Establishing the Calibration Curve of a Compressive Ophthalmodynamometry Device

The relationship between externally applied force and intraocular pressure was determined using an ex-vivo porcine eye model (N=9). Eyes were indented through the sclera with a convex ophthalmodynamometry head (ODM). Intraocular pressure and ophthalmodynamometric force were simultaneously recorded to establish a calibration curve of this indenter head. A calibration coefficient of 0.140 ± 0.009 mmHg/mN was established and was shown to be highly linear (r = 0.998 ± 0.002). Repeat application of ODM resulted in a 0.010 ± 0.002 mmHg/mN increase to the calibration coefficient.Clinical Relevance- ODM has been highlighted as a potential method of non-invasively estimating intracranial pressure. This study provides relevant data for the practical performance of ODM with similar compressive devices.

Central retinal artery and vein collapse pressure in giant cell arteritis versus nonarteritic anterior ischaemic optic neuropathy

Arteritic anterior ischaemic optic neuropathy and nonarteritic anterior ischaemic optic neuropathy are acute optic neuropathies, which have to be differentiated from each other. It was the purpose of this study to assess whether ophthalmodynamometry with an assessment of the collapse pressure of the central retinal artery (CRA) and vein (CRV) is helpful for that. Using a Goldmann contact lens-associated ophthalmodynamometer, the diastolic collapse pressure of the CRA and CRV were measured in six patients (eight eyes) with giant cell arteritis-induced anterior ischaemic optic neuropathy (GC-AION) and in 10 patients (12 eyes) with acute non-arteritic anterior ischaemic optic neuropathy (NAION). CRA collapse pressure was significantly (P=0.001; 95% confidence interval (CI): -68.7, -20.0) lower in the GC-AION group (52.7+/-24.6 arbitrary units) than in the NAION group (97.0+/-25.8 arbitrary units). CRV collapse pressure did not vary significantly (P=0.47). As measured by ophthalmodynamometry, CRA pressure is significantly lower in GC-AION than in NAION. CRV pressure does not vary markedly. These finding may be helpful for the clinical differentiation between GC-AION and NAION, and may give hints for the pathogenesis.

Ophthalmodynamometric differences between ischemic vs nonischemic retinal vein occlusion

PURPOSE

To estimate the central retinal vein pressure in patients with ischemic vs nonischemic central retinal vein occlusion (CRVO).

DESIGN

Prospective clinical observational comparative study.

METHODS

The study included 28 patients with CRVO, either of the ischemic type (n = 7) or the nonischemic type (n = 21). The control group consisted of 38 subjects without retinal disease. A new ophthalmodynamometer consisting of a Goldmann contact lens fitted with a pressure sensor into the holding grip of the contact lens, was used to indirectly estimate the central retinal artery and vein pressure.

RESULTS

Central retinal vein pressure was significantly higher in the ischemic CRVO group than in the nonischemic CRVO group (91.5 +/- 30.1 arbitrary units vs 52.4 +/- 32.5 arbitrary units; P = .014), in which it was significantly (P < .001) higher than in the control group (4.8 +/- 8.1 arbitrary units). Central retinal vein pressure was higher than the diastolic central retinal artery pressure significantly (P = .039) more frequently in the ischemic CRVO group (7/7 or 100%) than in the nonischemic CRVO group (8/21 or 38%) or the control group (0/38; P < .001). Central retinal artery pressure was significantly (P = .017) lower in the ischemic CRVO group (46.0 +/- 10.6 arbitrary units) than in the nonischemic CRVO group (64.5 +/- 22.8 arbitrary units), in which it was significantly (P = .016) lower than in the control group (79.9 +/- 22.3 arbitrary units).

CONCLUSIONS

Ophthalmodynamometric estimation of the retinal vein pressure may be helpful for the differentiation between the ischemic vs nonischemic type of CRVO. In the ischemic type, vein pulsations were usually observed at supradiastolic arterial values.

[Non-invasive determination of intracranial pressure. Physiological basis and practical procedure]

It has been shown in some recently published papers that the intracranial pressure can be determined by dynamometric measurement of the outflow pressure of the central retinal vein (VOP). The knowledge gained by the basic experiments of Baurmann in 1925 has been forgotten by the ophthalmic community for many years. In this paper the basic phenomena of venous collapse are outlined which are fundamentally different from the biomechanics of the arterial collapse phenomenon observed by ophthalmodynamometry. A practical guideline is given for the dynamometric measurement of venous outflow pressure which equals the intracranial pressure. Performing dynamometry of the central retinal vein enables the ophthalmologist to determine intracranial pressure in a non-invasive way.

Central retinal artery and vein collapse pressure in eyes with chronic open angle glaucoma

AIMS

To determine central retinal vessel collapse pressure in chronic open angle glaucoma.

METHODS

For 19 eyes with chronic open angle glaucoma and 27 eyes of a control group, central retinal vessel collapse pressure was measured by a Goldmann contact lens fitted with a pressure sensor in its holding grip.

RESULTS

Central retinal vein collapse pressure was significantly (p=0.001) higher in the glaucoma group than in the control group (26.1 (SD 26.4) relative units versus 6.1 (8.4) relative units).

CONCLUSIONS

Measured by a new ophthalmodynamometer, central retinal vein collapse pressure measurements may be abnormally high in eyes with chronic open angle glaucoma.

Ophthalmodynamometric assessment of the central retinal vein collapse pressure in eyes with retinal vein stasis or occlusion

PURPOSE

Using a new Goldmann contact lens associated ophthalmodynamometric device, it was the purpose of the present study to determine the central retinal vein collapse pressure in eyes with retinal vein occlusions or retinal venous stasis.

METHODS

The prospective clinical non-interventional comparative study included 19 patients with central retinal vein occlusion ( n=8), branch retinal vein occlusion (n=4), or retinal venous stasis (n=7) and 42 subjects of a control group. With topical anesthesia, a Goldmann contact lens fitted with a pressure sensor was put onto the cornea. Pressure was exerted on the globe by pressing the contact lens, and the pressure value at the time when the central retinal vein started pulsating was noted.

RESULTS

Central retinal vein collapse pressure measured 103.6+/-25.4 arbitrary units (AU) in eyes with central retinal vein occlusion what was significantly higher than in the eyes with retinal venous stasis (58.1+/-37.5 AU; p=0.02) and the eyes with branch retinal vein occlusion (43.8+/-25.5 AU; p=0.004). In the latter two groups, the measurements of the central retinal vein collapse pressure were significantly (p<0.001) higher than the measurements in the eyes of the control group (4.2+/-7.8 AU).

CONCLUSION

As measured by a new ophthalmodynamometer with direct biomicroscopic visualization of the central retinal vessels during examination, central retinal vein collapse pressure is significantly higher in eyes with central retinal vein occlusion, followed by eyes with branch retinal vein occlusion, eyes with retinal venous stasis and, finally, normal eyes. These findings may have diagnostic and therapeutic implications.

Reproducibility of ophthalmodynamometric measurements of central retinal artery and vein collapse pressure

BACKGROUND

To assess the reproducibility of ophthalmodynamometric measurements using a new, Goldmann contact lens associated, device allowing biomicroscopic visualisation of the optic disc.

METHODS

The prospective clinical study included 87 eyes of 58 subjects presenting with a normal fundus (n=40), or ocular diseases (n=47). With topical anaesthesia, a Goldmann contact lens, fitted with a pressure sensor mounted into the holding ring of the contact lens, was placed onto the cornea. Pressure was applied onto the globe through the contact lens, and the pressure values obtained when the central retinal vessels started pulsating were noted. The measurements were performed 10 times.

RESULTS

The mean coefficients of variation for redeterminations of the collapse pressure of the central retinal vein and artery were 16.3% (SD 11.4%), and 8.5% (4.1%), respectively.

CONCLUSIONS

A simple and new, Goldmann contact lens associated, ophthalmodynamometer allows central retinal artery and vein collapse pressure measurements which are reproducible in a clinical setting.

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.

Ophthalmodynamometry: a reliable method for measuring intracranial pressure

Under physiological conditions, the pressure in the central retinal vein is equal to or higher than the intracranial pressure (ICP) because the cerebrospinal fluid (CSF) passes the sheath of the optic nerve before draining into the cavernous sinus. The optic nerve sheath is where the ICP affects the retinal venous pressure. Ophthalmodynamometry (ODM) is a useful method for determining the central retinal artery pressure. While papilledema and a lack of venous pulsations are commonly used as a vague indication of the ICP, ODM may be advantageous for determining the pressure in the central retinal vein. Until now, however, the venous pressure has never been compared with the intracranial pressure. In the present study, the pressure in the central retinal vein was recorded in 31 patients while the ICP was simultaneously being recorded for various reasons. The results demonstrate a linear correlation (r = 0.968) between the pressure in the central retinal vein and the ICP. This correlation is of great practical value since until now, reliable intracranial pressure monitoring has only been possible by invasive means, by placing a probe either in the brain parenchyma or the ventricle. Ophthalmodynamometry is useful for momentary assessment of the ICP, can easily be repeated, and may be used whenever an elevated ICP is suspected in hydrocephalus, brain tumors and after head injury. However, it is not suitable for continuous ICP monitoring.

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.

Ophthalmodynamometry and corticosteroids in central retinal vein occlusion

PURPOSE

This is the first report of the monitoring of the clinical progress of a central retinal vein occlusion by measuring the retinal venous collapse pressure using ophthalmodynamometry.

METHOD

A 38-year-old woman with a nonischaemic central retinal vein occlusion received systemic prednisone. The dose of prednisone was increased and decreased both abruptly and gradually. The response was monitored by weekly measurements of visual acuity, retinal appearance and retinal venous collapse pressure. The retinal appearance was assessed by comparison of repeated stereo colour photographs and fluorescein angiographs. Retinal venous collapse pressure was estimated by taking the mean of four or more ophthalmodynamometric measurements.

RESULTS

An inverse relationship between the ophthalmodynamometric retinal venous collapse pressure and systemic prednisone dosage was observed. The visual acuity and retinal appearance remained unchanged throughout the follow-up.

CONCLUSIONS

Ophthalmodynamometry in this case was a useful method of quantitatively monitoring the response of central retinal vein occlusion to systemic prednisone. The response would not have been detected if only visual acuity and retinal appearance were used to monitor the progress.

Comparison of noninvasive methods to derive the mean central retinal artery pressure in man

PURPOSE

The pressure within the ophthalmic artery can be estimated by several noninvasive procedures based on measurements of the pressure either within the central retinal artery (CRA) or the brachial artery. In this study we compared 5 methods of deriving the mean pressure within the ophthalmic artery in 10 healthy volunteers 21 to 31 years of age.

METHODS

The pressure within the ophthalmic artery was calculated from estimates of the systolic and diastolic pressures within the CRA derived by suction ophthalmodynamometry (s-ODM), compression ophthalmodynamometry (c-ODM), interpolation from scleral compression/intraocular pressure (IOP) conversion tables, and measurements of the brachial blood pressure (BP).

RESULTS

Group average CRA pressure values varied significantly across techniques, with the largest difference among methods being about 15 mm Hg. CRA pressures derived by s-ODM or c-ODM and direct measurements of the IOP yielded statistically identical values. These latter values were significantly lower than CRA pressures estimated by either scleral compression/IOP conversion tables, or those predicted from brachial BP measurements with the arm held up alongside the head, both of which produced equivalent values. The highest estimates of CRA pressures were obtained when brachial BP values were derived with the arm in its normal anatomical position.

CONCLUSION

The patency of the vascular network to the eye and subsequent perfusion of intraocular neural tissue essential to normal visual function can be evaluated by simple clinical procedures. Although all techniques to estimate the pressure in the ophthalmic artery are relatively simple to use, they do not all yield the same absolute values and consequently should be interpreted in this light when used for either clinical or research purposes.

Biomechanics of ocular pneumoplethysmography

A mathematical analysis of ocular pneumoplethysmography is presented, based on the physiological, anatomical, and biomechanical properties of the eye. Ocular pneumoplethysmography is a clinical procedure involving elevation of intraocular pressure, by application of a suction cup to the sclera, to a level that exceeds ophthalmic artery systolic pressure. As decay in intraocular pressure is allowed, return of retinal artery pulsations indicates ophthalmic artery systolic pressure. We obtain a quantitative relationship between increase in intraocular pressure and applied vacuum, and compare the theoretical predictions with experiments on rabbits in which a variable descending vacuum was applied to bilateral scleral eyecups. The bilateral intraocular pressures were simultaneously recorded from cannulae in the respective vitreous bodies, and the pressures at which return of ocular pulsations were observed were correlated with the scleral vacuums. Regression lines were calculated for three serial determinations in each animal, with two groups of animals distinguished by the inner diameter of the eyecups used. The theoretical results indicate that the relationship between intraocular pressure increase and applied vacuum is independent of Young's modulus, and depends primarily on the ratio of the diameter of the vacuum cup to the diameter of the eye.

Differential effects of compression and suction ophthalmodynamometry on the scotopic blue-flash electroretinogram

Several studies have investigated the effect of elevated intraocular pressure with reduced ocular perfusion pressure on visual neural function by means of compression and suction ophthalmodynamometry. We compared the effects of nominally equivalent reductions in the ocular perfusion pressure induced by compression and suction ophthalmodynamometry retinal function as measured by flash electroretinography. Scotopic blue-flash electroretinograms were recorded in five subjects for baseline conditions; during a 40% reduction in the ocular perfusion pressure effected in a first test session by compression ophthalmodynamometry; and then in a second test session some 4 hours later by suction ophthalmodynamometry. Fifteen consecutive electroretinographic sets were recorded during scleral compression or suction, and also after compression or suction was removed. Compression and suction ophthalmodynamometry decreased the electroretinogram b-wave to different degrees; overall, the electroretinogram was attenuated more by compression than by suction ophthalmodynamometry. In the recovery phase, the group averaged b-wave quickly increased to exceed baseline after both scleral compression and suction. The trends for prolonged implicit times over the duration of the study were similar for compression and suction ophthalmodynamometry.

[Ulrich oculo-oscillodynamography in carotid artery stenosis and temporal arteritis]

Oculo-oscillodynamography (OODG) after Ulrich was performed on 21 patients suffering from unilateral hemodynamically relevant carotid stenosis. In ten patients the perfusion pressure was low on the affected side. In the other eleven patients there was no difference between the two sides and these patients were thought to have well-developed collateral anastomoses. In nine patients with temporal arteriitis low perfusion pressure was found by OODG on the side with the lower visual acuity. After systemic therapy with corticosteroids the perfusion pressure normalized on both sides.

Ocular pneumoplethysmography and ophthalmodynamometry in the diagnosis of central retinal artery occlusion

Ocular pneumoplethysmography and ophthalmodynamometry measure ophthalmic arterial system pressures to assess noninvasively the hemodynamics of the carotid system. A previously unreported circumstance in which these tests complement one another is central retinal artery occlusion. Typically, the ipsilateral retinal artery pressure, measured by ophthalmodynamometry, is greatly decreased or is zero, whereas the ophthalmic systolic pressure, measured by ocular pneumoplethysmography, is normal.

[Noninvasive diagnosis of occlusive processes of the brachiocephalic arteries: Doppler sonography compared to ophthalmodynamometry and ophthalmodynamography]

97 patients with suspected cerebrovascular disease were examined using ophthalmodynamometry/ophthalmodynamography and dopplersonography. In 49 of the patients we found haemodynamic changes typical of brachio-cephalic artery occlusion processes. In 36 patients angiography was performed either as a preparation for vascular surgery or for further clarification. Ophthalmodynamometry/ophthalmodynamography examination yielded diagnosis in 87%, dopplersonography and combined use of ophthalmodynamometry/ophthalmodynamography and dopplersonography in 94% of the brachio-cephalic artery occlusion processes.

Clinical-angiographic correlation of ophthalmodynamometry in suspected carotid artery disease. Prospective study

A prospective, clinical study of patients with suspected carotid artery disease compared the accuracy of compression and suction ophthalmodynamometry (ODM) with carotid artery stenosis determined by arteriography. Results were analyzed with respect to current criteria for classification and determination of "substantial" carotid artery disease. The best correlation for both procedures with arteriography was a ratio of the corrected intraocular pressure to the systolic brachial pressure. Both suction and compression ODM findings are equally accurate, with levels approaching 80%; however, neither test is sensitive enough to be used alone as a screening technique. Arteriography remains the best procedure for the determination of carotid artery disease.

Indirect ophthalmodynamometry: its comparison with direct ophthalmodynamometry in the detection of carotid artery occlusive disease

A comparison of results obtained by direct and indirect methods of ophthalmodynamometry on nine patients indicates that the indirect method provides dependable results. In some eyes, only the indirect method is possible. As with direct ophthalmodynamometry, a difference of 20% or greater between the two eyes suggests carotid insufficiency on the side of the eye with the lower pressure.

[Limits and possibilities of ophthalmodynamometry and ophthalmodynamography in the diagnosis of carotid occlusion (author's transl)]

In 67 patients suspected to suffer from cerebral vascular disorders or arterial occlusive disease results of ophthalmodynamometry and ophthalmodynamography were compared with those of carotid angiography. Especially in patients with angiographically substantiated carotid stenosis the results of ODM and ODG were extraordinarily poor. The findings of ODM and ODG proved to be non indicative in 29 out of 35 cases. The authors discuss the possible reasons of these disappointing results.

Measurement of dynamic stereoacuity and global stereopsis

Quantification of global stereopsis in addition to stereoacuity has been achieved by using dynamic random dot test patterns generated by inexpensive computer controlled integrated electronics. A pilot study revealed marked differences between the responses of a variety of clinically defective and normal subjects.

Ophthalmodynamometry. The technique, and its use in the detection of carotid artery occlusive disease

Carotid artery insufficiency is a major cause of cerebral stroke today. Ophthalmodynamometry is a procedure which measures the relative ophthalmic artery pressures between the two eyes, and is an important instrument in the detection of carotid artery insufficiency. The procedure for performing ophthalmodynamometry is detailed, and the significance of these findings is discussed. Specific indications for performing ophthalmodynamometry are presented. Finally, several complementary tests are discussed for the evaluation of patients with suspected carotid problems.

Experience with a noninvasive evaluation for cerebral vascular disease

This report describes a newly developed noninvasive method for extracranial cerebrovascular evaluation. Two hundred consecutive cases were studied at the Massachusetts General Hospital and matched with clinical and angiographic findings. There were three false negative and five false positive results. Two ulcerated plaques without stenosis were not detected. Management routes for different groups of patients with central nervous system symptoms are outlined. We emphasize the usefulness of monitoring postoperative ophthalmic artery pressure to aid in the early detection of carotid occlusion in patients developing neurologic symptoms following carotid endarterectomy.

Comparative evaluation of current ophthalmodynamometers

Seventy-five patients under 40 years of age with no history of ocular, cardiovascular, or cerebrovascular disease were examined with four commonly used ophthalmodynamometers. There was a significant difference in the absolute values measured with each instrument and the ophthalmic to brachial artery pressure ratio. The standard deviations were comparable between 8.1 and 10.2%. The absolute value of the average percent difference between the right and the left eye ranged from 3.6% with the Galin unit to 6.7% with the Sisler unit. Limits of +/- 15% for ophthalmic artery to brachial artery pressure ratio and 10% for right to left pressure difference should be used for 95% confidence levels. There was a small but definite correlation between the ocular coefficient of rigidity and pressure differences between direct and indirect instruments.

[Comparative ophthalmo-dynamographic and doppler-sonographic examinations (author's transl)]

The significance of directional Ultrasound-Doppler-Sonography with measurements at the fronto-medial and fronto-lateral arteries for the presence of a haemodynamically effective stenosis of the internal carotid artery between the bifurcation and the origin of the ophthalmic artery tells us more than Infratone-ophthalmodynamography (Hager). This paper compares results in a neurological practice obtained during a period of 2 years, from which some cases in the publication complete with the curves obtained are presented.

Slit lamp ophthalmodynamometry

A short clinical trial of the 'Dynoptor' Slit Lamp Ophthalmodynamometer has shown it to be a practical instrument. A mean O.A.P. of 52.3 mm/hg has been recorded.

[Ear to retina time and ophthalmodynamometry after ligation of the common carotid artery in rabbits (author's transl)]

Unilateral ligation of the common carotid artery was performed in rabbits. Before ligation, immediately thereafter, and 6 weeks later the ophthalmic artery pressure was determined and at the same time a synchronous measurement of the ear to retina time was done on both sides. The results were statistically analyzed (Tables 1-4). Ligation of the right common carotid artery resulted in a highly significant difference in systolic ophthalmic artery pressure between the two eyes of 16.4 mm Hg, and in diastolic pressure one of 13.0 mm Hg. After ligation of the left similar pressure differences of (systolic) 17.8 mm Hg and (diastolic) 15.2 mm Hg were shown. During the following 6 weeks these differences decreased considerably, to 41.5% and 29.2% after ligation on the right and to 33.5% and 36.6% after ligation on the left. The ear to retina time was markedly prolonged on the side of the ligation. This resulted in a highly significant side difference of 0.42 s immediately after ligation on the right common carotid artery and 0.4 s immediately after ligation on the left side. After 6 weeks these differences were only slightly reduced, to 80% and 72.7% respectively. These animal experiments demonstrate clearly that an acute occlusion of one common carotid artery in rabbits can easily be diagnosed by ophthalmodynamometry as well as by synchronous measurement of the ear to retina time. In chronic occlusions determination of the ear to retina time is superior to pressure measurement. This is of particular interest since in these experiments an ophthalmodynamometric method was used that is much superior to the clinical method of ophthalmodynamometry.

Ophthalmodynamometry in internal carotid artery occlusion

Retinal artery pressure was measured by ophthalmodynamometry in 15 patients with occlusion of the internal carotid artery in its extracranial part. Nine of the patients had severe neurological deficit whereas the remaining six had slight or intermittent symptoms. Retinal artery pressure was reduced on the side of the internal carotid artery occlusion in all patients studied. Near-zero low diastolic retinal artery pressure on the affected side was a common finding among patients with severe deficit and was also seen in some patients with slight deficit. Its presence strongly suggests occlusion of the ipsilateral internal carotid artery.

Ophthalmic arterial blood pressures measured by ocular plethysmodynamography

The indirect measurement of ophthalmic arterial blood pressure is an important index in the understanding of cerebral vacsular hemodynamics. Ophthalmodynamometry (ODM), the prototype for such measurement, is, however, replete with difficulties that have limited its widespread use. A preliminary evaluation of a new technique for ODM identified as ocular plethysmodynamography, has yielded accurate opthalmic blood pressure data without the attendant problems. Reproducible values for bilateral ophthalmic arterial pressure levels have been determined in 30 normal volunteers and the levels correlated to brachial arterial pressure levels. In a series of patients with arteriographically demonstrable carotid obstructive lesions, the preoperative and postoperative ophthalmic arterial blood pressure relationships exhibited excellent correlation with the roentgenographic and intraoperative data.

Asymptomatic occlusion of an internal carotid artery in a hospital population: determined by directional Doppler ophthalmosonometry

Reversal of blood flow in an ophthalmic artery as determined by directional Doppler ultrasound (OSM) was present in nine (3%) of 310 patients over 50 years of age who did not have complaints, diagnoses or examination findings suggesting disease of the central nervous system, and was present in nine (12%) of 73 patients with neurological disease selected as technical controls. Twenty-two of the control patients had four-vessel angiography. Five with OSM evidence of reversal of flow had functional occlusion of the appropriate internal carotid artery, and 17 without reversal did not. This study presents evidence that occlusion of an internal carotid artery frequently occurs without producing recognizable clinical dysfunction.