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PubMed1995

Depth of penetration of the neodymium: yttrium-aluminum-garnet laser in the human prostate and clinical results of high-dose laser energy in 50 patients.

We evaluated the treatment of the human prostate with the Nd:YAG laser using a Cytocare Prolase II fiber. We utilized this first in 12 patients prior to radical prostatectomy and then appropriately serially sectioned the prostate to measure the depth of penetration. The studies clearly revealed that 60 W of power and 60 s of pulse duration gave the most consistent depth of penetration in the human prostate model. This depth of penetration averaged 2 cm in the glands that were removed. At the same time there was absolutely no evidence of damage to the neurovascular bundle or to the capsule of the prostate using the above-mentioned dosimetry regime. This study was then transferred to our initial experience in treating 50 patients with benign prostatic hypertrophy and obstructive voiding symptoms. The first 25 patients were also treated with so-called spot radiation of the prostate, whereas the second 25 patients were treated by total photoirradiation of all visible endoscopic tissue. The results reveal that both groups of patients had a fairly highly satisfactory result as measured objectively with American Urological Association (AUA) symptom scores and uroflow studies. In the latter group (photoirradiation of all visible endoscopic tissue) a significantly higher dose of laser energy was utilized and a smaller failure rate was noted on a long-term basis in patients who subsequently came to transurethral resection of the prostate (TURP) because of failure of the laser procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Free-beam and contact laser ablation of benign prostatic hyperplasia with the KTP/Nd:YAG laser: efficacy and versatility.

This report details the use of the free-beam Nd:YAG laser alone and in combination with contact vaporization for treatment of benign prostatic hyperplasia. Improvements in urinary flow rates and symptoms were noted along with a high degree of patient satisfaction. The portable KTP/Nd:YAG laser wavelengths and the variety of optical fiber configurations provide versatility to the surgeon. This study further supports the use of laser energy as a means to treat urinary outflow obstruction from prostatic enlargement in selected cases.

Aged↗

PubMed1984

Neodymium YAG laser effects on rabbit lenses. A scanning electron microscopic investigation using Q-switched and mode-locked lasers.

The immediate and long-term effects of Q-switched and mode-locked neodymium (Nd) yttrium-aluminum-garnet (YAG) lasers on the fine structure of lens fibers were studied with stereomicroscopic and scanning electron microscopic methods. This study shows that both laser systems produced very restricted lesions that, at a 1-h survival time, were characterized by an empty central hole surrounded by a thin amorphous wall. Fibers adjacent to the hole looked normal, apart from some compression in the immediate vicinity of the hole. At medium and long-term survival times the empty bubbles now appeared to be filled with a crystal-clear amorphous mass. The wall surrounding the empty lesions had disappeared, and at medium survival times adjacent fibers incidentally showed fiber alterations like local swellings and microplicae. At 180 days the fibers surrounding the central mass showed numerous swellings, microplicae and confluence of fibers. These fiber alterations are also seen in different types of cataracts. Thus, short-pulsed laser lesions may act as cataractogenic centers.

Animals↗

PubMed2004

[Repigmentation of persistent laser-induced hypopigmentation after tattoo ablation with the excimer laser].

Hypopigmented skin developed following tattoo removal with the Q-switched Nd:YAG laser. The hypopigmented area remained unchanged for over 4 years, until the use of the 308-nm xenon-chloride excimer laser induced a significant repigmentation in 40 sessions over 14 months. The excimer laser has the potential to influence the reduced activity of the melanocytes, as demonstrated with electron microscopy.

Adult↗

PubMed1992

Characterization of ultraviolet laser-induced autofluorescence of ceroid deposits and other structures in atherosclerotic plaques as a potential diagnostic for laser angiosurgery.

Unstained frozen sections of normal and atherosclerotic human aorta and coronary artery were examined using histochemical and fluorescence microscopic techniques to identify the structures responsible for autofluorescence under 351 to 364 nm laser excitation. These structures included elastin and collagen in normal and atherosclerotic specimens, calcium deposits in calcified plaques, and granular or ring-shaped deposits histochemically identified as ceroid found in both calcified and non-calcified plaques. Qualitatively, both the color and intensity of ceroid autofluorescence differed greatly from that of elastin or collagen. The emission spectra of elastin, collagen, and ceroid were examined by microscopic spectrofluorimetry, and were found to differ significantly as well. When compared with spectra of elastin and collagen, spectra of ceroid were broader, shifted to the red, and were somewhat resistant to bleaching. We conclude that detection of laser-induced ceroid autofluorescence may aid in identifying plaques for laser ablation.

Angioplasty, Laser↗

PubMed2006

A control-matched comparison of laser epithelial keratomileusis and laser in situ keratomileusis for low to moderate myopia.

PURPOSE: To compare the visual and refractive outcomes of laser epithelial keratomileusis (LASEK) and laser in situ keratomileusis (LASIK) for the treatment of low to moderate myopia. DESIGN: Retrospective, nonrandomized, control-matched study. METHODS: The charts of 2257 eyes that underwent LASEK or LASIK treatment were reviewed. Patients who were 21 years of age or older having between -0.75 and -6.00 diopters (D) of myopia with up to -2.25 D of astigmatism were included. One hundred twenty-two LASEK-treated eyes were matched with 122 LASIK-treated eyes having preoperative spheres, cylinders, and spherical equivalent (SE) within +/-0.50 D. Both groups had similar preoperative best spectacle-corrected visual acuity (BSCVA), laser platform, and follow-up durations. Outcome measures were visual and refractive results. RESULTS: Preoperatively, the mean SE was -3.50 +/- 1.40 D for LASEK and -3.50 +/- 1.42 D for LASIK (P = .59). Postoperatively, the mean logarithm of minimum angle of resolution (logMAR) uncorrected visual acuity (UCVA) was 0.01 +/- 0.08 (20/21) for LASEK and 0.06 +/- 0.12 (20/23) for LASIK; the mean SE was -0.15 +/- 0.40 D for LASEK and -0.37 +/- 0.45 D for LASIK; and the mean logMAR of BSCVA was -0.03 +/- 0.06 (20/19) for LASEK and -0.02 +/- 0.05 (20/19) for LASIK. No eye lost 2 or more lines of BSCVA in both groups. CONCLUSIONS: Slight differences in the visual and refractive results between LASEK and LASIK were observed, despite the use of the same nomogram. Both procedures were safe, effective, and predictable. Nomogram adjustment may be necessary for LASIK surgeons adopting surface ablation.

Adult↗

PubMed2005

Influence of laser in situ keratomileusis and laser epithelial keratectomy on patients' reading performance.

PURPOSE: To evaluate the influence of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) on reading performance regarding reading acuity, reading speed based on print size, maximum reading speed, and critical print size. SETTING: Department of Ophthalmology, University of Vienna, Vienna, and Auge-und-Laser, Medicent Baden, Austria. METHODS: Fifty-two eyes of 34 patients (26 eyes per group) were studied. Best corrected LogMAR visual acuity (Early Treatment Diabetic Retinopathy Study charts), reading acuity, and reading speed were tested monocularly before LASIK or LASEK and 3 weeks after surgery. Reading acuity (LogRAD) and reading speed were determined with the standardized Radner reading charts. RESULTS: Preoperatively, the distance visual acuity and reading acuity were comparable between the LASIK and LASEK patients. Reading speed measurements also showed no statistical difference. Three weeks after refractive surgery, no statistically significant differences in the preoperative measures and between the 2 surgical procedures could be found in any tested parameters. The mean distance visual acuity was LogMAR -0.02 +/- 0.06 (SD) (LASIK) and LogMAR -0.05 +/- 0.07 (LASEK). The mean reading acuity was LogRAD 0.00 +/- 0.12 (97.7% of LogMAR) (LASIK) and LogRAD 0.04 +/- 0.16 (93.7% of LogMAR) (LASEK). The mean maximum reading speed was 235 +/- 35 words per minute (LASIK) and 240 +/- 37 words per minute (LASEK), and the mean critical print size was at LogRAD 0.48 +/- 0.19 (LASIK) and 0.49 +/- 0.17 (LASEK). CONCLUSIONS: In a standardized reading test setting, no significant effects of LASIK and LASEK on individual reading performance could be evaluated. This indicates that patients can expect to retain their normal visual function after refractive surgery with these 2 procedures under full light conditions.

Adult↗

PubMed2006

Effect of laser in situ keratomileusis and laser-assisted subepithelial keratectomy on retinal nerve fiber layer thickness.

PURPOSE: To evaluate and compare the influence of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) on the peripapillary retinal nerve fiber layer (RNFL) thickness. SETTING: Observational case series. METHODS: Twenty nonglaucomatous patients with mild to moderate myopia were included. One eye in each patient was randomly selected to have LASIK (Group 1, n = 20), and LASEK was performed in the fellow eye (Group 2, n = 20). The RNFL thickness measurements were performed using optical coherence tomography (OCT) preoperatively and 1 day and 1 month postoperatively. The RNFL thickness parameters were compared using repeated-measures 1-way analysis of variance (ANOVA) followed by multiple comparison tests in both groups. The main outcome parameter was RNFL thickness as determined by OCT before and after LASIK and LASEK. RESULTS: The mean age of the patients was 21 years +/- 3.2 (SD). The mean preoperative spherical equivalent was -4.23 +/- 1.71 diopters (D) in Group 1 and -4.16 +/- 1.68 D in Group 2. The mean ablation depth was 73.35 +/- 27.85 microm and 66.35 +/- 23.64 microm in groups 1 and 2, respectively. In Group 1, the mean average RNFL thickness, inferior average, superior average, temporal average, and nasal average were 98.2 +/- 5.6 microm, 128.6 +/- 11.9 microm, 120.38 +/- 10.2 microm, 65. 8+/- 7.1 microm, and 80.5 +/- 18.8 microm, respectively. None of the RNFL thickness parameters or RNFL ratios were found to have a significant change after surgery. In Group 2, the average RNFL thickness, inferior average, superior average, temporal average, and nasal average were 98.47 +/- 5.9 microm, 128.38 +/- 14.3 microm, 125.1 +/- 8.8 microm, 66.4 +/- 8.2 microm, 73.6 +/- 15.8 microm, respectively. No significant change was observed in any of the parameters following surgery. No significant alterations were noted in the RNFL parameters following LASIK or LASEK. CONCLUSIONS: Laser in situ keratomileusis and LASEK did not significantly affect the RNFL thickness parameters postoperatively.

Adult↗

PubMed2006

Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities.

PURPOSE: To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus (<350 microm) and corneal ectasia after laser in situ keratomileusis (LASIK) and to treat anterior stromal opacities. SETTING: Ophthalmology Department, School of Medicine, Gazi University, Ankara, Turkey. METHODS: Thirteen eyes (5 keratoconus, 3 macular dystrophies, 1 post-LASIK ectasia, 1 post-LASIK interstitial keratitis, 3 post-herpetic keratitis sequelae) of 13 patients were included in this prospective study. The treatment group was divided into corneal ectasia and stromal opacity groups. A donor stromal button approximately 350 microm thick received a 100 microm excimer laser ablation on the endothelium. The remaining cornea (epithelium, Bowman's membrane, and stroma) was punched with a 7.5 or 7.7 mm trephine. After transepithelial ablation of the host cornea to 200 mum thickness, the corneal button was sutured with interrupted 10-0 monofilament nylon. Sutures were removed between 3 months and 6 months postoperatively. Preoperative and postoperative simulated keratometric cylinders and corneal thickness values were compared using the Wilcoxon signed rank test. The postoperative spherical equivalent refraction and best spectacle-corrected visual acuity (BSCVA) between the groups were compared using the Mann-Whitney U test. RESULTS: The mean follow-up was 27.6 months +/- 8.3 (SD). All patients gained 2 lines or more of BSCVA, and no patient lost a line. The mean corneal thickness was 381.2 +/- 88.2 microm preoperatively, which significantly increased to 534.9 +/- 96.6 microm postoperatively (P < .05). The mean preoperative simulated keratometric cylinder was 7.44 +/- 7.18 diopters (D); postoperatively, it decreased to 2.61 +/- 1.73 D (P < .05). There was no significant difference in postoperative spherical equivalent refraction or BSCVA between the groups (P > .05). CONCLUSIONS: This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.

Adult↗

PubMedDate not supplied

Laser versus laser plus afterloading with iridium-192 in the palliative treatment of malignant stenosis of the esophagus: a prospective, randomized, and controlled study.

Thirty-nine patients with malignant stenoses of the esophagus (22 adenocarcinomas, 17 squamous cell carcinomas) were treated either with Nd:YAG laser recanalization alone (N = 20) or with laser recanalization and subsequent endoluminal afterloading irradiation with iridium-192 at a dose of 3 x 7 Gy (6 x 7 Gy). Squamous cell carcinoma patients in the afterloading group showed a prolonged dysphagia-free first interval (65 vs. 30 days, p less than 0.03), while patients with an adenocarcinoma did not share this benefit, and had a need for more frequent endoscopic procedures (p less than 0.05). The complication of esophagitis was only seen following afterloading treatment (21%, N = 4). Re-stenosis occurred in all patients. Neither the duration of relative dysphagia nor survival time was prolonged after endoluminal irradiation in adenocarcinoma or squamous cell carcinoma patients. After prior laser recanalization, palliative afterloading treatment with iridium-192 would seem helpful only in cases of squamous cell carcinoma with a high performance status with the aim of prolonging the first dysphagia-free interval.

Adenocarcinoma↗

PubMed1986

Percutaneous laser thermal angioplasty: initial clinical results with a laser probe in total peripheral artery occlusions.

A metal-tipped laser fibre was used during percutaneous angioplasty of femoral/popliteal or iliac artery occlusions in 56 patients. Primary success was achieved in 50 (89%) of these total occlusions, providing a channel for subsequent balloon dilatation. Before the procedure, 18 lesions had been judged untreatable by conventional angioplasty and four of the six failures were in these. Complications directly attributable to the laser probe were one case of vessel perforation and two cases of entry into vessel walls; these had no sequelae. Other acute complications were a distal thrombosis in a non-heparinised patient, requiring local streptokinase treatment, and two reocclusions and one transient peripheral embolic episode in the first 24 hours. The laser probe technique has potential for increasing the proportion of patients suitable for angioplasty.

Aged↗

PubMed1999

Fingerprint patterns from laser-induced azido photochemistry of spin-labeled photoaffinity ATP analogs in matrix-assisted laser desorption/ionization mass spectrometry.

The photochemical reaction of azide derivatives induced by ultraviolet (UV) laser in matrix-assisted laser desorption/ionization mass spectrometry (MALDI) is reported. A novel synthesized class of azide aromatic derivatives, spin-labeled photoaffinity non-nucleoside adenosine triphosphate (ATP) analogs which are useful probes in study of muscle contraction mechanism, is used in this investigation. In the negative ion MALDI spectra of these ATP analogs, "fingerprint" peaks corresponding to [M - 10 - 1]-, [M - 12 - 1]-, [M - 16 - 1]-, [M - 26 - 1]-, [M - 28 - 1]-, [M - 41 - 1]-, and [M - 42 - 1]- were observed with relative intensities depending on the MALDI matrix. Only the [M - 16 - 1]- is present in the similar mass spectra of the analog in which the azido group is replaced by a hydrogen. A model is suggested for the photochemical reactions of azide derivatives under UV laser irradiation. The photoreaction fingerprint information is diagnostically useful in characterization of azido compounds, especially for spin-labeled photoaffinity non-nucleoside ATP analogs.

Adenosine Triphosphate↗

PubMed1997

Laser photodissociation of insulin ions generated by matrix-assisted laser desorption.

A novel method for studying the ionization step of matrix-assisted laser desorption/ionization (MALDI) is demonstrated. A 193-nm pulse from an ArF excimer laser is used to photodissociate a portion of a plume of insulin ions generated by MALDI. Laser photodissociation (LPD) creates a "hole", i.e., a negative spike in the insulin peak in the time-of-flight (TOF) mass spectrum. The position of the hole in the mass spectrum provides useful measurements of the characteristics (position, time, and velocity) of insulin ions shortly after their creation. Although the performance of the method can be further improved, the data obtained could be used to refine our current understanding of MALDI and to improve the resolution of MALDI-TOFMS.

Insulin↗

PubMed2005

Comparative evaluation of diode laser trabeculoplasty vs frequency doubled Nd : YAG laser trabeculoplasty in primary open angle glaucoma.

AIMS: To evaluate the efficacy of diode laser trabeculoplasty (DLT) and frequency doubled Nd : YAG laser trabeculoplasty (YLT) in primary open angle glaucoma (POAG). METHODS: A total of 52 eyes of 35 patients with POAG were included. In all, 25 eyes underwent DLT (Group I) and 27 eyes underwent YLT (Group II). IOP, gonioscopy and visual fields were evaluated before and 3, 6, and 9 months and 1 year after the laser. An IOP<21 mmHg without medications or a decrease in the number of glaucoma medications with no progression of disc and field changes was considered a success. RESULTS: The mean age of patients in Group I was 57.72+/-8.1 years and the patients in Group II had a mean age of 59.85+/-7.76 years. The mean prelaser IOP was 24.93+/-1.49 mmHg and 25.36+/-1.57 mmHg. The mean IOP after DLT at 12 months follow-up was 18.0+/-0.93 mmHg and after YLT was 18.6+/-1.52 mmHg. The reduction of IOP was statistically significant in both the groups at 3, 6, 9, and 12 months (P<0.001), however there was no significant difference between the two groups. Success rates in both groups were similar, 92% in Group I and 92.6% in Group II. CONCLUSIONS: DLT and Fd YLT are equally effective in controlling IOP in eyes with POAG.

Adult↗

PubMedDate not supplied

[Excimer laser subepithelial ablation (ELSA) or laser epithelial keratomileusis (LASEK) - a new kerato-refractive procedure for myopia. Surgical technique and first clinical results on 24 eyes and 3 months follow-up].

BACKGROUND: Laser epithelial keratomileusis (LASEK) is a new keratorefractive surgical procedure to treat myopia and possibly other refractive errors, which combines the advantages while eliminating the disadvantages of both PRK (pain, corneal haze) and LASIK (flap complications, interface complications). Our results with LASEK are very promising and because this technique is currently not very popular in Germany we here with introduce the surgical technique and our first clinical results. PATIENTS AND METHODS: We treated 24 eyes (18 patients) by LASEK. The preoperative myopia was between - 1.50 and - 6.00 D with an astigmatism less than 1.00 D. Surgery starts with an incision in the epithelium by using a special microtrephine. After the application of 20 % ethanol for 20 seconds a hinged epithelial flap is created and the laser ablation performed with a Keracor 117 excimer laser. Finally, the epithelial flap is repositioned and secured using a bandage contact lens and artificial tears for 3 days. RESULTS: In all eyes the creation of the epithelial flap and its repositioning presented no problems. None of the eyes showed any postoperative epithelial instability. However, one eye lost the contact lens and the epithelial flap during the first postoperative day. Postoperatively, none of the patients complained of significant pain; however, the contact lens caused some foreign body sensation. After 3 months all eyes were within +/- 1.0 D and 20/24 eyes (84 %) within +/- 0.50 D of emmetropia (spherical equivalent). None of the eyes showed significant haze. CONCLUSIONS: Although, the number of treated eyes is small and the postoperative follow-up is short LASEK seems to be an effective and safe procedure for the treatment of myopia.

Adult↗

PubMed2004

[Laser in situ keratomileusis with a flying-spot excimer laser and a carriazo-barraquer microkeratome - outcomes after 6 months].

PURPOSE: To evaluate safety, efficacy, predictability and refractive stability of LASIK, using a flying-spot excimer laser, 91 eyes were examined during a 6-months follow-up. PATIENTS AND METHODS: Consecutively, 91 eyes were enrolled in the study, each eye previously underwent LASIK with the ESIRIS excimer laser (ESIRIS, supplier: eye-tech-solutions Schwind, Kleinostheim, Germany). 91 myopic eyes (mean preoperative refraction: - 5.4 D, range: - 3 to - 13.3 D, astigmatism: - 1 D, range: 1.3 to 3.5 D) were included. A full ophthalmological examination was performed during the first week, 1, 3 and 6 months postoperatively. RESULTS: 26 % of all eyes achieved an uncorrected visual acuity of 0.8, 35 % of 1.0 and 5 % 1.2 6 months postoperatively. 23 % of the eyes lost 1 line of best spectacle-corrected visual acuity (BSCVA), 25 % gained one or more lines of BSCVA. Refraction of 90 eyes were within +/- 1 D of emmetropia 6 months postoperatively. There was no change in spherical equivalent within the interval of 6 months, all eyes were within +/- 0.5 D. CONCLUSION: LASIK with the ESIRIS excimer laser was an effective and safe option with good stability and predictability within the specified interval.

Adult↗

PubMed2003

Non-ablative scar revision using a long pulsed frequency doubled Nd:YAG laser.

OBJECTIVE: Unsightly scars often are the only reminder of a previous surgical or traumatic wound. Surgical or ablative scar revision is sought by patients, sometimes unnecessarily. When the aesthetic drawback is mainly a result of hypervascularity or hyperpigmentation, these problems can be specifically targeted with a wavelength that is well absorbed by the two above mentioned chromophores. Some degree of epidermal tightening can also be achieved, which is sometimes useful in slightly atrophic scars. The average improvement after 2-3 sessions was 81% (75%-100%) clearance, as judged by an independent observer who reviewed pre- and post-treatment photographs. No undesired effects were reported. All our patients were satisfied and required no further treatment. METHODS: Selective photothermolysis by means of a long pulsed frequency doubled Nd:YAG laser (DioLite 532, IRIDEX Corporation, Mountain View, CA, USA) was used to eliminate the unsightly vascular and pigmented components of 23 mature scars (scars older than 2 years) in 22 consecutive patients. Energy densities of 17-22 j/cm2 were used with a 500 micron spot, or 65-90 j/cm2 with a 200 micron spot. RESULTS: overall scar clearance averaged 81% after 2.4 treatments. Facial scars showed the best clearance averaging 94% after 2 treatments. Inframammary scars were the most difficult to clear averaging 46%. Postoperative undesired effects were immediate erythema and swelling that subsided within 2-10 hours and microcrusting on 19/22 (88%) patients that resolved within one week. No other temporary or permanent undesired effects such as purpura, hypo- or hyperpigmentation were noticed, even in patients with darker skin types.

Adolescent↗

PubMed2001

Changes in relative light fluence measured during laser heating: implications for optical monitoring and modelling of interstitial laser photocoagulation.

Dynamic changes in internal light fluence were measured during interstitial laser heating of tissue phantoms and ex vivo bovine liver. In albumen phantoms, the results demonstrate an unexpected rise in optical power transmitted approximately I cm away from the source during laser exposure at low power (0.5-1 W), and a decrease at higher powers (1.5-2.5 W) due to coagulation and possibly charring. Similar trends were observed in liver tissue, with a rise in interstitial fluence observed during 0.5 W exposure and a drop in interstitial fluence seen at higher powers (1-1.5 W) due to tissue coagulation. At 1.5 W irradiation an additional, later decrease was also seen which was most likely due to tissue charring. Independent spectrophotometric studies in Naphthol Green dye indicate the rise in fluence observed in the heated albumen phantoms may have been primarily due to light exposure causing photobleaching of the absorbing chromophore. and not due to heat effects. Experiments in liver tissue demonstrated that the observed rise in fluence is dependent on the starting temperature of the tissue. Correlating changes in light fluence with key clinical endpoints/events such as the onset of tissue coagulation or charring may be useful for on-line monitoring and control of laser thermal therapy via interstitial fluence sensors.

Animals↗