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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↗
PubMed1994

Acute complications of excimer laser coronary angioplasty: a detailed analysis of multicenter results. Coinvestigators of the U.S. and European Percutaneous Excimer Laser Coronary Angioplasty (PELCA) Registries.

OBJECTIVES: The aim of this study was to document and analyze the incidence and consequences of complications of excimer laser coronary angioplasty. BACKGROUND: Excimer laser coronary angioplasty has been reported to be a safe and feasible alternative or adjunct to conventional balloon angioplasty, but serious and unique complications have been observed. METHODS: Data on 1,595 interventions of excimer laser coronary angioplasty in 1,521 patients were analyzed, using a merged data base from the U.S. and European Percutaneous Excimer Laser Coronary Angioplasty (PELCA) registries. RESULTS: Procedural success was achieved in 89.3% of interventions. Stand-alone laser angioplasty was performed in 17.8% of interventions. Complications included dissection (22.0%), vasospasm (6.1%), filling defects (4.8%), abrupt reclosure (6.1%), embolization (2.3%), perforation (2.4%), arrhythmia (0.7%) and aneurysm formation (0.3%). Major complications were non-Q wave myocardial infarction (2.3%), Q wave myocardial infarction (1.0%), coronary artery bypass grafting (3.1%) and death (0.7%). Logistic regression analysis revealed correlation between dissections and the use of larger catheter size (p = 0.0005), high energy per pulse levels (p = 0.0001 for native vessels), lesion length > 10 mm (p = 0.001) and presence of a side branch (p = 0.01). The incidence of perforations was higher in women (p = 0.004), in treatment of total occlusions (p = 0.02) and in the presence of a side branch (p = 0.03). Fatal complications were correlated with patients with multivessel disease (p < 0.0001), patients with acute myocardial infarction (p = 0.0009) and older patients (> 70 years old, p = 0.004). The incidence of major complications decreased after performance of 50 laser angioplasty procedures at one institution (p = 0.02). CONCLUSIONS: This analysis defines both the learning curve and the profile of complications for excimer laser angioplasty and provides insight into the selection of appropriate patients and proper performance of the procedure.

Acute Disease↗
PubMedDate not supplied

Theory concerning the ablation of corneal tissue with large-area, 193-nm excimer laser beams.

Excimer laser beams (193 nm) of uniform fluence were studied to find out why they produce corneal ablations deeper at the edge than the center. Ablation depth profiles were taken of porcine corneas, including five dehydrated samples. Hydrated corneas and polymethyl methacrylate were ablated with and without central masks. Ablation plumes were photographed. Hydrated porcine corneas showed patterns of central underablation. As the incident beam increased, the crater exhibited increasingly shallower central ablation while maintaining nearly constant depth at the edges. Dehydrated corneas did not vary significantly. Masks did not alter the depth or shape of craters near ablation edges, but depth adjacent to the images of the masks was more than twice that with no mask. Depth adjacent to the mask image was nearly the same as at the edge of the zone. The rate of change in depth with position was nearly equal in both areas. Maximum plume density was centered over the entire ablation with and without the mask. Redeposition of plume particles is not the major cause of central underablation. Propagating transverse energy from the absorption of photons by peptide bonds increases pressure on excited components within the irradiated area, increasing recombination, which raises the ablation threshold.

Animals↗
PubMedDate not supplied

Excimer laser angioplasty.

Excimer laser angioplasty is one of the newest procedures being used in interventional cardiology. Because of persistently high rates of restenosis with conventional balloon angioplasty (which may be attributed to the acceleration of atherosclerosis by remodeling and dilatation of diseased arteries) alternatives to remove and debulk atheromatous plaque are being explored. Among these, excimer laser angioplasty (ELA) has been developed as a modality that offers an alternative to percutaneous transluminal coronary angioplasty. The laser energy is delivered via fiberoptics to the target lesion and the plaque material is rendered into a gaseous state (vaporized) by breaking the molecular bonds. With proper training and patient selection, ELA has complication rates that are no higher than conventional balloon angioplasty. Preliminary data indicate that the laser is most successful in treating lesions that are not well treated with conventional balloon angioplasty. These include saphenous vein graft lesions, aorto-ostial lesions, long lesions (> 10 mm in length), moderately calcified stenoses, total occlusions, and percutaneous transluminal coronary angioplasty dilitation failures. The purpose of this article is to review the history and physics of ELA and to provide the nursing professional with an understanding of how the procedure is performed. Nursing considerations when caring for the patient undergoing this procedure are provided.

Aged↗
PubMed1998

Excimer laser refractive surgery.

Excimer laser photorefractive keratectomy and excimer laser in situ keratomileusis are relatively new treatment modalities that can be used to correct refractive errors of the eye. They are most commonly used to correct myopia (nearsightedness) but can also be used to correct hyperopia (farsightedness) and astigmatism. The excimer laser alters the refractive state of the eye by removing tissue from the anterior cornea through a process known as photoablative decomposition. This process uses ultraviolet energy from the excimer laser to disrupt chemical bonds in the cornea without causing any thermal damage to surrounding tissue. The modified anterior corneal surface enables light to be focused on the retina, thereby reducing or eliminating the dependence on glasses and contact lenses. We discuss in detail all aspects of excimer laser refractive surgery--techniques, indications and contraindications, clinical outcomes, and complications.

Humans↗
PubMed1996

Comparison of results of excimer laser correction of all degrees of myopia at 12 months postoperatively. The Melbourne Excimer Laser Group.

UNLABELLED: To examine prospectively the efficacy and safety of photorefractive keratectomy and photoastigmatic refractive keratectomy. METHODS: We treated 645 eyes (440 patients) with a VisX Twenty/Twenty excimer laser and followed them up for 12 months. RESULTS: The percentage of eyes with myopia between -5.01 and -10.00 diopters spherical equivalent within 1 and 2 diopters of emmetropia at 12 months was 65% (123 of 189) and 90% (170 of 189), respectively, whereas the corresponding percentages for eyes with myopia greater than -10.00 diopters spherical equivalent were 39% (16 of 41) and 56% (23 of 41), and for eyes with myopia of -5.00 diopters spherical equivalent or less, 87% (238 of 273) and 99% (270 of 273), respectively. Uncorrected visual acuity of 20/20 and 20/40 or better at 12 months was attained in 47% (129 of 273) and 87% (237 of 273) of the eyes with myopia -5.00 diopters spherical equivalent or less, respectively. At 12 months, 48 (25%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 or better and 135 (71%), 6/12. At 12 months, one eye (2%) with myopia greater than -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 and 11 (27%) of 41 eyes, 6/12. Ten (4%) of the 273 eyes with myopia of -5.00 diopters spherical equivalent or less, 15 (8%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent, and nine (22%) of the 41 eyes with myopia greater than -10.00 diopters spherical equivalent had lost two or more LogMAR lines of best-corrected visual acuity at 12 months. CONCLUSION: Excimer laser surgery is highly reliable for myopia of -5.00 diopters spherical equivalent or less and is less reliable for greater myopia.

Adult↗
PubMed1994

Predictors of outcome of percutaneous excimer laser coronary angioplasty of saphenous vein bypass graft lesions. The Percutaneous Excimer Laser Coronary Angioplasty Registry.

A total of 495 patients underwent treatment with excimer laser angioplasty for 545 saphenous vein graft stenoses. Clinical success was achieved in 455 of 495 patients (92%), as indicated by < or = 50% residual stenosis at every target lesion and no complication during hospitalization. At least 1 in-hospital complication occurred in 30 of 495 patients (6.1%): death (1.0%), bypass surgery (0.6%), and Q-wave (2.4%) or non-Q-wave (2.2%) myocardial infarction. Relative risk analysis showed that ostial lesions (n = 65) tended to have higher clinical success (success rate = 95%, adjusted odds ratio [OR] = 2.1 [95% confidence interval (CI) 0.62, 6.88]; p = 0.24) and lower complications (complication rate = 0%, OR = 0.10 [CI 0.01, 0.79]; p = 0.03) than lesions in the body of the vein graft. Lesions > 10 mm (n = 131) had lower success (success rate = 84%, OR = 0.30 [CI 0.16, 0.56]; p = 0.001) and higher complications (complication rate = 12%, OR = 3.3 [CI 1.6, 6.6]; p = 0.004) than discrete lesions. Lesions in small vein grafts < 3.0 mm (n = 76) tended to have increased success (success rate = 94%, OR = 1.55 [CI 0.70, 3.44]; p = 0.39) and lower complications (complication rate = 2.2%, OR = 0.31 [CI 0.10, 0.94]; p = 0.03). Thus, excimer laser-facilitated angioplasty has the most favorable outcome for discrete lesions located at the ostium of all grafts and in the body of smaller saphenous vein grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2005

Epithelial healing and clinical outcomes in excimer laser photorefractive surgery following three epithelial removal techniques: mechanical, alcohol, and excimer laser.

PURPOSE: To evaluate epithelial healing, postoperative pain, and visual and refractive outcomes after photorefractive keratectomy (PRK) using three epithelial removal techniques. DESIGN: Prospective, nonrandomized, comparative trial. METHODS SETTING: Department of Ophthalmology, Yonsei University College of Medicine and Balgensesang Ophthalmology Clinic, Seoul, Korea. INTERVENTIONS: For the PRK procedure, the corneal epithelium was removed in one of three ways: mechanically (conventional PRK [PRK]) in 88 eyes of 44 patients; using excimer laser (transepithelial PRK [tPRK]) in 106 eyes of 53 patients; or using 20% diluted alcohol, laser-assisted subepithelial keratomileusis (LASEK) in 106 eyes of 53 patients. MAIN OUTCOME MEASURES: Epithelial healing, postoperative pain, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and remaining refractive error. RESULTS: The mean postoperative pain scores were 4.84 +/- 1.45 for PRK, 4.71 +/- 1.62 for tPRK, and 4.63 +/- 1.52 for LASEK (P = .125). The mean epithelial healing rates were 12.3 +/- 4.6 for PRK, 15.2 +/- 4.9 for tPRK, and 18.1 +/- 5.2 mm2/day for LASEK (P < .001). The postoperative 6-month remaining mean spherical equivalents (diopters) were -0.46 +/- 1.01 for PRK, 0.18 +/- 0.91 for tPRK, and -0.82 +/- 1.18 for LASEK (P = .01). The LASEK group showed less favorable UCVA than other groups. There was no significant difference in BSCVA between the groups. CONCLUSIONS: Postoperative pain, subepithelial opacity and BSCVA were similar regardless of the epithelial removal procedure. A faster epithelial healing rate did not result in better visual or refractive outcomes. Using the same nomogram, tPRK resulted in a slight overcorrection, and LASEK resulted in a slight undercorrection.

Adult↗
PubMed2000

Transmyocardial laser revascularization with excimer laser: clinical results at 1 year.

BACKGROUND: Transmyocardial laser revascularization, a new strategy for the treatment of diffuse ischemic heart disease, uses laser technology for the theoretical purpose of forming transmyocardial channels in the heart to increase perfusion to ischemic zones. This report summarizes our initial clinical experience with the procedure. METHODS: Excimer transmyocardial laser revascularization was performed in a reversibly ischemic region of the heart in 15 patients. Ischemia and myocardial viability were evaluated by assessment of symptoms and of results of radionuclide single photon emission computed tomography imaging, exercise tolerance testing, and 24-hour Holter monitoring. RESULTS: No adverse events occurred as a result of the laser revascularization, although 1 patient with preoperative ventricular arrhythmias died 48 hours postoperatively as a result of refractory ventricular tachycardia. Angina class decreased significantly from base line values in patients who had undergone the procedure (mean Canadian Cardiovascular Association angina class, 3.5+/-0.5 at base line, 1.6+/-0.6 at 1 month, 1.5+/-0.8 at 3 months, 1.9+/-0.9 at 6 months, 1.8+/-0.8 at 12 months; p<0.002), and nitroglycerin requirements were similarly decreased in patients who had undergone laser revascularization (mean g/wk of sublingual nitroglycerin, 19+/-4 at baseline, 5+/-3 at 1 month, 4+/-2 at 3 months, 4+/-2 at 6 months, 2+/-1 at 12 months; p<0.02). Exercise tolerance testing demonstrated increase in exercise duration compared with base line values (mean minutes, 7.4+/-3.1 at base line, 8.0+/-3.9 at 1 month, 8.5+/-4.4 at 3 months, and 9.0+/-3.9 at 12 months; p>0.05); those increases were not large enough to be statistically significant, however. CONCLUSIONS: Our data are consistent with the concept that excimer transmyocardial laser revascularization in individuals with significant ischemic heart disease appears to be well tolerated, can be performed safely, and may lead to a reduction in ischemic symptomatology.

Adult↗
PubMed2005

Comparison of the 308-nm excimer laser and a 308-nm excimer lamp with 311-nm narrowband ultraviolet B in the treatment of psoriasis.

BACKGROUND: Psoriasis is a chronic, genetically determined inflammatory disease, characterized by an immunomediated pathogenesis, which affects approximately 1-3% of the population. Various modalities have been used for psoriasis treatment, including ultraviolet (UV) radiation. Narrowband UVB (311 nm) phototherapy is a well-established, widely used and highly efficient treatment for psoriasis, but a big disadvantage is that large areas of unaffected skin are irradiated along with the psoriatic lesions. OBJECTIVES: This investigation evaluates a 308-nm excimer laser and a 308-nm excimer lamp in comparison with 311-nm narrowband UVB in the treatment of patch psoriasis by using two different dose-increase schemes. MATERIALS AND METHODS: Fifteen patients with plaque psoriasis were enrolled in the study (first regime). Three different psoriatic lesions were treated with the 308-nm excimer laser, the 308-nm excimer lamp or 311-nm narrowband UVB three times per week. UVB doses were increased slowly and stepwise (1, 1, 2, 2, 3, 3, ...multiple MEDs). Sixteen patients were enrolled in the second regime. Two plaques were treated with the 308-nm excimer laser or with the 308-nm lamp with an accelerated scheme (2, 2, 4, 4, 6, 6, ...multiple MEDs) three times per week. We increased the UVB doses every second treatment (first and second regime) during the whole treatment. If blistering occurred, the blistered plaque was not treated on the next scheduled treatment. At every third visit and 1, 2 and 4 months after the last treatment a Psoriasis Severity Index (PSI) score was assigned in both regimes. RESULTS: Using Friedman analysis, the PSI scores did not show a statistically significant difference (P > 0.05) comparing 308-nm laser therapy, 308-nm lamp therapy and 311-nm narrowband therapy after 10 weeks in the first regime. The mean number of treatments to achieve clearance was 24. With the accelerated scheme, clearance could be achieved with fewer treatments and with half the cumulative dose of the first regime. Nevertheless, the side-effects such as blistering and crusting were also increased. CONCLUSIONS: Both 308-nm light sources can clear patch psoriasis in a similar manner to standard phototherapy, with the advantage of the ability to treat exclusively the affected skin and with a reduced cumulative dose, thus perhaps reducing the long-term risk of carcinogenicity.

Adult↗
PubMedDate not supplied

The excimer lasers.

The excimer lasers are a group of lasers that have found wide application in a variety of medical fields including dermatology, cardiology, ophthalmology, and orthopedics. The word excimer refers to excited dimer. These lasers operate in the ultraviolet range, and examples include the 193 nm argon-fluroide, 248 nm krypton-fluoride, 351 nm xenon-fluoride, and of particular interest to dermatology, the 308 nm xenon-chloride. These lasers utilize a mixture of a noble gas and a halogen as a lasing material. They were first used in medicine for their ability to produce cold tissue ablation, but more recently have been used in dermatology as a method of non-ablative phototherapy.

Adolescent↗
PubMed1990

Laser ring catheters in excimer laser angioplasty.

Percutaneous excimer laser angioplasty is dependent on a reliable and effective energy transmission through fiberoptic devices. Compared with bare fibers, ring catheters provide improved flexibility and a central channel for insertion of guide wires. Peripheral laser catheters (7-9 F) were used in 32 patients with arterial occlusive disease in the lower limbs. The technical success rate was 91%. Vessel wall dissections occurred in nine cases but caused no clinical sequelae in the preliminary follow-up period (1-6 months). The clinical application of the catheter devices proved to be safe.

Aged↗
PubMed1992

Excimer laser coronary angioplasty: results in restenosis versus de novo coronary lesions. Excimer Laser Coronary Angioplasty Investigators.

There is limited information regarding the use of excimer laser coronary angioplasty (ELCA) in patients with restenotic lesions. The purpose of this investigation was to compare the results of ELCA in patients with restenosis following prior PTCA with results obtained in de novo (no restenosis) patients. A retrospective review was obtained of all patients undergoing attempted ELCA at each of the 12 participating clinical investigative centers. There were 620 patients in the prior restenosis group and 949 in the de novo group. Both laser success (88% vs 78%) and procedural success (92% vs 88%) were higher in restenosis lesions compared with de novo lesions (P less than 0.001). Six-month follow-up was available in 40% of patients. Restenosis occurred in 49% of the prior restenosis group vs 44% of the de novo group (P nonsignificant) but death was more common in the de novo group (2.2 vs 0.4%, P = 0.01). ELCA can be performed with a high success rate in patients with restenosis following prior balloon angioplasty but recurrent restenosis following laser procedure remains a significant problem.

Adult↗
PubMed1993

Excimer laser coronary angioplasty of aorto-ostial stenoses. Results of the excimer laser coronary angioplasty (ELCA) registry in the first 200 patients.

BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) of aorto-ostial stenosis has been associated with a lower rate of acute success, a high risk of vessel closure, and late restenosis. The purpose of this report is to document a prospective multicenter trial of excimer laser coronary angioplasty (ELCA) of aorto-ostial stenosis involving the coronary arteries and saphenous vein grafts. METHODS AND RESULTS: Between December 1989 and May 1992, 206 aorto-ostial ELCA procedures were performed on 209 stenoses in 200 patients. Canadian Cardiovascular Society class III or IV angina was present in 76%. The distribution of stenosis locations was left main coronary (LM) in 26 (12%), right coronary (RCA) in 124 (59%), and vein grafts (VG) in 59 (28%). Adjunctive PTCA was performed in 72%. Procedure success defined as < or = 50% diameter stenosis without major complications was achieved in 90% (LM, 92%; RCA, 89%, VG, 90%). Quantitative angiographic analysis documented an improvement in stenosis diameter from 0.8 +/- 0.5 mm or 76 +/- 14% at baseline to 2.1 +/- 0.6 mm or 36 +/- 15% at completion (P < .01). The majority of the acute gain in diameter (1.0 +/- 0.6 mm) resulted from ELCA. A major complication during hospitalization occurred in 3.9% (death, 0%; Q-wave myocardial infarction, 0.5%; bypass surgery, 3.4%). The only logistic regression univariate and multivariate predictor of procedure failure was female gender. Six-month angiographic follow-up, available in 51% of eligible patients, documented an average lumen diameter of 1.7 +/- 1.0 mm and mean diameter stenosis of 46 +/- 26%. Restenosis (> 50% diameter stenosis) occurred in 39% (LM, 64%; RCA, 35%; VG, 35%). Restenosis was less likely when residual stenosis was < or = 35% (28% versus 53%, P < .05). Clinical events at follow-up were death, 2.7%; bypass surgery, 6.5%; myocardial infarction, 2.2%; and repeat angioplasty, 16.2%. Of the remainder, 78% were asymptomatic, class I or II for anginal symptoms. An adverse event during follow-up was more than twice as likely in the group with LM (50.0% versus 21.1%, P < .02). CONCLUSIONS: ELCA is acutely effective and safe therapy in patients with aorto-ostial stenosis. Six-month restenosis, adverse-event rates were higher and functional status was poorer in the group with LM stenosis. ELCA may be considered as an alternative to bypass surgery in carefully selected patients with isolated aorto-ostial stenosis of the RCA and saphenous vein grafts.

Adult↗
PubMed1989

Experimental corneal studies with the excimer laser.

The excimer laser is potentially capable of achieving wide area central corneal reprofiling because of its extreme precision and limited penetration into adjacent tissues. A beam modifying system designed for this application is described. Initial clinical studies in monkeys and in ten human patients with blind eyes were performed. Long-term clinical data and interim histologic analyses are available from these studies. The results indicate that following ablation with an ultraviolet laser in both humans and primates, the ablated tissue shows a normal healing reaction resulting in a mild to moderate stromal interface haze. The effects of this healing on best corrected vision must be elucidated through additional research. Some loss of refractive effect was seen early in the healing process with apparent stabilization.

Animals↗
PubMed1996

Homogeneous light distribution to reduce vessel trauma during excimer laser angioplasty.

Excimer laser coronary angioplasty (ELCA) is associated with vascular damage, caused by rapidly expanding water vapour bubbles and accumulation of insoluble gas. The size of the rapidly expanding bubbles and the volume of gas can be reduced by decreasing the laser pulse energy density. However, using current multifibre catheters, penetration through porcine aortic tissue was found to be impossible at energy densities < or = 45 mJ/mm2. By contrast, by employing a 660 microns bare fibre it was observed that efficient tissue crossing was possible at 12 mJ/mm2, with considerable reduction of the rapidly expanding bubble volume and insoluble gas production. We attribute this efficient tissue penetration at low energy densities to the absence of 'dead space' in the homogeneous light distribution (HLD) at the fibre tip. Accordingly we hypothesize the ELCA performed at lower energy densities may result in less mechanical trauma to the vessel wall when compared with ELCA using current multifibre catheters.

Angioplasty, Balloon, Laser-Assisted↗
PubMed2001

Angiogenesis three months after clinical transmyocardial laser revascularization using an excimer laser.

BACKGROUND AND OBJECTIVE: We present for the first time histologic findings 3 months after clinical transmyocardial laser revascularization using a XeCl excimer laser. STUDY DESIGN/MATERIALS AND METHODS: Histology was performed on a patient who died from a noncardiac cause 3 months post-excimer TMLR. RESULTS: In the treated myocardium, no patent channels were found but scars were seen with a linear distribution and in continuity with circumscribed small fibrotic endocardial and epicardial scars. The scars were highly vascularized by new vessels, ranging from small capillaries to large thin walled, and sometimes branching ectatic vessels. Sprouting of vessels into the adjacent myocardium was also observed. CONCLUSION: These results suggest that angiogenesis might play a role in the clinical improvement after TMLR.

Aged↗