Bowenoid papulosis of the penis: successful management with neodymium:YAG laser

Bowenoid papulosis of the penis is a recently described entity that clinically resembles benign verruca-like papular lesions but, histologically, it is identical to carcinoma in situ, Bowen's disease or erythroplasia of Queyrat. Although a few cases of spontaneous regression of bowenoid papulosis in men have been reported, conservative therapy, consisting of topical 5-fluorouracil, electrodissection or excision, is recommended. With these treatment modalities recurrences are not uncommon. We report 2 cases of extensive bowenoid papulosis of the penis treated successfully without scarring with the neodymium-yttrium-aluminum-garnet laser.     

Hemangioma of the glans penis. Its therapy by neodymium:YAG laser]

We report the case of a young male patient with a massive cavernous hemangioma of the glans penis that had developed since childhood. The patient complained of pain when standing for long periods and during erections; furthermore its appearance disturbed him for cosmetic reasons. After associated hemangiomas of the genitourinary tract had been excluded by ultrasonography, intravenous pyelogram and cystoscopy, laser coagulation of the hemangioma was performed with a neodymium:YAG laser with the patient under local anaesthesia. The results of this conservative form of therapy show that it represents an alternative to surgical procedures; we recommend laser coagulation as the treatment of choice in patients with penile hemangiomas. The pertinent literature is reviewed.     

Laser lithotripsy with the neodymium YAG laser

Laser-induced shock wave lithotripsy (LISL) with a Q-switched neodymium-YAG laser depends on the generation of a laser-induced breakdown in the fluid surrounding the stone. An oscillating plasma bubble is created, directing shock waves towards the stone. These cavitational effects fragment the calculus into small particles. A new bifunctional laser is introduced: this allows both nanosecond pulses for shock wave generation and disintegration of urinary calculi and millisecond pulses for biliary stones and tissue coagulation. It can be supplied with 320-, 400-, and 600-micron fibers. We have treated 189 ureteric stones in 185 patients with laser lithotripsy utilizing flexible ureteroscopes (n = 26) or rigid ureteroscopes (n = 159). It proved possible to fragment 179 stones into small pieces. In eight patients LISL was not successful. A rigid cystoscope that can be dismantled into an upper and lower hemisheath for the introduction of flexible endoscopes into the ureter without prior dilatation of the ureteral orifice was used in 15 patients.     

Urologic neodymium: YAG laser surgery

The advantages of each of the laser types used in urologic surgery are discussed and evaluated. Use of the Nd:YAG laser in urologic surgery is a recent advancement.     

Treatment of urethral diseases with neodymium:YAG laser

Over a thirty-month period, a wide variety of common urethral problems were treated on an ambulatory basis, with the neodymium:yttrium-aluminum garnet (Nd:YAG) laser. When used discriminately, laser treatment appears to be an effective modality for the management of selected urethral strictures. Thus far, excellent results have been obtained in 30 of 31 cases of short strictures where laser urethrotomy was performed as the first stricture procedure (average follow-up 10 months). Furthermore, in a series of 36 cases of secondary bladder neck contractures, all of the evaluated patients responded well (average follow-up 7 months). Good results were obtained in only 11 of 48 complicated strictures (average follow-up 14 months). However, while most of these extensive strictures were not eradicated, laser therapy generally produced a documented clinical improvement, comparable to urethrotomy or dilatation, in 15 of these cases. A series of 24 condylomata involving the urethra were treated satisfactorily, with no recurrences (average follow-up 13 months). Laser treatment also has been used successfully for the management of several urethral caruncles, urethral polyps, two meatal hemangiomas, one urethral carcinoma, and a distal duplicated urethra. Recently, the Nd:YAG laser has been applied to the prostatic urethra with vaporization of obstructing median bar hyperplasia. Favorable results have been achieved in 5 of 6 cases treated with a newly developed technique that utilizes direct laser contact. Retrograde ejaculation has not been encountered in these patients (average follow-up 6 months). All of these procedures have been accomplished in the office, largely without urethral catheterization. Lidocaine jelly occasionally supplemented with intravenous sedation provided satisfactory anesthesia.     

Renal preservation utilizing neodymium:YAG laser

Six patients with malignancies in a solitary kidney were treated with conservative renal parenchymal-sparing surgery utilizing the Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser. Three patients had transitional cell carcinoma in an upper pole calyx of a solitary kidney. The transitional cell carcinoma was treated definitively by the Nd:YAG laser through a nephroscope prior to partial nephrectomy. The 3 patients have been followed up for twenty-eight, eighteen, and six months, respectively. None of the patients has shown evidence of recurrent cancer on follow-up retrograde ureterograms or on urine cytology obtained from the renal pelves. Three patients with renal cell carcinoma in a solitary kidney had the tumor surgically excised utilizing the Nd:YAG laser in conjunction with standard surgical techniques. All the patients were elderly with compromised renal vasculature that prevented bench surgery with autotransplantation or occlusion of the renal artery. At sixteen, fourteen, and three months, respectively, there is no evidence of recurrent cancer on CAT scans obtained on these patients.     

Transscleral cyclophotocoagulation using a neodymium YAG laser

The effects of a neodymium: YAG laser, working in the free-running mode (1 and 20 millisecond pulses), upon the ciliary body via the transscleral route have been studied using 16 autopsy eyes. The experiments described were designed to find an efficient strategy of transscleral cyclodestruction of the ciliary body. It was found that pulse energies of between 6 and 7 Joules, an exposure duration of 20 milliseconds, and maximal defocusing are optimal. A beam, tangentially oriented and positioned 1/2 to 1 mm posterior to the limbus has a high probability of hitting the ciliary body and damaging the ciliary processes. In these experiments a first generation of contact lenses could not be demonstrated to have an advantageous effect.     

Safety of high-energy neodymium:YAG laser pulses in YAG sclerostomy

YAG sclerostomy was performed in 15 eyes of nine cynomolgus monkeys. Individual pulse energies ranged between 10 and 135 millijoules. Total pulse energy ranged between 2,000 and 36,000 millijoules in order to test the extreme range of energy that might be required. Both acute effects and chronic effects were studied in the corneal endothelium, the lens capsule, the iris, the ciliary body, the retina, and the sclera. Techniques included flat preparations of the corneal endothelium, paraffin sections for light microscopy, and scanning and transmission electron microscopy. Our conclusion is that individual pulse energies of up to 135 millijoules with a total of up to 36 joules of energy are safe in monkey eyes when performing YAG sclerostomy.     

Contact neodymium: YAG laser surgery in gastroenterology

Eighty-eight patients have been successfully treated endoscopically without complications using contact neodymium yttrium aluminum garnet: (YAG) laser probes (endoprobes) for tumors and bleeding and during open surgery (laser scalpel) to perform hepatic and pancreatic resections. The contact probes, made from a synthetic sapphire crystal with its optical properties, geometric design, thermal conductivity, and high melting temperature (2030 degrees C), have proven to be more effective than the current conventional non-contact method of delivering laser energy through a quartz fiber. Advantages include greater precision, sterility, avoidance of the tip melting, and lower neodymium: YAG laser energy required, resulting in reduced tissue damage. The configuration of the probes allows coagulation, cutting, or vaporization, depending on the clinical condition being treated.     

Transscleral cyclocoagulation using a neodymium:YAG laser

A series of pigmented rabbit eyes were treated with pulsed 10 msec (free running mode) neodymium:YAG laser burns to achieve transscleral cyclocoagulation. Grossly evident burns were created in the ciliary body with laser pulses of 1.5 joules of energy. Sustained reduction in intraocular pressure was obtained when 30 such laser burns were made in an eye.     

Contact neodymium: YAG laser surgery in gastroenterology

Summary Eighty-eight patients have been successfully treated endoscopically without complications using contact neodymium yttrium aluminum garnet: (YAG) laser probes (endoprobes) for tumors and bleeding and during open surgery (laser scalpel) to perform hepatic and pancreatic resections. The contact probes, made from a synthetic sapphire crystal with its optical properties, geometric design, thermal conductivity, and high melting temperature (2030 °C), have proven to be more effective than the current conventional noncontact method of delivering laser energy through a quartz fiber. Advantages include greater precision, sterility, avoidance of the tip melting, and lower neodymium: YAG laser energy required, resulting in reduced tissue damage. The configuration of the probes allows coagulation, cutting, or vaporization, depending on the clinical condition being treated.     

Treatment of invasive bladder cancer with a neodymium:YAG laser

In a controlled setting a neodymium:YAG laser is capable of producing a transmural coagulation of the bladder wall without perforation. A total of 21 patients with known muscle-invading bladder cancer underwent treatment with transurethral endoscopic application of neodymium:YAG laser energy. One patient suffered a sigmoid colon perforation that possibly was treatment-related but no other complications were observed. Four of 5 patients with clinical stage B1 and 3 of 6 with stage B2 lesions have had normal post-treatment biopsies. Local tumor control has been achieved in only 1 of 4 patients with a clinical stage C tumor and none of 6 with metastatic cancer, although palliative debulking was accomplished.     

Evaluation of mineral content of dentin treated with desensitizing agents and neodymium yttrium-aluminium-garnet (Nd:YAG) laser

The aim of this study was to evaluate the mineral content of dentin prepared using three different desensitizing agents and the Nd:YAG laser. The occlusal third of the crowns of 30 molar teeth were cut with a slow-speed diamond saw sectioning machine under water cooling. Dentin slabs from the 30 teeth were randomly divided into five experimental groups, each comprising six slabs. The five groups were treated as follows: group A, no treatment; group B, treatment with oxalate-containing desensitizing agent (BisBlock); group C, treatment with resin-based desensitizing agent (Admira Protect); group D, treatment with glutaraldehyde-containing desensitizing agent (Systemp); and group E, irradiation with the Nd:YAG laser (DEKATM ) at 0.40 W. The levels of Mg, P, Ca, K, and Na in each slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analyzed by one-way analysis of variance and the Tukey HSD test. The effect of desensitizing agents and laser irradiation on the dentin surface were evaluated using a scanning electron microscope. There were no significant differences between the groups (p > 0.05). Group E was showed the lowest Ca/P ratio. SEM showed that the resin-based agent occluded the dentinal tubules, the glutaraldehyde-containing agent increased the Ca/P ratio, and Nd:YAG laser irradiation decreased the Ca/P ratio. The mean percentages by weight of Ca, Mg, K, Na and P were not affected by Nd:YAG laser irradiation or any of the desensitizing agents.     

Transscleral neodymium: YAG laser cyclocoagulation for uncontrolled glaucoma

To determine the efficacy and safety of the procedure, we reviewed the records of 25 eyes of 25 patients who had received noncontact transscleral Nd:YAG laser cyclocoagulation for a variety of uncontrolled glaucomas. Thirteen to 35 pulses (mean, 22.7 pulses) had been placed 1 mm to 2 mm behind the limbus with an energy per pulse of 3.4 J to 8.2 J (mean 4.5 J). Follow-up ranged from 6 months to 23 months, with the exception of one eye, which had to be enucleated. Nine of the 25 eyes (36%) required one or two repeat treatments. Twelve (48%) had intraocular pressures at last follow-up of less than 21 mm Hg but greater than 4 mm Hg. Ten eyes (40%) developed moderate to severe pain transiently, and 10 (40%) developed substantial, but transient, inflammation. Transscleral Nd:YAG laser cyclocoagulation appears to be relatively effective and well tolerated.     

Intraocular lens design for the neodymium:YAG laser

Phacoemulsification was performed on both lenses of 24 rabbits. One eye received a lens implant with a convex-plano optic; the fellow eye received an implant with a convex-concave optic which separated the posterior surface of the implant from the posterior capsule by 0.2 mm, 0.3 mm, or 0.4 mm. A YAG laser capsulotomy was performed on all eyes immediately following surgery and an assessment of both microscopic and macroscopic YAG-induced lens damage was made. The meniscus optics with their capsule-implant separation showed significantly less YAG-induced damage than their convex-plano counterparts without this separation. Increasing the amount of capsule-implant separation beyond 0.2 mm did not enhance the degree of protection from YAG-induced damage.     

A new contact neodymium:YAG laser for cyclophotocoagulation

A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.     

Anterior capsulotomy with the neodymium: YAG laser: results and opinions

Three series and a control group of patients have been analyzed to study the early and long-term complications of neodymium: YAG laser anterior capsulotomy. In the author's opinion, the results have been favorable, and the procedure is recommended. It is important that a limited number of punctures be made, especially if there is any delay in surgery.     

Early clinical experience with a new generation Q-switched neodymium: YAG laser

We present early clinical results of Nd:YAG capsulotomy with a new generation Nd:YAG laser unit. We conclude that the new systems are as efficient as their early counterparts in noninvasive capsulotomy.