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At least 883 records · Page 49Linked to original sources
PubMedDate not supplied

A study of laser photocoagulation for polypoidal choroidal vasculopathy.

PURPOSE: To evaluate the efficacy of laser photocoagulation for polypoidal choroidal vasculopathy (PCV) involving the macula. METHODS: The records of 38 patients (47 eyes) undergoing laser photocoagulation for PCV causing serosanguineous detachment involving the fovea were reviewed and the results were evaluated. Ten eyes underwent photocoagulation to induce a fusion scar covering whole lesions consisting of both abnormal vessels and polypoidal lesions. Thirty-seven eyes underwent photocoagulation for only polypoidal lesions. When serosanguineous detachment recurred, additional photocoagulation was performed, targeting the causative lesions. Photocoagulation was performed with an argon dye laser or multicolor krypton laser. Final visual acuity, macular changes at the final visit, and the number of photocoagulations were evaluated. Follow-up period after the first photocoagulation was at least 1 year. RESULTS: Of the 10 eyes undergoing photocoagulation of whole lesions, 9 showed absorption of exudate and/or blood after one photocoagulation, and maintained or improved visual acuity. Of the 37 eyes undergoing laser photocoagulation of only polypoidal lesions, 20 (54%) showed decreased visual acuity because of recurrent or persistent exudation and/or classic choroidal neovascularization or, alternatively, because of atrophy at the fovea; 32 of the 37 eyes had undergone photocoagulation at least twice or more. CONCLUSION: Photocoagulation is recommended only for whole lesions.

Aged↗
PubMedDate not supplied

Long-term visual outcome in proliferative diabetic retinopathy patients after panretinal photocoagulation.

BACKGROUND: There is the need for a long-term study on the visual outcome of panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR) patients. CASES: We retrospectively reviewed the clinical course and visual results in 66 eyes of 59 patients with PDR who were followed-up for at least 10 years after argon or krypton laser PRP. OBSERVATIONS: Thirty-nine eyes had stage B-II, whereas 8 eyes had stage B-III retinopathy. Stage B-IV and B-V retinopathy were seen in 15 and 4 eyes, respectively. Although active stages of diabetic retinopathy were encountered after 5 years, complete regression could be successfully attained after 10 years. Long-term visual prospects were promising for eyes with stage B-II DR; 28.2% still enjoyed 20/40 or better visual acuity by 5 years. Most cases had maintained the same visual acuity at 10 years. Eyes with stage B-III DR did not attain 20/40 vision by 10 years. Panretinal photocoagulation in cases with neovascularization of the optic nerve head was seen to be beneficial but limited, suggesting that such cases might benefit from maximal initial and supplemental PRP followed by vitrectomy and intraoperative endophotocoagulation when necessary. Although 20% of the eyes with stage B-IV and 25% of the eyes with stage B-V DR had 20/40 or better visual acuity, analyses of the visual change revealed that about half the eyes with stage B-IV and all eyes with stage B-V DR experienced a visual loss of two lines or more. CONCLUSIONS: Progression of lens opacities, chronic macular edema, vitreous hemorrhage, macular traction, and neovascular glaucoma were the main causes of visual loss in this series. Panretinal photocoagulation for PDR provides good anatomical and visual outcome for 10 years or longer.

Adult↗
PubMed2002

Prediction of relative response factors for flame ionization and photoionization detection using self-training artificial neural networks.

The relative response factors (RRFs) of a flame ionization detection (FID) system and two pulsed discharge photoionization detection (PID) systems with different discharge gases are predicted for a set of organic compounds containing various functional groups. As a first step, numerical descriptors were calculated based on the molecular structures of compounds. Then, multiple linear regression (MLR) was employed to find informative subsets of descriptors that can predict the RRFs of these compounds. The selected MLR model for the FID system includes seven descriptors and two selected MLR models for the PID systems with argon- and krypton-doped helium as the discharge gases, respectively, include six and five descriptors. The descriptors appearing in the MLR models were considered as inputs for the self-training artificial neural networks (STANNs). A 7-7-1 STANN was generated for prediction of RRFs of the FID system, and two STANNs with the topologies of 6-7-1 and 5-6-1 were generated for the two PID systems. Comparison of the results indicates the superiority of neural networks over that of the MLR method. This is due to the nonlinear behaviors of relative response factors for all type of detectors studied in this work.

Flame Ionization↗
PubMed1999

Capillary electrochromatography with thermo-optical absorbance detection for the analysis of phenylthiohydantoin-amino acids.

Capillary columns were packed with 3 microns C18 stationary phase, interfaced with an ultraviolet-laser based thermo-optical absorbance detector, and evaluated for separation of a mixture of phenylthiohydantoin-amino acids. These columns demonstrated consistent performance with a relative standard deviation (RSD) for migration time of less than 1.5% and a separation efficiency of 216,000 plates/m for the electroosmotic flow marker, thiourea. The thermo-optical absorbance detector was based on a 248 nm krypton-fluoride excimer laser. Detection limits (3 sigma) ranged from 1.6 to 4.8 x 10(-7) M phenylthiohydantoin (PTH)-amino acid injected onto the column, which is a factor of three superior to those obtained in micellar electrokinetic chromatographic analysis of these compounds. A mixture of 17 PTH amino acids was injected onto the capillary; 13 components were nearly baseline resolved in 14 min.

Acetonitriles↗
PubMed1983

Hematoporphyrin derivative and laser photoradiation in the diagnosis and treatment of bladder cancer.

Diagnosis and treatment of 8 patients with malignant bladder tumors were performed with intravenous administration of hematoporphyrin derivative, followed by krypton-ion laser violet light photoradiation and argon-dye laser red light photoradiation therapy. Fluorescence permitting localization and evaluation of the lesion was recognized in all 8 patients. Photoradiation with red argon-dye laser light obtained complete remission in 6 patients, with followup from 6 to 18 months. To our knowledge this is the first report describing total regression of bladder tumors obtained by photoradiation. Swelling and edema were noted within 20 minutes after argon-dye laser photoradiation therapy of bladder tumors. Necrosis and partial covering of the tumor by a whitish necrotic mass were noted after 3 days. The whitish mass covered the entire tumor at 7 to 14 days. Gradual exfoliation of the mass was followed by disappearance of the tumor and regeneration of normal mucosa at 9 to 10 weeks.

Adult↗
PubMed1984

Lasers in ophthalmology.

Many sources of laser light are used in ophthalmology, most commonly the argon, krypton, and Nd:YAG laser. Each is described and evaluated regarding its qualities and advantages. Laser beam therapy can be used for a variety of ophthalmologic surgical procedures; it permits noninvasive, outpatient treatment that until recently has required invasive surgery. As laser knowledge advances, ophthalmic surgeons will be able to choose the wavelength appropriate to treat a variety of diseases.

Argon↗
PubMed1994

Fluorescence photodetection of neoplastic urothelial lesions following intravesical instillation of 5-aminolevulinic acid.

OBJECTIVES: Tiny papillary tumors and flat urothelial lesions such as dysplasia or carcinoma in situ can easily be missed during routine cystoscopy. Various methods for in vivo detection of fluorescing agents (preferentially localized in malignant tissue) have been developed. Most of them are based on systemically administered synthetic porphyrin compounds and require sensitive detection devices and image processing units for fluorescence visualization. The usefulness of intracellularly accumulated endogenous protoporphyrin IX (PPIX), induced by 5-aminolevulinic acid (ALA), for diagnosis of early bladder cancer and the correlation with cystoscopic, microscopic, and fluorescence findings was investigated. METHODS: ALA was instilled intravesically in 68 patients, followed by fluorescence cystoscopy with violet light from a krypton ion laser that produced fluorescence excitation. There were 299 biopsies obtained from fluorescing and nonfluorescing areas of the bladder. RESULTS: ALA-induced fluorescence could be easily observed with the naked eye during cystoscopy under violet light illumination. All tumor lesions were sharply marked with brightly shining red fluorescence. Correlation of fluorescence and microscopic findings gave a sensitivity of 100% and a specificity of 68.5%. There were 26 malignant or precancerous lesions that were missed during routine cystoscopy but were detected only by ALA-induced fluorescence. CONCLUSIONS: Labeling of urothelial lesions by PPIX fluorescence induced by intravesically instilled ALA seems to be a promising diagnostic procedure for malignant lesions that are difficult to visualize with standard cystoscopy.

Administration, Intravesical↗
PubMed2000

Chemical and physicochemical characterization of porous hydroxyapatite ceramics made of natural bone.

The properties of a porous hydroxyapatite ceramic produced by sintering of bovine bone were investigated by using a number of physicochemical methods such as scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), mercury intrusion porosimetry, krypton-adsorption, contact angle measurements, wide angle X-ray diffraction. Fourier transform infrared spectroscopy, thermal analysis, inductively coupled plasma optical atom emissions spectroscopy and flame atomic absorption spectroscopy. The results indicate that there are considerable differences between the ceramic and native bone. However, the most important properties with respect to the use of such ceramics as a biomaterial for filling bone defects namely the high porosity (> or = 57 +/- 2%) and the interconnecting pore system are maintained. While macropores with an average diameter of approx. 300 microm contribute 97% to porosity, micropores with an average diameter of 1.3 microm account for only 3% of the total porosity. The surface area was found to be approx. 0.1 m2/g. The contact angles of water (44.6 +/- 15.4 degrees, n = 5) and tetrahydrofurane (10 degrees) allow the processing of the ceramic to a drug carrier by incubation with aqueous or organic drug solutions. The ceramic is highly crystalline with crystal sizes of 1-7 microm and contains crystal bridges. The investigation of its chemical composition revealed small amounts of other inorganic compounds such as Ca4O(PO4)2, NaCaPO4, Ca3(PO4)2, CaO, and MgO. Besides trace amounts of aluminum, iron, magnesium, potassium, silica, sodium, vanadium and zinc it contains probably carbonated apatite.

Animals↗
PubMed1981

Retinal injury due to industrial laser burns.

Ocular industrial lasers burns in seven patients were analyzed as to cause, severity, and type of injury. Ocular damage ranged from minimal retinal burns to extensive areas of damage with commotio retinae and vitreous hemorrhage. Visual loss ranged from complete recovery without residual defect to a profound decrease in central acuity. The kinds of lasers causing these injuries were neodymium YAG, argon, krypton, and rhodamine dye. Severity of injury was related to several factors. Some degree of carelessness was involved in all injuries.

Accidents, Occupational↗
PubMed1983

Retinal pigment epithelial tears.

Retinal pigment epithelial tears have been recognized recently as a complication of retinal pigment epithelial detachments. They are characterized by sudden separation of detached from attached pigment epithelium at the margin of the detachment. Retraction of the overlying pigment epithelium occurs and exposes Bruch's membrane and choroid. Most pigment epithelial tears appear to arise spontaneously, but they also may occur following krypton red laser photocoagulation. The visual prognosis is poor in eyes in which the tear involves the subfoveolar pigment epithelium.

Aged↗
PubMed1989

Early retinal adhesion from laser photocoagulation.

Histopathologic examination of eight cynomolgus monkey eyes and one human eye revealed that both argon and krypton laser photocoagulation cause adhesion between the neurosensory retina and the retinal pigment epithelium (RPE) within 24 hours of treatment. The neurosensory retina remained attached at the sites of laser burns despite surrounding retinal detachment in untreated areas. This early adhesion with the laser is useful for the treatment of eyes in which the retina has been recently reattached such as at the end of a vitrectomy for a retinal detachment with proliferative vitreoretinopathy (PVR) or after a pneumatic retinopexy. It is also useful for the treatment of retinal breaks without detachment.

Adhesiveness↗
PubMed1989

Clinicopathologic study of organic dye. Laser in the human fundus.

One day before enucleation for choroidal melanoma, four patients consented to experimental laser photocoagulation for the purpose of comparing the histopathologic appearance of acute chorioretinal lesions produced by various dye laser wavelengths with krypton red and argon green laser controls. Three patients had simulated "light" and "heavy" treatment of an extrafoveal choroidal neovascular membrane (CNVM) with wavelengths 577 nm (yellow), 595 nm (orange), and 600 nm (orange). One patient had simulated panretinal photocoagulation (PRP) with four different dye laser wavelengths. Extrafoveal "light" treatment with the three dye wavelengths and both controls spared the inner retina and produced similar effects in the outer retina, pigment epithelium, and choriocapillaris. Choroidal penetration was deepest with the longer wavelengths (590-647 nm) in both "light" and "heavy" treatment groups. "Heavy" treatment gave varying degrees of full-thickness retinal uptake for all dye and both control wavelengths. Both ends of the orange spectrum (590-600 nm) produced the most severe inner retinal uptake. Panretinal photocoagulation produced similar full-thickness retinal uptake for all four dye wavelengths tested. These results indicate that caution should be used when treating "heavily" with 590 and 600 nm in the extrafoveal area.

Choroid↗
PubMed1989

The treatment of serous macular detachment secondary to choroidal melanomas and nevi.

The authors successfully treated with laser photocoagulation five patients who had a serous macular detachment secondary to leakage from a pigmented choroidal tumor. Three patients had dye leakage on fluorescein angiography from a choroidal neovascular membrane. The subretinal fluid resolved in all three patients after the neovascular membrane was obliterated by either krypton red (2 patients) or argon green (1 patient) laser photocoagulation. The other two patients had prominent leakage from a localized choroidal neovascular membrane as well as mild diffuse leakage over the entire tumor. Focal argon laser treatment to the neovascular membrane alone did not cause permanent resolution of the subretinal fluid. The fluid did resolve, however, after the entire area of diffuse leakage was retreated with photocoagulation. In one of the patients who received both focal and confluent laser treatment, the choroidal tumor grew in a collar-button fashion through Bruch's membrane at the original site of focal treatment. This eye was enucleated, and results of histopathologic examination showed a choroidal melanoma.

Aged↗
PubMed1998

Chemical composition measurements of the atmosphere of Jupiter with the Galileo Probe mass spectrometer.

The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995. Measurements of the chemical and isotopic composition of the Jovian atmosphere were obtained by the mass spectrometer during the descent over the 0.5 to 21 bar pressure region over a time period of approximately 1 hour. The sampling was either of atmospheric gases directly introduced into the ion source of the mass spectrometer through capillary leaks or of gas, which had been chemically processed to enhance the sensitivity of the measurement to trace species or noble gases. The analysis of this data set continues to be refined based on supporting laboratory studies on an engineering unit. The mixing ratios of the major constituents of the atmosphere hydrogen and helium have been determined as well as mixing ratios or upper limits for several less abundant species including: methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. Analysis also suggests the presence of trace levels of other 3 and 4 carbon hydrocarbons, or carbon and nitrogen containing species, phosphine, hydrogen chloride, and of benzene. The data set also allows upper limits to be set for many species of interest which were not detected. Isotope ratios were measured for 3He/4He, D/H, 13C/12C, 20Ne/22Ne, 38Ar/36Ar and for isotopes of both Kr and Xe.

Atmosphere↗
PubMed1997

Laser treatment of acquired vascular lesions.

Several quasi-continuous wave and pulsed lasers can effectively treat a variety of vascular lesions. The PDL follows the theory of selective photothermolysis, is safe for infants and children, and has a low incidence of side effects. It is successful in treating telangiectasias, spider and cherry angiomas, pyogenic granulomas, venous lakes, and poikiloderma of Civatte, as well as small leg telangiectasias. Quasi-continuous wave lasers such as the APTDL, copper vapor, krypton, and KTP lasers can be used to treat telangiectasias and other vascular lesions as well. Although they carry a higher risk of complications, they may prove more useful in treating larger caliber vessels. Although the PDL often produces superior clinical results than the quasi-continuous wave lasers, some patients may prefer these latter lasers because of the lack of post-operative purpura. Lastly, newer lasers, as well as noncoherent light sources, are being developed for the treatment of leg telangiectasias. Continuing advances in laser technology will enhance results, decrease side effects, improve equipment, and reduce costs, with great benefit to an increasing patient population.

Facial Dermatoses↗
PubMed1985

The excimer laser: gross, light microscopic and ultrastructural analysis of potential advantages for use in laser therapy of cardiovascular disease.

Excimer lasers are pulsed gas lasers that use a mixture of a rare gas and halogen as the active medium to generate pulses of short wavelength, high energy ultraviolet light. A krypton-fluoride gas mixture was used to achieve an excimer emission at a wavelength of 248 nm. A total of 30 atherosclerotic coronary artery segments were irradiated over a range of pulse energies (250 to 750 mJ), repetition rates (2 to 25 Hz), average powers (1.9 to 18.8 watts) and cumulative exposures (3 to 12 seconds). In no case was there gross, light microscopic or ultrastructural evidence of the pathologic injury typically associated with continuous wave laser irradiation of coronary artery segments. Similar results were achieved after excimer laser irradiation of 30 samples of myocardium. Excimer irradiation of calcified aortic valve leaflets accomplished focal debridement without pathologic tissue injury; when total debridement was attempted, however, gross charring was observed. The paucity of pathologic alterations observed after excimer irradiation of cardiovascular tissue may prove beneficial in precisely controlling laser ablation of pathologic tissue without injury to the surrounding normal tissue. Clinical application of excimer laser irradiation requires resolution of several issues, including the development of suitable fiber optics and laser coupling, evaluation of potential ultraviolet toxicity, and demonstration that ultraviolet light can be transmitted through a blood-filled system.

Coronary Disease↗
PubMed1989

CO2 laser laparoscopic surgery. Adhesiolysis, salpingostomy, laser uterine nerve ablation and tubal pregnancy.

Used endoscopically, the CO2 laser offers some advantages over other operative techniques for endometriosis and adhesions but, in spite of the continuing development of new instrumentation there are still problems with the system. The technique needs specialized equipment requiring ongoing biomedical maintenance and specialized technical care in the operating room. Some problems such as the intraperitoneal accumulation of smoke, gas leakage, and difficulty with maintenance of proper beam alignment still occur. In spite of these problems the advantages are numerous: the system allows precise bloodless destruction of diseased tissue and eliminates the risks of cautery. In the hands of an experienced laparoscopist, it appears safe and effective in vaporization of endometriotic lesions, utero-sacral neurectomy, adhesiolysis and salpingostomy. The judicious use of these techniques, combined with carefully planned further investigations by well-trained and experienced laparoscopists and continuing improvements in the delivery systems, will soon reveal the true efficacy of the CO2 laser laparoscope. If studies continue to show pregnancy rates and pain relief to be equivalent to those patients treated by laparotomy, CO2 laser laparoscopy will become the preferred procedure for the management of pelvic endometriosis and its associated adhesions, distal tubal occlusion, pelvic pain and tubal pregnancy. With the exception of using the argon laser to treat endometriosis, the selective absorption characteristic of lasers has not been greatly utilized. While the CO2 laser is heavily absorbed by water and hence vaporizes most cells in a rather indiscriminate fashion, this is not true for other wavelengths, such as argon, Nd-YAG, KTP, krypton, xenon, copper and gold vapour lasers. The energy form of each of these lasers has different properties of penetration, absorption, reflection and heat dissipation. Many of these lasers have not yet been evaluated in human subjects. An exciting, although not new, area of possible laser application involves the use of photosensitizers and fluorescing agents (Dougherty et al, 1978). Some recent experimental studies (Schellhas and Schneider, 1986; Schneider et al, 1988) may lead to new therapeutic possibilities. The surgical laser is not, however, a panacea. Only controlled trials carried out carefully over the next few years will clearly define its potential. In the meantime it is incumbent upon all of us to investigate the clinical, gynaecological and surgical applications in a careful, methodical and scientific manner.

Female↗
PubMed1994

The quantitative distribution of nebulized antibiotic in the lung in cystic fibrosis.

Nebulized antibiotic therapy in cystic fibrosis is an established procedure. The present study was designed to quantitate deposition, and assess its relation to the disease state. Twenty seven children and young adults with cystic fibrosis (mean 11.6 years, range 4-23 years, 12 females) were studied to establish the quantity and pattern of deposition of nebulized tobramycin in the respiratory tract. A single (120 mg) dose of nebulized 99 m technetium-labelled tobramycin was administered, and imaged with a gamma-camera. The mean penetration index (which compares the distribution of 81 m-Krypton gas with Tc-radioaerosol) was also used to measure peripheral deposition efficiency. The aerosol mass median diameter (MMAD) for the compressor-nebulizer system used was 5.3 u, measured with the Malvern Mastersizer. Serial sputum samples were fluroimmunoassayed for tobramycin in nine patients. A mean of 8.0 (SEM 1.0) mg tobramycin reached the lungs. There was no relationship between the total pulmonary deposition and indices of pulmonary damage in cystic fibrosis. Sixteen percent of the lung tobramycin reached the periphery. The greater the lung damage as indicated by FEV1 and Chrispin-Norman scores, the smaller the proportion of pulmonary tobramycin that reached the periphery. The mean penetration index increased with increase in the FRC, but bore no relation to other respiratory function tests or to chest X-ray scores. Sputum tobramycin concentrations reached levels bactericidal for Pseudomonas aeruginosa. Airway obstruction and damage affected the proportion of pulmonary tobramycin reaching the periphery. The proportion of tobramycin reaching the lungs was small and variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗