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Biomedical subjects

E M Kohner

Publications and source records attributed to E M Kohner.

At least 181 records · Page 10Linked to original sources
PubMed1977

Panretinal photocoagulation in central retinal vein occlusion: A randomised controlled clinical study.

A randomised controlled study of photocoagulation compared with no treatment in central retinal vein occlusion is reported. Forty-eight patients were allocated into treated and control groups by a random procedure 3 months after their first visual symptoms. For the analysis they were subdivided into (1) ischaemic type, and (2) hyperpermeability-response macular-oedema type of central retinal vein occlusion. In neither group did treatment confer benefit as far as visual acuity was concerned. However, iris, disc, and retinal neovascularisation improved after treatment in the ischaemic group. In addition none of the treated patients progressed to neovascular glaucoma. Macular-oedema improved in treated patients with the hyperpermeability response, but the visual field was affected and atrophic changes at the macular precluded visual improvement. It is concluded that photocoagulation should be used only to prevent complications in the ischaemic type of central retinal vein occlusion. It does not appear to be of value in the hyperpermeability group.

Adult↗
PubMed1977

The role of axoplasmic transport in the pathogenesis of retinal cotton-wool spots.

Small retinal arterioles in the pig retina were occluded by argon laser photocoagulation and the morphology and topography of the resulting lesions studied by ophthalmoscopy, histology, and electron microscopy. Two days after laser coagulation ischaemic necrosis of the inner retina was observed in the territory of occluded arterioles, and swollen axon terminals packed with cytoplasmic organelles were found in the retinal nerve-fibre layer on the peripheral border of the infarcts and their border nearest to the disc. These swellings gave rise to localised zones of opacification (cotton-wool spots) at the borders of the retinal infarcts, and similar zones developed in relation to the laser burns. Amino-acid uptake and transport in retinal ganglion cells was studied in these animals by autoradiography following an intravitreal injection of tritiated leucine. When 3H-leucine was injected at the same time as laser coagulation and arteriolar occlusion, label became concentrated in the swollen axon-terminals on the peripheral aspect of 2-day-old infarcts but was absent from the terminals on the disc side of infarcts. The accumulation of 3H-leucine and organelles was attributed to interruption of orthograde axoplasmic transport. When 3H-leucine was injected into the vitreous 2 days prior to laser occlusion, label became distributed throughout the axoplasm and then accumulated in swollen axon terminals on both sides of infarcts after a further 2 days. An obstruction to both orthograde and retrograde axoplasmic flow was thus demonstrated. We concluded that cotton-wood spots should be redefined as accumulations of cytoplasmic debris in the retinal nerve-fibre layer caused by obstruction of orthograde or retrograde axoplasmic transport in ganglion cell axons.

Animals↗
PubMed1976

Deterioration of glucose tolerance in hypertensive patients on prolonged diuretic treatment.

Glucose tolerance was investigated in 51 hypertensive patients before and after 1 and 6 years of treatment with oral diuretics. Glucose tolerance was unchanged after 1 year but had deteriorated significantly after 6 years' therapy. In a comparable group of 16 patients tested at similar intervals in which diuretic therapy had been given only for 3 of the 6 years there was no change in glucose tolerance, suggesting that prolonged oral treatment with thiazide diuretics is diabetogenic.

Administration, Oral↗
PubMed1976

Streptokinase in central retinal vein occlusion: a controlled clinical trial.

Forty patients with central retinal vein occlusion were allocated at random either to a treatment group given streptokinase followed by anticoagulatns or to a control group given no specific treatment. The two groups, which were each of 20 patients, were broadly similar in respect of clinical and laboratory values and similar in their initial visual acuity. At follow-up ("final" vision) the visual acuity in the treated group was significantly better than in the untreated group. Only one treated patient developed thrombotic glaucoma compared with four controls. Streptokinase may, however, have been responsible for vitreous haemorrhage (and permanent loss of vision) in three patients and hence probably has only a limited role in the treatment of central retinal vein occlusion.

Adult↗
PubMed1976

Fluorescein angiography and its prognostic significance in central retinal vein occlusion.

To determine the prognostic value of fluorescein angiograms in central retinal occlusion 75 patients presenting within the first three months of their initial visual symptoms were studied prospectively. The prognosis was found to be best (complete or partial resolution) in eyes with good capillary perfusion, an intact perifoveal capillary arcade, and leakage only from terminal venules and veins. A broken perifoveal capillary arcade and much capillary leakage, even in the absence of obvious capillary closure, were precursors of permanent macular oedema. All eyes with extensive capillary closure developed severe complications such as thrombotic glaucoma and neovascularization (pre-retinal fibrosis), and all became blind. Macular transit time and leakage from arteries and veins were not used as prognostic features. Fluorescein angiography during the first month of the initial visual symptoms was of prognostic value only in those cases with poor prognosis. The three-month angiogram was an accurate indicator of the visual outcome in all cases.

Capillaries↗
PubMed1976

Florid diabetic retinopathy and its response to treatment by photocoagulation or pituitary ablation.

A group of 34 patients with florid diabetic retinopathy are reported. Nine of these had at least one eye untreated and of these only two maintained vision at one year-the others were blind. Ten patients had 11 florid eyes treated by photocoagulation. At one year six were blind and five had good vision. At two years only three could still see. Of 20 pituitary-ablated patients with 29 florid eyes, only three were blind at one year. Even at five years, 12 of 17 eyes could see and only two patients were blind. The one- and two-year visual acuities were significantly better in the pituitary ablated eyes than in the untreated and photocoagulated ones (p = 0.01-0.03). It is suggested that for this rare form of retinopathy pituitary ablation remains the treatment of choice if vision is to be maintained.

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↗
PubMed1975

Plasma-lipids and glucose/insulin relationship in non-insulin-requiring diabetics with and without retinopathy.

Serum-lipid concentrations and their relationship to blood-glucose and serum-insulin were examined in non-insulin-requiring diabetics, 62 with and 45 without retinopathy. The age, sex-body-weight, and duration of known diabetes was comparable in the two groups. All were treated by diet only or diet and oral hypoglycaemic agents. Patients with retinopathy had higher fasting serumtriglyceride and serum--cholesterol levels than those without. Compared with a non-diabetic population, significantly more diabetics with retinopathy had raised derum-lipids. The lipid concentrations did not correlate with body-weight, serum-thyroid-stimulating-hormone levels, renal involvement, or fasting blood-sugar. While the blood-sugar concentrations were similiar in the two groups the absolute insulin increment and the relative insulin response to a 50 g. oral glucose load were significantly lower in those with retinopathy than in those without. The impairment of insulin response correlated significantly with the frequency of hyperlipidaemia. It is suggested that insulin deficiency with secondary hyperlipidaemia is characteristic of diabetic patients with retinopathy.

Adult↗
PubMed1975

The retinal blood flow in diabetes.

Retinal blood flow was studied in 9 normal volunteers and 36 diabetic patients. The method used was based on the measurement of the mean transit time of flourescein in the superior temporal quandrant of the retina and on estimation of the vascular volume by measuring vessels diameters. The results showed that patients with mild or no retinopathy had significantly increased volume flow compared with normals, those with moderate retinopathy had a slight but not significant increase and those with severe retinopathy had blood flow similar to that found in normals. The mean transit time was reduced significantly in those with mild or no retinopathy, but was similar to normals in those with moderate and severe retinopathy. Following succesful pituitary ablation and photocoagulation retinal blood flow was reduced compared with pre-treatment studies.

Adult↗
PubMed1975

Diabetic retinopathy.

Retinopathy is present in 60%-80% of long-term diabetics, and 5%-10% of diabetics surviving 20 yr from the time of diagnosis will be blind, mostly from retinopathy, which is now the commonest cause of newly diagnosed blindness in the 30-65 yr age group. The mean survival time after a diagnosis of retinopathy is only 5 yr. The natural history of diabetic retinopathy is now being understood more clearly. Mild background retinopathy, characterised by microaneurysms or scattered hard exudates, may progress to maculopathy, with macular vascular pathology leading to exudates and edema at the macula; this is most common in older patients. It may also lead to proliferative retinopathy, which may progress slowly with new vessels and fibrous-tissue formation, or rapidly with widespread capillary closure and soft-exudate formation, extensive neovascularisation, hemorrhages, and blindness. The changes of diabetic retinopathy can be documented using retinal photography, and several grading methods have been devised that are useful for evaluation treatment. The cause of diabetic retinopathy is still unclear. Evidence for incriminating genetic factors, growth-hormone excess, and hypoxia associated with changes in blood flow and retinal metabolism are reviewed. Insulin responses and plasma triglyceride seem to be different in maturity-onset diabetics with retinopathy when compared with those in whom this complication is absent. Most physicians agree that good diabetic control may both lower the incidence of retinopathy and reduce the speed of its progress. While there is little evidence that drugs are ever of much value in this condition, the role of photocoagulation both by laser and xenon arc is becoming clearer with increased experience of these techniques, and the current situation is reviewed. Pituitary ablation is a very drastic method of treatment and should never be used as a desperate measure in a patient with advanced proliferative disease. It is, however, the treatment of choice in early florid retinopathy, when it proves the only chance to arrest the condition. Some new techniques of vitreous surgery are now being developed and the possible role of these in the management of patients with advanced proliferative disease is briefly reviewed.

Adult↗