[Ocular blood flow regulation in glaucoma - examination with the ocular pressure flow analyzer (OPFA)]. / Okuläre Durchblutungsregulation beim Glaukom. Untersuchungen mit dem Ocular Pressure Flow Analyzer (OPFA).

BACKGROUND: The results of studies of ocular blood flow (BF) regulation of patients with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and ocular hypertension (OH) are presented. METHODS AND PATIENTS: Examinations were carried out with the "OPFA", a newly developed ocular pressure flow analyzer (producer: tpm Lüneburg) on 92 patients with newly diagnosed glaucomas, among whom 48 patients had POAG, 22 NTG and 22 OH, and compared with age-matched groups of healthy subjects. The OPFA uses pneumatic coupling through special scleral suction cups to record ocular pulses with highly sensitive transducers and a suction pump for simultaneously increasing intraocular pressure (IOP). Following local drop anaesthesia on both eyes, IOP is artificially raised to suprasystolic values. While continuously lowering IOP, the ocular pulse is then recorded with increasing ocular perfusion pressure. We obtain the relative ocular pulse blood volume by correlating the ocular pulse amplitudes with a calibration volume of 1 µl. This enables us to collect reproducible data on intra- and inter-individual pulse blood volume (PVoc). The ocular perfusion pressure pulse blood volume curve characterizes the respective individual ocular circulation as well as systolic and diastolic ocular perfusion pressures. RESULTS: In healthy subjects, the ocular pulse blood volume remains stable over a certain range of ocular perfusion pressure (ppoc) changes. After exceeding a critical point (CP), the ocular pulse blood volume drops. We refer to the difference between the CP and IOP as the autoregulatory capacity (AC). In patients with POAG and in patients with NTG, the AC was reduced significantly compared with the groups of healthy subjects. The mean AC of patients with OH remained within the normal range. The ROC curves showed at an optimal cut-off value for POAG a sensitivity of 75.0 % and a specificity of 97.9 %, for NTG a sensitivity of 77.3 % and a specificity of 100 %. In patients with POAG and OH, the ocular arterial pressures were elevated. In patients with NTG they remained unchanged compared with the healthy subjects. The ocular perfusion pressures did not change in POAG as well as in NTG and OH. CONCLUSIONS: In patients with POAG and in patients with NTG the ocular BF regulation was impaired and detected by the OPFA device with a high level of reliability. Ocular arterial blood pressures were increased as a result of vascular regulation to keep up the ocular perfusion pressure and to maintain ocular perfusion.

State anxiety by itself does not change political attitudes: A threat of shock experiment.

Previous research suggests that state anxiety may sway political attitudes. However, previous experimental procedures induced anxiety using political contexts (e.g., social or economic threat). In a pre-registered laboratory experiment, we set out to examine if anxiety that is unrelated to political contexts can influence political attitudes. We induced anxiety with a threat of shock paradigm, void of any political connotation. All participants were instructed that they might receive an electric stimulus during specified threat periods and none during safety periods. Participants were randomly assigned to one of two conditions: Political attitudes (implicit and explicit) were assessed under safety in one condition and under threat in the other. Psychometric, as well as physiological data (skin conductance, heart rate), confirmed that anxiety was induced successfully. However, this emotional state did not alter political attitudes. In a Bayesian analytical approach, we confirmed the absence of an effect. Our results suggest that state anxiety by itself does not sway political attitudes. Previously observed effects that were attributed to anxiety may be conditional on a political context of threat.

You see what you avoid: Fear of spiders and avoidance are associated with predominance of spiders in binocular rivalry.

What we see is the result of an efficient selection of cues in the visual stream. In addition to physical characteristics this process is also influenced by emotional salience of the cues. Previously, we showed in spider phobic patients that fear-related pictures gain preferential access to consciousness in binocular rivalry. We set out to replicate this in an independent unselected sample and examine the relationship of this perceptual bias with a range of symptom clusters. To this end, we recruited 79 participants with variable degrees of fear of spiders. To induce binocular rivalry, a picture of either a spider or a flower was projected to one eye, and a neutral geometric pattern to the other eye. Participants continuously reported what they saw. We correlated indices of perceptual dominance (first percept, dominance duration) with individual fear of spiders and with scores on specific symptom clusters of fear of spiders (i.e., vigilance, fixation, and avoidance coping). Overall, higher fear of spiders correlates with more predominace of spider pictures. In addition, this perceptual bias is uniquely associated with avoidance coping. Interestingly, this demonstrates that a perceptual bias, which is not intentionally controlled, is linked with an instrumental coping behavior, that has been implicated in the maintenance of pathological fear.

Time is a great healer: Peak-end memory bias in anxiety - Induced by threat of shock.

Recently, we demonstrated that the peak-end memory bias, which is well established in the context of pain, can also be observed in anxiety: Retrospective evaluations of a frightening experience are worse when peak anxiety is experienced at the end of an episode. Here, we set out to conceptually replicate and extend this finding with rigorous experimental control in a threat of shock paradigm. We induced two intensity levels of anxiety by presenting visual cues that indicated different strengths of electric stimuli. Each of the 59 participants went through one of two conditions that only differed in the order of moderate and high threat phases. As a manipulation check, orbicularis-EMG to auditory startle probes, electrodermal activity, and state anxiety confirmed the effects of the specific threat exposure. Critically, after some time had passed, participants for whom exposure had ended with high threat reported more anxiety for the entire episode than those for whom it ended with moderate threat. Moreover, they ranked their experience as more aversive when compared to other unpleasant everyday experiences. This study overcomes several previous limitations and speaks to the generalizability of the peak-end bias. Most notably, the findings bear implications for exposure therapy in clinical anxiety.

All's Bad That Ends Bad: There Is a Peak-End Memory Bias in Anxiety.

The peak-end memory bias has been well documented for the retrospective evaluation of pain. It describes that the retrospective evaluation of pain is largely based on the discomfort experienced at the most intense point (peak) and at the end of the episode. This is notable because it means that longer episodes with a better ending can be remembered as less aversive than shorter ones; this is even if the former had the same peak in painfulness and an overall longer duration of pain. Until now, this bias has not been studied in the domain of anxiety despite the high relevance of variable levels of anxiety in the treatment of anxiety disorders. Therefore, we set out to replicate the original studies but with an induction of variable levels of anxiety. Of 64 women, half watched a clip from a horror movie which ended at the most frightening moment. The other half watched an extended version of this clip with a moderately frightening ending. Afterward, all participants were asked to rate the global anxiety which was elicited by the video. When the film ended at the most frightening moment, participants retrospectively reported more anxiety than participants who watched the extended version. This is the first study to document that the peak-end bias can be found in the domain of anxiety. These findings require replication and extension to a treatment context to evaluate its implications for exposure therapy.

[Disordered peripapillary microcirculation in glaucoma patients]. / Störung der peripapillären Mikrozirkulation bei Glaukomatienten.

To study the haemodynamics of the peripapillary choroid, perfusion pressure videoangiography (PVA) was performed in six healthy subjects and in seven patients with primary open-angle glaucoma (poag). In healthy subjects the peripapillary part of the choroid starts filling at distinctly lower ocular perfusion pressures than other parts of the choroid. The mean difference in perfusion pressure between peripapillary and perimacular filling was 13.6 mmHg in the six healthy subjects. A different filling pattern of the choroid was found in the seven glaucoma patients. The mean difference in perfusion pressure between the beginning of peripapillary and the beginning of perimacular perfusion of the choroid was found to be as small as 1.9 mmHg. That the filling of the peripapillary choroid observed by PVA in healthy subjects is found to start at lower perfusion pressures than in the other parts is explained by autoregulative dilatation of the peripapillary choroidal arterioles resulting from artificially raised intraocular pressure during the PVA examination. In the poag patients the peripapillary choroidal arterioles were dilated either insufficiently or not at all. The following conclusions are drawn: (1) The peripapillary choroid of healthy persons shows effective autoregulation securing the blood supply to the prelaminar part of the optic nerve. (2) In poag the peripapillary choroid has lost the capability of effective autoregulation.

[White-noise field campimetry before and after artificial increase of intraocular pressure. Possible applications in diagnosis and evaluation of glaucoma]. / Rauschfeldkampimetrie vor und während künstlicher Augeninnendrucksteigerung. Einsatzmöglichkeiten in der Diagnostik und Bewertung des Glaukoms.

A total of 173 eyes (visual field defect stages O-V) of 99 glaucoma patients were investigated by means of conventional threshold-oriented suprathreshold automated test point perimetry using the Tübingen Automatic Perimeter (TAP) and by means of white-noise-field campimetry (flickering random dot pattern) using the Tübingen Electronic Campimeter (TEC). Most eyes were affected by primary open-angle glaucoma (119) or low tension glaucoma (35). The concordance between the two methods was good in 65 eyes (37.6%). Sufficient in 32 (18.5%) eyes, poor in 32 cases (18.5%) and inadequate in 44 eyes (25.4%). Among the last group of 44 eyes, 32 perceived a scotoma in the noise field (NF) but did not show any pathologic defect in conventional automated test point perimetry: the opposite constellation was found in only 12 eyes. In most cases, scotoma in the NF showed a change in both brightness and motion (noise) perception. No clear relationship between the type of glaucoma and a certain constellation of the aforementioned NF specifications could be found. Complete lack of noise perception in the scotoma occurred more frequently in advanced glaucoma (stage > or = IV). In 110 eyes of 63 of the glaucoma patients, white-noise-field campimetry was carried out during artificial IOP elevation achieved by suction-cup oculopression: during steplike increases of the negative pressure in the suction-cup up to maximum of 375 mmHg the following stages could be seen (the percentage of eyes that perceived each phenomena over the negative pressure range is shown in brackets): change in NF perception compared with initial findings (96.4%); impairment of central noise-field perception (78.2%); concentric constriction of NF (61.8%); complete breakdown of noise (field) perception (42.7%). A further, quantitative classification of these eyes was possible by evaluation of the negative pressure in the suction-cup that led to any one of these NF phenomena. The results demonstrate the usefulness of white-noise-field campimetry as a very fast screening method for detecting glaucomatous visual field defects. It can also be performed as a pressure tolerance test and thus be used to classify glaucomatous risk stages.

[Eye-pressure tonometry in prevention of glaucoma]. / Okulopressionstonometrie (OPT) in der Glaukompraxis.

Oculo-pression tonometry (OPT) was introduced in 1984 as a clinical method of examining ocular hydrodynamics. The method involves measuring intraocular pressure (IOP) by applanation tonometry performed before, during and after application of a pressure load that disturbs the dynamic balance between aqueous production and aqueous outflow. From the IOP before (P0) and immediately after (Pr0) the 8-min pressure load period, the outflow facility C(u) can be calculated: [formula: see text] The examinations performed so far have shown that (1) reduced outflow facility can be detected by OPT with a high degree of reliability, and (2) reduced outflow facility is always preceded by the development of glaucoma damage to the optic nerve head. A prospective study has shown that in the group of patients with reduced outflow facility but without glaucoma damage, 73% developed glaucoma damage with typical changes of the papilla and visual field within 3-7 years after the first examination.

[Effect of change in refraction by increasing intraocular pressure with the suction cup method on pattern reversal VECP]. / Einfluss der Refraktionsänderung bei Erhöhung des Augeninnendruckes mit der Saugnapfmethode auf das Pattern-reversal-VECP.

When IOP is increased by the suction cup method, refraction changes will occur, depending on the shape of the cup and the height of the IOP increase. Similar refraction changes were simulated in six healthy volunteers by employing spherical and cylindrical glasses during pattern-reversal visual evoked cortical potential (VECP) with various check sizes and amount of contrast. While the pattern-reversal VECP latencies were not influenced, the amplitudes were reduced considerably. By using contact lenses and a suitably shaped suction cup, refraction changes could be compensated for. In 22 healthy volunteers pattern-reversal VECPs were derived with and without the application of contact lenses with artificially raised IOP. A comparison showed that the amplitudes differed significantly. Without contact lenses a negative pressure of more than 40 mmHg resulted in a drop in the amplitudes with a plateau formed between 80 and 120 mmHg. With compensation by contact lenses the amplitudes are found to be unaltered or even slightly increased until a negative pressure of 120 mmHg is reached in the suction cup, after which they drop. Plotting the pattern-reversal VECP amplitudes (obtained with refraction changes being compensated for by contact lenses) against ciliary perfusion pressure, one finds the characteristic curve described by Ulrich et al., suggesting an autoregulative capacity between 15 and 20 mmHg in healthy persons. The latencies, which remain uninfluenced by refraction changes, are also not altered within an IOP increase of 15-20 mmHg.

Effects of low-intensity ultrasound on the central nervous system of primates.

The brains of anesthesized squirrel monkeys were exposed to 2.25 to 5 MHz ultrasound at low intensities (average power from 3 mW/cm2 to 0.9 W/cm2). The exposure produced evoked potentials recorded by EEG electrodes chronically implanted in the midline parietal region. Computer analysis of the waveforms showed that ultrasound produced a transient upward shift in both the peak frequency and in its amplitude. Complete adaptation occurred with 3 min of continuous exposure to either CW or pulsed irradiation.

Detection of disturbed autoregulation of the peripapillary choroid in primary open angle glaucoma.

BACKGROUND AND OBJECTIVE: This study is concerned with perfusion-pressure videoangiographic investigations, performed by combining oculo-oscillo-dynamography and videoangiography. Perfusion-pressure videoangiography permits an evaluation of local vascular resistance in the choroid relative to ciliary perfusion pressure. PATIENTS AND METHODS: Twelve healthy subjects, 21 patients with primary open angle glaucoma (POAG), and 27 patients with ocular hypertension were examined. RESULTS: Perfusion-pressure videoangiograms revealed that the peripapillary choroid (nasal main ciliary artery) filled at distinctly lower perfusion pressures than the paramacular region (temporal main ciliary artery) in all 12 healthy subjects, with a perfusion pressure difference of 12.5 +/- 4.9 mm Hg. In the 21 patients with POAG, the perfusion pressure difference between the beginning of peripapillary and paramacular perfusion was as small as 3.7 +/- 4.5 mm Hg. In the 27 patients with ocular hypertension, the perfusion pressure difference between the two circulatory regions was almost as high as in the healthy subjects. CONCLUSIONS: These examinations showed that (1) there exists efficient autoregulation in the peripapillary choroids of healthy subjects, (2) autoregulation is diminished or even absent in POAG, and (3) autoregulation is normal, increased, or slightly reduced in ocular hypertension.

Survival and revival times of the retina: ERG studies at total ocular ischemia in rabbits and cats.

Retinal survival and revival times were measured in cats and rabbits at controlled retinal temperatures. While the great difference between b-wave survival times in cats and rabbits was confirmed, the revival times were distinctly shorter (30 min) than those previously found.

Oculo-oscillo-dynamography: a diagnostic procedure for recording ocular pulses and measuring retinal and ciliary arterial blood pressures.

An objective noninvasive diagnostic procedure permitting continuous registration of ocular arterial pulsation and determination of retinal and ciliary arterial blood pressures is presented. Arterial pulsation of both eyes is recorded using two infrasound transducers which are connected pneumatically with suction cups placed temporally on the sclerae. By means of a suction pump the intraocular pressure (IOP) of both eyes can be raised artificially to desired values. It is thus possible to study the ocular pulse oscillogram at different IOP values and to determine retinal and ciliary arterial blood pressures without having to perform ophthalmoscopy. Results from first tests of the oculo-oscillo-dynamograph device and data obtained from 30 healthy persons are discussed.

[Oculo-oscillodynamography, a new procedure for the determination of ophthalmic artery blood pressure and ocular pulse curve analysis]. / Okulooszillodynamographie, ein neues Verfahren zur Bestimmung des Ophthalmikablutdruckes und zur okulären Pulskurvenanalyse.

OODG is a diagnostic method permitting assessment of ocular pulse curves and objective determination of blood pressures in the ophthalmic circulatory system (retinal and ciliary arterial blood pressures) simultaneously for both eyes, without dilatation of the pupils. Calibrated scleral suction cups pneumatically connected to a sensitive transducer are used to provide well reproducible ocular pulse recordings. The systolic retinal and ciliary arterial blood pressures and the diastolic ocular blood pressure are determined at artificially elevated IOPs from typical changes in the ocular pulse curves.

[Hemodynamic aspects of retinitis pigmentosa]. / Hämodynamische Aspekte bei der Retinopathia pigmentosa (RP).

While retinal vascular attenuation is a typical finding in retinitis pigmentosa (RP), studies on changes in choroidal vasculature have yielded contradictory results. In 44 patients with RP the relative pulse blood volumes were measured, and perfusion pressure videoangiography (PVA) was performed in 7 of them. Follow-up examinations were performed in 14 of the patients between 1.5 and 6 years later. The results show that the choroidal circulation is considerably reduced in RP patients; it was found to be further reduced at the follow-up examinations. PVA shows atrophy of the choroid capillary network. Characteristic changes occur not only in the retinal but also in the choroidal circulation, depending on the form, duration (stage) and prognosis of the disease.