Fig 1.
Schematic representation of the non-invasive intracranial pressure (ICP) measurement equipment Vittamed 205.
(A) Relevant orbit and brain anatomy in contact with the ICP measurement device. (B) Block diagram of the system control unit. ICA—internal carotid artery; IOA—intracranial part of the ophthalmic artery; EOA—extracranial part of the ophthalmic artery; TCD—transcranial Doppler; Pe—external pressure applied to the ocular globe.
Fig 2.
Example spectrograms of pulse waves of blood flow in the ophthalmic artery collected by a transcranial Doppler using different external pressure steps.
(A) 0 mmHg; (B) 48 mmHg. HR—heart rate.
Table 1.
Demographic data of the included subjects in this retrospective study.
Fig 3.
(A) A heart rate variation in a healthy volunteer. (B) A pressure increase of 4 mmHg per pressure Pe(t) step (time period of approximately 30 sec each) was used on the ocular globe from 0 mmHg to 48 mmHg.
Table 2.
Protocol parameters for the non-invasive intracranial pressure measurement according to group.
Table 3.
Results of the heart rate and tests of data normality at pressure steps from 0 mmHg to 48 mmHg.
Fig 4.
Histogram of HRdiff (parameter for the detection of the oculocardiac reflex) for subjects from all groups and 870 external pressure steps applied during all of the non-invasive intracranial pressure measurements.
Fig 5.
Heart rate (HR) variation at every external pressure step (Pe) applied on the ocular globe in the case of a 10% decrease in the MHR compared to the BHR.
(A) Healthy subject. (B) Glaucoma patient. (C) Healthy subject. (D) Healthy subject.