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At least 19 recordsLinked to original sources

PubMed1992

Comparison of retinal photocoagulation using pulsed frequency-doubled neodymium-YAG and argon green laser.

The photocoagulation effects on retinal and choroidal tissue of the argon green and pulsed frequency-doubled neodymium-YAG lasers were examined in rabbit eyes. In contrast to the continuous wave output of the argon green laser, the pulsed frequency-doubled neodymium-YAG laser produces a series of 1 microsecond pulses emitted at a repetition rate of 10 kHz. The high repetition rate results in pulse averaging, allowing relatively low peak powers to be used while producing average powers capable of thermal tissue effects. Photocoagulation lesions in the rabbit retina were placed in pairs using each of the lasers. Light microscopic comparison of the argon and neodymium-YAG burns revealed morphologically similar lesions for up to 14 days after photocoagulation, with damage predominantly at the level of the retinal pigment epithelium and outer retina. The high repetition rate, pulsed frequency-doubled neodymium-YAG laser produced thermal tissue effects similar to the continuous wave argon green laser.

Animals↗

PubMed1991

Lithotripsy of gallstones by means of a quality-switched giant-pulse neodymium:yttrium-aluminum-garnet laser. Basic in vitro studies using a highly flexible fiber system.

The quality-switched neodymium:yttrium-aluminum-garnet laser represents a new instrument for athermal fragmentation of gallstones by transformation of optical energy into mechanical energy in the form of shock waves via local plasma formation. A highly flexible 300-micron fiber transmission system was used in basic investigations to determine the influence of varying pulse repetition rates (5-30 Hz) and pulse energies (15 and 20 mJ) on shock wave intensity and stone fragmentation in vitro for 105 biliary calculi of known size and chemical composition. After performance of 1200 shock wave pressure measurements using polyvinylidenefluoride hydrophones, stone fragmentation was analyzed by determination of fragment removal rates (volume of fragments removed per fragmentation time), ablation rates (mean volume removed per laser pulse), and median fragment sizes for each laser setting. With the quality-switched neodymium:yttrium-aluminum-garnet laser system, all concrements could be reliably disintegrated into small fragments (median diameter, 0.7-1.7 mm). Compared with pure cholesterol stones, a significantly higher fragment removal rate was achieved in cholesterol stones containing 30% calcium phosphate (P = 0.039), in cholesterol stones containing 20% pigment (P = 0.015), and in pure pigment stones (P = 0.007). Fragment removal rates, local shock wave pressures, and median grain sizes were significantly higher at a pulse energy of 20 mJ than with 15 mJ. Shock wave pressures showed a distinct dependence on pulse repetition rates at 20 mJ, yet not at 15 mJ. Because there is no evident hazard of thermal damage to tissue using the quality-switched neodymium:yttrium-aluminum-garnet laser, it appears to be a promising device for nonsurgical biliary stone therapy.

Aluminum↗

PubMed1991

[The first experience with the concurrent effect of YAG-neodymium and YAG-erbium laser on experimental animal tissues and the possibility of its use in surgery].

To guarantee the necessary rate of cutting live tissues with adequate hemostasis along the line of the incision, the authors studied isolated and joint effect of radiations of AIG-neodymium and AIG-erbium lasers on the tissues of laboratory animals. The possibility of accomplishing intraoperative hemostasis on the parenchymal organs was studied in experiments with AIG-neodymium laser. A good dissection effect in cutting various tissues was produced in the second series of experiments with AIG-erbium laser. The simultaneous action of AIG-neodymium and AIG-erbium beams converged at one point on the surface of the biological object was studied in the third series of experiments. It was found that the effect ensures a good dissection of tissues with sufficient hemostasis. The results of dynamic morphological studies are shown. The possibility of using the device in surgery is discussed.

Animals↗

PubMed1986

Neovascular glaucoma following neodymium-YAG laser posterior capsulotomy.

Iris neovascularization and neovascular glaucoma were diagnosed in three diabetic patients following neodymium-YAG laser posterior capsulotomy. Each of the patients had previously undergone an uncomplicated extracapsular cataract extraction with insertion of a posterior chamber lens implant. These occurrences are consistent with the hypothesis that the posterior lens capsule may serve as a protective barrier to a diffusible vasoproliferative factor from the vitreous or retina. Both the beneficial optical effects and the potential adverse effects should be carefully considered prior to performing neodymium-YAG laser posterior capsulotomy in diabetic patients or other patients with ischemia in the fundus. Following neodymium-YAG laser posterior capsulotomy, these eyes should be closely followed up for signs of neovascularization and possible panretinal photocoagulation.

Cataract Extraction↗

PubMed1991

Late-onset elevation in intraocular pressure after neodymium-YAG laser posterior capsulotomy.

We retrospectively studied the long-term change in intraocular pressure after neodymium-YAG laser posterior capsulotomy. Uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens implantation was performed in 446 consecutive normal eyes (401 patients), 237 (53%) of which subsequently underwent uncomplicated neodymium-YAG laser posterior capsulotomy. Late-onset elevation in intraocular pressure was seen in three eyes (1.4%) after cataract surgery alone (mean follow-up, 2.7 +/- 1.7 years) and in 14 eyes (5.9%) after cataract and laser surgeries (mean follow-up, 3.0 +/- 1.1 years). This difference was statistically significant (P less than .03). These results suggest that, in addition to immediate changes in intraocular pressure, neodymium-YAG laser posterior capsulotomy may be associated with an increase in intraocular pressure long after the laser surgery, even in normal eyes without obvious postoperative complications.

Aged↗

PubMed1985

Histologic changes in rat brain tissue caused by neodymium-yttrium aluminum garnet laser irradiation. II. Cerebellum.

Histologic changes after neodymium-yttrium aluminum garnet laser irradiation were evaluated in the rat cerebellum. Irradiation of 60 W (corresponds to 45.2 W/mm2) to the posterior fossa was dangerous even in adult rats, although this value was safe for the rat cerebral hemisphere as previously reported. The histologic changes caused by neodymium-yttrium aluminum garnet laser irradiation were similar to those caused by thermal energies. To the adult rat cerebellum, 45 W (35.2 W/mm2) can safely be applied. For the further use of the neodymium-yttrium aluminum garnet laser in neurosurgery, our findings should be taken into consideration.

Animals↗

PubMed1991

Is the neodymium:YAG laser effective therapy for invasive bladder cancer?

The neodymium:YAG (yttrium-aluminum-garnet) laser can cause transmural coagulation necrosis of bladder tumor or bladder wall. Pathologic specimens of 18 patients prospectively treated with the neodymium:YAG laser before radical cystectomy were reviewed to compare the initial clinical stage of bladder tumor with the final pathologic stage and to assess the destructive tissue effects of neodymium:YAG laser therapy. Eleven of 18 patients were unchanged pathologically in stage of tumor or had tumor progression. Seven patients had a lower pathologic tumor stage; 3 of these patients had pathologic Stage T0 with no residual tumor, with the remainder of patients showing superficial disease. One asymptomatic small bowel injury was discovered at operation. Healing lesions showed marked granulation tissue, coagulation necrosis, and persistent ulceration.

Carcinoma, Transitional Cell↗

PubMed1989

Treatment of benign urethral strictures using a sapphire tipped neodymium:YAG laser.

Sapphire tips increase the energy density and cutting effect of a neodymium:YAG laser. Sapphire tipped neodymium:YAG laser fibers were used to perform urethrotomy in 24 men with benign urethral strictures. The cutting effect was inadequate in 10 patients. Of the 24 patients 16 (67%) had a recurrent stricture within 1 year. Sapphire tipped neodymium:YAG laser fibers offer no apparent advantage over cold knife urethrotomy for treatment of benign urethral strictures.

Dilatation↗

PubMed1990

Laser assisted urethral closure in the rat: comparison of CO2 and Neodymium-YAG laser techniques.

In 65 male rats a comparative study was undertaken to investigate a Neodymium-YAG and CO2 laser system for the microsurgical repair of longitudinal incisions of the rat urethra. Postoperative investigations included patency tests, necropsy and light microscopy. Use of the laser systems did not reduce operation time. The highest rate of postoperative strictures (90%), urethral fistulas (30%), urinomas (20%) and postoperative deaths (70%) was seen in the Neodymium-YAG laser group. CO2 laser repair was almost as efficacious as microsuture repair, except for a higher rate of urethral fistulas resulting from the initially weak laser weld. Based on these findings, the Neodymium-YAG laser seems unsuitable for urethral repair. Further studies in larger animals are warranted using a CO2 laser in combination with postoperative cystostomy for urinary diversion in order to avoid fistulas in the early postoperative period.

Animals↗

PubMed1991

The neodymium:YAG laser and the resectoscope for the treatment of menorrhagia.

OBJECTIVE: To assess the efficacy of destruction of the endometrium by ablation with a neodymium:YAG laser or resection with electrocautery in the management of menorrhagia. DESIGN: The efficacy of the treatment was assessed subjectively by each patient comparing the duration and amount of her menstrual bleeding before and after the operative procedure. Randomisation of treatments or patients was not undertaken. SETTING: The study was carried out in tertiary centres. Most of the procedures were undertaken in the Day Surgery Units of those centres. PATIENTS: A total of 64 patients underwent one or more procedures. One had continuous bleeding per vagina on hormone replacement therapy, all others had menorrhagia which they considered incapacitating. INTERVENTIONS: Of the patients 40 had removal of endometrium via a resectoscope and 24 had endometrial vaporisation with the neodymium:YAG laser. MAIN OUTCOME MEASURE: The outcome was assessed by each patient as amenorrhoea, hypomenorrhoea, attainment of normal menstrual amount or no change in menstrual loss. RESULTS: Both operative procedures were satisfactory in that amenorrhoea, hypomenorrhoea or normal menstruation was achieved in 87% of cases. Uterine perforation occurred on two occasions with thermal bowel injury in one patient. CONCLUSION: Destruction of the endometrium by the neodymium:YAG laser or the resectoscope is a successful way of managing menorrhagia in the absence of demonstrable pathological cause in nearly 90% of cases. The performance of the procedures as day cases with minimal discomfort makes them attractive alternatives to hysterectomy in the management of menorrhagia.

Danazol↗

PubMed1987

Cytotoxicity of the rare earth metals cerium, lanthanum, and neodymium in vitro: comparisons with cadmium in a pulmonary macrophage primary culture system.

The rare earth metals cerium, lanthanum, and neodymium each were evaluated in an in vitro cytotoxicity assay system using adult, male Sprague-Dawley rat pulmonary alveolar macrophages. Both the soluble chloride form of these metals and their insoluble metal oxides were studied. For comparison purposes, the cytotoxicities of cadmium chloride and cadmium oxide were also quantified in this test system. In general, regardless of the cytotoxicity parameter measured, i.e., cell viability, lysosomal enzyme leakage, or changes in cell surface morphology, cadmium was more toxic to these cells than were the rare earth metals. Of the rare earth metals studied, only lanthanum chloride (LC50 = 52 microM), cerium chloride (LC50 = 29 microM), and neodymium oxide (LC50 = 101 microM) displayed significant cytotoxicity in this test system. Cadmium chloride exhibited an LC50 value of 28 microM, whereas the LC50 value for cadmium oxide was found to be 15 microM. These findings suggest that rare earth metal fumes should be considered as cytotoxic to lung tissue and therefore potentially fibrogenic.

Animals↗

PubMed1991

Antioxidant protection mechanism of chick hepatic mitochondria exposed to lanthanum chloride & neodymium chloride treatment.

Acute lanthanum chloride (250 mg/kg body wt) and neodymium chloride (200 mg/kg body wt) administrations resulted in significant enhancement of glutathione level in chick hepatic mitochondria. However, glutathione-s-transferase activity was depressed. There was no alteration in the activity of glutathione reductase. Activity of glucose-6-phosphate dehydrogenase was not altered under lanthanum and neodymium treatment. There was a significant enhancement of intramitochondrial glutathione peroxidase and superoxide dismutase. Lipid peroxidation remains the same as control group of animals.

Animals↗

PubMed1985

Prevention of intraocular pressure elevation following neodymium-YAG laser posterior capsulotomy.

Thirty-two eyes of 32 patients were treated with 0.5% timolol, 2% pilocarpine, or normal saline five and 30 minutes following neodymium-YAG laser posterior capsulotomy in a randomized, double-masked study. Mean maximum intraocular pressure (IOP) elevation was 8 +/- 2 mm Hg following treatment with normal saline, 5 +/- 3 mm Hg following treatment with 2% pilocarpine, and 1 +/- 2 mm Hg following treatment with 0.5% timolol. Fewer patients treated with 0.5% timolol developed an IOP elevation of 5 mm Hg or more than control patients. On aphakic patient treated with 0.5% timolol developed a maximum IOP greater than or equal to 40 mm Hg. We found that treatment with 0.5% timolol after neodymium-YAG laser posterior capsulotomy provides partial protection from IOP elevation.

Aged↗

PubMed1985

The role of the vitreous in the intraocular pressure rise after neodymium-YAG laser capsulotomy.

Autologous liquid vitreous injected into the anterior chamber of the phakic owl monkey eye leads to markedly increased intraocular pressure (IOP) peaking at one to two hours. In contrast, neodymium-YAG laser shock waves focused in the center of the anterior chamber of the same animal led to a mild decrease in IOP. Debris produced by laser pulses focused on the residual cortex of owl monkey eyes that had undergone extracapsular surgery failed to increase the IOP. Similarly, injection of dialyzed vitreous did not have any significant influence on IOP. We conclude that the disruption of the integrity of the anterior cortical gel and the subsequent release of a dialyzable intravitreal substance with a molecular weight of less than 10,000 daltons into the anterior chamber may contribute to the IOP rise after surgical discission, including neodymium-YAG laser posterior capsulotomy.

Animals↗

PubMed1985

Neodymium-YAG laser sclerostomy in primates.

A one-stage sclerostomy procedure was performed "noninvasively" in four cynomolgus monkeys solely with the neodymium-YAG laser. The neodymium (Nd)-YAG laser was focused, for the most part, a few diopters behind the focus of the helium-neon aiming beam. This enabled optical breakdown to occur entirely within the sclera to produce a perforating micropuncture of the scleral tissue. Two monkeys were treated with higher energy (23 and 24 joules) and two were treated at lower energy levels (12 and 14 joules). An immediate reduction of intraocular pressure in the treated eye was associated with a significant increase in outflow facility. The sclerostomy remained patent for more than 180 days, as determined by tonography and histologic examination. Scanning electron microscopic examination of the cornea revealed no significant damage to the central cornea or to tissue adjacent to the visual axis in any of the treated eyes. However, there was some endothelial cell loss at the site of the laser treatment at the peripheral cornea and in the area immediately posterior to the incision; there was also a focal break in Descemet's membrane.

Animals↗

PubMed1986

Q-switched neodymium-YAG laser iridotomy in patients in whom the argon laser fails.

We conducted a short-term prospective clinical study to evaluate Q-switched neodymium-YAG laser iridotomy in 33 eyes with pupillary block glaucoma in which the argon laser was unable to create an iridotomy. These eyes had chronic angle closure glaucoma (11 eyes), acute angle closure glaucoma (five eyes), pseudophakic pupillary block (seven eyes), uveitic pupillary block (three eyes), and contralateral eyes (five eyes); also included were both eyes of a patient with a head tremor. In all eyes, a patent iridotomy was created in one treatment session, with a mean of 5 +/- 5 pulses and a mean total energy of 55 +/- 120 millijoules. Complications included iridotomy closure (two eyes with preexisting active uveitis), focal nonprogressive corneal opacities (six eyes), and minimal bleeding from the iridotomy margin (12 eyes). Q-switched neodymium-YAG laser iridotomy appears to be an effective next step in the management of pupillary block glaucoma prior to surgical iridectomy when argon laser iridotomy fails.

Argon↗

PubMed1986

Vitreous changes after neodymium-YAG laser photodisruption.

We investigated physicochemical changes in the vitreous body after photodisruption with a Q-switched neodymium-YAG laser. In vivo proton nuclear magnetic resonance imaging techniques were employed to assess alterations in the vitreous of irradiated rabbit eyes. Measurements of proton relaxation times (T1 and T2), viscosity, and chromatographic spectra were made in vitro on irradiated bovine and rabbit vitreous, and circular dichroism measurements were used to study changes in an irradiated sodium hyaluronate solution. Statistically significant changes in T1, were observed immediately after irradiation, but the small magnitude and reversibility of those changes, combined with the fact that the other measurements detected no changes, suggest that neodymium-YAG laser photodisruption does not have a direct deleterious effect on the structural integrity of the normal vitreous body.

Animals↗

PubMed1986

Neodymium-YAG vitreous surgery for phakic and pseudophakic malignant glaucoma.

Ciliary block (malignant glaucoma) developed in a phakic eye and a pseudophakic eye with a posterior chamber intraocular lens and an intact posterior capsule. In both cases, neodymium-YAG laser treatment (2 to 3 mJ) to the anterior vitreous relieved the blockage, and the anterior chamber returned to normal depth. When technically possible, the neodymium-YAG laser may be used to treat phakic and pseudophakic malignant glaucoma before resorting to surgical vitrectomy.

Adult↗