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PubMed1990

New refractive method for laser thermal keratoplasty with the Co:MgF2 laser.

We have observed corneal curvature changes from laser thermal keratoplasty with a Co:MgF2 laser. We studied corneal curvature changes in rabbits and have identified specific treatment patterns and laser parameters that can correct myopia and astigmatism. These corneal changes, some as large as 8 diopters, have been stable for at least one year, and slitlamp examination demonstrates clear central corneas with normal appearance.

Animals↗

PubMed1996

Astigmatic change 1 year after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group.

PURPOSE: To evaluate the surgically induced astigmatism (SIA) 1 year after excimer laser photorefractive astigmatic keratectomy (PARK) and photorefractive keratectomy (PRK). SETTING: Royal Victorian Ear and Eye Hospital, Melbourne, Australia. METHODS: This study comprised 333 PARK patients and 155 PRK patients treated with a VISX 20/20 excimer laser and followed prospectively for 12 months. Vector analysis of the change in astigmatism was used to calculate the SIA in the PRK group and the percentage of astigmatism corrected in the PARK group. RESULTS: Among patients with low cylinders astigmatic correction varied greatly, particularly in those treated for large amounts of myopia. The spherical PRK treatments yielded a mean induced postoperative astigmatism of 0.47 diopter. There was a linear relationship between this inadvertent SIA and increasing myopia. CONCLUSION: Excimer laser surgery for myopia creates a low degree of random, unpredictable SIA that may be the result of irregular epithelial thickening during postoperative healing. This creates a background noise of astigmatic change upon which the targeted astigmatic correction is superimposed.

Adult↗

PubMed1997

Predictability of excimer laser treatment of myopia and astigmatism by the VISX Twenty-Twenty. Melbourne Excimer Laser Group.

BACKGROUND: To determine the predictability of excimer laser photorefractive keratectomy (PRK) to correct myopia, astigmatism, or both between -1.00 and -19.00 diopters (D). SETTING: Royal Victorian Eye and Ear Hospital, East Melbourne, Australia. METHODS: This study comprised 1218 consecutive eyes treated with a VISX Twenty-Twenty excimer laser and followed prospectively for 12 months. Low myopia was treated with one ablation zone (6.0 mm), high myopia with two ablation zones (5.0 and 6.0 mm), and extreme myopia with three ablation zones (4.5, 5.0, and 6.0 mm). Maximum spherical treatment was 15.00 D at the corneal plane. Data were analyzed to determine the predictability of the postoperative outcomes by preoperative refraction. RESULTS: Nine hundred eighty eyes (80.5%) were available for the 12 month follow-up. The predictability of refraction and uncorrected and best corrected visual acuities progressively decreased with increasing myopia, although a comparable percentage of spherical correction was achieved at each diopter of myopia. The likelihood of losing lines of best corrected visual acuity and corneal haze increased with increasing myopia. CONCLUSION: These data can be used to counsel patients of likely outcomes of excimer laser PRK to correct myopia.

Adult↗

PubMed1998

Excimer laser correction of astigmatism with multipass/multizone treatment. The Melbourne Excimer Laser Group.

PURPOSE: To evaluate the accuracy of excimer laser correction of myopic astigmatism by multipass/multizone photoastigmatic refractive keratectomy (PARK). SETTING: Tertiary referral ophthalmic hospital with an associated private laser facility. METHODS: This study comprised a consecutive series of 332 eyes of 289 patients who were followed for 6 months. All patients were 18 years or older, had stable myopic astigmatism (up to a -19.0 diopters [D] spherical equivalent [SE] at the spectacle plane), and had a best corrected visual acuity of at least 20/60 in both eyes. All eyes were treated with a VISX Twenty-Twenty excimer laser. The correction was divided between ablation zones using a multipass/multizone treatment paradigm based on the amount of myopia and astigmatism. Patients were examined 1 week, and 1, 3, and 6 months after surgery. RESULTS: Analysis of the mean percentage of spherical correction across the range of myopic preoperative SEs treated demonstrated 90% correction for most amounts of myopic astigmatism. Eyes with low myopia (mean preoperative SE < or = -5.0 D) treated with < or = -1.0 diopter cylinder (DC) of astigmatism achieved a mean percentage of spherical correction of 91% versus 93% in eyes with high myopia (> -5.0 D mean preoperative SE). Eyes with low myopia treated with > -1.0 DC of astigmatism achieved a mean percentage spherical correction of 90% versus 89% in eyes with high myopia. The differences between the two groups were not statistically significant. Patients with high relative cylinder (> 80% of total sphere treated) achieved comparable results. Analysis of the astigmatic component of the treatment, independent of the spherical result, showed a trend toward overcorrection in the high myopia group with less than -1.0 DC and a mean astigmatic correction of 89 and 98%, respectively, in the low and high myopic astigmatism groups. The mean angle of error was +2.0 degrees. CONCLUSION: Multipass/multizone PARK for myopic astigmatism demonstrated a high degree of predictability and stability with desirable results for low and high levels of astigmatism across the range of myopic astigmatism treated by surface ablation.

Adult↗

PubMed2002

Clinical application of laser evoked potentials using the Nd:YAG laser.

The clinical interest of a new type of laser evoked potentials (LEPs) using Nd:YAG laser was assessed in the diagnosis of peripheral neuropathies affecting the small-diameter nerve fibres, and of spinal cord lesions, affecting the spinothalamic tract. Twelve patients aged from 26 to 79 years with sensory neuropathies (n = 6) or spinal cord lesions (n = 6) underwent neurophysiological examination of the lower limbs comprising quantitative sensory testing, i.e., the determination of vibratory and thermal thresholds (VT and TT), somatosensory evoked potentials (SEPs) to electrical stimulation and Nd:YAG LEPs. VT and SEPs were used to assess large-diameter afferent nerve fibres and the lemniscal pathways while TT and LEPs were used to assess small-diameter afferent nerve fibres and the spinothalamic tract. In addition, patients with peripheral neuropathy underwent also standard nerve conduction studies to explore large fibres and the recording of sympathetic skin responses (SSRs) to explore small fibres, whereas motor evoked potentials were performed in patients with spinal cord lesion. LEPs were absent bilaterally in all patients with polyneuropathy, even when TT remained within the normal limits and SSRs were present. LEPs were absent after stimulation of the affected limb in all patients with a spinal cord lesion, and allowed to detect subclinical contralateral lesion in two cases. LEPs following Nd:YAG laser stimulation are sensitive in the diagnosis of peripheral and/or central nervous system disorders and they give complementary information as compared to routine electrophysiological tests.

Aged↗

PubMed2001

Transmyocardial laser revascularization with the holmium:YAG laser: loss of symptomatic improvement after 2 years.

OBJECTIVE: Whether transmyocardial laser revascularization (TMLR) provides a long-term benefit in terms of relief of angina, improvement of exercise tolerance, left ventricular function, and myocardial perfusion. METHODS: Forty-one patients underwent TMLR using a holmium:YAG-laser, 14 as TMLR alone (group A), 27 with additional aortocoronary bypass grafting (group B). Follow-up was obtained at 6, 12, 18, 24, and 36 months in this prospective study. RESULTS: In group A patients CCS-class improved up to 18 months postoperatively, after 24 and 36 months postoperatively there was absence of a positive effect of TMLR: the CCS-class decreased to 2.4 as compared to 3.5 preoperatively After combined CABG and TMLR (group B) there was a significant decrease in angina at all times. The CCS-functional class in these patients was 1.7 at 36 months as compared to 3.5 preoperatively. There was no significant change in exercise tolerance as compared to preoperatively. Left ventricular ejection fraction did not improve in either of the groups. Thallium scintigraphy indicated no improvement in myocardial perfusion in laser treated areas. The perioperative mortality was 0%, the late mortality rate was 36% in group A and 11% in group B. CONCLUSIONS: In our experience, in the vast majority of patients who are subjected to TMLR alone the benefit of reduction or relief of angina and improvement in quality of life is only temporary. In addition there is no improvement in objective clinical parameters. We believe that TMLR should only be used in patients with severe angina refractory to medical treatment and requiring a symptomatic therapy.

Aged↗

PubMed1987

Ten year results of laser trabeculoplasty. Does the laser avoid glaucoma surgery or merely defer it?

The first 150 consecutive phakic eyes from 113 patients aged 40 years or more treated with laser trabeculoplasty were evaluated. Twenty-four patients (37 eyes) have died, two eyes developed spontaneous rubeosis, and one patient (one eye) was not available, leaving 110 eyes with a 6 to 10 years follow-up. Of the 37 eyes of dead patients (average age 80 years), only one eye had filtering surgery, and 33 of the other 36 eyes had a last recorded intraocular pressure of less than 21 mm Hg. Of the 110 eyes of living patients followed for 6 years, 33 had filtering surgery and 62 eyes (56 per cent) had an intraocular pressure of less than 21 mm Hg. Of 10 eyes followed for 10 years, eight had intraocular pressures less than 23 mm Hg, seven had pressures less than 21 mm Hg, and two had had filtering surgery. Eyes with advanced disc damage at the time of trabeculoplasty had a 51 per cent rate of later glaucoma surgery, while eyes with a cup/disc ratio less than 0.9 at trabeculoplasty had a glaucoma surgery rate of 16 per cent. Eyes of non-white patients did as well as eyes of white patients. Computer analysis of over 1,700 eyes with two-year follow-up indicated better long-term control when 100 or more laser burns were used for trabeculoplasty. Laser trabeculoplasty can defer surgery for the remaining lifespan in elderly patients, and has controlled primary open-angle glaucoma for over 10 years, but later glaucoma surgery is often required in eyes with far advanced glaucoma damage.

Adult↗

PubMed2000

Laser therapy of telangiectatic leg veins: clinical evaluation of the 810 nm diode laser.

Telangiectatic leg veins (TLV) are experienced by millions of women and men. As they cause significant cosmetic embarrassment, many women seek effective treatment. Options include sclerotherapy and treatment with different lasers. We investigated the safety and efficacy of an 810-nm diode laser in the treatment of TLV. Ten females had treatment to a >/= 25 cm2 area of TLV four times at 4-weekly intervals at 25-35 W, 0.1 s duration, 0.5 s interval and a 5-mm circular spot size (fluence of 12.7-17.8 J/cm2). Assessment of response was performed 4 weeks after the final treatment and patients were asked to complete a questionnaire requesting information regarding the treatment. No statistically significant clearing of the leg veins was demonstrated although some improvement was noted in individual patients. Side-effects were negligible, consisting of discomfort or mild pain. There was no scarring, purpura or pigment alteration. A visual analogue scale questionnaire (0-10) revealed that patients found the treatment acceptable (range, 4-10). Overall difference as assessed by the patients ranged from 0 to 8.4 and degree of satisfaction with the treatment from 0 to 9.8. Currently, the treatment of choice for TLV remains sclerotherapy. Our results suggest that the 810-nm diode laser is safe and well tolerated. Further research could establish whether effectiveness can be improved with higher fluences or in combination with sclerotherapy.

Adult↗

PubMed1996

A standard protocol for the evaluation of laser treatment of the prostate. The British Laser Urological Evaluation Society (BLUES)

OBJECTIVES: To present a standardized protocol, suitable for general use, for the evaluation of laser treatment of the prostate. METHODS: Many new operative treatments which are available to treat symptomatic prostatic enlargement are being accepted and offered to patients after scanty clinical evaluation, e.g. interventions using lasers. A consistent and standard protocol was developed, comprising data-recording sheets for patients' admission details, pre-operative assessments, operative details of laser ablation, post-operative in-patient progress and re-attendance, and subsequent out-patient follow-up. RESULTS: The protocol was tested by the members of BLUES and fulfilled their requirement for easy use in any department of Urology. It provides a simple way of accurately recording relevant data within a structured format with the additional advantage of permitting results to be expressed uniformly. CONCLUSION: The adoption of this protocol will allow valid comparisons of core data between studies assessing different procedures. The flexibility of the protocol enables it to be used, with minor modification, for the evaluation of any operative intervention aimed at relieving prostatic symptoms.

Clinical Protocols↗

PubMed1997

Interstitial laser coagulation in the treatment of benign prostatic hyperplasia using a diode-laser system with temperature feedback.

OBJECTIVE: To report the initial results of the treatment of patients with benign prostatic hyperplasia using interstitial laser coagulation (ILC) performed with a temperature-sensing laser system. PATIENTS AND METHODS: Twenty-five patients were treated using ILC and in 12, 78 temperature-power curves were recorded. The aim of the treatment was to maintain a temperature of 100 degrees C during the entire treatment cycle, using the temperature-triggered feed-back system. The time to reach the maximum temperature, the maximum temperature and the energy delivered were related to the location of the punctures within the prostate. The clinical outcome at 1 and 3 months was evaluated with symptom scores and uroflowmetry variables. RESULTS: Heating at the apex seemed to require less energy to achieve and maintain higher temperatures than heating of the median lobe or base of the prostate. Patients improved markedly 1 and 3 months after treatment; the respective mean symptom scores improved from 20.6 before treatment to 9.4 and 6.9, the maximum urinary flow rates from 9.1 mL/s to 14.1 mL/s and 20.3 mL/s and the post-void residual volume decreased significantly from 71 mL to 31 mL and 11 mL. No significant complications (incontinence, impotence or haemorrhage requiring transfusion) occurred. CONCLUSION: The energy needed to achieve coagulation differed at sites within the prostate, depending on local circumstances. Good results were obtained using the tissue-adaptive laser system.

Aged↗

PubMed2003

Endovenous laser treatment of the lesser saphenous vein with a 940-nm diode laser: early results.

BACKGROUND: Until now, endovenous laser treatment (ELT) of the lesser saphenous vein (LSV) has not been reported. OBJECTIVE: To evaluate efficacy and side effects for ELT of the LSV. METHOD: Otherwise unselected patients with an incompetent LSV were included. After perivenous infiltration of tumescent local anesthesia, laser energy (940 nm) was administered endovenously, either in a pulsed fashion or continuously during constant backpull of the laser fiber. Patients were scheduled for duplex follow-up at Day 1 and also at 1, 3, 6 and 12 months, postoperatively. RESULTS: Forty-one LSVs were targeted in 33 patients with a median age of 66 years (range, 35 to 93). Seventy-three percent of patients had skin changes (C4). Thirty-six percent had an open or healed venous ulcer (C5,6) and 15% a postthrombotic syndrome (ES AS,D PR). Thirty-nine LSVs (95%) completed ELT successfully. During a median follow-up interval of 6 months (range, 3 to 12 months), no recanalization event could be observed. Apart from one thrombosis of the popliteal vein in a patient with polycythemia vera, only minor side effects, particularly no permanent paresthesia, could be observed. CONCLUSION: ELT of the LSV under tumescent local anesthesia is feasible and effective. Caution is warranted with ELT of thrombophilic patients.

Adult↗

PubMed2000

Laser therapy: a randomized, controlled trial of the effects of low intensity Nd:YAG laser irradiation on lateral epicondylitis.

OBJECTIVE: To assess the effectiveness of low intensity laser therapy in the treatment of lateral epicondylitis. DESIGN: A double-masked, placebo-controlled, randomized clinical trial. SETTING: A physical medicine and rehabilitation clinic. PARTICIPANTS: Fifty-two ambulatory men and women (age range, 18-70 yr) with symptomatic lateral epicondylitis of more than 30 days in duration and a normal neurologic examination. INTERVENTION: Subjects were bloc randomized into 2 groups with a computer-generated schedule. All underwent irradiation for 60 seconds at 7 points along the symptomatic forearm 3 times weekly for 4 weeks by a masked therapist. The sole difference between the groups was that the probe of a 1.06-microm continuous wave laser emitted 204 mW/cm2 (12.24 J/cm2) for the treated subjects and was inactive for the control subjects. Subjects were assessed at the beginning, midpoint (session 6), and end (session 12) of treatment, as well as at follow-up 28 to 35 days after their last treatment. MAIN OUTCOME MEASURES: Pain in last 24 hours, tenderness to palpation, and patient's perception of change (benefit). RESULTS: The treated and untreated groups were well matched demographically. Masking was maintained for subjects and therapists; however, the groups did not vary to a statistically significant extent in terms of the main outcome measures either during treatment or at follow-up. Secondary outcome variables, such as grasp and pinch strength, medication use, and pain with grasp and pinch, also failed to statistically differ significantly between the groups. No significant treatment side effects were noted. CONCLUSION: Treatment with low intensity 1.06-microm laser irradiation within the parameters of this study was a safe but ineffective treatment of lateral epicondylitis. Further research seems warranted in this controversial area.

Adolescent↗

PubMed1999

Transmyocardial laser revascularization with the Holmium:YAG laser does not improve myocardial perfusion in the acutely ischemic heart: an experimental study measuring myocardial perfusion by a thermal imaging camera.

BACKGROUND: Transmyocardial laser revascularization (TMLR) is a new surgical therapy for patients with end-stage coronary artery disease refractory to conventional therapy. TMLR should act by improvement of perfusion of the lasered myocardium. Blood should be delivered from the cavity of the heart to the surface of the myocardium. The aim of this study was to measure perfusion of normal, ischemic, and ischemic myocardium after TMLR. METHOD: We used a new method of perfusion measurement by an infrared thermal imaging system in an open-chested adult sheep model with temporary and permanent occlusion of the dominant diagonal branch. RESULTS: A significant fall from normal perfusion of the myocardium to reduced after inducing ischemia (p<0.01) and a significant rise again after reperfusion (p<0.001) could be shown. Perfusion measurements after TMLR did not significantly differ from perfusion measurements after inducing ischemia (p=0.2). CONCLUSION: In the presented sheep model, laser revascularization could not improve myocardial perfusion after acute ischemia as seen by the infrared thermal imaging system.

Aluminum↗

PubMed1986

Laser-resistant guide probe for laser treatment of endoscopically impassable tumour stenoses.

A laser-resistant guide probe that can be placed endoscopically, for use in the laser treatment of impassable tumour stenosis is described. It meets the necessary requirements such as low level of absorption of YAG laser light (1,064 nm wavelength), high thermal stability and low heat conduction. So far, the probe has been used complication-free, in four patients.

Esophageal Stenosis↗

PubMed1992

[The Excimer laser. II. Initial experiences with the Excimer laser in Lucerne].

In the period between September 1990 and July 1991, 35 patients (46 eyes) were treated with the Excimer Laser. In 25 patients (34 eyes), a Myopia-Laser-Shaping was performed, one patient was treated for both myopia and astigmatism. In eight patients (10 eyes) correction of astigmatism was carried out. Two patients with recurrent erosions and one patient with superficial scarring of the cornea were treated. The authors review their initial experience with the Excimer Laser. The decision to initiate treatment must not be undertaken lightly, because the possibility of serious complications may not be neglected. This method shows promise in selected patients with light to medium degrees of myopia. In cases of severe myopia, our experience is encouraging. Subjectively, the patients are satisfied with the results, which do not fall short of their expectations. Further research and clinical experience in this area is urgently required.

Astigmatism↗

PubMed2001

Laser transmission through transparent membranes used in cutaneous laser treatment.

BACKGROUND: Some clinicians perform cutaneous laser treatments through transparent membranes to protect themselves and the surroundings from contamination by ejected tissue particles. Transmissibility of these membranes influences the tissue irradiance. OBJECTIVE: We compared the optical transmissibility of 8 membranes. METHODS: In part 1, a Schwartz Electro-Optics Q-switched alexandrite laser (wavelength of 720-800 nm, beam diameter of 3 mm) was directed through 8 membranes. A Molectron JD 2000 Joulemeter Ratiometer obtained measurements of percent loss of laser energy (for calculation of percent transmission) through each. To evaluate other wavelengths used in skin treatment, an SLM Aminco UV-VIS model 2000 spectrophotometer measured variance of transmission over a spectral region from 350 to 900 nm in 4 of the membranes. RESULTS: The samples listed in order of increasing amounts of light energy lost across the membrane as compared with control (direct irradiation) were as follows: (1) Handi Wrap plastic wrap: 7% loss, 93% transmission; (2) glass slide: 8% loss; (3) Bioclusive transparent dressing: 11% loss; (4) Tegaderm transparent dressing: 26% loss; (5) Vigilon dressing without plastic backing: 34% loss; (6) Vigilon dressing with one layer of plastic backing: 37% loss; (7) Acuderm dressing: 41% loss; and (8) OpSite IV: 48% loss. CONCLUSIONS: Transmissibility of the interposed membranes must be considered when determining the dosimetry of light energy required by the target tissue.

Laser Therapy↗

PubMed2001

Cardiac enzymes after transmyocardial laser treatment with CO2 laser.

OBJECTIVES: The aim of the present study was to examine postoperative serum levels of cardiac enzymes after transmyocardial laser treatment (TML) and to evaluate any associations between this release, postoperative cardiac events and change in ejection fraction after 3 months' follow-up. DESIGN: Forty-nine patients with angina pectoris Canadian Cardiovascular Society Angina Score Class III & IV refractory to medical therapy and untreatable by coronary artery bypass or percutaneous transluminal angioplasty treated with CO2 laser were included. Inclusion criteria were age less than 75 years, left ventricular ejection fraction greater than or equal to 30% and myocardial regions with reversible ischemia. Serum levels of aspartate aminotranspherase (ASAT), alanine aminotranspherase (ALAT) and MB-isoenzymes of creatine kinase (CK-MB) were followed during the first 72 h after surgery. Ejection fractions were estimated by multiple-gated acquisition ventriculography at inclusion and 3 months postoperatively. RESULTS: A significant increase in serum markers of myocardial necrosis was observed 8 h after surgery. A subsequent increase from 8 to 24 h after surgery was associated with the presence of postoperative cardiac adverse events. An inverse correlation was found between peak level of cardiac enzymes and change in ejection fraction from baseline to 3 months' follow-up. CONCLUSIONS: TML with CO2 laser is followed by a significant increase in serum levels of cardiac enzymes after 8 h. Further significant increases are associated with cardiac adverse events postoperatively. Peak enzyme values are inversely correlated with change in ejection fraction from baseline to 3 months' follow-up.

Angina Pectoris↗

PubMed1995

Laser-assisted disc decompression: a clinical trial of the holmium:YAG laser with side-firing fiber.

In order to evaluate the efficacy of laser-assisted disc decompression (LADD) as an alternative treatment modality for nonsequestered herniated nucleus pulposus of the lumbar spine, we used the Holmium:YAG laser with Sidefire laser fiber on 223 consecutive patients who met inclusion criteria. Patients were evaluated by an independent interviewer postoperatively, and at 1 week, 3 months, 6 months, and 1 year. Ratings were based upon the modified Macnab criteria. All patients presented with leg pain with or without back pain that had failed a minimum of 6 weeks conservative treatment (e.g., rest, NSAIDs, physical therapy, epidural steroid injections). Patients were not considered for LADD if the primary source of neurologic findings was a result of scar tissue from a previous discectomy, lateral recess or central stenosis, or sequestered discs. At 1 year postoperative follow-up, the surgical success rate was 84%. For patients requiring an additional LADD procedure, results at 6 month follow-up yielded surgical success rates of 92.3% and 90% for additional level and index level LADD, respectively. LADD appears to be a viable treatment modality for nonsequestered herniated nucleus pulposus recalcitrant to conservative treatment. LADD may represent a more cost-effective and safer treatment alternative to traditional invasive surgical procedures and other percutaneous methods.

Adolescent↗