SEARCH · PubMed Health

Results for “Light Coagulation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources

PubMed1982

Photocoagulation therapy of proliferative retinopathy in young onset type 1 (insulin-dependent) diabetes.

Fifty-one young onset Type 1 (insulin-dependent) diabetic patients with proliferative diabetic retinopathy before the age of 25 years were treated over a 3 year period by xenon photocoagulation. A few were treated additionally by argon laser, cryo- or diathermy-coagulation. The results of therapy with respect to both fundus disease and visual acuity were highly dependent on the fundus changes at the beginning of photocoagulation. Ater 3 years, 65% of eyes with peripheral neovascularization alone did not develop any new vessels. In contrast, only 20% with disc new vessels did not develop further neovascularization. Vitreous haemorrhage further reduced this percentage. The presence of blindness 3 years after treatment was rare in eyes with peripheral neovascularization alone (3%). However, 52% of eyes with disc neovascularization and vitreous haemorrhages were blind 3 years later.

Adolescent↗

PubMed1992

Percutaneous photocoagulation of deep vascular lesions using a fiberoptic laser wand.

A new technique is presented for the treatment of deep vascular lesions. A potassium-titanyl-phosphate (KTP), argon, or Nd:YAG laser is attached to a fiberoptic wand, which is passed percutaneously. The laser is activated and coagulates the lesion without direct injury to the skin. Eleven hemangiomas and two lymphangiomas have been treated using this technique. A reduction in size of the lesions was obtained in all patients. Repeat treatments were done to improve results in six patients. Conventional transcutaneous laser therapy was used as an adjunct in four patients. Average patient follow-up was 29 months. No major complications have been noted in this series. Percutaneous fiberoptic photocoagulation has been found to be a safe, long-lasting technique for the treatment of deep vascular lesions.

Adolescent↗

PubMed1992

[Dye laser coagulation of diabetic maculopathy].

Eighty eyes of 48 patients were followed after laser photocoagulation (615 nm) of the macula because of diabetic macular edema. The follow-up time was at least 6 months (average 10.2 months). The morphological status improved in more than 60% of eyes with focal edema but in only 40% of eyes with diffuse macula edema. Improvement of distance visual acuity was obtained in 35% of the eyes, mostly in those with good baseline acuity (greater than or equal to 0.7). The fraction with improved visual acuity decreased to 13% in eyes with a baseline acuity of 0.6 or less. Similar results were found for near visual acuity. The discrepancies between morphological and functional improvement are still unclear.

Adult↗

PubMed1989

[A laser coagulation technic in central retinal vein occlusion].

The authors analyze the method of laser therapy in venous retinal occlusions. In view of the different therapeutic approach in occlusion of the branch and the trunk of the retinal vein, the paper has two parts. In occlusion of the branch of the retinal vein the authors describe the applied techniques of laser photocoagulation recommended by L'Esperance--quadrant barrage, barrier of the macula and arteriolar constriction. Technical data on photocoagulation are presented. In the treatment of occlusions of the trunk of the retinal vein the authors use panretinal photocoagulation, however, only in the ischaemic form of occlusion as a prevention of neovascular glaucoma. The authors mention some of their own experience with the treatment of venous occlusions of the retina by argon laser photocoagulation and they present their own therapeutic schedule.

Humans↗

PubMed2004

[The histopathologic changes of human eyes after laser endoscopic cyclophotocoagulation].

PURPOSE: To observe the changes in ciliary processes in endoscopic cyclophotocoagulation, and propose the principle for choosing energy of laser and access of operating. METHODS: Endoscopic cyclophotocoagulation was performed in the human eyes donated for corneal transplantation through the limber or the pars plana. The coagulated tissue was checked histologically. RESULTS: The ciliary body was viewed clearly with the endoscope (E2). The best choice of energy was shuthe range from 0.4 W to 0.6W, and the most effective reaction was that the processes turned to be pale and shrunk. The main histopathologic changes were that the normal structure of ciliary body was destructed, the pigment epithelial cells and stroma degenerated and the no-pigment epithelial cells kept intact. CONCLUSION: Cyclophotocoagulation could be completed accurately visually under the endoscope. The principle of lowering intraocular pressure was the destruction of ciliary stroma and ciliary pigment epithelial cells.

Ciliary Body↗

PubMed1988

[Experimental analysis of in-depth temperature distribution in echo-guided in-depth irradiation with YAG laser].

In the echo-guided in-depth irradiation using YAG laser, liver cancer is spherically coagulated by the heat effect of YAG laser. To analyse the temperature distribution in the excised bovine and canine livers, the thermometric system was devised. The temperature distribution on the plane of laser fiber was displayed with isothermal lines drawn every 10 degrees C. Vaporized cavity, charcoal zone, and coagulated zone were formed in this order around the laser fiber tip. In charcoal zone, nuclei were pyknotic or disappeared, and cytoplasm became densely eosinophilic. In coagulated zone, hepatocytes were atrophic and degenerated. At the charcoal zone, the temperature was about 200 degrees C and at the outer margin of the coagulated zone, it was about 60 degrees C. Coagulated zone corresponded to the hyperechoic area on echogram. Tissue change was always greater than the hyperechoic area by 2 to 3 mm. Near the laser fiber tip, tissue was vaporized to generate very hot gas. This gas spread along the Glisson's sheath and caused degeneration of vessels and bile ducts. In order to prevent this side effect, gas evacuation system was devised. It was histologically ascertained that this system worked effectively for this purpose. Blood flow carried away heat energy during laser irradiation. In-depth temperature rose more rapidly by Pringle's maneuver. It was speculated Pringle's maneuver could shorten the irradiation time of YAG laser.

Animals↗

PubMedDate not supplied

Retinal neovascularization in sickle cell retinopathy.

Neovascularization of the retina occurs in several types of sickle cell hemoglobinopathies and is highly characteristic in appearance. It arises in the equatorial plane of the fundus following preliminary arteriolar occlusions and arteriolar-venular anastomoses. Neovascular sea fans arise at the interface of perfused and nonperfused portions of the retina, starting during the first decade of life and continuing for many years thereafter. Although some sea fans undergo spontaneous autoinfarction, most show progressive growth and constant intravitreal transudation of plasma components. Traction on the sea fans and the retina results in bleeding into the vitreous, retinal tears, and retinal detachment. Therapeutic intervention with a variety of coagulative techniques is feasible and is usually indicated whenever sea fans are discovered. All therapeutic modalities are capable of inducing significant complications. This is particularly true of argon laser photocoagulation when energy is concentrated into small areas (less than 200 mu) for short durations (less than 0.2 second). With appropriate precautions, photocoagulation results in a high rate of successful obliteration of neovascular tissue. Both vitrectomy and scleral buckling are valuable therapeutic procedures, but both have disproportionately high complication rates in eyes with the propensity for intravascular sickling of erythrocytes. Specific prophylactic measures are therefore indicated when these operative techniques are employed in patients with sickle cell diseases.

Adult↗

PubMed1992

[Fluorescein angiographic observation of cellular changes in the retinal pigment epithelium after laser photocoagulation].

Lesions in the retinal pigment epithelium (RPE) of 16 pigmented rabbits were produced by dye laser photocoagulation using with three different wavelengths: 514, 577 and 630 nm. The power setting and exposure time was the same throughout. The size of the coagulation spot was set either at 500 or 1,000 microns. The retinal lesions were examined by high resolution fluorescein angiography on day 2, 7 and 30 after photocoagulation. Scanning electron microscopic examination of RPE was also performed in selected cases. On fluorescein angiography, the damaged RPE cells appeared as negative fluorescent spots with intense fluorescent margins, throughout the period of observation. The size of the lesion also remained constant. There were no difference in the damage or recovery of RPE cells in relation to the 3 different laser wavelengths. In some area of lesion, the fluorescein angiographic findings closely matched those observed by scanning electron microscopy.

Animals↗

PubMed1994

Fibrin-glue-coated collagen fleece in lung surgery--experimental comparison with infrared coagulation and clinical experience.

Diffuse parenchymal bleeding and major air leaks still present a challenge to the thoracic surgeon. This study was therefore designed to evaluate efficacy and handling of fibrin-glue-coated collagen fleece, to address these problems. In an experimental part defects were produced in lungs of troll pigs to compare the use of the fleece with infrared coagulation. Immediate airtightness and postoperative adhesions were evaluated. Scores were designed to evaluate quality and extension of the adhesions. In a clinical study parenchymal resection sites were sealed with fibrin-glue-coated collagen fleece in 52 patients. No patient suffered from postoperative bleeding. In three cases air leaks were still present on the third postoperative day, representing a 5.8% failure rate. 92.3% of the patients showed neither postoperative hemorrhage nor prolonged air leaks. A fixed combination of collagen fleece and fibrin glue consequently can be considered as a valuable tool in thoracic surgery.

Animals↗

PubMed1990

[The use of argon laser coagulation in the combination treatment of patients with tuberculous chorioretinitis].

The outcomes of argon laser coagulation (ALC) of active tuberculous chorioretinal foci (mainly of exudative and hemorrhagic nature, macular and paramacular localization) in 26 patients are illustrated. The coagulation was performed concurrently with a combined general and local antituberculosis therapy (with 48 patients as controls). The developed direct ALC technique was used together with antibacterial therapy of the total surface of the inflammation focus itself. The examination findings prove that the effectiveness of the above technique is high, since the disappearance of the clinical signs of the inflammatory activity is achieved in a relatively short time (45 days); acute conditions and relapses are prevented; complications are excluded; and an evident economic effect is produced (the shorter period of hospitalization, less duration of the main therapeutic regimen and lower frequency of relapses).

Adult↗

PubMed1992

Laser treatment of esophageal and gastric lesions.

Lasers have contributed in a significant way to the evolution of therapeutic endoscopy. Their ability to coagulate and ablate tissue precisely has been applied to a wide variety of lesions in the upper gastrointestinal tract. Meanwhile, the number of nonlaser devices has also continued to expand, making it necessary to frequently reassess their respective roles. Available evidence suggests that current laser equipment is best suited for the palliative ablation of tumors, especially in the esophagus. On the other hand, the hemostatic properties of the laser are still indicated in the control of vascular malformations but have been largely displaced in the management of peptic ulcer disease by other, more convenient and less expensive methods. With a new generation of laser equipment likely to be introduced soon, these comparisons will undoubtedly need to continue for some time.

Esophageal Diseases↗

PubMedDate not supplied

Ocular blood flow velocities in patients with proliferative diabetic retinopathy before and after scatter photocoagulation: a prospective study.

INTRODUCTION: Color Doppler imaging allows for simultaneous two-dimensional anatomical imaging and Doppler measurement of blood flow velocity. Chemicals are released during the development of a thermal lesion caused by photocoagulation. METHODS: A prospective study compared ocular blood flow velocities (ophthalmic artery, posterior ciliary arteries, central retinal artery, central retinal vein and vortex veins) before and 30 minutes after the first episode of scatter photocoagulation (650, 0.1 s, 500 microns argon laser) in 25 patients with proliferative diabetic retinopathy, using a color Doppler imaging unit (Toshiba Sonolayer SSA-270 A with a 5.0 MHz PLF-503 ST phased-array scanning head). RESULTS: Systolic, diastolic and mean arterial blood flow velocities were higher after photo-coagulation than before. There was a significant difference in the ophthalmic artery; diastolic (P < 0.01), mean velocity (P < 0.05), posterior ciliary arteries; systolic (P < 0.01), diastolic (P < 0.001), mean velocity (P < 0.05), central retinal artery; mean velocity (P < 0.05), central retinal vein; systolic (P < 0.001) and vortex veins; systolic (P < 0.01), diastolic (P < 0.01). Ophthalmic artery systolic and end-diastolic velocities declined with age in diabetic patients before scatter photocoagulation; these changes were not significant (systolic: r = -0.33, diastolic: r = -0.30). DISCUSSION: During and after thermal lesion caused by photocoagulation, there is a dynamic inflammatory and an autoregulatory response of the retinal circulation, causing changes in the ocular circulation.

Adolescent↗

PubMedDate not supplied

[Laser coagulation of the retina in patients with diabetes after posterior-chamber lens implantation].

The possibility of laser coagulation of the retina after implantation of posterior-chamber lenses was examined in 44 patients with diabetes mellitus. Three-speculum Goldman's lens could be used to examine the central zone in 40 patients, the median periphery in 36 patients, and the utmost periphery in 6 patients. The principal causes impeding the examination of the retina were (1) posterior capsule opacity, (2) inadequate mydriasis because of synechias between the iris and the intraocular lens. The number of patients in whom the fundus oculi could be examined was reducing with time. Mydriasis of 8 mm was found necessary for the examination of the total fundus oculi of the artiphakic eye.

Aged↗

PubMed1993

Comparison of magnetic resonance images and the histopathological findings of lesions induced by interstitial laser photocoagulation in the brain.

Interest has developed in using magnetic resonance (MR) imaging to monitor the volume of tissue destroyed by interstitial laser photocoagulation (ILP). In these experiments, ILP was induced in the normal brains of 9 anesthetized cats by delivering 1.5 W of continuous-wave Nd:YAG laser energy (1,064 nm) from a single 400-microns core optical fiber for 1,000 s. The irradiations were monitored using proton spin-echo MR imaging during and immediately after ILP and at postirradiation survival times of 2, 5, and 14 days. At 2 days postirradiation, the necrotic thermal lesion consisted of a central cavity surrounded by 2 concentric zones of coagulative necrosis, one dense and the other dispersed. The lesion shrank and the zonal appearance became less obvious over the 14 day survival period. An enhancing halo on contrast-enhanced T1-weighted images acquired immediately postirradiation best approximated the total lesion diameter at 2 days. These images also indicated that the volume of tissue destroyed during ILP corresponded better to the necrotic volume determined at 2 days than at 5 days and 14 days postirradiation. T2-weighted images acquired during and immediately after ILP consistently underestimated the total lesion diameter at 2 days.

Animals↗

PubMed1991

[Indications for coagulation in diabetic maculopathy].

Macular changes of 333 eyes of 266 diabetic patients were analized regarding number of microaneurysms, area of intraretinal lipids and hermorrhages and the amount of leckage and capillary occlusion in fluorescein angiography. The changes were observed in a central and peripheral area centered around the fovea. The distribution of the changes observed were correlated with the visual acuity of the patients. Only the number of peripheral microaneurysms and the presence of foveal intraretinal edema correlated with a reduction in visual acuity. These parameters are therefore clinical indicators for the severity of diabetic maculopathy. Regarding the visual acuity after a minimal follow up of six months the presence of foveal intraretinal edema was the most important factor with a high risk of short term visual loss. The presence of fovealmacular edema might therefore be the most important indicator for macular photocoagulation treatment.

Adolescent↗

PubMed1994

[Multicenter prospective study of retinopathy of prematurity--III. Timing of the coagulation therapy and the course of retinopathy of prematurity after coagulation].

We reviewed the records of 360 cases of retinopathy of prematurity (ROP) in 12 institutions in Japan, and investigated the timing of the coagulation therapy and the course of ROP after coagulation. The first coagulation therapy was performed at 9.6 weeks after birth and 35.9 weeks of postconceptional age on the average. The severity index in individual infants also showed that the disease became worse during the period from 32 to 36 weeks of postconceptional age. However, the fundus was clearly visible and there was no primary hazy media during this period. On the basis of the results of the timing of the first treatment, the visibility of the fundus, and the severity index in individual infants, we concluded that an ophthalmological examination with special care should be performed during the period from 32 to 36 weeks of postconceptional age.

Humans↗

PubMed1992

[Effects of argon laser irradiation of the iris on the concentration of aqueous prostaglandins and cyclic AMP].

In order to elucidate the influence of acute ocular inflammation on the aqueous humor dynamics and intraocular pressure (IOP), we carried out argon laser photo-coagulations on the rabbit irises and determined the concentrations of aqueous humor prostaglandins (PGs), cyclic AMP and protein. The IOP changed in a biphasic manner, i.e. initial hypertension and later hypotension. The concentrations of aqueous humor PG E2, PG F2 alpha and protein increased markedly after laser irradiation and then decreased gradually, although the concentrations of PG E2 and protein remained significantly higher than the baseline values at 24 hours after the irradiations. The concentrations of aqueous cyclic AMP of the irradiated eyes and control eyes were 67.8 pmol/ml and 29.3 pmol/ml, respectively. We presumed that the increase in concentration of aqueous cyclic AMP and breakdown of the blood-aqueous barrier by PGs caused the reactive hypotension.

Animals↗

PubMedDate not supplied

[Preliminary results of laser coagulation of the retina in the treatment of diabetic retinopathy in pregnant women].

The authors observed a group of 16 pregnant women aged 22-38 years with insulin-dependent diabetes of D, R, RF class (accor. to White). All the patients were treated by conventional insulin therapy. The fundus in 8 of them (16 eyes--group 1) was normal, in following 8 the fundus showed changes of the type of simple retinopathy (13 eyes--group 2) and proliferative retinopathy (3 eyes--group 3). Laser photocoagulation of the fundus changes was executed in 9 eyes. In the final period of gravidity the group 1 and 2 did not exhibit any new changes or intensification of the already existing; this could be connected with application of an intensive conventional insulin therapy. All the eyes (group 1 and 2) except one showed stabilization of the retinal changes after laser treatment.

Adult↗