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PubMed1994

Transscleral contact krypton laser cyclophotocoagulation for treatment of glaucoma.

PURPOSE: To evaluate the usefulness of the krypton laser for transscleral contact cyclophotocoagulation. METHODS: Transscleral contact krypton laser cyclophotocoagulation was performed in 62 eyes of 57 patients with therapy-resistant glaucoma. A minimum follow-up for 6 months was obtained for 59 eyes. The krypton laser was delivered via a fiberoptic probe with compression of the sclera by the probe. The energy used was 4 to 5 J per application at the tip of the probe with an exposure time of 10 seconds. RESULTS: The intraocular pressure (IOP) decreased from the baseline mean of 34.8 +/- 11.0 mmHg to 20.4 +/- 8.3 mmHg within 10 days, to 22.6 +/- 12.5 mmHg at 1 month, to 21.3 +/- 11.3 mmHg at 3 months, and to 20.9 +/- 9.1 mmHg at 6 months postoperatively. Intraocular pressures of 8 to 24 mmHg were obtained in 62% of the eyes at 1 month, 60% at 3 months, and 73% at 6 months postoperatively with one or more cyclophotocoagulations but no other hypotensive procedures. The corresponding success rates after 6 months were 82% for eyes in which the procedure was performed to preserve vision and 50% for eyes in which the procedure was performed to relieve pain. No clinical signs of scleral injury or cyclodestruction-related loss of vision were detected. CONCLUSIONS: Krypton laser cyclophotocoagulation appears to be an effective and well-tolerated means of lowering IOP in therapy-resistant glaucoma. An advantage of the method is that standard retinal krypton photocoagulators can be used for the procedure.

Ciliary Body↗
PubMed1993

Comparisons of photocoagulation treatment in exudative age-related macular degeneration with the blue-green argon, green argon and red krypton laser wavelengths.

Between November 1975 and December 1989, we examined 1,540 patients with age-related macular degeneration (ARMD). 297 eyes of 270 of these patients received photocoagulation treatment (from L.S.A.) for exudative ARMD, including choroidal neovascular membranes (CNVMs) and retinal pigment epithelial detachment. Initially, only the blue-green argon laser was available. From 1983 onwards we could choose between the blue-green argon, green argon and red krypton laser wavelengths. The 270 treated patients were followed for a minimum of 6 and a maximum of 168 months posttreatment (median 16 months). Of the 297 eyes, 138 received treatment with the blue-green argon, 36 with the green argon and 123 with the red krypton laser. Eyes with subfoveal and juxtafoveal NVMs were treated with the krypton laser. Also assigned to krypton photocoagulation were extrafoveal NVMs accompanied by hemorrhage. There was no statistical difference in the results of the three treatment modalities as judged by visual acuity. But, green argon is preferable to blue-green argon since it is absorbed less by the xantophyll pigment. On the other hand, krypton laser appears to be at least as effective as green argon in extrafoveal neovascularization and is certainly the treatment of choice in subfoveal and juxtafoveal NVMs.

Aged↗
PubMed1993

Energy levels needed for cyclophotocoagulation: a comparison of transscleral contact cw-YAG and krypton lasers in the rabbit eye.

The energy levels needed for cyclophotocoagulation using either transscleral contact krypton or cw-YAG lasers were compared in pigmented rabbits. The same transscleral laser probe was used for both lasers. With the krypton laser, 0.25 J of energy caused macroscopically detectable lesions, and 1.5 J led to widespread destruction of the ciliary body. With the cw-YAG laser, the first detectable lesions were produced at 0.5 J. Similarly, at higher energies, twice as much energy was required using the cw-YAG as compared with using the krypton laser to produce comparable lesions. Histologically, lesions of the same macroscopic severity made with the two lasers were similar. We conclude that the transscleral contact krypton laser is an efficient instrument for cyclophotocoagulation. Although these results may not be directly applied to human eyes, it appears that the poorer scleral transmission of the krypton beam is offset by its higher level of absorption in the pigmented epithelium of the ciliary body.

Animals↗
PubMed1998

Krypton laser suture lysis.

BACKGROUND AND OBJECTIVES: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: The krypton laser can be successfully used to cut 10-0 nylon sutures following trabeculectomy surgery.

Aged↗
PubMed1984

Krypton laser trabeculoplasty. A clinical report.

Krypton red (647.1 nm) or krypton yellow (568.2 nm) laser trabeculoplasty was performed in 15 phakic eyes of 14 patients. After an average follow-up of five months, these patients had an average drop of intraocular pressure of 8.9 mm Hg. In addition, in eight of these patients studied, argon laser trabeculoplasty was performed in the opposite eye. After an average follow-up of more than five months in these eight patients, the average drop of IOP was 7.2 mm Hg in the eyes with krypton laser trabeculoplasty and 6.8 mm Hg in the eyes with argon laser trabeculoplasty. This preliminary study indicates that laser trabeculoplasty may be effectively performed with krypton wavelengths.

Aged↗
PubMed1992

An evaluation of Technegas as a ventilation agent compared with krypton-81 m in the scintigraphic diagnosis of pulmonary embolism.

A ventilation agent that provides good quality lung images, which is cheap, easy to use and non-toxic, with a low radiation dose, has long been sought. Technegas, an ultrafine aerosol of technetium-99m-labelled carbon, was developed with these qualities in mind. We have studied Technegas in a clinical setting to evaluate some of these qualities. Twenty-five patients referred with a diagnosis of suspected pulmonary embolism were investigated during the same study using both krypton-81 m and Technegas as ventilation agents in conjunction with 99mTc-macroaggregated albumin as a perfusion agent. Technegas provided images which were of satisfactory quality. Images were obtained relatively easily and without discomfort to the patient, and Technegas has the advantage of always being available. A semi-quantitative regional assessment was employed which showed a good correlation (r = 0.499, P less than 0.001) between Technegas and krypton-81 m ventilation. We report on an effect not previously found to be significant, that is lung regions were better ventilated with Technegas than with krypton-81 m. This altered the diagnostic probability rating of pulmonary embolism in a number of patients (n = 3, 12%) compared with krypton-81 m. This effect was also noted in a further 8 patients (32%) without a change in the diagnostic probability. We offer possible explanations for this phenomenon.

Female↗
PubMed1979

Assessment of coronary venous bypass graft function using krypton-81m.

Fifteen patients with intractable angina pectoris underwent coronary angiography and coronary arterial bypass graft surgery. After the operation, a continuous infusion of krypton-81m was delivered into each graft. A gamma camera and multichannel analyzer were used to record the regional myocardial distribution of perfusion provided by each graft. The disappearance of myocardial activity at the end of each infusion was used to calculate the flow per unit volume in the myocardial distribution provided by each vessel. Myocardial perfusion provided by the grafts to all the major coronary arteries were recorded individually as high spatial resolution images. Myocardial flow rates in the distribution of each graft were measured using the washout of krypton-81m. The rates were 0.5 to 2.0 ml/g per min in the 13 patients with no evidence of previous myocardial infarction. Krypton-81m was infused into grafts to the left anterior descending coronary artery in two patients with a history and electrocardiographic evidence of previous anterior myocardial infarction. The grafts provided poor perfusion to the anterior and apical portions of the ventricles. An experimental model of myocardial perfusion was used to demonstrate that the washout of krypton-81m can be used to measure flow per unit volume within or above the physiologic range.

Angina Pectoris↗
PubMed1985

Right ventricular ejection fraction measured by first-pass intravenous krypton-81m: reproducibility and comparison with technetium-99m.

Study of the effects of various diseases and therapeutic manipulation of pulmonary vascular resistance on the right ventricle has been restricted by methodologic limitations. The radioactive gas in solution, krypton-81m was used to study the right ventricle and the technique was compared with a technetium-99m method. In 22 subjects, first-pass krypton-81m right ventricular ejection fraction, acquired both in list mode and electrocardiogram-gated frame mode, correlated well (r = 0.81 and 0.86, respectively, p less than 0.01) with that determined by technetium-99m first-pass studies over a broad range of ventricular function. The reproducibility of the technique was excellent (r = 0.84 and 0.95 for each acquisition mode, respectively). Krypton-81m first-pass studies provide accurate and reproducible estimates of right ventricular function. Use of krypton allows multiple measurements, with or without perturbations, over a short period of time.

Heart Ventricles↗
PubMed2006

Krypton laser photocoagulation induces retinal vascular remodeling rather than choroidal neovascularization.

The purpose of this study is to analyze the retina and choroid response following krypton laser photocoagulation. Ninety-two C57BL6/Sev129 and 32 C57BL/6J, 5-6-week-old mice received one single krypton (630 nm) laser lesion: 50 microm, 0.05 s, 400 mW. On the following day, every day thereafter for 1 week and every 2-3 days for the following 3 weeks, serial sections throughout the lesion were systematically collected and studied. Immunohistology using specific markers or antibodies for glial fibrillary acidic protein (GFAP) (astrocytes, glia and Muller's cells), von Willebrand (vW) (vascular endothelial cells), TUNEL (cells undergoing caspase dependent apoptosis), PCNA (proliferating cell nuclear antigen) p36, CD4 and F4/80 (infiltrating inflammatory and T cells), DAPI (cell nuclei) and routine histology were carried out. Laser confocal microscopy was also performed on flat mounts. Temporal and spatial observations of the created photocoagulation lesions demonstrate that, after a few hours, activated glial cells within the retinal path of the laser beam express GFAP. After 48 h, GFAP-positive staining was also detected within the choroid lesion center. "Movement" of this GFAP-positive expression towards the lasered choroid was preceded by a well-demarcated and localized apoptosis of the retina outer nuclear layer cells within the laser beam path. Later, death of retinal outer nuclear cells and layer thinning at this site was followed by evagination of the inner nuclear retinal layer. Funneling of the entire inner nuclear and the thinned outer nuclear layers into the choroid lesion center was accompanied by "dragging" of the retinal capillaries. Thus, from days 10 to 14 after krypton laser photocoagulation onward, well-formed blood capillaries (of retinal origin) were observed within the lesion. Only a few of the vW-positive capillary endothelial cells stained also for PCNA p36. In the choroid, dilatation of the vascular bed occurred at the vicinity of the photocoagulation site and around it. Confocal microscopy demonstrates that the vessels throughout the path lesion are located within the neuroretina while in the choroid (after separation of the neural retina) only GFAP-positive but no lectin-positive cells can be seen. The involvement of infiltrating inflammatory cells in these remodeling and healing processes remained minimal throughout the study period. During the 4 weeks following krypton laser photocoagulation in the mouse eye, processes of wound healing and remodeling appear to be driven by cells (and vessels) originating from the retina.

Animals↗
PubMed1985

Clinical use of ultrashort-lived radionuclide krypton-81m for noninvasive analysis of right ventricular performance in normal subjects and patients with right ventricular dysfunction.

The ultrashort-lived radionuclide krypton-81m, eluted in 5% dextrose from a bedside rubidium-81m generator, was intravenously infused for rapid imaging of the right-sided heart chambers in the right anterior oblique projection adjusted for optimal right atrioventricular separation. Left-sided heart and lung background was minimized by rapid decay and efficient exhalation of krypton-81m, requiring no algorithm for background correction. A double region of interest method decreased the variability in the assessment of ejection fraction to 5%. In 10 normal subjects, 11 patients with pulmonary hypertension, 4 patients with right ventricular outflow tract obstruction and 4 patients with right ventricular infarction, right ventricular ejection fraction determined by krypton-81m equilibrium blood pool imaging ranged from 14 to 76%. The correlation between these values and those determined by cineangiography according to Simpson's rule was close: r = 0.93 for all data points (p less than 0.001), r = 0.92 for studies at rest (p less than 0.001) and r = 0.93 for exercise studies (p less than 0.001). Exercise-related changes in right ventricular function revealed a disturbed functional reserve with pulmonary hypertension and right ventricular infarction, whereas in compensated right ventricular outflow tract obstruction there was a physiologic increase in ejection fraction with exercise (p less than 0.001). Thus, equilibrium-gated right ventricular imaging using ultrashort-lived krypton-81m is a simple, accurate and reproducible method with potential for serial assessment of right ventricular ejection fraction in a variety of right ventricular anatomic and functional abnormalities, both at rest and during exercise. Advantages of this method include an extremely low radiation dose to patients and clear right atrioventricular separation without the need to correct for background activity.

Adult↗
PubMed2001

Transscleral contact krypton laser cyclophotocoagulation for treatment of posttraumatic glaucoma.

PURPOSE: To evaluate the usefulness of the krypton laser for transscleral contact cyclophotocoagulation in the treatment of posttraumatic glaucoma. PATIENTS AND METHODS: A total of 18 eyes of 18 patients with therapy-resistant posttraumatic glaucoma treated with krypton laser cyclophotocoagulation from 1991 to 1996 were included in this review. The krypton laser was delivered by a fiberoptic probe with simultaneous compression of the sclera. The energy used was 3 to 5 J per application at the tip of the probe, with an exposure time of 10 seconds. The treatment covered 90 to 360 degrees of the ciliary body with approximately 10 applications per quadrant. RESULTS: With one or more cyclophotocoagulation treatments, the intraocular pressure decreased from the baseline mean (+/- standard deviation) of 32.6 +/- 12.8 mm Hg to 23.6 +/- 10.3 mm Hg (n = 17) at 1 month, to 21.8 +/- 7.5 mm Hg (n = 13) at 3 months, to 22.5 +/- 7.6 mm Hg (n = 13) at 6 months, and to 19.6 +/- 10.5 mm Hg (n = 18) at the last control visit (mean, 19.4 months; range, 3 weeks to 73 months) after cyclophotocoagulation but no other glaucoma procedure. At baseline, 17 (94%) of 18 patients were taking glaucoma medication, as were 15 (83%) of 18 patients at the last control visit. One (6%) case of phthisis occurred. CONCLUSIONS: Krypton laser cyclophotocoagulation is an effective and reasonably well tolerated means of lowering intraocular pressure in posttraumatic glaucoma. Because of the refractory nature of the disease, repeated treatments may be needed.

Adult↗
PubMed1984

[Effects of red krypton and monochromatic green argon lasers in the foveal region. A clinical and experimental study].

The destruction of senile neovascular membranes in the central avascular region of the macula using argon laser is difficult and associated with complications. Yellow pigment in this region absorbs the blue component of the conventional argon laser radiation. In this study, we compared laser of different wavelenghts: red krypton and green argon. Light and electron microscopic studies on non-human primates were performed at one hour and three weeks following laser burns. With the red krypton laser maximum damage was seen at the level of choriocapillaris and the choroïd, although the pigment epithelium was also destroyed. With the green argon laser the maximum absorption occurred at the level of the pigment epithelium. A clinical and angiographic study showed that the destruction of juxtafoveal neovascular membranes by both these lasers was possible after one or several treatment sessions. After an average follow-up period of 45 months, visual acuity was stable or improved in 10 out 17 eyes treated with the green argon laser and in 27 out of 53 eyes treated with the red krypton laser. Our results suggest that the red krypton laser offers a better alternative for the treatment of neovascular membranes located near the foveola since less unnecessary damage is induced. Outside the xanthophyllic area there is no major difference between the different wavelengths.

Animals↗
PubMed1981

Retinal vessel photocoagulation: a quantitative comparison of argon and krypton laser.

Retinal arteries of owl monkeys were photocoagulated with single exposures to argon laser green light (514 nm), krypton laser green light (531 nm), and krypton laser yellow light (568 nm). The distribution of damage along the vessel in different retinal layers was characterized geometrically after serial sectioning of the histopathologic material. Krypton laser radiation (green and, to an even greater extent, yellow) produced measurably greater effects on retinal vessels and adjacent structures than on deeper retinal levels; argon laser radiation (green) produced greater effects on the pigment epithelium. Krypton yellow produced the greatest total effect. The location of damage to the retinal arteries and pigment epithelium differed, with the peak of the damage around the arteries being farther from the optic disc than was the peak of the pigment epithelial damage.

Animals↗
PubMed2001

Transscleral contact krypton laser cyclophotocoagulation for treatment of glaucoma in children and young adults.

PURPOSE: To evaluate the usefulness of the krypton laser for transscleral contact cyclophotocoagulation (CPC) in the treatment of glaucoma in young patients. DESIGN: Retrospective noncomparative interventional case series. PARTICIPANTS: Transscleral contact krypton laser CPC was performed in 27 glaucomatous eyes of 22 young patients (mean age, 10.5 +/- 5.6 years; range, 11 months-19.4 years). METHODS: The treatment was delivered by means of a fiberoptic probe with compression of the sclera by the probe. The power used was 300 to 500 W per application at the tip of the probe with an exposure time of 10 seconds. MAIN OUTCOME MEASURES: The primary outcome measure is a change in intraocular pressure (IOP). RESULTS: Of the patients who received CPC in both eyes, one eye was randomly chosen for statistical analysis. The mean overall follow-up time was 43.3 +/- 25.3 (median, 36.5; range, 1-82) months after the initial CPC. Preoperatively, the mean intraocular pressure was 35.0 +/- 7.9 mmHg (n = 22). After one or more CPCs, the mean IOP was decreased to 21.5 +/- 8.7 mmHg (n = 22) at 1 month (P < 0.001), to 23.4 +/- 8.6 mmHg (n = 18) at 3 months (P < 0.001), to 25.0 +/- 12.1 mmHg (n = 19) at 6 months (P < 0.01), to 22.1 +/- 9.1 mmHg (n = 16) at 1 year (P < 0.01), and to 22.6 +/- 10.3 (n = 11) at 2 years (P < 0.01). After one or more krypton CPCs, but no other glaucoma procedures, an IOP level of 8 to 21 mmHg or a decrease in IOP of more than 30% was obtained in 14 of 22 (64%) eyes at the last follow-up. No permanent hypotonia, phthisis bulbi, or devastating CPC-related complications were noted. CONCLUSIONS: Krypton laser CPC is a well-tolerated means of lowering IOP in young patients with glaucoma, but repeated treatments may be needed.

Adolescent↗
PubMed2005

Photoionization of small krypton clusters in the Kr 3d regime: evidence for site-specific photoemission.

Kr 3d ionization energies of small, variable size krypton clusters are investigated by photoelectron spectroscopy, where the size regime of clusters with an average size N< or =30 is studied. Characteristic shifts in Kr 3d ionization energies to lower binding energies are found compared to the bare atom. These are also different from those of large krypton clusters. Moreover, we find evidence for photoionization of the krypton dimer. Its 3d ionization energy is barely shifted relative to the atomic value. Results from model calculations considering different isomers and cluster sizes as well as defect sites give evidence that the experimental results can be related to photoionization from different surface sites in variable size krypton clusters. This can be related to site-specific photoemission in small Kr clusters. The results are compared to size effects in Kr 3d near-edge features of variable size Kr clusters as well as recent results on Kr 3d photoionization of large Kr clusters.

Journal Article↗
PubMed2006

Preferential site occupancy of krypton atoms on free argon-cluster surfaces.

Argon clusters have been doped with krypton atoms in a pick-up setup and investigated by means of ultraviolet and x-ray photoelectron spectroscopy (UPS and XPS). The width of the krypton surface feature in the XPS spectra from mixed krypton/argon clusters has been studied and found to be narrower than in the case of homogeneous krypton clusters. By considering known spectral broadening mechanisms of the cluster features and the electron binding energy shift of the cluster surface feature relative to the atomic signal, we conclude that krypton ad-atoms preferentially occupy high-coordination surface sites on the argon host-cluster.

Journal Article↗
PubMed1997

The radioactivity of atmospheric krypton in 1949-1950.

The chemical element krypton, whose principal source is the atmosphere, had a long-lived radioactive content, in the mid-1940s, of less than 5 dpm per liter of krypton. In the late 1940s, this content had risen to values in the range of 100 dpm per liter. It is now some hundred times higher than the late 1940 values. This radioactivity is the result of the dissolving of nuclear fuel for military and civilian purposes, and the release thereby of the fission product krypton-85 (half-life = 10.71 years, fission yield = 0.2%). The present largest emitter of krypton-85 is the French reprocessing plant at Cap-de-la-Hague.

Journal Article↗
PubMed1987

Krypton and argon laser photocoagulation for central serous chorioretinopathy.

Based on medical records, the authors divided 86 eyes of 84 patients with central serous chorioretinopathy with serous detachment of the macula and retinal pigment epithelial leakage on fluorescein angiography into three groups: no laser treatment (45 eyes), argon laser treatment (26 eyes), and krypton laser treatment (15 eyes). One or more episodes of recurrence developed during the follow-up period in 10 untreated eyes (22%), 9 argon-treated eyes (35%), and 0 krypton-treated eyes. The difference in recurrence rate between argon- and krypton-treated eyes was statistically significant. The findings suggest that whenever laser treatment is indicated, krypton red laser photocoagulation may reduce the incidence of recurrence in eyes with central serous chorioretinopathy.

Adult↗