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PubMedDate not supplied

[Idiopathic parafoveal telangiectasias].

The authors describe the clinical and angiographic picture of idiopathic parafoveal telangiectasis in 6 patients (10 eyes). Three forms of the condition were distinguished: edematous, occlusive, and with subretinal shifts. A natural course of the process is traced, the criteria and terms of laser coagulation are defined.

Adult↗
PubMed1976

The problems of retinal blood flow in diabetes.

Three methods are available for measurement of retinal blood flow: cinefluroescein angiography, measurement of mean transit time, and estimation of volume flow by laser-Dopler velocimetry. Cineangiography requires intra-arterial injection for volume flow measurement, and this greatly inhibits its use. Difficulties also arise in estimating the relation of the axial to the mean flow, since it is now known that the retinal flow is plug flow. Transit time measurement using fluroescein has recently been automated and thus allows for more accurate measurement and better estimation of volume flow. The problems of estimating vascular volume and allowing for leakage have not been overcome. Laser-Doppler velocimetry measures mean red cell velocity but its relation to volume flow has not been established. Using the mean-transit-time method, several authors have found reduced transit time and increased volume flow in patients with mild and no retinopathy, compared to normals and those with more severe lesions, This most probably is due to autoregulatory adaptation and, possibly, to hypoxia. In more severe retinopathy, flow is reduced and there are large areas of nonperfusion. These areas are the result of abnormality of the endothelial cells and also of the blood within the vessels, which probably coagulates more easily than in normals. These areas are of importance because they stimulate the growth of new vessels.

Blood Coagulation Disorders↗
PubMed1989

Laser radiation tissue interaction.

Mechanisms of interaction between laser radiation and biological tissue are reviewed. Scattering and absorption determine the penetration of radiation into tissue; the heterogeneity of tissues prevents exact model calculations of in-depth energy deposition. The high irradiances, achievable with pulsed lasers, can induce nonlinear absorption, optical breakdown and plasma formation in tissues. Heat conduction and heat convection as well as the build-up and propagation of pressure transients damage tissue outside of the absorbing volume. The limitations to the validity of the first-order rate processes as a description for thermal tissue coagulation and the possibilities for novel photochemistry are discussed.

Animals↗
PubMed1992

The influence of argon laser panretinal photocoagulation on the rabbit ERG c-wave.

We observed the influence of panretinal photocoagulation on the ERG c-wave in rabbit eyes. DC-registered ERGs were recorded from rabbit eyes before and after photocoagulation, and compared with those of the fellow eyes. The rabbits were subdivided into 3 groups according to application numbers: 500, 1000, and 1500 spots. The ERG c-waves were found to have totally disappeared in all rabbits 3 days after panretinal photocoagulation, then reappeared with various intervals. In the 500 spot group, the c-wave reappeared after one week, and almost reached control levels in one and a half months. In the 1000 spot group, a 10 day delay was noted, and 90% of control levels were regained after 6 months. In the 1500 spot group, the c-wave didn't reappear until 2 weeks later, and regained 70% (of the control level) after 6 months. The recovery rates were related to the number of laser applications. These results indicate that the ultimate degree of recovery in c-wave amplitude and the time required for the reestablishment of retinal pigment epithelium function both depend on the size of the coagulated area.

Animals↗
PubMed1992

Optimal nonsurgical treatment of hemorrhoids: a comparative analysis of infrared coagulation, rubber band ligation, and injection sclerotherapy.

Despite an abundance of nonsurgical hemorrhoid therapies, none has been consistently more efficacious. By combining data from multiple clinical trials in a meta-analysis, the present study compared the efficacy and complications of infrared coagulation, injection sclerotherapy, and rubber band ligation to determine the optimal nonoperative hemorrhoid treatment. All published clinical trials comparing the three methods were identified by computer search and review of appropriate English language journals. Five trials studying 863 patients satisfied all inclusion criteria. Results demonstrated that similar numbers of patients were asymptomatic 12 months after treatment, regardless of initial therapy. However, significantly fewer patients undergoing rubber band ligation required additional treatment because symptoms had recurred. Although rubber band ligation demonstrated greater long-term efficacy, it was associated with a significantly higher incidence of posttreatment pain. In contrast, infrared coagulation was associated with both fewer and less severe complications. Thus, when all factors are considered, infrared coagulation may in fact be the optimal nonoperative hemorrhoid treatment.

Hemorrhoids↗
PubMed1985

[Recurrence of vasoproliferative activity after photocoagulation. A fluorescence-angiographic study].

Although photocoagulation is no cure for diabetic retinopathy, it slows down or, in favourable cases, prevents further progression. In order to achieve the desired therapeutic effect, photocoagulation has to include the ischaemic mid-periphery of the retina. Following a latency period of varying duration during which no further progression is evident either on ophthalmoscopic examination or fluorescein angiography, recurrence of neovascularization is observed in some cases. The therapeutic management entails additional panretinal photocoagulation, in particular at the periphery. The authors report on 75 patients who, following panretinal photocoagulation, were treated by additional argon-laser coagulation.

Diabetic Retinopathy↗
PubMed1977

[Clinical experience with the O'Malley LOG2 photocoagulator (author's transl)].

Clinical experience with a combination of the Clinitex photocoagulator and the Sadamel auxiliary apparatus (Fankhauser and Lotmar) is reported. This equipment proved to be very suitable for the photocoagulation therapy of degenerative and vascular processes and appeared to be only slightly inferior to the Zeiss apparatus. The coagulation at the posterior pole of the eyeball, within the distribution area of the temporal vessels, was somewhat more difficult than with the Zeiss apparatus: the longer coagulation times which are involved when smaller coagulation fields are used require more skill and experience. With coagulation outside the distribution area of the temporal vessels, on the other hand, no differences were observed in comparison with the Zeiss equipment. The Clinitex-Sadamel combination provides a practical apparatus for the photocoagulation therapy of retinal and choroidal disorders. In this combination the use of the O'Malley coagulator was extended to include photocoagulation, also through the three-reflector contact glass.

Anesthesia↗