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At least 739 records · Page 41Linked to original sources

PubMed1977

Relationship between perimetric eccentricity and retinal locus in a human eye. Comparison with theoretical calculations.

A blind but grossly normal eye was removed because of severe pain. With the patient's consent, photo-coagulation markers were placed along the horizontal meridian of the retina prior to surgery. The angular coordinates in visual space of the markers were determined by an ophthalmoscopic procedure. The loci of the markers were also determined in a flat preparation following enucleation. The relationship between retinal arc and perimetric eccentricity was found to be approximately linear up to at least 50 degrees. Our findings validate earlier theoretical calculations within this range.

Female↗

PubMed1983

Origin of macrophage in photocoagulated rabbit retina.

To identify the hematogenous origin of macrophages in the photocoagulated retina, a technique of labeling blood monocytes with colloidal carbon prior to the coagulation was used. Colloidal carbon was given intravenously to adult pigmented rabbits twice daily for 5 days, and 3 days after the last injection xenon flash photocoagulation was performed on the retina. The circulating blood cells and the coagulated portions of the retina and choroid were then examined using electron microscopy. At the time of photocoagulation, circulating blood monocytes contained several clusters of carbon granules in the cytoplasm. Two days after coagulation, monocytes with carbon granules were observed to penetrate the Bruch's membrane. In the coagulated retina, macrophages with carbon granules were observed, while retinal pigment epithelial cells contained no carbon granules. Two months after coagulation, macrophages with carbon granules remained in the retina, and a few proliferated pigment epithelial cells contained carbon granules in the cytoplasm. These carbon granules were considered to be derived from degenerated macrophages. These results indicate that hematogenous monocytes invade the retina from the choroid through the Bruch's membrane and are transformed into macrophages, some of which degenerate in the retina and are phagocytized by pigment epithelial cells.

Animals↗

PubMed1998

[Therapeutic arthroscopy for recurrent temporomandibular luxation].

Surgery is sometimes indicated in cases of recurrent temporomandibular joint dislocation (luxation). Among the panel of available techniques, therapeutic arthroscopy with retrodiscal tissue and oblique protuberance coagulation has been used to prevent new episodes. Therapeutic arthroscopy was used for 6 patients. Outcome was considered to be satisfactory in 66% with a mean 3.1-year follow-up. This technique can be recommended as first line therapy when surgery is indicated. In case of failure, eminectomy is scheduled.

Adult↗

PubMed1978

[Photocoagulation and vitreous growth. Experiments on development of the vitreous (author's transl)].

The examination in optical section of sheep eyes, photocoagulated several months previously, shows a disturbed vitreous growth above the destroyed retinal areas (Figs. 2-4). The shape of the resulting deficiencies of vitreous structure (holes) suggests that the vitreous is produced by retinal elements and develops by appositional growth. Holes above lesions due to photocoagulation in an early developmental stage are longer (Fig. 1a; Fig. 2) than those above photocoagulations in later stages (Fig. 1b; Fig. 4). Holes above lesions with intensive retinal destruction (Fig. 2a; Fig. 4a) produce more important vitreous deficienceis than do weaker coagulations (Fig. 2b). Structural deficiencies, though extensive at first, become less important during further growth (Fig. 1c; Fig. 2c; Fig. 3 shows transverse sections at a deep and superficial level through the holes of Figure 2c), which is a sign that in the retinal scars a regeneration of elements producing vitreous occurs. Apart from the theoretical implications concerning the development of the vitreous, the results of our experiments should be considered when photocoagulating children.

Animals↗

PubMed2002

Prenatal diagnosis for multiple pregnancies.

In multiple pregnancies, first trimester ultrasound is crucial to diagnose chorionicity, to detect major structural defects, and to screen for chromosomal abnormalities based on nuchal translucency measurement. The efficacy of nuchal translucency measurement screening in twins might be improved when combined with first trimester maternal serum screening. In twins as in singletons, the risk of fetal loss attendant to chorionic villi sampling and to amniocentesis are similar. When an invasive procedure is indicated in twins, chorionic villi sampling has, over amniocentesis, the advantage of allowing selective termination to be performed in the first trimester, when the procedure related risk of miscarriage is minimal. It has the disadvantage of leading to ambiguous results in up to 2% of cases. While chorionic villi sampling is the choice technique in pregnancies at very high risk, amniocentesis is still indicated in cases at more moderate risk. In monochorionic pregnancies, selective termination can now be performed using a variety of techniques including bipolar or monopolar cord coagulation, and, in acardiac twins, alcohol ablation. However, selective termination remains more hazardous in monochorionic than in dichorionic pregnancies. The outcome of the twin-to-twin transfusion syndrome has been substantially improved by laser photocoagulation of placental shunts and by amniodrainage, but randomized trials are needed to establish the optimal therapeutic strategy, and further pathophysiologic research might result in new treatments.

Amniocentesis↗

PubMed1989

[Visual status in diabetic maculopathy after central photocoagulation].

Diabetic macular edema is shown to be treated successfully by central focal argon laser coagulation in most cases. Since February 1986, diabetic patients with macular edema were evaluated prospectively and treated by focal argon laser coagulation and/or grid pattern. A second group of diabetic patients with comparable macular edema and similar retinal changes was explored retrospectively. Visual acuity after treatment in relation to preoperative visual acuity was measured and statistically compared with visual acuity of the second group without laser treatment. The results show that laser treatment is important for stabilization of visual acuity but does not increase visual acuity beneath 0.2. Indications for treatment are discussed.

Diabetes Complications↗

PubMed2000

[The effects of photocoagulation on the electrical activity of the diabetic retina].

The aim of photocoagulation in diabetic retinopathy is to destroy ischaemic retina because this produces a vasogenic factor, responsible of neovascularization. Retinal burn reduces the number of photoreceptors and effects the transmission of nervous impulse in areas close to those coagulated. It is presumable therefore that electroretinographic parameters will be significantly modified after treatment. 23 diabetic patients where investigated, resulting 43 scotopic electroretinograms, 41 photopic electroretinograms and 46 flicker electroretinograms, each eye being considered separately. The statistic analysis showed significant alterations with laser treatment of the amplitudes of a and b waves in both scotopic and photopic conditions as well as diminished amplitude of the flicker test.

Aged↗

PubMedDate not supplied

[Retinal vessels before and after photocoagulation in diabetic retinopathy. Determining the diameter using digitized color fundus slides].

BACKGROUND: Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slides or negatives. In the present study we used a technique to examine vessel diameters by digital image analysis of color fundus slides. We investigated in a retrospective manner diameter changes in twenty diabetic patients before and after panretinal laser coagulation. MATERIAL AND METHODS: Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (red, green, blue). Since vessel contrast was the highest in the green channel, we assessed grey value profiles perpendicular to the vessels in the green channel. Diameters were measured at the half-height of the profile. RESULTS: After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization. CONCLUSIONS: Splitting digitized images into color planes enables objective measurements of retinal diameters in conventional color slides.

Adult↗

PubMed1981

[Coagulation therapy of proliferative diabetic retinopathy in juveniles (author's transl)].

51 selected juvenile diabetics (diabetes before the age of 12 and proliferative retinopathy before the age of 25) were treated over a 3-years-period by xenon-photocoagulation, in a minor percentage additionally also by argonlaser-, cryo- or diathermy-coagulation. Results of therapy regarding both fundus disease and visual acuity are highly dependent from the morphologic aspect of the fundus at the beginning of coagulation. Eyes with peripheral neovascularizations alone have no more neovascularizations in 65% after 3 years, this is true for eyes with papillary neovascularizations in only 20%. Vitreous hemorrhage further reduces this percentage. Blindness after 3 years is rare in eyes with peripheral neovascularizations alone (3%). On the other side 52% of eyes with papillary neovascularizations and vitreous hemorrhages are blind after 3 years.

Adult↗

PubMed1991

Development of a computer-aided surgery system: three-dimensional graphic reconstruction for treatment of liver cancer.

Simulation of the needle puncture and volume estimation for the tumors in the liver were carried out with the three-dimensional image reconstruction system, which consists of a medical image acquisition system, a data processing system, and a graphic display. A set of sliced-image data from a computerized tomography and/or a magnetic resonance imaging was used to reconstruct the liver, the vessels, and the tumors of the patients with liver cancer. A good agreement of anatomic locations of both the intrahepatic vessels and the tumors between the reconstructed liver model and the echography done intraoperatively was observed. Surgical simulations with these graphic models clearly indicated safety areas for needle puncture in the laser coagulation therapy. In addition liver volumes were calculated within 3% of error in comparison to the measured values. These results indicate that the computer-aided surgery system is a highly promising method that avoids cumbersome stereoscopic recognition of the anatomical location of the diseased area and the vessels, before and after surgery.

Aged↗

PubMed1990

[Coagulation of experimental gunshot wounds of the liver and spleen using plasma argon flow].

Experiments were conducted on 26 dogs to study the possibility of debridement of gunshot wounds of the liver and spleen with plasma argon flow. The method was found to be highly effective in providing final hemo- and cholestasis. The elaborated ++plasma coagulation method allows organ-preserving operations to be undertaken and may be recommended for use in field surgery. Analysis of morphological changes in the tissues showed that the wounds of the liver and spleen heal in the usual period of time without coarse cicatricial deformity of the tissues.

Animals↗

PubMed1990

[Endoscopic laser coagulation of the tumor in patients with cancer of the esophagus and proximal portion of the stomach].

The paper discusses the results of treatment of 152 cases of cancer of the esophagus and proximal part of the stomach presenting with grade III-IV dysphagia. In 107 patients, treatment included endoscopic laser coagulation of tumor: in 52 the procedure was combined with radiation and in 18 cases-with chemotherapy, whereas in 37 patients the method was used alone for palliation only attempting at return to enteral nutrition. Histories of 45 patients with esophageal cancer who had received standard treatment served as control. Laser coagulation-associated lethality was 1.9%. Normal food passage was restored in 97.6% of esophageal cancer patients and in 96% of those with cancer of the proximal part of the stomach. The mean overall survival was 8.7, 8.4 and 7.3 months for the study groups and 3.2 months only for controls. The mean dysphagia-free survival was 48.5 days.

Adenocarcinoma↗

PubMed1989

[Photocoagulation treatment in hemorrhagic branch vein occlusion involving the macula. A new approach].

Hemorrhagic infarction of the inner retinal layer in vein occlusion disables the ophthalmologist from placing the photocoagulation at the "usual" level of the pigment epithelium. On the other hand, resorption of the photocoagulation energy by hemoglobin gives the change of placing coagulation in the inner retinal layer with complete destroying of the retinal capillaries. The not affected part of the macula in branch vein occlusions can thus be prevented from being destroyed by the chronic edema. A photocoagulation barrier is placed between the macula and the affected side. The unavoidable destruction of parts of the nerve-fiber-layer has to be taken into account. If therapy does not start too late, excellent results can be obtained.

Female↗

PubMedDate not supplied

MR imaging-guided interstitial Nd:YAG laser phototherapy: dosimetry study of acute tissue damage in an in vivo model.

A dosimetry study of acute tissue damage induced by interstitial application of the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser was performed with magnetic resonance (MR) imaging. The MR appearance of the lesion was correlated with gross and histopathologic findings. Seventy-six lesions were induced in rabbit muscle with laser power outputs of 5-20 W and exposure times of 20-600 seconds. MR imaging was performed immediately after laser exposure. T2-weighted spin-echo images clearly showed the acute thermal injuries caused by laser energy deposition and correlated best with histopathologic findings. These images showed three distinct layers, corresponding to central ablation, coagulative necrosis, and interstitial edema, respectively, in the pathologic findings. Lesion diameters measured on MR images showed a linear correlation with those in gross sections. Lesion volume increased not only with increasing total energy delivered but with increasing power output for a fixed total energy delivered. MR imaging is an accurate modality for dosimetry studies of laser-induced acute lesions.

Animals↗

PubMed1994

Laparoscopic treatment of polycystic ovarian disease.

There has been a recent surge of interest in laparoscopic treatment of polycystic ovarian disease (PCOD) that is unresponsive to first-line ovulation-inducing agents. Laparoscopic treatment options include multiple ovarian punch biopsy, ovarian electrocauterization and laser vaporization or photo-coagulation. These procedures are relatively easy to perform, devoid of major complications, and yield satisfactory ovulation and conception rates. Adhesion formation, however, is a potential complication following such procedures. Furthermore, women subjected to laparoscopic destructive ovarian procedures also need to be critically assessed regarding other long-term risks, such as premature ovarian failure. Laparoscopic treatment of PCOD, at present, should be viewed as experimental awaiting further trials assessing its long-term safety.

Electrocoagulation↗

PubMedDate not supplied

Stellate ganglion block alleviates pseudo-obstruction symptoms followed by episodes of hypermetropia: case report.

BACKGROUND AND OBJECTIVES: The chronic intestinal pseudo-obstruction due to visceral myopathy is a disorder resembling bowel obstruction but without mechanical occlusion. Frequently, parenteral nutrition becomes the final palliative treatment. A patient affected with this syndrome for 16 years was suffering causalgic pain provoked by intraveneous perfusion. Stellate ganglion block was requested in the hope of maintaining the perfusion. METHODS: Stellate ganglion block not only stopped the pain but unexpectedly, it temporarily relieved the pseudo-obstruction symptoms. Two radiofrequency coagulations in the stellate ganglion prolonged the beneficial effects on gastrointestinal transit for more than 3 weeks, after which the symptoms returned. Multidisciplinary and multicenter advice was that further destructive treatments not be attempted. RESULTS: Repetitive stellate ganglion blocks with 2 mL of bupivacaine 0.75% restored gastrointestinal function for more than 3 weeks. However, after performance of radiofrequency coagulation, infiltration with bupivacaine was followed by hypermetropia on the right eye of 2 weeks duration. CONCLUSIONS: The relationship between stellate ganglion block and gastrointestinal function has not been described. This case report does not provide sufficient information to recommend this technique for pseudo-obstruction symptoms. Moreover, the result in this case is a fortuitous observation, lacking a clear scientific explanation. Further study may be warranted.

Adult↗

PubMed1992

[Basic study of myocardial coagulation by intraoperative laser ablation: in the presence and absence of blood].

To investigate whether the efficacy of laser ablation therapy is affected by the color of the target organ, we irradiated 9 canine hearts through the epicardium with Nd-YAG laser (200 J, 400 J), and compared coagulated myocardial volume in the beating heart (reddish) with that in the stopped heart (whitish) infused with 0 degrees C saline (cardioplegic model) via a coronary artery. The coagulated myocardial volume of the beating heart was significantly larger than that of the arrested heart, indicating the YAG laser energy is absorbed by red myocardium to greater extent than it is by white myocardium. In conclusion, during intraoperative laser ablation, the presence or absence of blood in cardiac tissue is an important factor for safe irradiation.

Animals↗

PubMed1989

Contact transscleral irradiation of the human chorioretina with continuous-wave Nd:YAG laser.

We performed contact transscleral chorioretinal photocoagulations with a continuous-wave Nd:YAG laser on two human eyes affected by choroidal melanomas. An optical-fiber system without any focalization tip was used to deliver the laser energy by placing the fiber in contact with the sclera in the position corresponding to the chorioretinal area to be photocoagulated. With a power of 4 W and an exposure time of 0.5 s, frank white coagulations were obtained. Histological and ultrastructural examination evidenced that the choroidal pigment and the retinal pigment epithelium were the target structures of the radiation. No substantial alterations of the sclera were noted while a good adhesion between the retina and the pigment epithelium cells was observed. The results obtained show that transscleral contact lasers may be safely used in the treatment of some pathologies of the ocular fundus.

Choroid↗