[Contact lens dynamometry influences the systemic blood circulation: clinical significance]. / Die Kontaktglasdynamometrie beeinflusst den Systemkreislauf: Folgerungen für die Praxis.

BACKGROUND: The diastolic and systolic pressure in the ophthalmic artery (OAPdia, OAPsys) as well as the venous pulsation pressure (VPP) can be determined by contact lens dynamometry (CLD). With these parameters, carotid artery stenosis, ocular perfusion, e.g., in glaucoma patients and the cerebrospinal pressure can be examined indirectly. In the underlying study comparative data were collected and it was investigated to what extent CLD itself leads to changes of the systemic blood pressure. SUBJECTS/METHODS: In the course of a prospective trial CLD was performed in 162 eyes of 81 healthy volunteers (mean age 41.0 ± 17.3 years). VPP, OAPdia and OAPsys were measured. A mean was calculated from 5 single readings. Directly before and after CLD automated blood pressure measurements according to Riva-Rocci (RR) and the heart rate were obtained in both arms. RESULTS: In the entire group, the mean VPP was 21 ± 9 mmHg on the right side and 19 ± 8 mmHg on the left side. The mean OAPdia was 60 ± 14 mmHg on the right and 67 ± 14 mmHg on the left side. The mean OAPsys was 91 ± 17 and 101 ± 21 mmHg, respectively. The mean variation coefficient from 5 single readings was 13/16 % for VPP (right/left), 7.4/8.2 % for OAPdia and 6.2/6.2 % for OAPsys. The difference between right and left eyes concerning OAPdia and OAPsys was statistically significant (Wilcoxon test; p < 0.001). VPP and OAPsys were not correlated with age, OAPdia showed a weak correlation with age on the right side (Spearman R = 0.23; p = 0.03). Blood pressure (RR) dropped from a mean 137/84 to 135/82 mmHg in the right arm and from 135/84 to 132/83 mmHg in the left arm. The change of the diastolic values of the right side and of the systolic values of the left side reached statistical significance (p < 0.05). The difference of the systolic blood pressure and the heart rate before and after CLD were weakly correlated (Spearman R = - 0.28; p = 0.01). The extent of the systemic blood pressure drop was not correlated with the maximum force affecting the globe. CONCLUSIONS: The slightly lower blood pressure after CLD could be related to the oculocardiac reflex. This has to be confirmed in further trials with continuous blood pressure determination. In agreement with literature reports, significant differences between right and left eyes were found regarding OAPdia and OAPsys.

Ophthalmodynamometry for ICP prediction and pilot test on Mt. Everest.

BACKGROUND: A recent development in non-invasive techniques to predict intracranial pressure (ICP) termed venous ophthalmodynamometry (vODM) has made measurements in absolute units possible. However, there has been little progress to show utility in the clinic or field. One important application would be to predict changes in actual ICP during adaptive responses to physiologic stress such as hypoxia. A causal relationship between raised intracranial pressure and acute mountain sickness (AMS) is suspected. Several MRI studies report that modest physiologic increases in cerebral volume, from swelling, normally accompany subacute ascent to simulated high altitudes. OBJECTIVES: 1) Validate and calibrate an advanced, portable vODM instrument on intensive patients with raised intracranial pressure and 2) make pilot, non-invasive ICP estimations of normal subjects at increasing altitudes. METHODS: The vODM was calibrated against actual ICP in 12 neurosurgical patients, most affected with acute hydrocephalus and monitored using ventriculostomy/pressure transducers. The operator was blinded to the transducer read-out. A clinical field test was then conducted on a variable data set of 42 volunteer trekkers and climbers scaling Mt. Everest, Nepal. Mean ICPs were estimated at several altitudes on the ascent both across and within subjects. RESULTS: Portable vODM measurements increased directly and linearly with ICP resulting in good predictability (r = 0.85). We also found that estimated ICP increases normally with altitude (10 ± 3 mm Hg; sea level to 20 ± 2 mm Hg; 6553 m) and that AMS symptoms did not correlate with raised ICP. CONCLUSION: vODM technology has potential to reliably estimate absolute ICP and is portable. Physiologic increases in ICP and mild-mod AMS are separate responses to high altitude, possibly reflecting swelling and vasoactive instability, respectively.

Contact lens dynamometry: the influence of age.

PURPOSE: To examine the influence of age on systolic (systOAP) and diastolic (diastOAP) blood pressure in the ophthalmic artery (OA) measured by a new contact lens dynamometer (CLD). METHODS: In a prospective cross-sectional clinical trial, 106 eyes of 106 patients (58 women, 48 men) were examined. A nearly uniform age distribution was achieved by recruiting subjects in seven age groups, with at least 12 in each decade. Blood pressure in the OA was measured with a new CLD. Arterial blood pressure at the upper arm was measured by cuff, according to the Riva-Rocci (RR) METHOD: Main outcome measures were: SystOAP and diastOAP in the OA and systolic (systRR) and diastolic (diastRR) pressures in the subclavian artery. RESULTS: The blood pressures showed the following linear regression equations in association with age: systRR (mm Hg) = 115 + 0.45 × age (years) (R = 0.50; P < 0.00001); diastRR (mm Hg) = 72 + 0.28 × age (years) (R = 0.42; P < 0.00001); systOAP (mm Hg) = 61 + 0.93 × age (years) (R = 0.74; P < 0.0001); and diastOAP (mm Hg) = 44 + 0.37 × age (years) (R = 0.57; P < 0.0001). CONCLUSIONS: The relative slopes of the regression lines relating age to diastolic and systolic pressures are steeper in the ophthalmic than in the subclavian artery, indicating that the pressures in the ophthalmic artery increase faster with age than do the associated pressures in the subclavian artery, as measured by the standard sphygmomanometry. This phenomenon may be explained by progressive stiffening of the walls in the carotid and ophthalmic arteries. The effect of age should be taken into account whenever interpreting ophthalmodynamometric measurements for clinical diagnostic purposes.

Ophthalmodynamometric diagnosis of unilateral ischemic ophthalmopathy.

PURPOSE: To describe a patient presenting with typical signs of vascular occlusive retinopathy. DESIGN: Observational case report. METHODS: A 65-year-old man experienced painless unilateral loss of vision to 4/20 in his left eye. Ophthalmoscopy of the left eye showed pronounced attenuation of the retinal arterioles, ischemic retinal edema, and a few intraretinal hemorrhages. Fluorescein angiography revealed a diffusely reduced retinal perfusion typical of retinal occlusive disease. Using a new ophthalmodynamometer with a pressure sensor at the mounting support of a conventional Goldmann contact lens, we additionally measured the diastolic central retinal artery collapse pressure. RESULTS: The diastolic central retinal artery collapse pressure was significantly lower in the left eye than in the right eye (14.7 +/- 2.4 relative units vs 51.7 +/- 4.3 relative units; P <.001). Both values were significantly (P =.03) lower than those in a control group (80.9 +/- 6.9 relative units). Doppler sonography revealed a total occlusion of the left carotid artery and a nonrelevant stenosis of the right carotid artery. CONCLUSIONS: A new ophthalmodynamometric device consisting of a pressure sensor at the mounting support of a Goldmann contact lens was helpful in detecting carotid artery occlusion leading to ischemic ophthalmopathy.

Intracranial pressure in microgravity conditions: non-invasive assessment by ophthalmodynamometry.

BACKGROUND: As well known from former manned spaceflight experiments (German D2-Mission/German D1-Mission 1985/German-Russian MIR-Mission 1 992/German-D2-Mission 1993), fluid shift after entry into microgravity leads to a rapid increase in pressure and volume within the upper compartments of the human body. This has been proven by precise measurements with automatic selftonometers for intraocular pressure. HYPOTHESIS: There is little doubt, that a very similar--even more, marked--increase of intracranial pressure happens soon after entry into microgravity. This may be the cause for some of the reported hormonal and even neurological changes in metabolism. There is no non-invasive method to assess these important increases in pressure. METHODS: Ophthalmodynamometry in general allows for rather precise estimation of intracranial BP, but so far the method was too complicated for routine application, specifically in spaceflight conditions. Therefore, using the microprocessor controlled technology of our automatic selftonometer we have designed a very precise automatic instrument which can be applied by the astronaut/kosmonaut. The measurement takes only a few seconds. CONCLUSIONS: This easily applied, non-invasive method would allow for completely new insights into these important changes and explain some of the clinical consequences noted so far.

[Contact glass tonometer]. / Das Kontaktglastonometer.

BACKGROUND: This paper presents a tonometer built into a contactlens, which allows to measure the eye-pressure and to perform ophthalmoscopy at the same time. Artificially induced changes of the eye-pressure and their influence on the visible fundus can now be checked simultaneously. The contactlens-tonometer (CGT) also is able to record continuously the pulse-curve, which can indicate any circulatory problem. So, the device is expected to give us additional diagnostic criteria of early glaucoma. Each ophthalmologyst in the field will be able to perform with this device a oculodynamometry in an easy way. By this it is possible to estimate the pressure-tolerance of the optic disk from glaucoma-patients. MEASUREMENTS: There have been taken some measurements on enucleated human eyes, comparing our device with a Statham-transducer in the vitreous. We found a good correlation. In a second step, we made measurements (65) on healthy volunteers, comparing the device with Perkins-Tonometry. RESULTS AND CONCLUSIONS: We found a correlation (R = 0.58). The error of the measurements was about +/- 3 mm Hg. Considering both, the deviation of the Perkins-Tonometer with which our results were compared, and the fact of a good correlation (R = 0.999) in the study with the enucleated human eyes, we found that the contact-lens-tonometer measures the intraocular pressure exactly. In future studies, we want to analyze the dynamic component of the measurements.

[Wound stability of the "no-stitch" technique in various incision sites and depths]. / Wundstabilität der "No-stitch"-Technik bei verschiedener Schnittlokalisation und -tiefe.

BACKGROUND: Supported by experiments on cadaver eyes the no-stitch technique seems to possess higher wound strength. Until now there have been no clinical trials addressing this subject. This prompted us to investigate the wound strength with varying incision depth and incision site in a prospective randomized and controlled clinical trial. METHODS: For this study 162 patients with a 7-mm tunnel incision were recruited. They were divided into the following subgroups: Primary incision depth of 300 microns versus 500 microns, limbal incision versus scleral incision, scleral incision in 12 h position versus temporal scleral incision, limbal incision in 12-h position versus temporal limbal incision. The wound strength was measured by an ophthalmodynamometer on the first postoperative day and after 1 week at the site with the least mechanical stability adjacent and posteriorly to the primary incision. RESULTS: On the first day after surgery the wound strength was best in the temporal scleral incision with an ophthalmodynamometer reading of 37.6 +/- 4.1 kPa and it was the least in the 12-h limbal incision with an ophthalmodynamometer reading of 21.8 +/- 5.4 kPa. After 1 week also the wound strength was best in the temporal scleral incision with 38.4 +/- 2.1 kPa and it was the least in 12-h limbal incision with 30.9 +/- 7.5 kPa. CONCLUSIONS: These findings demonstrate that the site of the primary incision is a very important factor in determining the mechanical wound strength concerning resistance against external pressure. The wound strength was best in the temporal scleral incision.

[A new device for measuring blood pressure in the ophthalmic artery: automated vacuum ophthalmodynamometer]. / Novyi pribor dlia izmereniia davleniia krovi v glaznichnoi arterii--avtomatizirovannyi vakuumnyi oftal'modinamometr.

A new vacuum ophthalmodynamometer is suggested. When measuring the orbital artery pressure, ophthalmic tone elevation is achieved via creating vacuum in suction cup located on the sclera. Changes in the design helped improve the accuracy of measurements and their safety, as against the known analogs. Vacuum ophthalmodynamometer may be used to activate the routes of intraocular fluid discharge after fistulization surgery, preoperative reduction of intraocular pressure, vacuum compression test carried out to diagnose glaucoma.

[Relation of negative pressure difference and artificially elevated intraocular pressure using the suction cup method]. / Die Beziehung zwischen negativer Druckdifferenz und künstlich erhöhtem Augeninnendruck bei der Saugnapfmethode.

This paper presents regressions and the range of scatter of measured values for current standard ophthalmologic suction cups for the first time. The scatter range is similar to that of blood pressure measurements made by the Riva-Rocci method. Using the regressions presented here it is possible to deduce the increase in pressure from the negative pressure difference in the suction cup; this can be done with sufficient accuracy and the amount of time required is acceptable.

[Automatic biometry and keratometry in comparison with the manual technic]. / Automatische Biometrie und Keratometrie im Vergleich zur manuellen Technik.

In order to determine the power of intraocular lenses more easily prior to cataract surgery, we compared the results obtained by automatic measurement of the corneal refractive power by the Humphrey Autokeratometer with manually obtained measurements using the Zeiss ophthalmometer. Similarly, the axial length was determined by automatic measurements using the Digital B System IV (Cooper Vision) and manual measurements using the Ophthascan S (Biophysic Medical). Statistical evaluation showed that there were no significant differences in the corneal refractive power determined by the two methods or in the IOL power calculated using the SRK formula. Therefore, automatic measurement of both corneal refractive power and axial length following the above method can be a useful alternative to the preoperative determination of the IOL power.

[Ocular hemodynamics following suction cup oculopression]. / Okuläre Hämodynamik nach Saugnapfokulopression.

In the study reported here the authors investigated the influence on ocular perfusion pressures of suction-cup oculopression, a procedure which permits oculopression without orbital compression. Patients over 50 years of age were examined before cataract extraction. Ulrich's method of ocular oscillodynamography was used to determine ocular perfusion pressures. A Mikuni and Yoneyama suction-cup dynamometer was applied for suction-cup oculopression. Ocular hypotonia following suction-cup oculopression was adequate and comparable to that achieved by other oculopression methods. After oculopression a significant increase in ocular perfusion pressures (retinal, ciliary, and diastolic) was found. However, ocular blood pressure remains constant after oculopression. Moreover, the increase in ocular perfusion pressure could not be explained by oculocardiac reflexes, because there was no change in systemic arterial blood pressure. It must be assumed, therefore, that the increase in ocular perfusion pressures is caused by a lowering of resistance, i.e., a drop in intraocular pressure.

[Ulrich and Ulrich oculo-oscillodynamography: results in patients with healthy eyes]. / Okulo-Oszillo-Dynamographie nach Ulrich und Ulrich: Ergebnisse bei Augengesunden.

Ulrich and Ulrich's method of oculo-oscillodynamography (OODG) is a relatively new method which enables the systolic retinal, systolic ciliary, and systolic ocular perfusion pressure or respectively blood pressure to be measured. The results obtained by the present authors are in good agreement with those of Ulrich and Ulrich (n = 30). The intraocular pressure values obtained with this method correlate somewhat less well with the systemic blood pressure than is the case with suction cup ophthalmodynamometry. However, the correlation coefficients are sufficiently high to permit their application in ophthalmological diagnosis. The results presented here indicate that the diastolic ocular pressure should be determined by applying the formoscillatory criterion. The positive intercept in the regression equations can be explained by the assumption that the regression is curvilinear at systemic blood pressure values which are generally not encountered in humans in whom OODG is of diagnostic importance. It is suggested that the linear regression is a sufficiently exact model at the systemic blood pressures most frequently measured. Normal OODG values can be read off easily from the diagrams published here.

[Assessment of aqueous humor dynamics with Ulrich oculopressure tonometry]. / Beurteilung der Kammerwasserdynamik mit der Okulopressionstonometrie nach Ulrich.

Oculopression tonometry according to Ulrich can be used for the judgement of the facility of outflow like the tonography according to Grant. As shown by us for the first time, oculopression tonometry can also serve to evaluate aqueous humor formation. The results of a planned prospective study in 30 glaucoma patients and in 30 healthy volunteers are shown. It can be concluded that the recovery time of the intraocular pressure seems to be a better criterion for the diagnosis of glaucoma than the intraocular pressure measured immediately after the artificial pressure enhancement.

Experiences with a new procedure for the measurement of the ophthalmic artery pressure: ophthalmomanometry-Doppler.

A novel, noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction, called ophthalmomanometry-Doppler, is presented. This technique uses a device consisting of a chamber with an apperture hermetically adaptable to the orbital borders. The chamber is equipped with a Doppler probe and an arrival pipe for compressed air connected to a manometer. The OAP measurement procedure consists of applying a pressure in the chamber while the Doppler probe detects periorbital Doppler signals. The systolic OAP corresponds to the Doppler signal disappearance during chamber pressure increase. Studies performed on normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the ophthalmomanometry-Doppler device were highly correlated with simultaneous ipsilateral intra-arterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.85, n = 40). The ophthalmic pressure index (OAP/ICP and OAP/BAP ratio, respectively) ranged from 0.60-0.77 with a mean (+/- SD) of 0.68 (+/- 0.04) in the 50 normal subjects. Preliminary clinical trials show diminished OAP/BAP ratios in patients with occlusive carotid disease ipsilateral to hemodynamically significant lesions. The values obtained on these normal subjects provide baseline data for further investigation of pathologic conditions. This new procedure is simple, convenient, rapid, and safe and provides reproducible information on both OAP and flow parameters, which are important indices in the evaluation of severe carotid artery disease.

[Ocular hemodynamics in central and branch artery occlusions]. / Okuläre Hämodynamik bei Zentral- und Astarterienverschlüssen.

Ocular oscillodynamograms (OODG) were made in 9 patients with an occlusion of the central artery and 11 patients with an occlusion of one branch artery. While there were no pathologic findings in patients with branch artery occlusions, it was not possible to record any systolic-retinal oscillations of the pulse in patients with an occlusion of the central artery. In three cases the systolic ciliary perfusion pressure was also low owing to carotid stenosis.

[Ulrich oculo-oscillodynamography: initial results in carotid stenoses]. / Okulo-Oszillo-Dynamographie nach Ulrich: Erste Ergebnisse bei Carotisstenosen.

Oculo-oscillodynamography (OODG) after Ulrich was performed in 11 patients suffering from a monolateral, hemodynamically relevant carotid stenosis identified by Doppler sonography. All of the pressure parameters which can be measured by OODG--systolic retinal, systolic ciliary, and diastolic ocular perfusion pressure--were low on the side concerned. In contrast to the already-established methods of measuring ocular perfusion--ophthalmodynamometry and ophthalmodynamography after Hager--the advantages of OODG are that it not only enables the systolic retinal pressure to be differentiated from the systolic ciliary or diastolic ocular perfusion pressure, but also permits the results of the investigation to be illustrated graphically, so that objective evaluation is possible.

A simple technique for Doppler ophthalmodynamometry.

A novel method to assess carotid and intraocular blood flow and pulse pressures is presented. This procedure can be performed by personnel not trained in ophthalmoscopy, and is valid in eyes with opaque media. It is noninvasive, requires no elaborate equipment, and may be useful as an adjunct to ophthalmodynamometry.