb dissection with krypton green laser: technique and outcomes.

PURPOSE: Lasers have been used to treat dysfunctional blebs, but the laser remodeling of blebs that dissect into the palpebral fissure has not been reported. We describe the unique use of krypton green laser to treat dissected blebs and discuss treatment outcomes. PATIENTS AND METHODS: Retrospective review of consecutive patients undergoing laser bleb reductions (LBRs) over a 6-year period. Failure was defined as persistent dissection and/or symptoms or loss of intraocular pressure (IOP) control despite medications. RESULTS: Sixteen patients underwent a total of 23 LBRs and were followed-up for a mean of 12.4 months (median = 9.5 mo). Ten patients (63%) were treated successfully, and 6 patients (37%) failed treatment. Persistent dissection and/or symptoms were the most common reasons for failure (5/6), whereas 1 patient lost IOP control. Three (30%) of those treated successfully required the reintroduction of ocular hypotensive medications for pressure control. The mean IOP increased from 9.1 +/- 5.2 mm Hg before treatment to 11.7 +/- 8.1 mm Hg after treatment (P = 0.02). Common complications included intraoperative discomfort (26%), conjunctival injection (22%), postoperative discomfort (13%), and dissection into the untreated side (9%). In the failure group, more laser spots (P = 0.05) and higher power levels (P = 0.00001) were used. CONCLUSIONS: Krypton LBR may be a useful initial treatment modality for symptomatic bleb dissection. Success rates may be modest, but most adverse effects are mild and/or transient; however, significant loss of IOP control can occasionally occur.

Aged↗
PubMed2006

Integrated optoelectronic probe including a vertical cavity surface emitting laser for laser Doppler perfusion monitoring.

An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a laptop computer. The computer sound processor is utilized for acquisition and digital signal processing of the incoming Doppler signal. In this paper, the design of the laser Doppler perfusion monitor is described and its performance is evaluated. We demonstrate our perfusion monitor to be less sensitive to subject motion than a commercial fiber-optic device. For medium and high perfusion levels, the performance of our integrated probe is comparable to the fiberoptic flowmeter containing a normal edge-emitting laser diode. For very low perfusion levels, the signal-to-noise ratio of the fiber-optic device is higher. This difference can mainly be attributed to the shorter coherence length of the VCSEL compared with the edge-emitting laser diode.

Diagnosis, Computer-Assisted↗
PubMed1995

The changing profile of patient selection, procedural techniques, and outcomes in excimer laser coronary angioplasty. Participating Investigators of the Percutaneous Excimer Laser Coronary Angioplasty Registry.

During the course of development of excimer laser angioplasty, several changes in patient selection and technique have occurred. It is uncertain, however, whether these changes have been associated with improved procedural outcome. In this study, multivariable regression methods were used to identify the factors responsible for clinical success, major complications, and vessel perforation in 2,041 consecutive patients treated with excimer laser coronary angioplasty. The overall rates of clinical success were 89%, major complications 7.5%, and vessel perforation 2.1%. Clinical success was 86% in patients treated with prototype catheters, 89% with flexible catheters, 92% with extremely flexible catheters, and 95% in patients treated with directional eccentric catheters (P < 0.001). By multivariable analysis, clinical success increased with each subsequent catheter design (odds ratio [OR] = 1.4 per iteration [95% confidence interval 1.2, 1.6]), and with improved lesion selection. Major complications were reduced when operators had performed more than 25 cases (rate = 6.5%, OR = 0.7 [0.5, 0.9]), and the incidence of vessel perforation was decreased when the size of the target vessel was > 1.0 mm larger than the diameter of the laser catheter (rate = 1.1%, OR = 0.3 [0.2, 0.5]). In conclusion, during the course of clinical investigation with excimer laser angioplasty, procedural outcome has improved. These results emphasize the importance of careful patient selection and procedural technique to enhance the success of excimer laser angioplasty.

Aged↗
PubMed1990

Prospective randomised trial of laser therapy only and laser therapy followed by endoscopic intubation for the palliation of malignant dysphagia.

Forty six consecutive patients admitted for the relief of malignant dysphagia were prospectively randomised to receive laser therapy only or initial laser therapy followed by endoscopic intubation. Twenty patients were treated in each group with six exclusions. The patients' swallowing ability was assessed before and during the remainder of their life on a 0-4 scale with 0 being normal swallowing and 4 total dysphagia. The patient's quality of life was measured at the same times, using a physician's assessment (QL index) and the patient's own assessment using a linear analogue self assessment (LASA). There was a significant correlation between all the QL index and the LASA scores collected (n = 126; rs = 0.594, p less than 0.001). The mean monthly dysphagia grade correlated with the QL index (rs = 0.433, p less than 0.001) and the LASA (rs = 0.272, p less than 0.002). There was no significant difference in the dysphagia grade before or after treatment in either group. Dysphagia fluctuated more in those treated with the laser only, however, than in those with a tube inserted. There was also no significant difference in the quality of life measured between the two groups of patients. The complication rate (laser only 10%, laser/intubation 40%, p less than 0.05) was significantly higher in intubated patients. The recurrent dysphagia rate (laser only 25%, laser/intubation 45%, NS) was higher in patients treated with intubation, but they required fewer endoscopic procedures. Overall both procedures were effective in relieving dysphagia and in maintaining quality of life. There was no procedure related mortality in either group.

Adenocarcinoma↗
PubMed1988

Laser angioplasty: controlled delivery of argon laser energy.

A laser catheter system that integrates balloon and fiberoptic technologies was evaluated. In vitro tissue studies were conducted to compare the tissue response to laser irradiation from a bare optical fiber (undiverged light beam) and from a fiber with an optical assembly (diverged light beam). An in vivo study of occluded and unoccluded canine femoral arteries examined coaxial alignment of the diverged light beam and the resultant thermal effects. In the in vitro studies, a diverged laser light beam effected maximum tissue ablation (mean crater diameter, 1.81 mm +/- 0.44) at a distance of only 3 mm from the optical fiber tip. The in vivo study demonstrated the ability of a specially designed balloon catheter to align the diverged laser beam coaxially within the arterial lumen. This laser catheter system successfully avoids the risks of inadequate tissue removal and perforation.

Angioplasty, Balloon↗
PubMed1989

Percutaneous excimer-laser and excimer-laser-assisted angioplasty of the lower extremities: results of initial clinical trial.

Percutaneous peripheral excimer-laser angioplasty at 308 nm was used for treatment of 30 patients with peripheral vascular disease. Twenty-eight patients underwent laser-assisted balloon angioplasty, and two patients underwent laser angioplasty alone. Acute angiographic and clinical success was achieved in 24 of 31 (77%) femoropopliteal stenoses and occlusions. Seven of nine (78%) stenoses, six of seven (86%) short (0-5 cm) occlusions, seven of eight (88%) medium-length (6-10 cm) occlusions, three of four (75%) long (11-15 cm) occlusions, and one of three (33%) extreme (greater than 15 cm) occlusions were successfully treated. Inability to treat total occlusions was in each case related to a failure to maintain coaxial position and subintimal passage of the fiber. These cases demonstrate the feasibility of safely performing percutaneous peripheral excimer-laser or excimer-laser-assisted angioplasty. The overall frequency of restenosis after a mean follow-up period of 9.1 months was 29%. The data suggest that these procedures may be useful for the treatment of peripheral vascular disease in selected patients.

Adult↗
PubMed1990

Stereotactic interstitial laser-hyperthermia using Nd-YAG laser.

Laser hyperthermia using Nd-YAG laser was studied experimentally and clinically to treat deep-seated brain tumors. Histological changes, temperature profile, and modification of the blood-brain barrier were studied using cat and rat brains. In a clinical study 5 patients with brain tumors were treated with laser hyperthermia using this computed tomography-stereotactic technique. All tumors of these patients disappeared on computed tomography, and 3 of the 5 patients are still alive without recurrence. It was possible to make optimal lesion and to have accurate peripheral temperature control by using the combination of the Komai stereotactic method and the SLT Nd-YAG laser system. Interstitial laser hyperthermia using this method is easy and safe to use, and it is beneficial to treat deep-seated brain tumors.

Adult↗
PubMedDate not supplied

Laser endarterectomy: a comparison of thrombotic potential following CO2 laser vs surgical endarterectomy.

Although laser endarterectomy has recently been suggested as useful in the treatment of arteriosclerotic obstructions, the "in vivo" clotting effects have not been well delineated. In this study, the common carotid and femoral arteries of ten mongrel dogs were exposed, and alternating 1 cm segments of each artery were treated with surgical endarterectomy and low-powered CO2 laser endarterectomy. Segments were then harvested, and subjected to histologic examination and vascular prostacyclin synthesis determinations, as measured by 6-keto PFG1a radioimmunoassay. Gross examination and light and scanning electron microscopy showed increased platelet aggregation and more extensive damaging of the underlying media of the laser compared to the surgical segments. Six-keto PFG1a levels were significantly lower (p = 0.001) in the laser compared to surgical sites (mean 232 +/- 72 pg/mg vs 515 +/- 144 pg/mg), or controls (895 +/- 337 pg/mg). These findings suggest that laser endothelial evaporation leads to increased thrombotic potential in the early post-operative period in comparison to surgical endarterectomy.

6-Ketoprostaglandin F1 alpha↗
PubMed2006

In vivo corneal confocal microscopy comparison of intralase femtosecond laser and mechanical microkeratome for laser in situ keratomileusis.

PURPOSE: To assess and compare corneal modifications induced by IntraLase PulsionFS femtosecond laser and mechanical microkeratome Hansatome for laser in situ keratomileusis (LASIK) using the new-generation Heidelberg Retina Tomograph II (HRT II)/Rostock Cornea Module confocal microscope. METHODS: In this case-control study, 24 eyes of 12 patients were examined with the HRT II in the follow-up of IntraLase femtosecond laser for LASIK myopic surgery. Twenty eyes of 10 patients were also examined after microkeratome Hansatome-LASIK surgery. In both groups, the patients underwent the first follow-up examination on day 7 and the last 12 months after surgery. Morphologic modifications of corneal architecture were evaluated, and comparisons were made between the two flap-formation techniques. RESULTS: Evaluation of both groups on day 7 showed keratocyte transformation, most likely related to cellular activation beneath the interface. The flap margin after the IntraLase technique appeared microscopically as a clear-cut edge that included the epithelial plug. At month 2, secondary fibrosis, adjacent to the still well-defined IntraLase flap edge, was observed. This reaction diminished with time, leaving a fibrotic scar adjacent to a wound constriction originating from the surrounding stroma. The flap margin of the mechanical microkeratome had the appearance of a less clearly identified fibrotic scar with no epithelial plug. CONCLUSIONS: This study reveals morphologic similarities between the interfaces obtained by femtosecond laser and mechanical microkeratome, probably because the same excimer laser performed the photoablation. However, the IntraLase flap margin showed greater fibrotic scarring than that induced by the mechanical microkeratome.

Adult↗
PubMed1989

Bioinhibition of human fibroblast cultures sensitized to Q-switch II dye and treated with the Nd: YAG laser: a new technique of photodynamic therapy with lasers.

Kodak Q-switch II dye has recently proven to be an effective biostimulative agent on normal human fibroblast cultures. The potential for this dye as a new chemosensitizing agent for the treatment of connective tissue diseases and wound healing with the Nd:YAG laser was examined. Two normal fibroblast cell lines were first sensitized to a nontoxic dose of Q-switch II dye, then subjected to treatment with an Nd:YAG laser at 1,060 nm, with varying levels of energy and temperatures determined by a reproducible method of dosimetry. The results indicate that Q-switch II dye at nontoxic doses of 0.1 micrograms/ml enhances the cytotoxic effects of the Nd:YAG laser at temperatures as low as 36 degrees C. Furthermore, at physiological temperature ranges as low as 24 degrees C to 34 degrees C, cell duplication was inhibited, but cell viability was not affected. Similar results were not observed when fibroblast cultures were treated with the laser alone. These observations suggest that Q-switch II dye is an effective chemosensitizing agent for the Nd:YAG laser and could potentially be used to reduce collagen deposits in conditions such as keloids and hypertrophic scars.

Benzopyrans↗
PubMed1995

Laser endometrial ablation with the neodynium: yttrium-aluminium garnet (Nd-YAG) laser: a review of ninety consecutive patients.

OBJECTIVE: To assess the effectiveness of laser endometrial ablation in women with dysfunctional bleeding. DESIGN: A retrospective analysis of 90 patients. SETTING: Department of Gynaecology, King George Hospital, Barley Lane, Goodmayes, Essex IG3 8YB, U:K. SUBJECTS: Ninety patients with dysfunctional uterine bleeding who were hysteroscopically suitable for laser endometrial ablation. INTERVENTIONS: Endometrial laser ablations using the neodynium-yttrium-garnet laser at 70 watts power output. MAIN OUTCOME MEASURES: Patient satisfaction/dissatisfaction at 6 months follow-up and response to repeat ablation. RESULTS: A total of 117 procedures were carried out on the 90 patients. There was one suspected perforation which was not confirmed at subsequent hysterectomy and one primary hemorrhage which required tamponade with Foley catheter. There were three cases of fluid overload with no clinical evidence of fluid over-load syndrome. All five major complications occurred in the first six months or 'learning phase' of the study. During this period, there were proportionately more treatment failures after one attempt (52.8% versus 42.6%) than the second six months of the study. Overall, 53.3% of the patients were satisfied with the initial ablation and 73.3% were satisfied after repeat ablations. CONCLUSION: Endometrial laser ablation is a major advance in the management of dysfunctional uterine bleeding, especially in patients who would otherwise have had a hysterectomy.

Adult↗
PubMed1988

Continuous wave (CW) dye laser vs. CW argon laser treatment of port wine stain (PWS).

Pulsed dye laser treatment has shown specific vessel damage and thrombosis and good clinical bleaching of PWS at lower energy densities than continuous wave (CW) argon laser treatment. Based on a pilot study with CW dye laser treatment of PWS, we wanted to investigate whether CW dye laser would be more beneficial in PWS treatment than argon laser treatment. The hypothesis was tested in 20 randomized PWS patients, but no difference in treatment results was detected between the two treatment modalities.

Adolescent↗
PubMedDate not supplied

Laser in situ keratomileusis for the correction of hyperopia from +1.25 to +5.00 diopters with the Technolas Keracor 117C laser.

PURPOSE: To assess the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) in patients with hyperopia and to evaluate the visual and refractive results of the procedure. METHODS: LASIK was performed on 85 eyes of 53 patients for correction of hyperopia, with a preoperative mean manifest spherical equivalent refraction of +3.31 +/- 0.69 D (range, +1.25 to +5.00 D) and mean refractive astigmatism of +0.91 +/- 1.06 D (range, 0 to +3.00 D). The Carriazo-Barraquer (Moria) manual microkeratome was used to create the corneal flap, and laser ablation was performed using the Technolas Keracor 117C excimer laser with an ablation zone diameter of 6.0 mm and a transition zone diameter to 9.0 mm. Follow-up was 12 months for all patients. RESULTS: Refraction was stable by 3 months after surgery. At 1 year after LASIK, the mean manifest spherical equivalent refraction was +0.43 +/- 0.57 D (range, -1.25 to +2.00 D) and refractive astigmatism was reduced to a mean of 0.36 +/- 0.30 D (range, 0 to 1.00 D). Fifty-two eyes (61.2%) had a manifest spherical equivalent refraction within +/- 0.50 D of emmetropia, and 76 eyes (89.4%) were within +/- 1.00 D. Uncorrected visual acuity was 20/20 in 21 eyes (24.7%) and 20/40 or better in 79 eyes (92.9%). Spectacle-corrected visual acuity was reduced by two lines in one eye (1.2%) and improved by two lines in five eyes (5.9%). There were no significant complications. CONCLUSION: LASIK was an effective, safe, and predictable procedure for the correction of hyperopia up to +5.00 D and hyperopic astigmatism up to +3.00 D with the Technolas Keracor 117C excimer laser. The large size of the corneal flap obtained by the Carriazo-Barraquer (Moria) manual microkeratome facilitated laser ablation entirely in the exposed corneal stromal bed.

Adult↗
PubMedDate not supplied

Laser in situ keratomileusis results of DOS and windows software versions for the Nidek EC-5000 excimer laser using the same nomogram.

PURPOSE: To compare the results of laser in situ keratomileusis (LASIK) correction for myopia and myopic astigmatism between the previous DOS software version and the Windows software version for the Nidek EC-5000 excimer laser, using the same nomogram. METHODS: This retrospective review included 2021 eyes (980 patients) after LASIK using the Nidek EC-5000 excimer laser. Of these, 1,632 eyes were corrected with the DOS software version and the other 389 eyes were corrected with the Windows software version of the laser. Both groups were treated with the same surgical nomogram. Minimum follow-up time was 6 months. Patients were classified into range of myopia: low, moderate, and high. RESULTS: Postoperative uncorrected visual acuity was not statistically significantly different between the two groups in any range of refractive error. There was no loss of best spectacle-corrected visual acuity for any patient. Uncorrected visual acuity equal to or better than 20/40 was achieved in 96.3% of eyes in the Windows version group and 94.9% in the DOS version. CONCLUSION: Results for the correction of myopia or myopic astigmatism were similar using the Nidek EC-5000 excimer laser with either the DOS software version or Windows software version, with the same surgical nomogram.

Adolescent↗
PubMedDate not supplied

Femtosecond laser flap creation for laser in situ keratomileusis: six-month follow-up of initial U.S. clinical series.

PURPOSE: To evaluate clinical performance of a femtosecond laser for flap creation in laser in situ keratomileusis (LASIK). METHODS: A prospective, consecutive series of 208 eyes (122 patients) undergoing LASIK between June 2000 and November 2000 using a femtosecond laser for creation of the corneal flap were evaluated for the incidence of complications. A subset of 114 patients who underwent myopic procedures and who were followed for 6 months was analyzed using standard outcome measures. RESULTS: In 4 of 208 eyes (1.9%), suction was lost during the procedure, causing the flap resection to be interrupted. However, in all four of these eyes the procedure was successfully performed 5 to 45 minutes after re-applanation of the eye. No postoperative complications or adverse events were observed in any treated eye. In the subgroup of 96 eyes undergoing plano correction and followed for 6 months (preoperative spherical equivalent refraction range -0.63 to -12.40 D), 98% (94 eyes) achieved uncorrected visual acuity of 20/40 or better; 94% (90 eyes) achieved 20/30 or better, 79% (76 eyes) achieved 20/25; and 55% (53 eyes) achieved 20/20 or better--all without benefit of retreatment. CONCLUSION: Femtosecond laser corneal flap creation is a safe and effective alternative to traditional mechanical microkeratomes. Standard LASIK nomograms appeared to apply equally well to the all-laser LASIK procedures. The potential for improved flap safety, reproducibility, flexibility, as well as for additional corneal applications are now being explored.

Corneal Stroma↗