Krypton Laser Research Articles

THE ACCELERATION OF WOUND HEALING IS NOT ATTRIBUTED TO LASER SKIN TRANSMISSION

A study was carried out to observe the acceleration of wound healing using different wavelengths of laser, and to assess the role played by the amount of laser transmitted by the skin during wound healing in rats. An oval full thickness skin wound was created aseptically with a scalpel on the shaved back of the two groups of rats, control and treatment groups. Treatment was carried out with HeCd, Argon, HeNe, Krypton and GaAlas lasers, at doses of 10, 20, and 30 J/cm2 with a treatment schedule of 3 times per week. Our results show that the rate of wound healing acceleration in days (AccD) were 15.09%, 22.93%, 29.24%, 14.54%, 23.21% and 20.37% using optimum stimulation dose of 20 J/cm2 and wavelengths of 442 nm, 488-514 nm, 632 nm, 670 nm, 780 nm and 830 nm. The results suggest that HeNe laser with 632nm was the most effective in promoting wound healing when compared to other wavelengths used in this study. The measurement of laser skin transmission indicated that this would rise correspondingly as the wavelength of the laser in the spectral range of 442 nm to 830 nm. The results suggest that laser skin transmission is not proportionate to the amount of laser biostimulation. The acceleration of wound healing may not be attributed to skin transmission.

Expression of vascular endothelial growth factor and its receptor (KDR/flk-1) mRNA in experimental choroidal neovascularization

Purpose. Vascular endothelial growth factor (VEGF) is an angiogenic peptide that has been suggested to be important in the pathogenesis of choroidal neovascularization. We investigated the transcription of VEGF and its receptor KDR/flk-1 genes during the development of experimentally induced choroidal neovascularization. Methods. Rat VEGF or KDR cDNA was inserted in PGEM or pBluescript to prepare antisense or sense riboprobes. Multiple krypton laser burns were applied to the posterior pole of pigmented rat eyes according to a previously described protocol which produces choroidal neovascularization. At intervals of up to 4 weeks after photocoagulation, the eyes were removed and cut into thin sections. The sections were subjected to in situ hybridization with digoxigenin (DIG)-labeled single-strand rat VEGF and KDR cDNA riboprobes. Results. In normal adult rat retinas, VEGF and KDR mRNA expression was mainly observed in the ganglion cell and the inner nuclear layers. During the development of neovascularization, VEGF and KDR mRNAs were detected in retinal pigment epithelial-like cells, fibroblast-like cells and endothelial cells in neovascular lesions. The level of expression was strongest at 1 week after photocoagulation in lasered lesions, and decreased by 4 weeks after photocoagulation. Conclusions. Our findings demonstrate that expression of VEGF and its receptor KDR may play a role in the formation of experimentally induced choroidal neovascularization. In this study, VEGF and its receptor were co-localized, suggesting that an autocrine and/or paracrine mechanism may be operative.

Targeted Disruption of the FGF2 Gene Does Not Prevent Choroidal Neovascularization in a Murine Model

Choroidal neovascularization (CNV) is the major cause of severe visual loss in patients with age-related macular degeneration. Laser treatment is helpful for a minority of patients with CNV, and development of new treatments is hampered by a poor understanding of the molecular signals involved. Several lines of evidence have suggested that basic fibroblast growth factor (FGF2) plays a role in stimulating CNV. In this study, we tested this hypothesis using mice with targeted disruption of the FGF2 gene in a newly developed murine model of laser-induced CNV. One week after krypton laser photocoagulation in C57BL/6J mice, 34 of 60 burns (57%) showed fluorescein leakage and 13 of 16 (81%) showed histopathological evidence of CNV. At 2 weeks, CNV was detected in 9 of 10 burns (90%) in which a bubble had been observed at the time of the laser treatment. Electron microscopy showed fenestrated vessels with large lumens within choroidal neovascular lesions. Two weeks after laser-induced rupture of Bruch's membrane, 27 of 36 burns (75%) contained CNV in FGF2-deficient mice compared with 26 of 30 (87%) in wild-type control mice, a difference that is not statistically significant. This study demonstrates that FGF2 is not required for the development of CNV after laser-induced rupture of Bruch's membrane and provides a new model to investigate molecular mechanisms and anti-angiogenic therapy in CNV.

Expression of cell adhesion molecules and vascular endothelial growth factor in experimental choroidal neovascularisation in the rat

AIMSTo investigate the longevity and reproducibility of choroidal neovascularisation (CNV) induced by krypton laser photocoagulation in the rat. The presence of cell adhesion molecules (CAMs) and vascular endothelial growth factor...

Krypton Laser Suture Lysis

Traditionally, the argon laser has been used with suture lysis. The authors evaluate the krypton laser and define the parameters for the successful use of the laser with this procedure. Five consecutive patients undergoing combined cataract and trabeculectomy surgery who were considered candidates for this procedure underwent krypton laser suture lysis. Three laser suture lysis contact lenses were used during this procedure. None of the patients underwent adjuvant chemotherapy in the form of either 5-fluorouracil or mitomycin-C. All five patients were successfully treated with the krypton laser. In all cases, the 10-0 nylon sutures were cut. No complications were observed in any patients. The only side effect observed was occasional mild pain noted by the first few patients during the procedure. As the krypton laser settings were adjusted, this problem was corrected. The krypton laser can be successfully used to cut 10-0 nylon sutures following trabeculectomy surgery.

Evaluation of the Echographic Contribution to the Parasurgical Treatment of Melanomas of Small Dimensions

In this work we underlined the contribution of echography in the parasurgical treatment (photocoagulative) of melanomas of small dimensions. Fourteen patients were examined; some of them were treated with argon laser, others with krypton laser. The echographic examination was performed with the A-B scan technique, naturally accompanied by fluorangiography before and after the operation. An accurate echographic and fluorangiographic follow-up makes it posible to control the evolution of the lesions efficaciously. From this work it is clear how echography gives highly reliable results which allow us, therefore, both to make an adequate therapeutic decision and to evaluate the efficaciousness of the treatment itself.

The Krypton Yellow-Green Laser for the Treatment of Facial Vascular and Pigmented Lesions

There has been a bewildering increase in the number and types of lasers available to the modern surgeon for the treatment of a variety of lesions. Pigmented and vascular lesions lend themselves to laser therapy and are common presentations in the cosmetic practice. While many different lasers may be effective for the treatment of these lesions, each has its own advantages and disadvantages. A detailed understanding of the specific properties and the applicability of the different lasers is vital if one is to successfully incorporate these lasers into one's practice. In this article, we discuss the different types of lasers available for the treatment of these lesions, discuss the specific indications and limitations and present our experience with the krypton laser.

The KrF Direct Drive Fusion Concept

In collaboration with other laboratories, we are beginning a program to study and demonstrate the scientific, technical and economic feasibility of power production using laser fusion. The program, based on the development of a high average power Krypton Fluoride laser, is described in this paper.

Automatic Static Threshold Perimetry Is Useful for Estimating the Effects of Laser Photocoagulation on Diabetic Maculopathy

Focal photocoagulation was performed on 18 eyes in 18 diabetes patients; a visual acuity test, fluorescein angiography and automated static threshold perimetry by Octopus automated static perimetry (program 31) were conducted before and 1, 3 and 6 months after krypton laser photocoagulation. Central field sensitivity and total loss were measured by automated static threshold perimetry. Group A (13 eyes) had a total loss of less than 150 dB. In these subjects, mild fluorescein leakage was detected within the area of the vascular arcade. In group B (5 eyes) with a total loss of greater than 150 dB, diffuse fluorescein leakage was also detected outside the vascular arcade. The central field sensitivity was reduced in 2 eyes of group B. The total loss worsened in 8 eyes of group A (61.5%) and 5 eyes of group B (100%). Inspection of photographs gave the impression that the degree of fluorescein leakage and the area of the avascular zone on fluorescein angiography accorded with total loss, thus suggesting that total loss reflects visual functions better than visual acuity or central field sensitivity. Therefore, automated static threshold perimetry appears to be a useful method for estimating visual functions after photocoagulation in diabetic maculopathy patients.

Trans‐scleral krypton laser cyclophotocoagulation: Our experience of its use on patients with neovascular glaucoma

Trans-scleral cyclophotocoagulation is an efficacious method in neovascular glaucoma (NVG) treatment. We have used it with krypton laser on 12 eyes of 12 patients affected by NVG with algetic symptoms. Six months after treatment, intraocular pressure was down enough for the pain to disappear. Executional simplicity and the possibility of modulating the intensity of the treatment are grounds for the encouragement of the technique's use in NVG.

High-power discharge with a plasma cathode in dense gases

An attempt is made to create an electric-discharge source for pumping argon, krypton, and xenon dimer lasers. The device is based on a method proposed previously by the authors, wherein confinement of the discharge is achieved by removing the cathode spot from the main discharge region and closing the discharge to the spot along a narrow extended auxiliary plasma channel. The conditions for the formation of such a discharge are investigated. The high stability of the sparkless stage of the discharge permits the first-ever attainment of energy depositions at the level of 100 J/cm2 at pressures ∼10 atm, a level several orders of magnitude higher than is attainable by conventional methods. A discharge cell and power supply system are designed for a multisectional discharge with an active length of 200 mm, and the reliability of the entire apparatus is demonstrated in long-term use.

Krypton fluoride laser pulse shortening by stimulated thermal scattering on a liquid surface

Pulse shortening of the backscatter of a KrF excimer laser beam focused on the surface of n-hexane is reported. Simultaneous measurements of the backscattered beam, a Fresnel reflected beam, incoherent scattered photons from a liquid surface, and a transmitted beam are performed. The results show that the surface reflected beam disappears followed by beam expansion and the transmitted beam is reduced to form a filamentlike structure with the onset of backscatter. The pulse width of the backscattered beam shows a clear dependence on the focal position in the liquid. Incoherent scattering is sharply enhanced when the laser beam is focused at the liquid surface where the backscattered beam is especially short. The observed phenomena indicate that stimulated thermal scattering is the pulse shortening mechanism.

Photochemically induced colonic ischaemic lesions: a new model of ischaemic colitis in rats

Background—Recent clinical studies suggest that ischaemic colitis is caused by a microcirculatory disturbance that involves thrombosis of the colon.Aim—To establish a new model of photochemically induced ischaemic colitis in rats.Methods—Thirty...

Study of porous silicon obtained by krypton ion implantation and laser annealing

An ellipsometric technique is used to study the formation of a finely porous layer saturated with atoms of an inert gas in a crystalline silicon lattice that has been doped by high doses of krypton and then irradiated by nanosecond laser pulses. The changes in the complex refractive index of this layer induced by laser pulses at different powers are studied. A scanning field ion microscope is used to follow the transformation of the pores, as the energy per unit area of the annealing laser light is varied, and to estimate their sizes.

Confocal Raman Microscopy of Chromosomes, Cells and Eye-Lenses

Abstract A confocal scanning Raman microscope was constructed for spectroscopy and microscopy of biological samples (Fig. 1). The microscope contains an illumination system in which a focused krypton laser beam, of which the 647.1 nm line is used to reduce damage, is scanned over the sample using a scanning mirror which moves around two orthogonal axes. Raman scattered light is collected by a water immersion objective which directs the light on the scanning mirror. Spectral analysis takes place in a monochromator with two exit ports: one for spectroscopical purposes the other one for imaging. An image is made by scanning the light, present in the Raman band passed by the monochromator, over a CCD using a second scanning mirror which moves synchronously with the first mirror. The spatial resolution is of the order of 0.3 × 0.3 × 1.2 μm3 (x,y,z). With this microscope we studied the following samples:

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.

A Patientʼs Questionnaire Evaluation of Krypton Laser Treatment of Facial Telangiectases

Facial telangiectasia is a common disfiguring condition in modern society. Recently the krypton laser has been advocated as an effective modality for treatment of facial telangiectasia.To compare the effectiveness and incidence of adverse effects of the krypton laser with that of the copper vapor laser in the treatment of facial telangiectasia.Two hundred consecutive patients treated with the krypton laser were asked to complete a questionnaire evaluating the treatment; 149 (74.5%) patients responded.The krypton laser was as effective as the copper vapor laser in treating facial telangiectasia. In addition, there was a significant reduction in pain experienced and the incidence of adverse effects was reduced in patients treated with the krypton laser.Selection of pulse duration to approximate the thermal relaxation time of the target blood vessel is critical in minimizing adverse effects of laser photocoagulation to facial telangiectases.

Growth factors in age-related macular degeneration: pathogenic and therapeutic implications.

To investigate the role of growth factors in choroidal neovascularization in humans with age-related macular degeneration (ARMD) and in rats with choroidal neovascularization produced by krypton laser photocoagulation. Autoradiography using 3H-thymidine in laser-treated rats. Light- and electron-microscopic immunocytochemistry using antibodies to several different growth factors and to the fibroblast growth factor (FGF) receptor. Tissues studied included the retinas of rats that had received krypton red laser photocoagulation, which induces formation of choroidal neovascularization 6-8 weeks after laser treatment, choroidal neovascular membranes (CNVMs) removed surgically from humans with ARMD and whole human eyes obtained postmortem with macular choroidal neovascular lesions from ARMD. Nuclei of retinal pigment epithelium (RPE) and choriocapillary cells in laser-treated rats were labeled with 3H-thymidine up to 80 days after photocoagulation, maximally at 2-7 days after laser treatment. At all intervals, RPE cells in treated areas immunolabeled for aFGF and bFGF. Labeling was strongest within lysosomes. RPE cells in untreated regions did not immunolabel for growth factors. RPE cells from CNVMs in the maculas of humans with ARMD also immunolabeled for aFGF and bFGF. Some choriocapillary endothelial cells in human CNVMs became labeled in a regular array along their anteluminal and luminal plasma membranes with anti-bFGF antibodies and, in a similar pattern, with antibodies to the FGF receptor. Finally, serial sections from some CNVMs in ARMD patients were immunostained alternately for bFGF and for vascular endothelial growth factor (VEGF). RPE cells and choriocapillary endothelial cells in these membranes immunostained for VEGF. Many immunostained for both bFGF and VEGF. In whole human eyes with macular CNVMs RPE cells in regions of normal retina did not immunostain for these growth factors. Several growth factors are not expressed at detectable levels by immunocytochemistry in normal RPE cells in rats or humans but do appear following photocoagulation or the development of CNVMs in ARMD. This suggests that these growth factors have a pathogenic role in choroidal neovascularization. Possibly, bFGF and VEGF act synergistically to accelerate neovascularization. The up-regulation of VEGF in CNVMs is of special interest because up-regulation of this growth factor in other systems appears to be stimulated by tissue hypoxia. Till now, hypoxia has not been considered a major pathogenic agent in the development of CNVMs in ARMD or other macular diseases.

Clinical evaluation of a method for detecting superficial surgical transitional cell carcinoma of the bladder by light-induced fluorescence of protoporphyrin IX following the topical application of 5-aminolevulinic acid: preliminary results.

In bladder cancer, conventional white light endoscopic examination of the bladder does not provide adequate information about the presence of "flat" urothelial lesions such as carcinoma in situ. In the present investigation, we examine a new technique for the photodetection of such lesions by the imaging of protoporphyrin IX (PpIX) fluorescence following topical application of 5-aminolevulinic acid (ALA). Several hours after bladder instillation of an aqueous solution of ALA in 34 patients, a Krypton ion laser or a filtered Xenon arc-lamp was used to excite PpIX fluorescence. Tissue samples for histological analysis were taken while observing the bladder wall either by means of a video camera, or by direct endoscopic observation. A good correlation was found between the PpIX fluorescence and the histopathological diagnosis. On a total of 215 biopsies, 143 in fluorescent and 72 in nonfluorescent areas, all visible tumors on white light cytoscopy appeared in a bright red fluorescence with the photodetection technique. In addition, this method permitted to discover 47 unsuspected carcinomatous lesions on white light observation, among which 40% were carcinoma in situ. PpIX fluorescence induced by instillation into the bladder of 5-ALA is an efficient method of mapping the mucosa in bladder carcinoma.

Flow cytometric analysis and confocal imaging of anticancer alkylaminoanthraquinones and their n‐oxides in intact human cells using 647‐nm krypton laser excitation

Flow cytometric analysis and confocal imaging of anticancer alkylaminoanthraquinones and their n‐oxides in intact human cells using 647‐nm krypton laser excitation