Determination of the Avogadro constant by counting the atoms in a 28Si crystal.

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, NA = 6.022,140,78(18) × 10(23) mol(-1), is the most accurate input datum for a new definition of the kilogram.

The effects of visual field changes and ocular hypertension on the visual evoked potential.

The effects of visual field changes and ocular hypertension on visual evoked potentials were investigated by photopic ERG and by luminance and pattern-reversal EPs on 116 glaucomatous and on 7 normal eyes. The problem was approached by way of four investigations: Firstly, which nerve structures are affected by glaucoma and how do visual field defects caused by glaucoma influence the EP? The results show a functional diminution of all intraocular nerve structures in which the prelaminary part of the optic nerve is most affected. The EPs, especially the pattern-reversal EPs, are markedly diminished if the visual field defects extend inside the 10 degree boundary. Differences in the visual field defects of both eyes and the course of the sickness can be well observed by the EPs. Secondly, which preoperative prognosis for visual acuity produced by the EP can be given to patients who have a dense cataract in addition to glaucoma? A postoperative improvement of the visual acuity can be expected if the L-EPs are within the standard deviation. If the EP is distinctly diminished and does not increase with increasing stimulus intensity, then there is no hope for an improvement of the visual acuity after the operation. Thirdly, does a decrease of intraocular pressure in chronic and acute glaucoma influence the EP? In acute glaucoma with pressure levels of 50 mmHg or more, and sometimes in chronic glaucoma with pressure levels of about 30 mmHg, an increase of the amplitude of the EP and an improvement of the visual field could be noticed after pressure regulation. Fourthly, what is the behaviour of the EP in normal and glaucomatous eyes at experimentally elevated intraocular pressure? The amplitudes of the ERG components show a gradual decrease in normal as well as in glaucomatous eyes when intraocular pressure is increased and are maintained when intraocular pressure reaches systolic ophthalmic blood pressure. On the other hand, the EPs show a strong decrease in amplitude when intraocular pressure exceeds the mean ophthalmic blood pressure, particularly in the case of glaucomatous eyes.

Cortical potentials evoked by a TV pattern reversal stimulus with varying check sizes and stimulus field.

With the use of television equipment the influence of check size and stimulus field on the pattern evoked cortical potentials was investigated. Maximum responses were found with 20' and 40' checks. The major part of the responses was initiated from a ring between 1.25 degrees and 2.5 degrees eccentricity, though relatively per stimulus area the response became progressively larger the smaller the stimulus field.

[Test performance with minimal alcoholic intoxication]. / Testleistungen bei Minderalkoholisierung.

Driving ability of 34 males under minor influence of alcohol was tested at the ART 90 test unit of the Austrian Road Safety Board. Furthermore, 22 males not under the influence of alcohol, formed part of the sober control group. Some months previously, all volunteers had completed a driver aptitude test consisting of identical tests for all participants. Therefore a before-and-after analysis as well as a comparison of the different groups could be carried out by means of MANOVA. A high motivational level was guaranteed in the first tests as all test persons' driver qualification depended on the results of their driver aptitude tests. Months later they were invited to participate in this study on a voluntary basis. The second tests took place immediately after a social evening at which 8 volunteers were present at any one time. To create conditions as near to reality as possible, only alcohol that would be readily available to the public was served. An entertainer ensured an equally cheerful and relaxed atmosphere in both the experimental and control groups. Alcohol levels were measured by means of the Siemens breathalyser. Results show that as early as an average alcohol level of 0.67/1000 performance is significantly impaired: three times more errors in concentration tests, twice as many errors in reaction tests, twice as many observation errors in visual structuring and a considerable reduction of reactive stress tolerance. On the other hand quantitative dimensions of performance such as reaction time are not significantly impaired. In addition, the readiness to take risks increases with alcohol consumption as is shown by means of questionnaire.

[Correlation between inpatient and ambulatory psychotherapy from the viewpoint of the family physician]. / Verbindungswege zwischen stationärer und ambulanter Psychotherapie aus hausärztlicher Sicht.

Very often the position of the family doctor is being reduced to a mere "doorkeeper" (a person who just lets the patients in and out). He should, however, be the first person being addressed also by patients with psychic and psychosomatic problems, which requires a fundamental education in psychosomatic or psychotherapeutic medicine. Compared to specialists or doctors working in hospitals the advantage of a family doctor is that the patients already trust him, and, furthermore, he is familiar with the family background. He functions as interpreter of the patients' complaints, and--given a certain indication--he combines medication and psychotherapy, which are the two essential parts of psychotherapy being carried out by a doctor. If the symptoms exceed his competence, he must send the patient to a specialist who can cope with his problems. His personal advice is essential in such a case. After having been released from stationary medical treatment, the patient should have the possibility to consult his family doctor again for the sake of continuous medical treatment. A successful combination of stationary and out-patient psychotherapy can be negatively influenced by the following facts: devaluation of the family doctor's competence by specialists or offending of the family doctor's feelings of self-reliance because of a supposed failure.

[The electroretinogram and the visual evoked potential in normal and glaucomatous eyes (author's transl)]. / Das Elektroretinogramm und das evozierte Sehrindenpotential bei normalen und an Glaukom erkrankten Augen.

The functional changes of the intraocular nerve structures caused by glaucoma were examined electro-ophthalmologically. The OPs, the photopic and scotopic ERG to examine the receptor and bipolar layers, as well as the EPs, elicited by luminance and pattern-reversal stimuli, for evaluation of the signal conduction in the optic nerve, were recorded. The problem was approached by way of three investigations: first was the question of which nerve structures are affected by glaucoma and exactly how the loss of visual field due to glaucoma can be determined. For this reason, 55 glaucomatous eyes with regulated intraocular pressure and different visual field losses were examined. The results show a functional diminution of all intraocular nerve structures in which the prelaminary part of the optic nerve is most affected. Differences in the visual field loss of both eyes can be well determined by the EPs. Second, the electro-ophthalmologic behavior in seven normal and eight pressure-regulated glaucomatous eyes was studied by gradually elevated intraocular pressure in order to obtain better insight into the functional pathology of glaucoma. The elevation of intraocular pressure was performed with a Müller spring dynamometer in five steps, depending on the ophthalmic blood pressure. The pressure behavior of the ERG components and the EPs is different. The amplitudes of the ERG components show a gradual decrease in normal as well as in glaucomatous eyes when intraocular pressure is increased, and are maintained when intraocular pressure reaches ophthalmic blood pressure. On the other hand, the EPs show a strong decrease in amplitude when intraocular pressure exceeds the mean ophthalmic blood pressure, particularly in the case of glaucomatous eyes. This behavior can be explained by a high pressure sensitivity of the preliminary part of the optic nerve, even greater in glaucomatous eyes. Third, the influence of pressure decrease on the electrical response was examined in glaucomatous eyes with chronic and acute pressure increase before and after pressure regulation. A mean pressure decrease of 37-13.6 mm Hg in ten eyes with chronic pressure increase led to no change in electrical responses other than a phase shift on the pattern-reversal EPs. In five cases with acute pressure increase, an amplitude increase on the luminance EPs was noticed after pressure regulation, with unchanged systemic blood pressure and almost unchanged ERG components. However, in one case an amplitude decrease on luminance EPs and ERG components was found with simultaneous blood pressure decrease. The increase of the amplitudes of the luminance EPs and the phase shifts of the pattern-reversal EPs can be explained as the functional improvement of the prelaminary part of the optic nerve caused by pressure decrease due to improved blood circulation in the prelaminary part of the optic nerve...

[Chandler syndrome--a case report]. / Das Chandler-Syndrom--eine Falldemonstration.

Chandler's syndrome is a particularly rare form of unilateral secondary glaucoma, in which--besides other symptoms--corneal epithelial edema occurs even when intraocular pressure rises slightly to above 20 mmHg. For 3 years now the authors have had a patient under observation whose condition corresponds to Chandler's syndrome. A remarkable feature of this case is that corneal edema occurred at physiological pressure levels. The symptoms and course are described; a brief differential diagnostic review is given and therapeutic possibilities are pointed out.

[A follow-up study of combined cataract/trabeculectomy operation]. / Nachuntersuchung bei kombinierter Katarakt-Trabekulektomieoperation.

In the past 12 years 69 combined trabeculectomy/cataract operations have been performed at Graz University Eye Clinic. Of these, 33 were examined after an average interval of three years. In 23 cases intraocular pressure was regulated without therapy, and four eyes were regulated with additional therapy. In five eyes no satisfactory pressure could be reached and one eye was lost due to late infection. In ten cases a hyphema appeared; in seven cases registered a rise in intraocular pressure was recorded and in two cases a flat chamber. In view of the great variety of indications this method seems to be especially suitable for elderly patients.

[A case of papillophlebitis]. / Ein Fall von Papillophlebitis.

A case history of a young man with recurrent papillophlebitis. The fluorescein angiogram showed an extensive hyperfluorescence of the disk and surrounding retinal veins in the venous and late phase. The electro-ophthalmological findings were normal in both eyes, while computerized perimetry demonstrated an enlarged blind spot in the bad eye but was normal in the other. The paper concludes with a description of the differential diagnosis of papillophlebitis, papillitis and papilledema caused by vascular occlusive disease or increased intracranial pressure.

[Clinical experience with different methods of treating herpes corneae (author's transl)]. / Klinische Erfahrungen über die Therapie des Herpes corneae mit verschiedenen Behandlungsmethoden.

The modes of action of IDU and TFT were compared in tests employing them both as a monotherapy and in combination with iodine debridement in 60 patients suffering from superficial herpetic keratitis. The combination therapy was used for patients showing only dendritic stains in the corneal epithelium, while the monotherapy was used for patients who had additional lesions in the region of Bowman's membrane. Both with the monotherapies and the combination therapies the average duration of healing was shorter with TFT.

[Electroophthalmologic studies of papillitis, vascular papilledema and obstructed papilla]. / Elektroophthalmologische Untersuchungen bei Papillitis, vaskulärer Papillenschwellung und Stauungspapille.

The photopic electroretinogram (ERG) and the brightness visually evoked cortical potentials (HEPs) were recorded from patients with oedema of the optic disc caused by papillitis (7 patients), by vascular disease (10 patients) and by intracranial hypertension. For the ERG a Henkes-electrode in reference to an earlobe electrode was used. The H-EPs were recorded bipolar in the midline 5% to 25% and unipolar 15% in reference to an earlobe electrode (inion to nasion = 100%). For evaluation the amplitudes and the peaktimes of the a- and b-wave of the ERG were measured. In the H-EPs the amplitudes and the peaktimes of a negatives peak at approximately 70 ms (NGZ) and a positive peak at approximately 120 ms (PGZ) were obtained from the bipolar recording and a positive peak at approximately 100 ms (PGZ) and a negative peak at approximately 140 ms (NGZ) obtained from the unipolar recording were measured. The photopic ERGs of the affected eye showed normal values, however the H-EPs were distinctly pahtological. With the exception of the negative peaktime (NGZ) of the bipolar leads of the intracranial hypertensive papiloedema, all peaktimes were lengthened and amplitudes decreased. These findings were especially evident in the bipolar tracings of papillitis and unipolar tracings of intracranial hypertension.

[Comparison of preoperative retinometer values with postoperative visual acuity after surgery of epiretinal membranes]. / Vergleich des präoperativen Retinometerwertes mit dem postoperativen Visus nach Chirurgie epiretinaler Membranen.

BACKGROUND: We report about our clinical experience when comparing the preoperative retinometer values with the postoperative visual acuity after microsurgical excision of epiretinal membranes (ERM). PATIENTS AND METHODS: Pars plana vitrectomy with membrane peeling was performed in 56 eyes of 53 patients. Preoperatively, we obtained the distant and near visual acuity and the retinometer value. Postoperatively, we compared the preoperative retinometer value to the best postoperative visual acuity. RESULTS: The preoperative retinometer value was in 39 eyes (70 %) equal to the best postoperative distant visual acuity (+/- 1 line) and in 34 eyes (61 %) equal to the best near visual acuity (+/- 1 line). A difference of + 2 or - 2 lines or more from the retinometer value was found in 17 eyes (30 %) for the best postoperative distant visual acuity and in 22 eyes (39 %) for the best near visual acuity. 49 eyes (87.5 %) had a better visual acuity after pars plana vitrectomy, 6 eyes (10.7 %) had equal visual acuities and one eye (1,8 %) was worse than the preoperative visual acuity. The average improvement of vision after the operation was + 2.5 lines for the distant and + 2.4 lines for the near visual acuity. CONCLUSIONS: The preoperative retinometer examination is a precise method for obtaining the visual acuity of patients selected for pars plana vitrectomy with membrane peeling. Uncertain results can be achieved in eyes with very opaque ERM and ERM with macular edema.

[Comparative examinations in goniotrepanation and trabeculectomy (author's transl)]. / Vergleichende Untersuchungen nach Goniotrepanation und Trabekulektomie.

In 20 patients with glaucoma simplex (15 cases) or angle closure glaucoma (5 cases) a trabeculectomy had been done on one eye and a goniotrepanation on the other eye within a period of a few days. As far as the operation-technic concerns neither ofthe two methods revealed a remarkable advantage nor a disadvantage. All patients have been controlled up to one year after the operations. There were only a few postoperative complications in both groups. There was no significant difference in the regulation of the intraocular pressure.

[TV-pattern reversal stimulus (VECPs) in determination of refraction (author's transl)]. / Objektive Refraktiometrie durch Fernsehmuster-evozierte kortikale Potentiale (Muster-VECP).

Pattern reversal VECPs show a dependence on visual acuity and therefore are suitable for objective determination of refraction, this method, however, was of limited clinical use for two reasons, as, on the one hand, the required impulse parameter was difficult to change using the traditional mechanically functioning pattern stimulator and, on the other hand, diagnosis war very timeconsuming. Using a pattern impulse picture presented on a monitor by an electornic impulse apparatus all impulse parameters can easily be changed and throught he introduction of a microprocessorsystem the evaluation can be observed on-line.

[Electroophthalmologic and fluorescein angiographic studies in a case of exudative retinal detachment with spontaneous healing]. / Elektroophthalmologische und fluoreszenzangiographische Untersuchungen bei einem Fall von exsudativer Netzhautablösung mit Selbstheilung.

Electroophthalmological and fluorescein angiographic studies were performed on a 13 year old girl with exsudative detachment of the retina during a hypertensive crisis. The ERG showed a significant reduction during the course of the detachment. After healing the ERG values had improved as compared to those values recorded during the acute illness, but never reached normal levels. The lesions of the retina and the pigment epithelium caused by the detachment were responsible for pathological EOG. The fluorescein angiography showed circumscript and conglomerate lesions in the pigment epithelium.

[A case of unilateral retinitis pigmentosa]. / Ein Fall von einseitiger Retinopathia pigmentosa.

A case of unilateral retinitis pigmentosa observed over a period of 15 years is reported. The affected eye showed all typical pathologic manifestations, while in the healthy eye all findings--including ERG and EOG-- were normal. In spite of the unequivocal ophthalmological diagnosis the condition should be regarded as a tapetoretinal degeneration with the clinical picture of unilateral retinitis pigmentosa so long as there is no evidence that it is hereditary.

[Acute psychogenic strabismus in psychosomatic disorders (author's transl)]. / Psychogenes Schielen im Rahmen psychoorganischer Erkrankungen.

Two cases of convergent strabismus with acute onset are described. One case was caused by a psychogenic disorder, the other by a basilar meningitis.

[Assessment of lesions in various sections of the visual pathway]. / Die Beurteilung von Läsionen im Sehbahnbereich.

The suitability of ultrasonography, computer tomography and Octopus perimetry is illustrated with reference to an investigation carried out in 60 patients. First, the characteristic symptoms are described, depending on the localization of the lesion in the visual pathway. Then the advantages and disadvantages of the various examination methods are compared. In the orbita, echography is the most accurate method in the anterior segments, while the balance shifts increasingly in favor of CT toward the retrobulbar region. As far as intracranial tumors are concerned, there is good correlation between CT and VF findings in the case of sellar processes and pathologic changes of the midline and occipital lobe. In the frontotemporal region, on the other hand, VF defects are found in only one-half of the cases, while in the case of vascular lesions there is no apparent correlation between perimetry findings and the size of the lesion demonstrated on the computer tomogram. The importance of the Octopus for early recognition of such lesions is discussed.

[Surgical method for the treatment of irreversible angle-closure glaucoma and aphakic glaucoma. Direct ciliary body coagulation with partial cyclodialysis]. / Operationsmethode zur Behandlung des irreversiblen Winkelblockglaukoms und des Aphakieglaukoms. Direkte Ziliarkörperkoagulation mit partieller Zyklodialyse.

Among 16 patients aged from 31 to 86 there were 13 cases of hemorrhagic glaucoma, three cases of secondary glaucoma from iritis and one case of secondary angle-closure glaucoma after trauma. Reduction in intraocular pressure was achieved by a surgical method which primarily aims to improve the outflow of aqueous humor. The ciliary body is laid bare by preparation of a scleral flap, a partial cyclodialysis is attached on both sides and the ciliary body is induced to stricture by coagulation, so that a large enough cleft is created. Before the operation, pressure ranged from 34 to 64 mm Hg; after the operation, during postoperative periods of observation lasting from two to 32 months, there were 14 cases in which the pressure was below 25 mm Hg and two cases with 30-40 mm Hg respectively. In view of the good results and the few complications, this method of operation can be recommended for treatment of both irreversible angle-closure glaucoma and aphakic glaucoma.

[Electrophysiological and fluorescence-angiographical examinations in a case of fundus albipunctatus cum hemeralopia congenita (author's transl)]. / Elektrophysiologische und fluoreszenzangiographische Untersuchungen bei einem Fall von Fundus albipunctatus cum hemeralopia congenita.

Electrophysiological and fluorescenceangiographical examinations were carried out in a case of fundus albipunctatus cum hemeralopia congenita. In the ERG a diminished scotopic b-wave was conspicuous, which reached the normal size after longer dark adaptation. It was possible to distinguish between albipunctatus-dots and druses by fluorescenceangiography. While the latter became clearly visible in the phase of choroidic-fluorescence the ophthalmoscopically perceptible albipunctatus-dots lost their visibility.