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At least 649 records · Page 36Linked to original sources
PubMed1992

Laser microsclerostomy for primary open angle glaucoma: a review of laser mechanisms and delivery systems.

A number of different lasers and delivery systems are currently used in experimental sclerostomy procedures. These are discussed with reference to their performance in terms of cutting accuracy and trauma to the adjacent tissues. Lasers emitting wavelengths close to the absorption peaks of water in the mid-infrared region and organic polymers in the far ultraviolet region have a short absorption pathlength in the sclera and produce the least adjacent thermal tissue trauma. These ablating lasers cannot be delivered gonioscopically, and contact endoscopic techniques trap hot expanding gases within the forming sclerostomy channel causing secondary thermal and mechanical damage. Optimal results should be obtained using an ablating laser delivered either through an open mask or a modified endoscopic system incorporating an adequate exhaust mechanism.

Endoscopy↗
PubMed2000

Quantitation of mRNA expression in glomeruli using laser-manipulated microdissection and laser pressure catapulting.

BACKGROUND: Laser-manipulated microdissection (LMM) is a method to cut out a single cell or limited tiny region from a specimen under microscopic observation by a laser beam. Laser pressure catapulting (LPC) is a method to push up and collect samples that were microdissected using a strong laser. METHODS: To induce experimental glomerulonephritis, anti-Thy1.1 monoclonal antibody (OX-7) was injected intravenously into rats. Control and disease model kidneys were obtained. Six-micrometer thick cryostat sections were mounted onto a 1.35 microm thin polyethylene membrane. Ten glomeruli were collected from 6 microm frozen sections of rat kidney by LMM and LPC. Isolated glomeruli were used to quantitate the expression of mRNA by real-time polymerase chain reaction (PCR). RESULTS: Transforming growth factor-beta1 (TGF-beta1) mRNA was not detected in glomeruli isolated by the LMM and the LPC methods on day 0, although G3PDH mRNA was measurable in the same samples. On day 7 after the treatment with OX-7, the ratio of TGF-beta1/G3PDH mRNA was 1.89 +/- 0.96 (N = 6). CONCLUSIONS: We established methods to isolate glomeruli from standard histochemical specimens by LMM and LPC, and to quantify mRNA expression in the targeted glomeruli using real-time PCR. We confirmed the up-regulation of TGF-beta1 mRNA expression in isolated glomeruli from frozen sections of the anti-Thy1.1 glomerulonephritis model.

Animals↗
PubMed1999

Laser hair removal: a review and report on the use of the long-pulsed alexandrite laser for hair reduction of the upper lip, leg, back, and bikini region.

BACKGROUND: The mechanism and permanence of laser-assisted hair removal remains a formidable task in the medical community. OBJECTIVE: The purpose of this study was to determine the safety and long-term efficacy of the long-pulsed or normal mode alexandrite infrared laser for hair depilation. METHODS: Beginning in October 1996, a total of 31 anatomic sites on 22 patients ranging in age from 25 to 59 years (mean 42 years) were evaluated to assess hair removal. Treatment sites included 17 upper lips, 9 legs, 2 backs, and 3 bikini regions. Eligible patients were of Fitzpatrick skin types I-III. Patients were treated using the long-pulsed alexandrite infrared laser at 755 nm, single-pulse technique, 10 mm spot size, 10% overlap, pulse durations of 5, 10, and 20 msec, and a fluence of 20 J/cm2. Subjective patient improvement and objective, blinded graded improvement was assessed at 1, 2, 3, and 6 months. RESULTS: Objective blinded grading at 6 months revealed that hair reduction varied both with the pulse duration and anatomic location. Maximum reductions observed were 40%, 56%, 50%, and 15% for the lip, leg, back, and bikini areas, respectively. Upper lip hair reduction increased from 40% to 54% at 6 months when a second treatment was performed 8 weeks after the initial treatment. CONCLUSION: The long-pulsed alexandrite laser is safe and effective in reducing hair growth. Treatment efficacy varies with the anatomic location, pulse duration, and number of treatments. A single-pulse technique utilizing a 10 msec pulse duration at 20 J/cm2 produced the greatest hair reduction. No permanent adverse effects occurred on skin types I-III at the parameters tested.

Adult↗
PubMed2003

Laser treatment with a 1064-nm laser for lower extremity class I-III veins employing variable spots and pulse width parameters.

BACKGROUND: The long-pulsed 1064-nm Nd:YAG laser (employing varying spot sizes, pulse widths, and fluences) has gained popularity for treating lower extremity blue and red vessels that are less than 4 mm in diameter. OBJECTIVE: To evaluate the efficacy of high-power 50-ms 1064 Nd:YAG laser in the treatment of class I-III lower extremity vessels. METHODS: Ten female patients (mean age of 39 years) had a 5-cm2 area of veins measuring 0.2 to 3 mm in diameter treated with up to three treatment sessions using a new 1064 Nd:YAG laser, with the end point being 100% vessel clearing after three treatments. Red vessels were treated with a spot size of 1.5 mm, a fluence of 400 to 600 J/cm2, a pulse width of 30 to 50 ms; blue vessels of 1 to 3 mm were treated with a spot size of 3 mm, a fluence of 250 to 370 J/cm2, and a pulse width of 50 to 60 ms. Macrophotographic imaging evaluations by blinded observers using a quartile scale and a patient satisfaction scale were employed to evaluate results. RESULTS: At month 3 after the final treatment session, 20% of all vessel types had 50% to 75% improvement. Equal clearing was noted for blue and red vessels. At month 6, 80% of patients had a greater than 75% clearing. Ninety percent of patients were highly satisfied with the treatment results at 6 months. CONCLUSION: By varying spot size, fluence, and pulse duration, a long-wavelength 1064-nm Nd:YAG laser can achieve excellent results for treating both blue and red lower extremity vessels that are less than 3 mm in diameter.

Adult↗
PubMed2003

Endovenous laser surgery of the incompetent greater saphenous vein with a 980-nm diode laser.

BACKGROUND: In recent years, the minimal endoluminal invasive alternatives against surgical ligation and stripping for the treatment of incompetent greater saphenous vein (GSV) have been explored. Endovenous laser surgery is one of these endoluminal alternatives, and its clinical results are being reported at up to 3 years. OBJECTIVE: To evaluate the safety and efficacy of a 980-nm diode laser for the elimination of the incompetent GSV. METHOD: Fifteen limbs in 12 patients with incompetent GSV were treated via an endovenous route with a 980-nm laser under local anesthesia in an outpatient setting. The effects were evaluated clinically along with duplex ultrasound at 1, 4, and 12 weeks after the treatment to determine efficacy and possible complications. RESULTS: Complete occlusion and retraction of treated GSV in all patients were observed during the 12 weeks of the postoperative period. There have been no significant complications to be concerned. CONCLUSION: The endovenous 980-nm diode laser surgery is a relatively simple, safe, office-based procedure that is expected to promise favorable results while a long-term follow-up is awaited.

Adult↗
PubMed2002

Contrast-echocardiography: confirmation of patency of laser channels after transmyocardial laser revascularization.

AIMS: Apart from casuistic autopsy results there is no long-term evidence for channel perfusion after transmyocardial laser revascularization in humans. METHODS AND RESULTS: Fifteen consecutive patients aged 63+/-17 years were investigated 71+/-15 days after coronary artery bypass surgery and/or transmyocardial revascularization with 13-37 (20+/-5) channels (CO(2) laser, 40 J/pulse). Echocardiography was performed after injection of 6 ml echo contrast medium into left ventricular cavity and after injection of 3 ml contrast medium into the left main coronary artery. In five patients with additional bypass surgery to the same region, we also injected 3 ml contrast medium into bypass graft. We could prove in 10 of 15 patients (67%) one or two laser channels in the apical left ventricular myocardium. Channels were perfused exclusively during systole. During following heart cycles myocardium was opacified up to a mean width of 1.4+/-0.4 cm, a mean depth of 0.71+/-0.1cm, and a mean area of 1.0+/-0.6 cm(2). Contrast medium was washed out via coronary venous system in 9+/-8 systoles. CONCLUSION: This is the first clinical evidence of long-term laser-channel patency in humans showing perfused myocardium via left ventricular cavity.

Contrast Media↗
PubMed1993

Sutureless laser-welded anastomosis of the femoral artery and vein in rats using CO2 and Nd:YAG lasers.

In a comparative study, it was demonstrated that sutureless, laser-welded, end-to-end anastomoses in the rat femoral artery and vein are feasible, using either CO2 or Nd:YAG laser. Conventional microsurgical suture anastomoses served as the controls. Patency rates in experimental animals and controls were equal (96 to 100 percent). No aneurysms were observed. For successful laser welding, the anastomosis must be completely tension-free. In arteries, this was accomplished only by interposition of a graft from the contralateral artery. The absence of any foreign-body reaction and the saving in operative time support the use of sutureless laser welding.

Anastomosis, Surgical↗
PubMed1995

[Suitability of various lasers for interventions from the tympanic membrane to the foot plate (Er:YAG, argon, CO2 s.p.--, Ho:YAG laser].

The Erbium:YAG-laser is a good tool for microresection of bone and soft tissue from the ear drum, to the ossicles and extending to the footplate. The mechanism of ablation is based on the fact that the emission of infrared light is of the same wavelength at which water has its peak of optimal light absorption. 14% of bone is water, just sufficient force for ablation. At 50 mJ impulses the temperature in the centre stays below the coagulation point. 500 impulses of 50 mJoule definitely remain below the acoustic risk. In 44 guinea pigs 500 x 50 mJ caused a temporal threshold shift of maximal 38 dB at 2000 cps which recovered after 90-135 min. In 60 tympanoplasties neither tinnitus nor audiological side effects of the laser application were measured. The ear drum is perforated by 1 (-3) impulses. This can be done even in children after superficial anaesthesia (2% pantocaine drops) to drain the middle ear. The laser perforation of 0.3 mm [symbol: see text] will close after a day and has to be re-opened in the office to avoid tubes. We do not yet know how often general anaesthesia and removal by suction of too viscous mucus remain nevertheless necessary. With the Er:YAG laser parts of the ossicles can be cut out of the intact chain, without contact and trauma, nearly without loss of bone tissue. This allows better radicality in removing cholesteatomas or scars with less destruction. 500 impulses of 50 mJ ablate 32 mg of bone, i.e. the weight of an incus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

[Measuring corneal thickness in photo-keratectomy with a reflectometry incorporated into the laser beam of the excimer laser].

PURPOSE: To integrate a newly developed OLCR instrument into the optical system of the excimer laser. The instrument is designed to perform corneal pachymetry before, during, and after corneal photoablation and thus allow for a precise and continuous on-line measurement of the corneal photoablation process. METHODS: The conditions required to integrate the OLCR instrument into the excimer laser optics were investigated. With a technical setting providing on-line data of corneal thickness, three groups of 8-10 corneae received central keratectomies of 27 (group 1), 82 (group 2) and 163 (group 3) microns calculated central depth and 7.38 mm diameter. All measurements were performed with OLCR and ultrasound. RESULTS: The OLCR instrument was coupled into the optical system of the excimer laser and a useful signal obtained at SLD power levels of 40 microW incident on the cornea. Individual corneal thickness measurements were obtained before, during and after the photoablation procedure. In group 1, the ablation was 50.3 (40-68) microns measured with ultrasound and 30.2 (27-38) microns measured with OLCR. In group 2, the ablation was 101.1 (80-113) microns measured with ultrasound and 93.3 (76-109) microns measured with OLCR. In group 3, the ablation was 210.6 (190-227) microns measured with ultrasound and 188.4 (181-197) microns measured with OLCR. The precision (standard deviation) for measurements of individual corneas was 1-2 microns with OLCR and up to 12 mm in Ultrasound measurements. CONCLUSION: With this interferometric method, continuous, non-contact measurement of corneal thickness before, during and after excimer laser photoablation were performed. By establishing a feed-back control between the pachymetric measurements and the photoablation process, the precision of excimer ablation may possibly be further increased.

Animals↗
PubMed2000

Dark skin tissue reaction in laser assisted hair removal with a long-pulse ruby laser.

BACKGROUND: Photo-epilation has become an accepted modality for the removal of unwanted hair. However, adverse effects may occur in darker skin patients. Treatment with the ruby laser is generally advised for skin types I-III. Treatment of over 3000 patients (skin types I-III) in our clinic has resulted in a minimal percentage (approximately 3%) of adverse effects. Increasing pulse duration should allow the epidermis to cool and thus minimize thermal damage so that treatment can be extended to dark skin patients. OBJECTIVES: The purpose of our study was to compare tissue reaction in dark skin patients (skin type IV) after treatment with a long-pulse (20 msec) ruby laser and compare the reaction with a 1 msec ruby laser treatment. RESULTS: Hair removal efficacy was determined to be similar with both pulse durations, but tissue reaction was more severe, including eschar and hypopigmentation, following treatment of dark skin patients with the 1 msec protocol. Increasing the pulse duration to 20 msec appears to result in safe and efficacious ruby laser treatment even for darker skinned patients.

Hair Removal↗
PubMed1999

Laser-assisted autologous hair transplantation with the Er:YAG laser.

Autologous hair transplantation has become an established therapy for irreversible alopecia. With the advent of CO2 lasers, new procedures have developed. However, CO2 lasers are associated with some disadvantages, and the introduction of the erbium YAG laser has led to further improvements. A case illustration of this technique is given here, and a study of 50 patients has been initiated to further evaluate the potential of this laser.

Alopecia↗
PubMed1993

Comparison between laser meniscectomy with excimer and Ho:YAG lasers.

The authors report their experiences using the excimer laser and holmium:YAG laser in arthroscopic meniscal surgery. Histologic and ultrastructural aspects caused by laser irradiation on meniscal tissues are evaluated. Two groups of 10 patients, each suffering from a bucket-handle lesion of the internal meniscus, were used for this study. The histologic results of the study confirm the clinical reliability of the laser even in the presence of different ultrastructural frames.

Arthroscopes↗
PubMed1994

Ultrapulse carbon dioxide laser removal of periocular wrinkles in association with laser blepharoplasty.

Removal of periocular wrinkles is a common yet difficult problem. There are many techniques currently available, all of which have some drawbacks. With the advent of new generation ultrapulse carbon dioxide lasers, skin can now be resurfaced successfully with minimal risk and side effects. In our study of 36 patients we assessed the benefit of using ultrapulse carbon dioxide (CO 2) laser to resurface the periorbital skin in association with transconjunctival lower lid CO 2 laser blepharoplasty. We found that 36/36 (100%) patients had good to excellent results. The incidence of side effects was very low. We also found that 2/36 (5.6%) of patients developed mild clinically insignificant hypopigmentation and 1/36 (2.8%) developed mild scarring, which resolved with one injection of triamanalone 10 mg/ml. No patients had hyperpigmentation. In addition, 1/36 (2.8%) patients developed transient ectropion, which resolved spontaneously in 6 weeks. We conclude that ultrapulse CO 2 laser is an excellent method for treating periocular wrinkle lines and can be readily performed in conjunction with a transconjunctival lower lid blepharoplasty.

Adult↗
PubMed1998

Middle ear laser office ventilation (LOV) with a CO2 laser flashscanner.

BACKGROUND: Laser assisted ventilation of the middle ear with a defocused laser beam has been performed on adults in an office setting without anesthesia. OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of a highly controlled, char-free CO2 flashscanner technology for the ventilation of the middle ear in young children, at this stage under general anesthesia, and later without anesthesia. METHODS: A CO2 flashscanning laser, in conjunction with a micromanipulator, was used on 21 SOM patients ages 3-7 years old, with followup at 2 months. Operating time is approximately 5 minutes. RESULTS: Postoperative results show average patency of 2-3 weeks without adverse effects. Of the treated patients, 53% did not require a second treatment, whereas 47% still suffered from otitis media and needed a second treatment. CONCLUSION: The CO2 flashscanner laser technology is effective and safe for middle ear ventilation and provides excellent control of the perforation diameter. It is already being performed in an office setting with sedation on a limited basis with very promising preliminary results. Based on the current study and on 70 additional cases with longer interval followup, we anticipate the office technique to become widely used in the future.

Ambulatory Surgical Procedures↗
PubMed1994

Probabilistic laser safety: ocular damage models for Q-switched neodymium and ruby lasers.

International standards for the protection of the eyes from the hazards of laser radiation define a nominal ocular hazard distance as a distance beyond which an individual would not be expected to suffer any adverse biological effects. The nominal ocular hazard distance, and any associated hazard zones, are calculated using a deterministic technique. This technique does not consider the likelihood that an eye will be irradiated, or the probability that if any eye is exposed, then some level of ocular damage will result. An alternative method of hazard assessment, without compromising safety, is to adopt a probabilistic approach in which the ultimate safety criterion is that the expectation of someone receiving ocular damage must be less than some acceptable risk level. An important element in this assessment is an ocular damage model, which predicts the probability with which a laser exposure will cause permanent eye damage. This paper describes a rationale for the use of the minimum ophthalmoscopically visible lesion as a threshold criterion for the development of ocular damage models. A brief review of existing ocular damage threshold data for Q-switched neodymium:YAG and ruby lasers is presented, and ocular damage models for these lasers systems are derived.

Eye Injuries↗
PubMed1997

Laser fragmentation of pancreatic duct stones using a rhodamine laser with an automatic stone-tissue detection system. Basic in-vitro studies.

OBJECTIVES: The aim of our study was to examine the suitability of a rhodamine 6G laser with an integrated stone-tissue detection system (STDS) for fragmenting pancreatic stones. METHODS: A total of 64 pancreatic duct stones were measured for weight, diameter, main chemical components and in some cases for their computerized tomography density. Recognition of all stones was checked with the standard STDS or a prototype version. Number of fragmentation pulses, total fragmentation energies and correlation with the individual stone parameters were determined. The quality of the tissue-detection mode was evaluated in postmortem pancreata. RESULTS: The standard STDS detected only 45% of the pancreatic stones correctly. When using the prototype, the detection rate improved significantly up to 75% (P < 0.01). All laser pulses were cut off if tissue contact occurred. All the stones were completely disintegrated by the laser pulses. A slight correlation was found only between the required fragmentation energy and the stone weight (linear regression: R2 = 0.77); other factors had no significant impact. CONCLUSION: The rhodamine 6G laser is suitable for the fragmentation of pancreatic stones in vitro. The integrated STDS is less effective for pancreatic stones than reported for biliary stones.

Calculi↗
PubMed2007

Changes in scanning laser polarimetry before and after laser capsulotomy for posterior capsular opacification.

PURPOSE: To investigate changes in scanning laser polarimetry with variable corneal compensation (GDx-VCC) parameters caused by posterior capsular opacification (PCO). METHODS: In this comparative case-control series, 20 eyes due to undergo YAG laser capsulotomy for PCO were recruited. GDx-VCC was performed before and after laser capsulotomy, and digital photographs were taken of the PCO to assess their severity and type. The other eye of each subject was used as the control group. RESULTS: Typical scan score was significantly improved after laser from 33 to 55.1 (P=0.001; n=19) and TSNIT score was significantly lower, dropping from 62.3 to 58.9 (P=0.03; n=19). There was no change in the nerve fiber index. All parameters in the control group remained unchanged except the Q-score which rose from 8.1 to 8.8 (P=0.05; n=16). There was no correlation between severity of PCO or the pearly/fibrous nature and the change in parameter values. CONCLUSIONS: We conclude that in subjects being considered with GDx-VCC, the presence of visually significant PCO may introduce artifact as judged by the typical scan score.

Aged↗
PubMed2006

Endovenous laser ablation of the great saphenous vein with a 980-nm diode laser in continuous mode: early treatment failures and successful repeat treatments.

PURPOSE: To investigate the efficacy of lower-energy endovenous laser treatment for great saphenous vein (GSV) incompetence and treatment parameters associated with early treatment failure. MATERIALS AND METHODS: Sixty consecutive endovenous laser treatments (32 left, 28 right; 57 initial treatments, three repeat treatments) in 48 patients (13 men, 35 women; mean age, 55.2 +/- 12.9 years), with bilateral treatments in nine patients, were studied. Preprocedural clinical signs, etiology, anatomy, and physiologic classifications demonstrated class 2 limbs in 11.7% of cases, class 3 limbs in 25.0%, class 4 limbs in 48.3%, and class 5 limbs in 15.0%. All initial and repeat treatments were performed with lower-energy with use of a 980-nm diode endovenous laser at 11 W in continuous mode. Patients wore class II compression stockings for 2 weeks and were followed up at 1, 3, and 6 months with clinical and duplex ultrasound examinations. Treatment failures were diagnosed at 3 months on the basis of GSV patency or lack of clinical improvement. Diameter and length of GSV treated, treatment energy parameters, and clinical outcomes were prospectively measured and compared between successful and failed treatments. RESULTS: The initial treatment success rate was 94.7% (54 of 57). The mean maximum diameter of successfully treated GSVs was 1.12 +/- 0.52 cm, and the mean maximum diameter of GSVs in which treatment failure occurred was 2.05 +/- 0.23 cm (P = .008). Mean total energy applied for successful treatments was 1,131.3 +/- 248.1 J, and mean total energy applied for failed treatments was 1,439.6 +/- 425.0 J (P = 0.053). Mean unit energy applied for successful treatments was 32.7 +/- 7.5 J/cm, and that for failed treatments was 32.8 +/- 4.9 J/cm (P = .986). All patients in whom treatment failed were successfully treated again with a mean total energy of 1,393.0 +/- 81.0 J and a mean unit energy of 29.4 +/- 4.9 J/cm. There were no significant differences in mean total energy or unit energy applied among successful, failed, and repeat treatments (P > .05). Mean follow-up duration was 6.8 months. CONCLUSIONS: Endovenous laser treatment with lower energy appears to be safe and effective. Larger GSV diameter is associated with early treatment failures.

Female↗