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PubMed1984

A comparison of neodymium: YAG and argon laser iridotomies.

A prospective short-term clinical study evaluated argon and Q-switched neodymium:YAG laser iridotomies in 40 eyes of 20 patients with primary chronic angle-closure glaucoma. All patients had bilateral iridotomies with one eye randomly assigned to argon laser and the fellow eye to neodymium:YAG laser therapy. In all eyes a patent iridotomy was created in one treatment session. A mean of 12 +/- 11 and 0.033 +/- 0.025 J were needed for iridotomy formation in argon and neodymium:YAG treated eyes respectively. No neodymium:YAG and six (30%) argon iridotomies had marked closure requiring retreatment. Immediate postoperative intraocular pressure elevation greater than 10 mmHg was seen in seven (35%) argon and six (30%) neodymium:YAG-treated eyes. Nine (45%) eyes treated with the neodymium:YAG laser had bleeding from the iridotomy site. No acute lens damage was found in the neodymium:YAG eyes while seven (35%) lenses in the argon group had focal opacities. Seven (35%) neodymium:YAG and five (25%) argon treated eyes had focal nonprogressive corneal opacities above the iridotomy site. Specular microscopy showed a significant central corneal endothelial loss in argon laser treated eyes. No eyes had detectable retinal damage.

Adult↗

PubMed1999

Treatment of spider veins using a 10 millisecond pulse-duration frequency-doubled neodymium YAG laser.

BACKGROUND: The pulsed dye laser has been the standard for treating vascular lesions. Although quite effective for treating facial vessels and port-wine stains, spider veins of the lower extremities are more difficult to treat. Recent studies have shown that lasers with longer pulse durations are more effective at treating spider veins. A new long-pulse frequency-doubled Neodymium:YAG laser has been developed with a 10-ms pulse duration and sufficient energy to enable treatment with a 3- or 4-mm diameter treatment beam. OBJECTIVE: To determine the effectiveness of the long pulse Neodymium:YAG laser for treating spider veins of the lower extremities. METHODS: Spider veins less than 0.75 mm in diameter on the legs of 15 female volunteers were treated in 1 or 2 areas. Treatments were administered through a water-cooled chill tip using the frequency-doubled Neodymium:YAG laser with a 10-ms pulse duration. A dose of 16 J/cm2 was administered, completing 3 passes over each visible vein during each session, for a total of 2 sessions administered 6 weeks apart. Photographs of treatment areas were digitally analyzed for degree of vessel clearance. RESULTS: Computer-based image analysis revealed clearing of over 75% of veins following 2 treatments with 16 J/cm2. Side effects were minimal, and the treatments were well tolerated. CONCLUSIONS: The 532 nm, 10 ms pulse duration, frequency-doubled Neodymium:YAG laser is safe and effective for treating spider veins of the lower extremities less than 0.75 mm in diameter, in patients with Fitzpatrick skin Types I-III.

Adult↗

PubMed1981

[Histological changes following endovesical neodymium-YAG-laser irradiation (author's transl)].

Experimental animal research was used to compare the coagulatory qualities of the argon laser and the Neodymium-YAG laser to results obtained through electrocoagulation. The argon laser effects a necrosis near the urinary bladder wall surface, and when the energy density is increased, it may ablate the tissue to the point of perforation. In contrast, the Neodymium-YAG laser effects a bandshaped necrosis that penetrates all layers of the urinary bladder wall without primarily resulting in an ablation of tissue. Electrocoagulation results in irregularly demarcated necroses of varying depths, which can be explained by the uncontrolled flow of the high-frequency currents according to the paths of least resistance. The Neodymium-YAG laser is the one most suited for transmural coagulation of defined areas within the urinary bladder wall due to the even spread of its thermal energy that is independent of the affected tissue structure, as well as to its deep coagulatory qualities which in turn are due to the laser's minimal tissue absorption. The Neodymium-YAG laser allows the setting of reproduceable, sharply demarcated necroses into the bladder wall with an ensuing complete destruction of all wall layers. The wall framework within the necrotic area, however, remains intact, so that the danger of perforation is kept at a minimum.

Animals↗

PubMed1994

[Effect of neodymium on the crystal structure of human dental enamel in vitro].

The possibility of neodymium incorporation into hard tissues of permanent teeth has been investigated. The amount of neodymium was determined by X-ray microprobe analysis. The result indicates that different phases of enamel apatite have been recristallised. Neodymium compounds have appeared while the amount of some minerals in enamel have decreased. Neodymium could be an effective agent in stabilization of the apatite structure of dental enamel.

Crystallization↗

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↗

PubMed1984

One hundred neodymium-YAG laser ablations of obstructing tracheal neoplasms.

Forty patients with obstructing, nonresectable tracheal neoplasms underwent 100 ablations with the neodymium-yttrium-aluminum garnet (YAG) laser. The laser allows bloodless resection and vaporization of tumors. Unlike the carbon dioxide laser, the neodymium-YAG laser can be used with the flexible bronchoscope and has an excellent effect on coagulation. Thirty-four patients had primary lung malignancies (epidermoid in 24); 4 had metastatic malignancies; and 2 had benign lesions. Results have been excellent in 22, fair in 10, and poor in 8. No patient has died or had a deleterious result. Complications have occurred in only 1 of 89 ablations done with the flexible bronchoscope. We believe that the neodymium-YAG laser is effective in opening major tracheal or bronchial obstructions and offers substantial symptomatic improvement in patients who are short of breath. Although this treatment is only palliative, the results have been excellent in more than half of the patients.

Aged↗

PubMed1981

Safety and efficacy of Neodymium-Yag laser photocoagulation: an experimental study in dogs.

Acute and chronic experiments were carried out in 26 beagle dogs to study the safety and efficacy of Neodymium-Yag laser photocoagulation in the treatment of bleeding gastric lesions. Continuous high power (50-60 W) Neodymium-Yag laser photocoagulation applied to the exposed stomach of the dog produced evaporation lesions that reached the muscle layer after six to 10 seconds and caused free perforation after 10 to 12 seconds. The tissue damage caused by these long lasting exposures was closely related to the working distance. Moreover, long pulses of high power photocoagulation were not always effective in stopping experimentally induced gastric bleedings. Short pulses (1/2-1 s) of very high power (60-70 W) caused less tissue evaporation, which reached the muscle layers only after 14 to 18 pulses and caused free perforation after 22 to 24 pulses. The tissue damage was not related to the working distance when short pulses were used. Repeated shots of high power Yag laser radiation always resulted in stopping the experimental bleedings without deep injury. It is concluded that high power Neodymium-Yag laser photocoagulation is safe and may be used with success in the treatment of bleeding gastric lesions if the radiation is performed in shots of short duration (1 s or less). Clinical studies in man are warranted and indicated.

Animals↗

PubMed1999

Side-firing Neodymium:YAG laser prostatectomy.

Not until 1991 did laser therapy for benign prostatic hyperplasia become a feasible option for the practicing urologist. Prior to the development of side firing free beam laser delivery devices contact Neodymium:YAG, laser therapy for BPH was of limited applicability. Since 1991, refinements in laser device technology have allowed the urologist to expand the potential for Neodymium:YAG coagulative prostatectomy. Multiple studies over the past five years have demonstrated equivalence in efficacy and safety to conventional electrocautery TURP. Holmium:YAG laser technology may be a significant advance again on free beam side firing Neodymium:YAG laser prostatectomy.

Humans↗

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↗

PubMed1995

Video-assisted thoracic surgical resection with the neodymium:yttrium-aluminum-garnet laser.

Since January 1991, we have performed 79 video-assisted neodymium: yttrium-aluminum-garnet laser resections for pulmonary nodular or interstitial disease. Pathologic examination demonstrated malignancy in 59 patients (32 primary and 27 metastatic), benign nodules in 11, interstitial processes in seven, and granulomatous disease in two. There were 39 men and 40 women with a mean age of 63.4 +/- 12.5 years. Thirty-nine patients underwent resection with the neodymium:yttrium-aluminum-garnet laser alone and 40 had lesions resected with a combination of laser and endoscopic stapling. Laser excision was performed for lesions deep in the substance of the lung or on its effaced surface; both are locations that make stapling alone difficult. Fifteen of 32 patients with a diagnosis of primary lung malignancy underwent open anatomic resections. Pulmonary reserves of the other 17 patients were inadequate for further resection. Operative time, duration of chest tube placement, length of hospital stay, and complication rate were compared with those for 72 patients undergoing video-assisted thoracic surgical resection of nodules with staplers alone. Although operative time for laser-assisted procedures was longer (p < 0.05), there were no differences in duration of chest tube placement or hospital stay compared with stapled resections. The complication rate for laser-treated cases was not higher than for stapled resections and consisted primarily of air leaks lasting 2 to 7 days. The neodymium:yttrium-aluminum-garnet laser is a safe and precise primary or adjunctive tool for video-assisted thoracic surgical pulmonary resection.

Adult↗

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↗

PubMed1997

Prospective multicenter ProLase II clinical trial of neodymium:yttrium-aluminum-garnet laser prostatectomy.

OBJECTIVES: To assess the clinical efficacy of neodymium:yttrium-aluminum-garnet (YAG) laser coagulation prostatectomy using a broad-angle, divergent-beam, side-firing fiber. METHODS: Eighty adult men with voiding symptoms caused by benign prostatic hyperplasia were enrolled in a prospective multicenter study of free-beam neodymium:YAG laser prostatectomy performed with the ProLase II side-firing delivery fiber. Voiding outcomes were assessed at 3, 6, and 12 months postoperatively. RESULTS: At 1-year follow-up, peak urinary flow rates were increased by 105%, postvoid residual urine volumes had decreased by 38%, and the AUA symptom index had decreased by 60%. Serious treatment-related complications occurred in 3 of 80 patients (3.8%). The reoperation rate through 1-year follow-up was 2.7%. CONCLUSIONS: Neodymium:YAG laser prostatectomy performed with the ProLase II delivery fiber has proven safe and efficacious with durable results through 1 year in the relief of symptomatic bladder outlet obstruction due to benign prostatic hyperplasia.

Aged↗