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At least 19 recordsLinked to original sources
PubMed1993

Randomized comparison of krypton versus argon scatter photocoagulation for diabetic disc neovascularization. The Krypton Argon Regression Neovascularization Study report number 1.

BACKGROUND: The Krypton Argon Regression of Neovascularization Study (KARNS) was designed to compare the efficacy of red krypton versus blue-green argon laser photocoagulation for the management of high-risk proliferative diabetic retinopathy. METHODS: A prospective, randomized clinical trial was performed in 24 clinical centers. Patients (n = 696, 907 eyes) with diabetes and neovascularization of the disc (NVD) of one-third disc area or greater in extent were assigned at random to either argon or krypton laser scatter (panretinal) photocoagulation. The major endpoint of the regression of NVD to less than one-third disc area in extent at 3 months was evaluated by comparisons of gradings of the fundus photographs obtained at baseline and follow-up. RESULTS: At 3 months' follow-up, the proportion of eyes with regression of NVD to less than or equal to one-third disc area in extent were 41.1% in the argon-treated group and 41.8% in the krypton-treated group (P = 0.92). The odds of regressing to this extent of NVD at 3 months for argon-treated eyes versus krypton-treated eyes was 0.98 (95% confidence interval, 0.74-1.31). CONCLUSION: Scatter laser photocoagulation with either krypton red or argon appears to be equally effective in the treatment of proliferative diabetic retinopathy with NVD.

Adolescent↗
PubMed1993

Comparison of retinal lesions produced by transscleral krypton laser photocoagulation, transpupillar krypton laser photocoagulation and cryocoagulation.

We compared the retinal lesions produced by transscleral and transpupillar krypton lasers and cryocoagulation. Transscleral laser photocoagulation was applied under indirect ophthalmoscope visual control with indentation of the sclera by the laser probe. Transpupillar laser was performed with a Volk 90D lens. The power and the spot size were adjusted to create lesions of similar size and intensity as in transscleral photocoagulation. The output power needed for transscleral photocoagulation was 0.2W with exposure time of 3-5 sec. In the transpupillar photocoagulation the output power was 0.3W and the exposure time 2-3 sec, respectively. The lesions were studied histologically 1h, 1, 3, 7, 30 and 60 days after treatment. Histopathological studies of the krypton laser lesions revealed destruction and scarring of the outer layers of the retina and the choroid. The lesions produced by transpupillar and transscleral laser appeared to be rather similar. These results indicate that, in the rabbit eye, there is no difference between the lesions produced by the transpupillar or transscleral route of laser application. Transscleral laser application may have clinical advantages over transpupillary laser in the eyes with hazy media or in other cases when transpupillar laser is not possible.

Animals↗
PubMed1981

Fundus photocoagulation with the argon and krypton lasers: a comparative study.

Photocoagulation of the monkey fundus with an argon-krypton laser photocoagulator was performed. Lesions produced by argon and krypton wavelengths were compared at various power settings, spot sizes, and exposure durations. At low energy levels argon laser lesions appeared clinically stronger than those produced by the krypton mode. Lesions in the foveal area produced with the argon laser demonstrated more extensive microscopic damage to the inner retinal layers than did those produced with the krypton laser. Histologically, both modalities affected the outer layers of the retina. However, the krypton wavelength affected more of the choriocapillaries and the larger choroidal vessels than the argon wavelengths. Conversely, argon laser coagulation of the retinal vessels damaged the perivascular tissue in the nerve fiber layer more than the krypton laser did. Rupture of Bruch's membrane and choroidal hemorrhage occurred frequently with the krypton laser at low energy levels when a small spot size and a short coagulation time were used. Both complications were less likely to occur with argon burns at similar dosage parameters. By choosing larger spot sizes and longer coagulation times for the krypton laser, these complications were prevented.

Animals↗
PubMed1982

Red krypton laser therapy of macular and retinal vascular diseases.

If the theoretical advantages of krypton laser over argon laser are proven clinically, this modality will be an important adjunct in the management of many of the leading causes of blindness. Our preliminary observations in over 400 cases treated with krypton laser correlate well with the theoretical and histopathologic observations of others. Possible advantages of krypton laser therapy for choroidal neovascularization (CNV) include its ability to penetrate foveal xanthophyll and retinal blood vessels and to minimize damage to the nerve fiber layer. Krypton also penetrates the xanthochrome in nuclear sclerotic cataract. The major disadvantage is increased choroidal hemorrhage. In proliferative retinopathies krypton penetrates moderate vitreous hemorrhage. It may minimize both epiretinal membrane changes and continuation of vitreo-retinal traction. It can be used after fluorescein injection. Disadvantages include increased choroidal hemorrhage and increased pain, often requiring retrobulbar anesthesia. Krypton laser cannot close surface neovascularization or stop bleeding by photocoagulating its source. The role of argon laser in CNV or how it benefits proliferative retinopathies is still not understood. The Macular Photocoagulation Study will help define the role of argon and krypton laser for CNV. A similar clinical trial to compare the efficacy of krypton laser to the proven efficacy of argon laser in the treatment of proliferative diabetic retinopathy is still anticipated.

Choroid↗
PubMed1985

Experiments on the absorption of argon and krypton laser by blood.

Experiments were performed to determine the absorption by and transmission through blood of argon blue-green (ABG) and green (AG) and krypton red (KR) laser light. Krypton was transmitted better through intact erythrocytes than argon. The difference between krypton and argon was greater if the erythrocytes contained oxygenated hemoglobin (Hb) than deoxygenated Hb. None of the wavelengths penetrated well a confluent blood specimen only 4 cells thick. Branch retinal vein occlusions were created in monkeys causing scattered areas of retinal hemorrhage. Argon burns placed in areas of retinal hemorrhage caused much inner or full thickness retinal damage. Krypton passed through the inner retinal hemorrhage without causing damage and created a burn at the level of the retinal pigment epithelium and inner choroid. Preretinal hemorrhages were created in rabbits by perforating Bruch's membrane with a high intensity krypton burn. Argon burns placed over the preretinal hemorrhages were absorbed much more than krypton burns. Neither argon or krypton however could penetrate even moderately thick preretinal hemorrhages to cause an underlying retinal burn.

Adult↗
PubMed1997

Comparison of wound healing process using Argon and Krypton lasers.

OBJECTIVE: We compared the wound healing process on Sprague-Dawley rats between Argon Laser and Krypton Laser, and calculated the laser actual doses after correction on wound healing on rats and estimated the clinical doses on wound healing for human skin. SUMMARY BACKGROUND DATA: Laboratory work provided some support for the use of low-intensity laser radiation in wound healing. Some studies found that laser irradiation may either enhance, inhibit, or has no effect on the function of a variety of microorganisms and cells. Animal studies also offered some basis for treatment. Improvements, particularly in the earliest phases of wound healing, have been reported following laser irradiation. METHODS: We used Argon Laser (488-514 nm) and Krypton Laser (670 nm) in the study. The laser beam was delivered through a system of fiber optic in Argon Laser and reflector in Krypton Laser. The rats treated were restrained in a Plexiglas cage without anesthesia during the laser irradiation period. The percentage of the wound healing acceleration in days and size, actual doses, and estimated clinical doses were calculated as follows: AccD = (1-TD/CD) x 100%, AccS = (1-TA/CA) x 100%, AD = D(in) - D(gl) - D(SR) and ECD = AD = D(sr), respectively. RESULTS: The acceleration effects of wound healing in days (AccD) were 22.93% and 14.54%, size reductions (AccS) were 41.93% and 30.41% at the optimal stimulative incident dose of 20 J/cm2. Zero bioactivation shown at the incident doses of 80 J/cm2 and 100 J/cm2. The inhibitory effects of wound healing in days were -7.72% and -3.37%, in size reduction were -13.35% and -12.88% at the maximal inhibitory incident dose of 140 J/cm2 for Argon and Krypton Lasers, respectively. The actual doses were 5.21 J/cm2 and 4.03 J/cm2, the estimated clinical doses were 5.50 J/cm2 and 4.25 J/cm2 at optimal stimulative incident dose 20 J/cm2 for Argon and Krypton Lasers, respectively. CONCLUSIONS: Low power laser therapy at the appropriate dosimetric parameters can provide the acceleration effects of wound healing on rats. The effects were dependent with the doses and laser wavelengths used. In this experiment, the optimum stimulative dose was 20 J/cm2 and the Argon Laser with 488 nm was more effective than the Krypton Laser with 670 nm. The zero bioactivation and inhibition effect of wound healing on rats occurred in Argon Laser and Krypton Laser.

Animals↗
PubMed1985

Continuous determination of regional myocardial blood flow with intracoronary krypton-81m in coronary artery disease.

Pacing-induced changes in regional coronary flow were studied continuously with krypton-81m by intracoronary infusion in 25 patients: 21 with 50% or greater diameter narrowing of 1 or more left coronary arteries (group I) and 4 with less than 50% diameter reduction of a left coronary artery (group II). No changes occurred in group II. In group I, krypton-81m perfusion decreased progressively in all areas with more than 70% diameter narrowing, with a simultaneous increase in normal regions. At the end of pacing during angina, krypton-81m perfusion was reduced to 81 +/- 4% of control in areas with 71 to 90% diameter reduction (n = 8) and to 69 +/- 6% in areas with more than 90% diameter narrowing (n = 15). In contrast, in regions with 50 to 70% diameter reduction changes were variable (decrease in 4 regions, increase in 2 and an unchanged distribution in 1 region). Krypton-81m perfusion decreased early, before general signs of ischemia in areas with more than 90% diameter reduction, whereas this decrease occurred later in regions with 71 to 90% diameter narrowing, concurrently with ST-segment changes but before anginal pain. Although all signs of ischemia had disappeared between 2 and 5 minutes after pacing, changes in krypton-81m distribution persisted in most areas for 5 to 15 minutes after pacing. It is concluded that the functional significance of coronary arterial narrowing can be assessed with a continuous intracoronary infusion of krypton-81m. Changes in regional distribution persisted after cessation of pacing-induced ischemia, indicating an ongoing decrease in regional myocardial blood flow.

Adult↗
PubMed1995

The influence of treatment extent on the visual acuity of eyes treated with Krypton laser for juxtafoveal choroidal neovascularization. Macular Photocoagulation Study Group.

PURPOSE: To examine the direct relationship between the extent of treatment with krypton red laser photocoagulation and visual acuity loss in eyes with choroidal neovascularization secondary to ocular histoplasmosis or age-related macular degeneration. PATIENTS AND METHODS: Photographic and visual acuity records from 129 eyes treated in the Ocular Histoplasmosis Study--Krypton Laser and 224 eyes treated in the Age-Related Macular Degeneration Study--Krypton Laser were reviewed. The proportion of eyes with severe visual acuity loss (6 or more lines of loss) was examined for subgroups of eyes based on the distance of the neovascular lesion from the center of the foveal avascular zone and on the extent of laser treatment to the lesion. Differences in the proportions with severe visual acuity loss were evaluated by longitudinal data analysis methods. RESULTS: Among eyes in the Ocular Histoplasmosis Study--Krypton Laser with lesions less than 200 microns from the center of the foveal avascular zone, only 5% of eyes with laser treatment that covered the foveal side and had a narrow (< or = 100 microns) border of treatment to adjacent uninvolved retina experienced severe visual acuity loss compared with approximately 25% of eyes with either some of the foveal side of the lesion left untreated or a wide border of treatment on the foveal side. Treatment extent had little influence on severe visual acuity loss in eyes in the Ocular Histoplasmosis Study--Krypton Laser with neovascular lesions 200 to 500 microns from the center of the foveal avascular zone or in eyes in the Age-Related Macular Degeneration Study--Krypton Laser with lesions in either distance category. CONCLUSIONS: Accurate, complete treatment of choroidal neovascularization close to the foveal center is required to provide the patient with the best chance of avoiding further severe visual acuity loss, especially in patients with ocular histoplasmosis. Even among experienced retinal specialists, the required accuracy of treatment is difficult to achieve.

Adolescent↗
PubMed1989

Red krypton and blue-green argon laser diabetic panretinal photocoagulation.

Eyes with three or four diabetic retinopathy risk factors received laser panretinal photocoagulation with random selection of either blue-green argon (42 eyes) or red krypton (40 eyes) laser to determine if one laser was superior to the other. After 6 months, visual acuity preservation or improvement was obtained in 33 (79%) argon- and 34 (84%) krypton-treated eyes. Peripheral IV-4e visual field constriction of 7% occurred with argon and 10% with krypton. Vitreous hemorrhaging after treatment occurred in 1 argon- and in 6 krypton-treated eyes. Complete disc neovascular regression was obtained in 27 (67%) of 40 argon- and 19 (56%) of 34 krypton-treated eyes, with partial regression occurring in 8 (20%) argon- and 8 (24%) krypton-treated eyes. The two treatments produced essentially equal results.

Adolescent↗
PubMed1997

High-pressure krypton gas and statistical heavy-atom refinement: a successful combination of tools for macromolecular structure determination.

The noble gas krypton is shown to bind to crystallized proteins in a similar way to xenon [Schiltz, Prangé & Fourme (1994). J. Appl. Cryst. 27, 950-960]. Preliminary tests show that the major krypton binding sites are essentially identical to those of xenon. Noticeable substitution is achieved only at substantially higher pressures (above 50 x 10(5) Pa). As is the case for xenon, the protein complexes with krypton are highly isomorphous with the native structure so that these complexes can be used for phase determination in protein crystallography. Krypton is not as heavy as xenon, but its K-absorption edge is situated at a wavelength (0.86 A) that is readily accessible on synchrotron radiation sources. As a test case, X-ray diffraction data at the high-energy side of the K edge were collected on a crystal of porcine pancreatic elastase (molecular weight of 25.9 kDa) put under a krypton gas pressure of 56 x 10(5) Pa. The occupancy of the single Kr atom is approximately 0.5, giving isomorphous and anomalous scattering strengths of 15.2 and 1.9 e, respectively. This derivative could be used successfully for phase determination with the SIRAS method (single isomorphous replacement with anomalous scattering). After phase improvement by solvent flattening, the resulting electron-density map is of exceptionally high quality, and has a correlation coefficient of 0.85 with a map calculated from the refined native structure. Careful data collection and processing, as well as the correct statistical treatment of isomorphous and anomalous signals have proven to be crucial in the determination of this electron-density map. Heavy-atom refinement and phasing were carried out with the program SHARP, which is a fully fledged implementation of the maximum-likelihood theory for heavy-atom refinement [Bricogne (1991). Crystallographic Computing 5, edited by D. Moras, A. D. Podjarny & J. C. Thierry, pp. 257-297. Oxford: Clarendon Press]. It is concluded that the use of xenon and krypton derivatives, when they can be obtained, associated with statistical heavy-atom refinement will allow one to overcome the two major limitations of the isomorphous replacement method i.e. non-isomorphism and the problem of optimal estimation of heavy-atom parameters.

Journal Article↗
PubMed1986

Red krypton and blue-green argon panretinal laser photocoagulation for proliferative diabetic retinopathy: a laboratory and clinical comparison.

The effects of PRP with red krypton laser are essentially identical to those produced with blue-green argon laser. Burns of the rabbit retina produced with these two different lasers are almost the same. In a prospective and randomized clinical trial of proliferative diabetic retinopathy treatment there was no significant difference between PRP using these two different lasers. The characteristic changes of rabbit fundi 3, 7, and 30 days after PRP with red krypton laser were almost the same as those following blue-green argon laser. Both types of treatment frequently produced small vitreous hemorrhages and exudative retinal detachments, but choroidal thickening occurred more frequently with argon treatment. These changes were transient and had resolved within 30 days of treatment. The microscopic changes consisted of pigment epithelial disruption with pigment migration into the retina, heat coagulation of the photoreceptors, disruption of the outer and inner nuclear layers with atrophy of the nuclei, and temporary swelling of the nerve fiber layer. The untreated retina and choroid between burns was not involved and appeared normal at each period. Thirty days after treatment, the scarring produced by these two types of burns was identical. Seventy-one eyes with proliferative diabetic retinopathy having three or four retinopathy risk factors were treated with panretinal laser photocoagulation, and followed in a prospective study for 6 months. Thirty-six eyes were randomly selected for blue-green argon treatment, and 35 were randomly selected for red krypton treatment. The incidence of undesired side effects during the first 2 weeks following treatment was almost identical between the two groups. However, by 1 month the majority of eyes in both groups had visual acuities equal to or better than the pretreatment acuities and complete regression of NVD. Six months after treatment, the majority of eyes in both groups continued to have visual acuities equal to or better than the pretreatment acuities with fewer cases having larger losses of vision in the krypton treated group. Loss of peripheral visual field was equal with the two types of treatment having a minimal decrease with the IV-4e isopter, but substantial loss with the I-4e isopter. Additional vitreous hemorrhage rarely occurred in either group, but was slightly more frequent in those treated with krypton. Complete regression was accomplished in most eyes with pretreatment disc and/or NVE in both groups, but persistence of neovascularization was more frequent in those treated with krypton. Overall, the wavelength used seemingly had little effect on the result.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMedDate not supplied

Krypton red laser photocoagulation in selected cases of central serous chorioretinopathy.

Krypton red laser photocoagulation was carried out in 15 eyes with chronic, uncomplicated monocular central serous chorioretinopathy. All patients had vocations requiring excellent binocular vision, and could not work effectively with their current visual acuity. Krypton red was selected as the most suitable photocoagulative source, given the nature of the disease, the tissue-selectiveness of krypton red laser on the retinal pigment epithelium, and the relative inability of the macular luteal pigment and capillary beds of the inner retinal layers to absorb the red wavelength. Visual acuity improved in all 15 eyes, and to at least 20/30 (6/9) in 12 eyes (80%). The visible effects of krypton red laser photocoagulation on the retinal pigment epithelium were minimal and, although nine eyes had had focal leaks within 100 microns of the foveal avascular zone and 12 eyes had been photocoagulated within the maculopapillar bundle, no adverse clinical effects were observed. In carefully selected cases, then, krypton red laser photocoagulation appears to be suitable and safe for the treatment of central serous chorioretinopathy in a tissue-specific manner.

Choroid↗
PubMed1986

Krypton and argon laser photocoagulation effects in subretinal hemorrhage.

Previous studies suggested that krypton laser photocoagulation was more effective in the treatment of macular diseases than argon laser. Furthermore, it could perform photocoagulation more effectively in some lesions with subretinal hemorrhage, because the krypton laser beam was poorly absorbed by hemoglobin. In the present experiment, hemorrhagic retinal detachment was produced in monkey eyes with Q-switched Nd-YAG laser, and 4 weeks later photocoagulation was performed with krypton and argon lasers to compare the differences in the effects of these two lasers. When the subretinal hemorrhage and a heavy coagulation effect was produced in the detached retina, but no coagulation effects were observed in the choroid. Krypton laser beam could go through the hemorrhage and certain coagulation effects were observed in the choroid and the detached retina. It is suggested that krypton laser photocoagulation is more effective in the lesions behind subretinal hemorrhages than photocoagulation with argon laser.

Animals↗
PubMed1997

A patient's questionnaire evaluation of krypton laser treatment of facial telangiectases. A comparison with the copper vapor laser.

BACKGROUND: 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. OBJECTIVE: 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. METHODS: Two hundred consecutive patients treated with the krypton laser were asked to complete a questionnaire evaluating the treatment; 149 (74.5%) patients responded. RESULTS: 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. CONCLUSION: 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.

Cicatrix↗
PubMed1992

Comparison of photocoagulation with the argon, krypton, and diode laser indirect ophthalmoscopes in rabbit eyes.

PURPOSE: The purpose of this study is to compare photocoagulation with the argon green, krypton red, and diode infrared laser indirect ophthalmoscopes in an experimental setting. METHODS: Photocoagulation was performed with each of the laser indirect ophthalmoscopes in a grid pattern within one sector of the same eye of 14 Dutch-belted rabbits. Treatment was performed either with or without scleral depression. Measurements of the retinal burn diameters were performed after hemisecting the globes, and the burns were examined with light microscopy. RESULTS: Variation in burn intensity and diameter (10% to 28%) was common with all 3 laser indirect ophthalmoscopes. Five times more output energy was required to make equivalent burns with the diode laser indirect ophthalmoscope than with the argon or krypton laser indirect ophthalmoscopes. Choriovitreal hemorrhages only occurred during scleral depression. Histopathologically, the argon green laser indirect ophthalmoscope burns spared the choroid and inner sclera, while the intense krypton and diode burns had full-thickness choroidal involvement and even thermal injury to the inner sclera. Scleral depression reduced the mean energy required to create equivalent burns with all three laser indirect ophthalmoscopes. There was a 10% to 40% reduction in the mean retinal burn diameter with scleral depression (argon green, P < 0.0005; krypton red, P < 0.0005; and diode, P < 0.025). CONCLUSION: Photocoagulation with the argon green, krypton red, or diode infrared laser indirect ophthalmoscopes is a safe and effective method of retinal ablation. Decreasing the posterior nodal distance of the eye with scleral depression will produce a smaller spot on the retina with the laser indirect ophthalmoscope.

Animals↗
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↗