Intracranial pressure (ICP) monitoring is important in managing neurosurgical, neurological, and ophthalmological patients with open-angle glaucoma. Non-invasive two-depth transcranial Doppler (TCD) technique is used in a novel method for ICP snapshot measurement that has been previously investigated prospectively, and the results showed clinically acceptable accuracy and precision. The aim of this study was to investigate possibility of using the ophthalmic artery (OA) as a pressure sensor for continuous ICP monitoring. First, numerical modeling was done to investigate the possibility, and then a pilot clinical study was conducted to compare two-depth TCD-based non-invasive ICP monitoring data with readings from an invasive Codman ICP microsensor from patients with severe traumatic brain injury. The numerical modeling showed that the systematic error of non-invasive ICP monitoring was < 1.0 mmHg after eliminating the intraorbital and blood pressure gradient. In a clinical study, a total of 1928 paired data points were collected, and the extreme data points of measured differences between invasive and non-invasive ICP were − 3.94 and 4.68 mmHg (95% CI − 2.55 to 2.72). The total mean and SD were 0.086 ± 1.34 mmHg, and the correlation coefficient was 0.94. The results show that the OA can be used as a linear natural pressure sensor and that it could potentially be possible to monitor the ICP for up to 1 h without recalibration.

Background and Objective: Glaucoma is a progressive optic neuropathy in which the optic nerve is damaged. The optic nerve is exposed not only to intraocular pressure (IOP) in the eye, but also to intracranial pressure (ICP), as it is surrounded by cerebrospinal fluid in the subarachnoid space. Here, we analyse ICP differences between patients with glaucoma and healthy subjects (HSs). Materials and Methods: Ninety-five patients with normal-tension glaucoma (NTG), 60 patients with high-tension glaucoma (HTG), and 62 HSs were included in the prospective clinical study, and ICP was measured non-invasively by two-depth transcranial Doppler (TCD). Results: The mean ICP of NTG patients (9.42 ± 2.83 mmHg) was significantly lower than that of HSs (10.73 ± 2.16 mmHg) (p = 0.007). The mean ICP of HTG patients (8.11 ± 2.68 mmHg) was significantly lower than that of NTG patients (9.42 ± 2.83 mmHg) (p = 0.008) and significantly lower than that of HSs (10.73 ± 2.16 mmHg) (p < 0.001). Conclusions: An abnormal ICP value could be one of the many influential factors in the optic nerve degeneration of NTG patients and should be considered as such instead of just being regarded as a “low ICP”.

Ventriculoperitoneal shunt placement is the most commonly used treatment of normal-pressure hydrocephalus (NPH). It has been hypothesized that normal-tension glaucoma (NTG) is caused by the treatment of NPH by using the shunt to reduce intracranial pressure (ICP). The aim of this study is to review the literature published regarding this hypothesis and to emphasize the need for neuro-ophthalmic follow-up for the concerned patients. The source literature was selected from the results of an online PubMed search, using the keywords “hydrocephalus glaucoma” and “normal-tension glaucoma shunt”. One prospective study on adults, one prospective study on children, two retrospective studies on adults and children, two case reports, three review papers including medical hypotheses, and one prospective study on monkeys were identified. Hypothesis about the association between the treatment of NPH using the shunt to reduce ICP and the development of NTG were supported in all reviewed papers. This suggests that a safe lower limit of ICP for neurological patients, especially shunt-treated NPH patients, should be kept. Thus, we proposed to modify the paradigm of safe upper ICP threshold recommended in neurosurgery and neurology into the paradigm of safe ICP corridor applicable in neurology and ophthalmology, especially for shunt-treated hydrocephalic and glaucoma patients.

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Purpose To analyze the cerebrovascular autoregulation (CA) dynamics in patients with normal-tension glaucoma (NTG) and high-tension glaucoma (HTG) as well as healthy subjects using noninvasive ultrasound technologies for the first time. Methods The CA status of 10 patients with NTG, 8 patients with HTG, and 10 healthy subjects was assessed, using an innovative noninvasive ultrasonic technique, based on intracranial blood volume slow-wave measurements. Identified in each participant were intraocular pressure, ocular perfusion pressure, and CA-related parameter volumetric reactivity index (VRx), as well as the duration and doses of the longest cerebral autoregulation impairment (LCAI). In addition, we calculated the associations of these parameters with patients’ diagnoses. Results The VRx value, the LCAI dose, and duration in healthy subjects were significantly lower than in patients with NTG ( P < 0.05). However, no significant differences were noted in these parameters between healthy subjects and HTG and between NTG and HTG groups. Conclusions NTG is associated with the disturbed cerebral blood flow and could be diagnosed by performing noninvasive CA assessments. Translational Relevance The VRx monitoring method can be applied to a wider range of patient groups, especially patients with normal-tension glaucoma.