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PubMed1982

Effects of argon and krypton laser on experimentally detached retinas.

Krypton and argon laser photocoagulation on the foveas and blood vessels of experimentally detached monkey retinas were studied clinicopathologically. In this manner heat transmission from the retinal pigment epithelium (RPE) to the overlying sensory retina was avoided. Krypton lesions bypassed the sensory retina on every occasion to produce major photocoagulative effects at the level of the RPE and choroid. Argon laser wavelengths damaged the overlying retina in the foveal areas as well as in perivascular structures. Although the krypton laser appears preferable for treatment of macular diseases, proper parameters should be used to avoid serious complications.

Animals↗
PubMed1980

Tomographic assessment of cerebral perfusion using a single-photon emitter (krypton-81m) and a rotating gamma camera.

Continuous carotid infusion of short-lived krypton-81m (t1/2 13 sec) yields an assessment of regional cerebral perfusion. This assessment can be obtained in three dimensions if activity is recorded with a rotating gamma camera and a computer to reconstruct krypton-81m distribution in tomographic sections. These showed several advantages over conventional views: (a) visualization of blood-flow distribution within brain structures (gray and white matter, basal ganglia); (b) more accurate location and evaluation of areas of relatively reduced or increased perfusion; (c) better definition of patterns of collateral circulation; (d) greater sensitivity and specificity in detecting and defining blood-flow changes during physiological activation studies. A limitation of the krypton-81m technique is its invasiveness. However, this study shows that the combination of new advances in radiochemistry with single-photon emission computed tomography may result in accessible methods for assessing, noninvasively and in three dimensions, the behavior of cerebral function in man.

Brain Diseases↗
PubMed1981

[Ventilation studies of the lung with krypton-81m].

During a 2-year study period it was found that krypton-81m was useful in routine clinical practice. During this period 1563 technetium-99m perfusion studies and 807 krypton-81m ventilation studies were performed. A distinct advantage of krypton-81m was the ease with which multiple views could be obtained. These views could be directly compared with those of preceding perfusion studies. However, interruptions in the regular supply of rubidium-81/krypton-81m generators affected 17,1% of perfusion studies and xenon-127 should be a suitable substitute for these periods.

Humans↗
PubMed1993

Argon green vs krypton red laser photocoagulation of extrafoveal choroidal neovascular lesions. One-year results in age-related macular degeneration. The Canadian Ophthalmology Study Group.

This multicenter randomized controlled clinical trial performed in Canada was designed to determine whether krypton red laser or argon green laser is superior for treatment of choroidal neovascularization located between 200 and 2500 microns from the center of the foveal avascular zone in patients with age-related macular degeneration. Two hundred ten patients were randomly assigned to treatment with either argon green or krypton red laser, of whom 191 (91%) were determined eligible. Of the eligible patients, 185 (97%) had sufficient follow-up for a comparison of primary-outcome visual acuity at 1 year. We conclude, with 95% confidence, that the krypton red laser is no better than the argon green laser for the treatment of well-defined extrafoveal choroidal neovascularization.

Argon↗
PubMed1977

The determination of the diffusion coefficient of krypton in rabbit ocular tissue.

The validity of the inert gas clearance method for measuring choroidal blood flow has recently been demonstrated by studying the diffusion of krypton in ocular tissue. In this study the diffusion coefficients of krypton in rabbit ocular tissue were calculated from measurements of the diffusion coefficients of xenon. The mean values for the diffusion coefficients of krypton obtained in this study were 1.6 X 10(-5), 0.76 X 10(-5), 0.80 X 10(-5), and 1.2 X 10(-5) cm.2 per second for the sclera, choroid, retina, and vitreous, respectively.

Animals↗
PubMed1994

Evaluation of argon green vs krypton red laser for photocoagulation of subfoveal choroidal neovascularization in the macular photocoagulation study. Macular Photocoagulation Study (MPS) Group.

OBJECTIVE: To evaluate the risks and benefits of argon-green compared with krypton red laser photocoagulation in the treatment of subfoveal choroidal neovascularization (CNV). DESIGN: Prospective randomized clinical trial assessing efficacy of laser treatment vs no treatment in the course of subfoveal CNV. Patients randomly assigned to laser treatment were randomly allocated to either argon green or krypton red laser photocoagulation. Scheduled follow-up for periods up to 5 years was performed. SETTING: Tertiary retinal referral centers. PATIENTS: Individuals with age-related macular degeneration and new subfoveal CNV or recurrent subfoveal CNV enrolled in the Foveal Photocoagulation Studies of the Macular Photocoagulation Study. MAIN OUTCOME MEASURES: Visual acuity, contrast sensitivity, reading spread, persistent and/or recurrent CNV, and treatment complications. RESULTS: There was no significant difference in average loss of visual acuity or contrast sensitivity from baseline levels in eyes treated with either wavelength. From baseline, eyes treated with argon green laser in the Subfoveal Recurrent CNV Study lost an average of 12 words per minute less than eyes treated with krypton red laser. Comparable rates of persistent and recurrent CNV were observed in the two laser treatment groups. Focal retinal vascular narrowing was more common in eyes treated with argon green laser. CONCLUSIONS: Small differences in outcomes favored argon-green treatment of subfoveal CNV, but the only statistically significant difference observed between green- and red-laser treatments was a smaller loss of reading speed among argon green-treated eyes in the Recurrent CNV Study. The multiple analyses performed in these two Macular Photocoagulation Study trials failed to identify any consistent clinically and statistically significant differences between green- or red-laser treatment in the management of eyes with subfoveal CNV.

Aged↗
PubMed1995

Clinically successful contact transscleral krypton laser cyclophotocoagulation. Long-term histopathologic and immunohistochemical autopsy findings.

OBJECTIVE: To report long-term histopathologic findings 10 months after contact transscleral krypton cyclophotocoagulation. METHODS: The tissue response in a successfully treated eye was analyzed by light microscopy and a panel of 11 antibodies to epithelial, mesenchymal, and inflammatory cells. RESULTS: A 75-year-old man with uncontrolled angle recession glaucoma was treated with transscleral contact krypton cyclophotocoagulation (17 burns, 3.5 J each) 10 months before his death. The intraocular pressure fell from 28 to 17 mm Hg 6 months after therapy. Confluent scars straddled the posterior pars plicata and the anterior pars plana. The ciliary processes were destroyed, but the sclera and zonules were intact. Vimentin and cytokeratin 8 and 18 persisted in the degenerated ciliary epithelium. The inner connective-tissue layer and the ciliary muscle had atrophied, as shown with antibodies to the HNK-1 epitope, desmin, and alpha-smooth-muscle actin. Macrophages with phagocytized pigment and single T cells were present instead. No unusual inflammatory infiltrate was present in the choroid of either eye. CONCLUSIONS: Clinically effective ablation of ciliary processes is achieved with contact krypton laser. Little chronic inflammation and no signs of sympathetic ophthalmia were present. Atrophy of the ciliary muscle may reduce accommodative capacity in younger patients undergoing cyclophotocoagulation.

Actins↗
PubMed2005

Introducing krypton NMR spectroscopy as a probe of void space in solids.

A wealth of information about porous materials and their void spaces has been obtained from the chemical shift data in (129)Xe NMR spectroscopy during the past decades. In this contribution, the only NMR active, stable krypton isotope (83)Kr (spin I = (9)/(2)) is explored as a novel probe for porous materials. It is demonstrated that (83)Kr NMR spectroscopy of nanoporous or microporous materials is feasible and straightforward despite the low gyromagnetic ratio and low abundance of the (83)Kr isotope. The (83)Kr line width in most of the studied cases is quadrupolar dominated and field-strength independent. A significant exception was found in calcium-exchanged zeolites where the field dependence of the line width indicates a distribution of isotropic chemical shifts that may be caused by long-range disorder in the zeolite structure. The (83)Kr chemical shifts observed in the investigated materials display a somewhat different behavior than that of their (129)Xe counterparts and should provide a great resource for the verification or refinement of current (129)Xe chemical shift theory. In contrast to xenon, krypton with its smaller atomic radius has been demonstrated to easily penetrate the porous framework of NaA. Chemical shifts and line widths of (83)Kr are moderately dependent on small fluctuations in the krypton loading but differ strongly between some of the studied samples.

Journal Article↗
PubMed2005

Infrared spectra of water clusters in krypton and xenon matrices.

The infrared absorption spectra of the water molecules and small water clusters, (H(2)O)(n) with n = 2-6, trapped in solid argon, krypton, and xenon matrices have been investigated. The infrared bands of the water clusters with n = 5 and 6 in krypton and n = 3, 4, 5, and 6 in xenon matrices have been identified for the first time in the bonded OH stretching region. The frequency shifts in the bonded OH stretching band of the water dimer and trimer in xenon matrices show fairly large deviations to the red from the empirical correlation between the matrix shifts and the square root of the critical temperatures of the matrix material. The observed anomalous shifts suggest that the water dimer and trimer in solid xenon are trapped in multiple sites, and that the structures of the preferential trapping sites are different from those in argon and krypton matrices.

Journal Article↗
PubMedDate not supplied

Clinicopathologic correlation of krypton and argon laser photocoagulation in a patient with a subfoveal choroidal neovascular membrane.

Krypton-red laser photocoagulation for choroidal neovascular membranes has been shown to produce inner retinal sparing in contrast to argon blue-green or argon-green laser photocoagulation, which causes full-thickness retinal destruction. However, previous histopathologic reports have involved only primates or humans without known macular degeneration. Clinicopathologic features of a case in which a human eye with a choroidal neovascular membrane, associated with age-related macular degeneration, was photocoagulated on four occasions with the argon-green and krypton-red lasers are presented. The results of this study confirm previous reports of the inner retinal sparing noted with krypton-red laser photocoagulation in comparison with argon blue-green or argon-green laser photocoagulation.

Aged↗
PubMedDate not supplied

Relative efficacy of the argon green, argon blue-green, and krypton red lasers for 10-0 nylon subconjunctival laser suture lysis.

BACKGROUND AND OBJECTIVE: To determine the optimal wavelength for subconjunctival laser suture lysis. MATERIALS AND METHODS: 130 black monofilament 10-0 nylon sutures were sewn subconjunctivally into the bare sclera of enucleated rabbit globes. The lowest energy levels facilitating laser suture lysis were determined for the argon green (514.5 NM), argon blue-green (488.0 NM, 514.5 NM), and krypton red (647.1 NM) wavelengths. In addition, absorption spectroscopy was performed on the suture material and conjunctiva using the Perkin Elmer W/VIS Lambda 2 spectrometer. RESULTS: Krypton red produced the fewest buttonhole defects, and it was also the most efficient energy source for suture lysis (P = 0.0001) under nontenectomized conjunctiva. Absorbance spectra studies revealed peak absorbance at 628 NM for the 10-0 nylon suture material. CONCLUSIONS: Based on animal and absorption spectroscopy studies, krypton red may be a safer and more efficient wavelength for subconjunctival laser suture lysis.

Animals↗
PubMed1990

Krypton laser photocoagulation for idiopathic neovascular lesions. Results of a randomized clinical trial. Macular Photocoagulation Study Group.

The Idiopathic Neovascularization Study--Krypton Laser is a multicenter randomized controlled clinical trial conducted to determine whether krypton red laser photocoagulation is useful in preventing or delaying loss of visual acuity in eyes that have either choroidal neovascularization 1 to 199 microns from the center of the foveal avascular zone or choroidal neovascularization 200 microns or farther from the foveal avascular zone center with associated blood and/or blocked fluorescence extending within 200 microns of the foveal avascular zone center in the absence of any other clinically significant eye disease. Eligible lesions could have blood or blocked fluorescence that extended through the entire avascular zone. Patients were assigned to laser photocoagulation (n = 24) or to observation only (n = 25). With 65% of these patients followed up for 5 years and 85% for 3 years, there is evidence that krypton laser treatment is beneficial. After 3 years of follow-up, 2 (10%) of 20 treated eyes in comparison with 7 (37%) of 19 untreated eyes had lost six or more lines of visual acuity (P = .15). Furthermore, more untreated eyes than treated eyes had experienced such losses at each point in follow-up after the 3-month examination. The findings from this trial taken with findings of other trials conducted by the same investigators for lesions similar in appearance and location but secondary either to age-related macular degeneration or to ocular histoplasmosis support the conclusion that patients with idiopathic parafoveal neovascularization benefit from laser treatment.

Adult↗
PubMed1990

Krypton laser-induced lens opacity as a complication of retinal photocoagulation.

Lens opacification is a well-documented complication of argon laser photocoagulation, particularly in eyes with preexisting cataracts. In eyes with media opacity, the krypton laser is frequently used for its superior penetrating qualities. To date, lens opacification from krypton application has not been documented. We report such a case in a cataractous eye with a vitreous hemorrhage undergoing panretinal photocoagulation. Factors previously implicated in the etiology of laser-induced lens damage were not present. The opacities were similar to those produced by the argon laser. We present a mechanism for understanding laser-induced lens damage and speculate on the difference between the interaction of argon versus krypton laser energy with lens constituents.

Cataract↗
PubMed1989

Iatrogenic choroidal neovascularization after krypton red laser photocoagulation.

A major cause for failure of krypton red laser photocoagulation in patients with exudative age-related macular degeneration has been the development of recurrent choroidal neovascularization adjacent to the previously treated areas. After reviewing the possible causes of recurrences, it is apparent that a certain number are iatrogenic, ie, induced by krypton red laser causing disruption and damage to the pigment epithelium-Bruch's membrane-choroidal complex. We describe three separate episodes in two patients of iatrogenic recurrent choroidal neovascularization after krypton red laser photocoagulation.

Aged↗
PubMed1994

Argon green vs krypton red laser photocoagulation for extrafoveal choroidal neovascularization. One-year results in ocular histoplasmosis. The Canadian Ophthalmology Study Group.

OBJECTIVE: To determine whether the krypton red laser is superior to the argon green laser or vice versa for treatment of choroidal neovascularization located between 200 and 2500 microns from the center of the foveal avascular zone in patients with ocular histoplasmosis syndrome. DESIGN: Multicenter, randomized, controlled clinical trial. SETTING: Ophthalmologic clinics throughout Canada. PARTICIPANTS: Patients who provided informed consent, were aged 18 years or older, and had extrafoveal membranes associated with ocular histoplasmosis syndrome. RESULTS: One hundred forty-one patients were randomized, 134 (95%) of whom were determined eligible. Of the eligible patients, 128 (96%) had sufficient follow-up for the primary outcome comparison of visual acuity at 1 year. In the argon green laser group, there was a mean increase of 3 letters at 1 year, while in the krypton red laser group there was a mean decrease of 2.5 letters in visual acuity. CONCLUSION: The krypton red laser is no better than the argon green laser for the treatment of well-defined extrafoveal choroidal neovascularization secondary to ocular histoplasmosis syndrome.

Adult↗
PubMed1995

[Comparative study on frequency-doubled Nd: YAG laser, krypton laser and diode laser photocoagulation for diabetic maculopathy].

Twenty six eyes of thirteen patients with diabetic maculopathy (Fukuda's classification AI, AII, BI) were treated with frequency-doubled Nd:YAG laser (6 eyes) or krypton laser (7 eyes) in one eye and diode laser (13 eyes) in the other eye. Group A was treated with frequency-doubled Nd: YAG laser and diode laser, and group B was treated with krypton laser and diode laser. The visual acuity, visual field (Octopus program 31) and fundus were examined at one month, 3 months, and 6 months after photocoagulation. Visual acuity was stable in all eyes. The central 30 degree visual sensitivity decreased more after diode laser treatment than after that of the other lasers. Krypton laser photocoagulation maintained the better visual function and was easy to use followed by frequency-doubled Nd: YAG laser. Because the appearance immediately after diode laser lesion was weaker than one hour after coagulation, it was difficult to get the proper power setting.

Adult↗
PubMed1996

[Comparative study on diode laser (680 nm) and krypton laser mild photocoagulation--histological findings and therapeutic outcome for diabetic maculopathy].

A histopathological study of macaca monkey retina-choroid was carried out for one month after mild photocoagulation with a diode laser (680 nm) and a krypton laser (647 nm). Both lasers produced the same damage to the outer layer of retina and to the melanocytes of 1/3 of the inner choroid. Mild focal photocoagulation was done for 6 patients (12 eyes) with diabetic maculopathy. The patients were 41 to 67 years old, suffering from diabetes mellitus for 5 to 25 years. The grade of their retinopathy was Fukuda's classification AI, AII, and BI. AII eyes were tested before and 3-6 months after photocoagulation for corrected visual acuity, fluorescein angiography, and visual field sensitivity by Octopus automated static perimetry. Visual acuity was stable in all cases. Central sensitivity was better in 2 eyes and unchanged in 4 eyes in both types of laser photocoagulation. In cases of total loss, one eye was improved, 4 eyes were unchanged and one eye was worsened by diode laser photocoagulation and one eye was improved, 2 eyes were unchanged and 3 eyes were worsened by krypton laser photocoagulation. The diode laser (680 nm) might be as useful for ophthalmic laser treatment as the krypton laser.

Adult↗
PubMed1988

S-process krypton of variable isotopic composition in the Murchison meteorite.

Current theories on the origin of the chemical elements explain the abundance of medium-heavy and heavy nuclides to be due to the capture by pre-existing lighter nuclides of free neutrons on either a slow timescale (s-process) or a rapid timescale (r-process). Experimental evidence in support of these theories comes from the analysis of carbonaceous chondrites. In acid-resistant residues of these meteorites a kind of xenon has been found, the isotopic composition of which matches almost perfectly that predicted for s-process xenon. We report data that allow us, for the first time, to derive with reasonable precision the full isotopic spectrum of s-process krypton as well. We show that this s-Kr in a residue from Murchison meteorite did not originate in one single s-process but rather is a mixture of contributions from stellar environments where the density of free neutrons was not the same. The astrophysical conditions under which this Krypton has been produced were distinct from those that have been invoked to explain the Solar System s-process abundance. Similar to the 13C-rich carbon component in an aliquot of the same residue, the s-process Kr from different astrophysical sites has retained its identity during the accumulation and subsequent history of the meteorite.

Extraterrestrial Environment↗