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Biomedical subjects

W Leydhecker

Publications and source records attributed to W Leydhecker.

32 records · Page 2Linked to original sources
PubMed1977

[The diagnostic and prognostic significance of increase intra-ocular pressure (author's transl)].

A single tonometry observation is not very relevant due to considerable interobserver variations which are also found in applanation tonometry. Furthermore, the intraocular decreases by repeated applanation tonometry and intra-ocular pressure that change for as much as 8 mm Hg in 1 minute has been found in continous pressure recordings. There are in addition diurnal pressure variations and pressure alterations with the position of the body. Therefore, the diurnal pressure curve is much more important than the single tonometric value. The prognosis and also the decision to start medical treatment depends upon the height of the pressure, the family history diabetes, vasoclerosis, low blood pressure, heart insufficiency, age, disease of the carotid artery, anemia, the size of the excavation, the condition of the visual field, the reliability of the patient and the pressure lowering effects of pilocarpine, which can be very different individually. Rarely pressures of 26 mm Hg or more can be left untreated. If unfavourable factors are combined, even in pressures of 20 mm Hg it should be tested if pilocarpin lowers the intra-ocular pressure considerably. There is no magic number of pressure where treatment has to be started.

Adult↗
PubMed1977

[The early diagnosis of glaucoma as a social medical problem (author's transl)].

Tonometric mass screening for industrial nations is not recommended. Amongst the reasons against mass screening is to be emphasized the sufficient prevention of glaucoma blindness, if the reading glasses are prescribed by the ophthalmologist and if he measures the intraocular pressure in each patient over 40 years of age. In developing countries the programmes are completely different since here no medical treatment is possible. The cost benefit calculation is presented for such mass screening, which should be directed to the early recognition of simple glaucoma and which should combine tonometry and Friedman Analyzer field study. Pilot studies should show, whether it is useful or not to include the inspection of the optic disc. Glaucoma teams could be associated with the cataract eye camps. Their work must be coordinated by a center, which evaluades the results of the examination teams and changes directives accordingly.

Blindness↗
PubMed1976

[Mass screening for glaucoma].

Mass-screening of the population over 40 years by tonometry is not recommended for developed countries. However, tonometry of each patient attending the ophthalmologist, is absolutely necessary. Omitting tonometry is only justified, if special reasons prevent it, for example inflammations. If reading-glasses are always prescribed by the ophthalmologist and tonometry is done on each such patient, then this is the adequate and sufficient protection of the population against glaucoma blindness. Preventive examinations of the group in the highest danger to become blind from glaucoma, i.e. persons of 55-65 years of age, might perhaps be useful, if the tonometric limit is set high (30 mmHg) and if a check of the visual field by the Friedman-Analyzer is combined with tonometry. The aim of such examinations would not be the detection of suspicious or very early forms (tonometric glaucoma), but to screen for definite glaucoma cases with field-defects, which undetected would become blind. It seems, however, questionable, if the motivation of this age group will be sufficient. This should be found out by pilot-tests. In developing countries the question of mass-screening is entirely different. There glaucoma patients must be filtered out, in whom surgery is less risky than waiting without treatment. This can only be done by mass-screening including tonometry by the borderline-tonometer glaucotest, perimetry by the Friedman-Analyzer and estimation of the cup/disc-ratio.

Aged↗
PubMed1976

Histochemical evaluation of enzymes in the rabbit corneal endothelium after short-term storage.

Isolated rabbit corneae were stored at a temperature of 4 degrees C in McCoy's 5a medium (modified) containing 5% dextran T 40 and gentamycin sulphate (250 mug/ml) for a varied number of days. The endothelium of the corneae was examined by light- and electron-microscopic histochemical methods for ATPase, TPPase, and SDH. The activity of each enzyme in the endothelia, stored for 6 days, was found to resemble the enzyme activities in the fresh corneal endothelium. By 8 days, the SDH activity was lowered and specific staining for ATPase and TPPase was decreased. In the 12 day-stored endothelium, the SDH and TPPase activities could not be detected. From these results, it was gathered that the isolated cornea stored in the medium for 6 days may be used in keratoplasty.

Adenosine Triphosphatases↗
PubMed1976

[Light and electron microscopic studies on short-term preserved corneae (author's transl)].

Rabbit corneae were stored at a temperature of +4 degrees C in the following media: 1. 5% Dextran T40, 2. McCoy's Medium 5a (modified), 3. Dextran T 40+McCoy's 5a Medium + gentamicin sulphate (250 mug/ml). The endothelia of the corneae were examined by light and electron microscopy after preservation for a varied number of days. The structure of the endothelia, stored for 1, 6, 12, 18 days, was compared to fresh corneal endothelial cells. The results indicate that corneae preserved in Dextran 5% T40 + McCoy's 5a Medium + gentamicin sulphate might be equivalent to fresh corneal tissue in keratoplasties.

Animals↗
PubMed1976

Uptake of horseradish peroxidase (HRP) by the endothelium of the short-term stored rabbit cornea.

In vitro study of the uptake of horseradish peroxidase (HRP) by the corneal endothelium was carried out on rabbit corneae which were stored in a preserving medium for various periods. The stored corneae were incubated in HRP solution with or without adenosine triphosphate (ATP). The number of pinocytotic vesicles decreased as the storage time was prolonged. Addition of ATP to the HRP solution led to an increase in the pinocytotic vesicles in all storage periods. The pinocytosis in the 12-day stored corneal endothelium was only observed when the tissue was incubated in an HRP solution containing ATP. From these results, it was concluded that the viability of the stored corneae can be evaluated with uptake of HRP by the endothelial cell, and that the addition of ATP leads to an enhancement of pinocytotic activity in the endothelial cell.

Adenosine Triphosphate↗
PubMed1976

The intraocular pressure: clinical aspects.

Only a few conclusions can be mentioned: The IO pressure of the normal eye is not fixed, but shows spontaneous variations of pulsatory, respiratory, vasomotoric and diurnal type. The highest and lowest point of a 1 minute tracing can differ for 8 mm Hg. Very short acting tonometers are, therefore, less reliable than those with slower reactions, which will average some of the quicker oscillations. Normal limits of diurnal variations are 5 mm Hg with peaks below 25 mm Hg and differences between right and left eye of less than 4 mm Hg. The range of pressure of an eye is more important than a definite value which is true for the moment only. Factors which influence the IO pressure in healthy subjects are discussed in detail, such as age, sex, eye muscles, sports, muscular spasmus, child birth, position of the body, real or simulated tonometry, and mental stress. Difficulties in tonometry are discussed. In applananation tonometry, +/- 2.5 mm Hg must be accepted as the possible error of clinical results. This is not caused by any lack in the construction of the instrument, but by the combination of interobserver variation in reading the instrument, spontaneous pressure changea and an individually different decrease of pressure in consequence of repeated measurements. It is concluded that the rigidity of the living eye cannot be measured with a satisfactory degree of exactness. For the clinical purpose of early diagnosis, the diurnal tension curve combined with the tonography test of the author are the best methods. Early normalization of intraocular pressure is the safest means to prevent damage of the optic nerve. In spite of the individual variations of pressure and the inaccuracies of any single tonometry, the present methods of tonometry are clinically sufficient to form an opinion about the diagnosis and also about the success of our treatment, the aim of which is to normalize the pressure through the 24 hours below 20 mm Hg.

Adult↗
PubMed1976

[Is a medical treatment of glaucomatous field defects possible? Results of a double blind study (author's transl)].

46 patients with field defects due to simple glaucoma were treated with beta-Acetyldigoxin (given as "Placebo") or with beta-acetyldigoxin and Bencyclan (given as Verum) in tablets over 6 months, under strict double-blind conditions and after the elimination of the learning effect of perimetry. 56 out of the 69 eyes which could be evaluated, showed no change of the field during that period, in spite of increasing field defects during the preceeding months in some of them. A deterioration of the field was observed in 3 eyes treated with placebo, 10 eyes became better, one with placebo and 9 with Verum. Digitalis can evidently stop a deterioration and, in exceptional cases, even enlarge the field. Bencyclan with digitalis was found to have a definitely better effect and enlarged field in 9 out of 41 eyes which were treated with the drug, probably by the change of viscosity of the blood perhaps in addition to vasodilation and a better action of the heart. The effect is statistically-significant (p less than 5%).

Bencyclane↗
PubMed1976

Pneumatonographic studies on normal and glaucomatus eyes.

A new methodological approach, embodied in the pneumatonograph, has been used to study the intraocular pressure, intraocular pulse and aqueous humor dynamics of normal and glaucomatous eyes. Comparative measurements of intraocular pressure in seated subjects by the Goldmann instrument and the pneumatonograph indicate close agreement over a wide range of pressures. On changing from the sitting to the supine position, it has been found by pneumatonometry that there is a significant increase of intraocular pressure in all eyes. In glaucomatous eyes, this postural response ranged up to as high as 12 mm Hg. Comparison of Schiotz and pneumatonometric pressure measurements on supine patients showed that the Schoitz values are significantly lower. This discrepancy of the values is in keeping with recent studies indicative that the Schiotz calibration is in error by 3-6 mm Hg. The coefficient of outflow facility was measured by a procedure of applanation tonography employing pressure-volume relations for the living human eye. The range of values found for normal eyes was significantly different from those of glaucoma eyes. It is concluded that pneumatonography is a useful method for improving the effectiveness of glaucoma diagnosis and clinical management.

Adult↗
PubMed1976

[Projects of the international agency for the prevention of blindness (author's transl)].

The International Agency for the Prevention of Blindness (IAPB) had a meeting in Bethesda, in which the author took part as the chairman of the glaucoma prevention committee. Priority was given to the 6 causes of preventable blindness. These are onchocercosis, trachoma, keratomalacia, cataract, glaucoma and injuries. Projects for prevention of blindness were discussed. In developing countries eye care can reach the population only by mobile units with an eye specialist and allied personnel. The training of such health personnel in 3 different levels and the curriculum for each level was also discussed.

Allied Health Personnel↗