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PubMedDate not supplied

Krypton laser membranotomy for premacular hemorrhage.

BACKGROUND: To evaluate the safety and effectiveness of krypton laser membranotomy. METHODS: Eleven patients (12 eyes) with premacular hemorrhage were enrolled from April 1998 to November 2002. The causes of premacular hemorrhage were proliferative diabetic retinopathy (7 patients, 8 eyes), Valsalva retinopathy (3 patients) and leukemia (1 eye). Krypton laser was used to create a membranotomy on the sloping edge of the premacular hemorrhage. Five eyes with proliferative diabetic retinopathy were treated with inferior panretinal photocoagulation and laser membranotomy simultaneously. After intravitreal dispersion of premacular blood, fundus examinations were performed in all eyes and fluorescein angiography in 5 patients to evaluate the retinal damage. RESULTS: Vision was improved within 2 weeks after surgery in all eyes with premacular hemorrhage, which received krypton laser membranotomy. No retinal damage was seen at the site of membranotomy. No eye needed vitrectomy postoperatively during the follow-up (mean, 17 months). CONCLUSION: Krypton laser membranotomy appears to be a safe and simple alternative procedure for treating selected cases of premacular hemorrhage. Further trials are necessary to evaluate its benefit.

Adolescent↗
PubMed1979

Krypton-81m in the physiologic assessment of coronary arterial stenosis in man.

Fifteen patients with frequent anginal chest pain underwent diagnostic cardiac catheterization. After coronary arteriography a specially designed cardiac catheter was seated in the aortic root, permitting the continuous infusion of krypton-81m into the right and left aortic sinuses. A gamma camera, areas of interest and a visual display unit were used to record images and the regional myocardial equilibrium of activity before, during and after a standarized atrial pacing test. The unique physical properties of krypton-81m allowed the continuous imaging and recording of moment to moment changes in regional myocardial perfusion. This investigation revealed that when the coronary arteriogram was normal or revealed lumonal stenosis of less than 50 percent, regional myocardial perfusion was uniform at rest and during stress. Two patients with a previous history of myocardial infarction had defects of regional perfusion at rest and during stress. Krypton scintigraphy demonstrated reversible regional defects in myocardial perfusion during stress in seven patients with greater than 70 percent stenosis of one or more coronary arteries. Alterations in regional myocardial perfusion occurred within 30 seconds of the start of atrial pacing in all the patients and preceded the onset of electrocardiographic signs of ischemia or chest pain.

Adult↗
PubMed2004

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant.

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80-90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km. At distances up to 40 km, the false alarm rate is less than 3.5%. On average, the fuel released 28 TBq krypton-85 per kg plutonium. For weapons-grade plutonium, the krypton signal would be lower by a factor of 2. Hence, the given percentages correspond to the detection probabilities for the separation of a significant quantity (8 kg) of plutonium per weekly sample under the specific meteorological conditions of the WAK. The minimum separation rates that could have been detected are 2 gram of weapons-grade plutonium per week at a distance of less than 1 km, 40 g/week at 5 km, 200 g/week at 39 km, and 1000 g/week at 130 km.

Air Pollutants, Radioactive↗
PubMed2004

Krypton laser membranotomy in the treatment of dense premacular hemorrhage.

BACKGROUND: Neodymium:YAG (Nd:YAG) laser and argon laser membranotomy have been used in patients with premacular hemorrhage to drain premacular blood into the vitreous cavity and rapidly clear the hemorrhage. However, the Nd:YAG laser appears to be difficult to use, and argon laser energy may be more likely to be absorbed by the ocular media. We performed a study to evaluate the safety and effectiveness of krypton laser membranotomy in selected cases of premacular hemorrhage. METHODS: Sixteen patients (17 eyes) with dense premacular hemorrhage for 2 weeks or less were enrolled from April 1998 to February 2004. The causes of premacular hemorrhage were proliferative diabetic retinopathy (PDR) in 12 eyes, Valsalva retinopathy in 3 eyes, leukemia in I eye and retinal arterial macroaneurysm in I eye. Krypton laser was used to create a membranotomy on the sloping edge of the premacular hemorrhage. Five eyes with PDR were treated with inferior panretinal photocoagulation and laser membranotomy simultaneously. After intravitreal dispersion of premacular blood, fundus examination was performed in all eyes and fluorescein angiography in five eyes to evaluate retinal damage. RESULTS: All eyes had visual improvement within 2 weeks postoperatively. No retinal damage was seen at the site of membranotomy in any eye. No eye needed vitrectomy postoperatively during a mean follow-up duration of 18.6 months. INTERPRETATION: Krypton laser membranotomy appears to be a safe and simple alternative procedure for treating selected cases of premacular hemorrhage. Further trials are necessary to evaluate its benefit.

Adolescent↗
PubMed1983

The effects of red krypton and green argon laser on the foveal region. A clinical and experimental study.

The destruction of senile neovascular membranes in the central avascular region of the macula by 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, the authors used lasers of different wavelengths: red krypton and green argon. Optical and electron microscopic studies on nonhuman primates were performed at 1 hour and 6 weeks. Maximum damage was seen at the level of the internal choroid with krypton laser and at the level of the pigment epithelium with green argon laser. A clinical and angiographic study showed that the destruction of the juxtafoveal neovascular membranes by both lasers was possible. Our clinical experience suggests that the red krypton laser offers a better alternative for treatment of neovascular membranes located near the foveola than the green argon laser.

Animals↗
PubMedDate not supplied

Clinicopathologic correlation of krypton red, argon blue-green, and argon green laser photocoagulation in the human fundus.

One day before the scheduled enucleation for a choroidal melanoma, a patient agreed to have experimental laser burns placed in her fundus for the purpose of comparing the histopathologic effects of krypton red, argon green, and argon blue-green laser photocoagulation. When photocoagulation burns were applied to simulate treatment for a juxtafoveal choroidal neovascular membrane ( NVM ) there was relative inner retinal sparing with krypton red and transretinal effects with argon green. When treatment was applied outside the macula to simulate scatter or panretinal photocoagulation (PRP), there were no differences in histopathologic effect. This suggests that krypton red laser photocoagulation may be advantageous in treating juxtafoveal neovascular membranes, but is of no particular advantage when treating outside the macula.

Argon↗
PubMedDate not supplied

Histopathology and ultrastructure of krypton and argon laser lesions in a human retina-choroid.

The authors studied a normal eye 24 hours after retinal treatment with argon and krypton photocoagulation. The findings indicate the relative sparing of the inner retina and greater choroidal effects of krypton when compared with argon photocoagulation. Bruch's membrane was not completely ruptured as long as the energy densities of burns were kept low. Krypton wavelengths are transmitted more effectively to the pigment epithelium and choroid. Therefore, the use of relatively lower and therefore safer power densities compared with the argon laser should suffice for the treatment of diseases at this level.

Argon↗
PubMed1986

Internal limiting membrane wrinkling after argon and krypton laser photocoagulation of choroidal neovascularization.

A retrospective study was performed to determine the prevalence and risk factors for internal limiting membrane (ILM) wrinkling following successful argon and krypton laser photocoagulation of choroidal neovascular membranes. The study included 139 eyes with presumed ocular histoplasmosis syndrome (POHS) and age-related macular degeneration (AMD). Argon treated eyes with POHS had a significantly higher prevalence of ILM wrinkling (30/63, 47.6%) than those with AMD (6/40, 15%, P = 0.0007). Krypton treated eyes also demonstrated a higher prevalence of ILM wrinkling in eyes with POHS (3/12, 25%) than in eyes with AMD (2/19, 10.5%) but this difference was not significant. In general, argon-treated eyes had a greater prevalence of ILM wrinkling than krypton treated eyes (35.0% vs 16.1%, P = 0.046). Factors which appeared to increase the risk of ILM wrinkling included intensity of treatment, area of the neovascular membrane, and the presence of subretinal blood.

Adult↗
PubMed1985

Massive choroidal haemorrhage as a complication of krypton red laser photocoagulation for disciform degeneration.

A 78-year-old man with perifoveal subretinal neovascularization originally treated with krypton red laser was re-treated. An attempt was made to produce a "chalky white" burn at the site of the neovascular frond. Immediately after a burn, a brisk choroidal haemorrhage followed, apparently from a ruptured choroidal vessel. Bleeding occurred subretinally and into the vitreous, blinding the patient. While the krypton red laser carries advantages over the argon laser in the treatment of subretinal neovascular fronds, this case indicates that hard burns with the krypton laser carry a risk of massive subretinal haemorrhage.

Aged↗
PubMedDate not supplied

Saturation curve in gases of high atomic number at pressures up to 8 atm. I. Krypton and xenon.

The saturation curve has been studied in xenon and in krypton up to a pressure of 8 atm. An empirical formula has been found that describes the fraction of current collected over a wide range of voltages, pressures, ionization intensities, and electrode spacings. This is of practical value in the design of ionography chambers. For krypton the collection fraction fKr = (1 + 0.25eta-1.74)-1, and for xenon fXe = (1 + 0.16eta-1.88)-1, where eta = Fp-0.7Vd-2q-1/2 with F = 3.61 X 10(-7) and 2.50 X 10(-7) for krypton and xenon, respectively. The ranges of the variables covered in the experiments were p = 1-8 atm, V = 5-25000 V, d = 0.3-1.3 cm, and q = 4 X 10(-9)-6 X 10(-8) A/cm3.

Atmospheric Pressure↗
PubMed1979

A comparative histopathological study of argon and krypton laser irradiations of the human retina.

A series of comparative exposures to both argon and krypton lasers have been made at 3 locations in a human retina--the fovea, the macula, and intraretinal vessels. In the fovea argon irradiations resulted in damage to both the inner and outer retinal layers as a result of absorption within the pigment epithelium and the macular pigment, while krypton exposures damaged the outer retina and the choroid. In the macula both systems resulted in damage to the outer retina, and again sufficient krypton radiation passed into the choroid to induce blood vessel occlusion, haemorrhage, and oedema. When intraretinal vessels were irradiated, only with argon was sufficient energy absorbed within the vessels to damage them or their surroundings in the inner retina. The implications of these findings are discussed in relation to the therapeutic uses of lasers.

Argon↗
PubMed1996

Comparative effects of argon green and krypton red laser photocoagulation for patients with diabetic exudative maculopathy.

AIMS/BACKGROUND: Focal treatment of diabetic macular oedema is usually done using a haemoglobin absorbing wave-length, such as argon green laser. This study aimed to compare photocoagulation with argon green (514 nm) and krypton red (647 nm), which is poorly absorbed by haemoglobin, in the focal treatment of patients with diabetic exudative maculopathy. METHODS: A total of 151 eyes of 78 outpatients were assigned randomly to receive either argon green (n = 79) or krypton red (n = 72) laser treatment. Pretreatment and post-treatment ocular examinations included visual acuity, fundus biomicroscopic examination, and fluorescein angiography. A total of 141 eyes of 73 patients were available for evaluation after 1 year follow up. RESULTS: No statistically significant difference was found between the two treatment groups with respect to visual acuity results, resorption of hard exudates, and resolution of focal retinal oedema. CONCLUSION: Krypton red laser was effective in the treatment of diabetic exudative maculopathy. Our data suggest that differential absorption of the various wavelengths by haemoglobin within microaneurysms may not be an important factor for ultimate success of focal treatment.

Adult↗
PubMed1990

Argon versus krypton panretinal photocoagulation side effects on the anterior segment.

The modification of corneal sensitivity, accommodation, pupillary diameter and endothelial cell density after argon versus krypton panretinal photocoagulation were studied prospectively in 88 eyes of 64 diabetic patients with proliferative diabetic retinopathy, randomized for one of the two laser treatments. In both groups a marked internal ophthalmoplegia and reduction of corneal sensitivity occurred after laser photocoagulation. At no time, 2, 90 and 180 days after PRP, were these parameters significantly different. Endothelial cell loss was non significantly greater in the krypton group. The results indicated that the side effects commonly observed on the anterior segment after PRP are comparable using argon or krypton lasers.

Accommodation, Ocular↗
PubMed1999

[A clinical observation of krypton yellow laser photocoagulation for cystoid macular edema in nonproliferative diabetic retinopathy].

OBJECTIVE: To evaluate the clinical effects of krypton yellow laser photocoagulation for cystoid macular edema (CME) in nonproliferative diabetic retinopathy (NPDR). METHODS: 52 eyes (37 cases) with CME in NPDR were treated with local or grid macular krypton yellow photocoagulation, and according to the course they were divided into two groups: group I ( or= 7 months). The follow-up was 1 year. The visual acuity and the degree of macular edema in various period were analyzed and compared. RESULTS: The mean visual acuity was 0.27 +/- 0.21 before treatment and 0.53 +/- 0.26 after treatment (P < 0.01), 90.4% was increased, 5.8% was stable and 3.8% was decreased. CME disappeared completely in 55.8% of the patients, disappeared partially in 42.3% and stable in 1.9%. In group I the visual acuity was improved in 81.5% of the patients at post-treatment 1 month; at post-treatment 6 months, the visual acuity was increased in 100% of the cases, CME disappeared completely in 70.4% and disappeared partially in 29.6%. In group II, the visual acuity was improved in 20% of the patients at post-treatment 1 month, and at post-treatment 6 months in 88%, CME disappeared completely in 40% and disappeared partially in 56%. The differences in the rate of visual recovery and therapeutic effects between the two groups were statistically significant (P < 0.01). CONCLUSIONS: Krypton yellow laser is prominently effective and selective for CME in NPDR. The effects are related to the course of the disease, and the therapeutic results are better in cases receiving early treatment.

Adult↗
PubMed2003

[Study on the experimental model of krypton laser-induced choroidal neovascularization in the rats].

OBJECTIVE: To evaluate the feasibility of krypton laser-induced choroidal neovascularization (CNV) model in the Brown Norway rats in order to establish the foundation for studying the mechanism of CNV and for the development of treatment for CNV. METHODS: Experimental eyes in 33 rats were received a series of 10 krypton red laser (647 nm) lesions per eye (360 mW, 50 micro m, 0.05 s). Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed, then the rats were sacrificed immediately, the eyes were enucleated and processed for histopathologic examination and transmission electron microscopy on days 3, 7, 14, 21, 28 and 56. RESULTS: CNV was firstly appeared on day 7 after photocoagulation, reaching the peak on day 21. The incidence of CNV was 76.0%. Disciform leakage staining appeared in the FFA. ICGA showed that the disciform area was filled with CNV. CNV was ascertained by light microscopy and electron microscopy. The thickness of laser-induced CNV was increased from day 7 to day 21 (P < 0.01) and no significant progress occurred after day 21 (P > 0.05). CONCLUSIONS: The present studies demonstrated that krypton laser photocoagulation could be used to produce choroidal neovascularization experimental model in the Brown Norway rat. CNV can be induced rapidly by the method, persists for a long period and at a high successful rate.

Animals↗
PubMed2004

[Krypton laser photocoagulation at low power setting for age-related macular degeneration complicated with subfoveal choroidal neovascularization].

OBJECTIVE: To evaluate the efficacy of krypton laser photocoagulation for treatment of age-related macular degeneration (AMD) complicated with mainly subfoveal classic choroidal neovascularization (CNV). METHODS: Seventeen eyes of 17 cases, aged 50 - 74 years (averaged 60.8 years) with mainly subfoveal classic choroidal neovascularization were treated with krypton laser at lower power setting. The treatment was completed in one session. Another course of treatment was given 4 weeks later if there was active leakage demonstrated at the CNV area. Visual acuity, anterior segment and fundus examination, perimetry test, fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed before and after treatment. The follow-up period was 3.5 years on average (1 - 8 years). RESULTS: There was no immediately decrease of visual acuity after treatment. All treated eyes showed absorption of hemorrhages and/or exudates and diminished leakages. Visual acuity was stable in 8 eyes; improved in 6 eyes (>/= 2 lines), and decreased in 3 eyes (</= 2 lines). The central scotoma showed no significant changes after the treatment. Closure of CNV was confirmed on FFA/ICGA and no recurrence was found in 9 cases during 3 years follow-up. CONCLUSION: Krypton laser photocoagulation at low power setting is an effective treatment for AMD with mainly classic subfoveal choroidal neovascularization.

Aged↗
PubMed1987

[Right ventricular function in patients with chronic obstructive pulmonary disease measured by krypton-81m].

Right ventricular function was assessed at rest and during exercise in patients with chronic obstructive pulmonary disease (COPD). Right ventricular ejection fraction (RVEF) was measured by first-pass radionuclide angiography using ultrashort-lived radionuclide krypton-81m. The half-life of this nuclide is only 13 sec, and it is completely expired from the lungs. These properties allow measurement of RVEF without correcting for background activity. In 30 patients with cardiac or pulmonary disease, RVEF was first measured by krypton-81 m scintigraphy (Kr-RVEF), then by technetium-99m (Tc-RVEF), without changing the patients' positions. In eight of the 30 cases, right ventricular cineangiography (RVG) was performed within 72 hrs after the radionuclide study, and RVEF was measured according to the Chapman's rule (RVG-RVEF). Kr-RVEF correlated significantly with Tc-RVEF (r = 0.87), and also with RVG-RVEF (r = 0.80). In 10 patients with stable COPD, who had severe hypoxemia (PaO2 less than or equal to 60 mmHg) and pulmonary hypertension [mean pulmonary arterial pressure (mean PAP) greater than or equal to 20 mmHg], and in seven normal control subjects, radionuclide angiographic and hemodynamic monitoring were performed at rest and during supine ergometer exercise. Kr-RVEF at rest was 47.6 +/- 5.4% (mean +/- SD) in patients with COPD and was 54.1 +/- 4.8% in normal subjects. Kr-RVEF during exercise was 51.8 +/- 7.3% in the patients, and 62.3 +/- 3.2% in the normal subjects. Hemodynamically, mean PAP and pulmonary vascular resistance (PVR) increased significantly during exercise, but the RV end-diastolic volume index (RVEDVI) did not change. There was inverse correlation between Kr-RVEF and mean PAP (r = -0.51) or PVR (r = -0.47) as an index of RV afterload. However, there was no correlation between Kr-RVEF and RVEDVI as an expression of RV preload. These findings suggest that a poor response by RVEF during exercise in patients with COPD is associated with elevation of afterload. Thus, right ventricular imaging techniques using the ultrashort-lived nuclide krypton-81 m allow noninvasive, serial and accurate assessments of right ventricular function in patients with COPD.

Aged↗
PubMed1984

Automation in krypton laser photocoagulation.

Histologic study of lesions produced by krypton red (647.1 nm) and krypton yellow (568.2 nm) laser lights reported here suggests advantages in alternating these two wavelengths in photocoagulation. Selection of the best wavelength to be used in a given location on the retina should result from pre-determined absorbance conditions in that location. The feasibility of the relative measurement of absorbance in different fundus locations by measurement of the relative reflectance is discussed. Instrumentation for these measurements and for switching from one wavelength to the other is described. Instrumentation for the possible expansion of krypton laser applications to clinical problems in the anterior segment also is suggested.

Animals↗