Introduction Intracranial pressure (ICP) can currently only be assessed via invasive methods. A reliable, non-invasive ICP measurement approach would greatly improve accessibility of screening for patients with suspected pathological ICP. The relationship between intraocular hemodynamics, intraocular pressure (IOP), and ICP is well established and could form the basis for a non-invasive approach. This study will investigate the correlation of the above-mentioned variables. Methods Fundoscopy videos were acquired on adult patients admitted to the neurosurgical intensive care unit. The arteriole (A) and venule (V) diameters were measured, and the A/V ratio was calculated. The A/V ratios were correlated to data from the patient’s invasive ICP monitoring device and IOP. A mixed-model linear regression was used to assess the correlation between IOP and A/V ratio, ICP, and optic nerve sheath diameter. Results Intraparenchymal ICP correlated with the A/V ratio. When differences in IOP were accounted for, the A/V ratio could be used to distinguish between measured mean ICP >15 and ≤15 mmHg (p<0.05). Absolute ICP values could not be estimated. Conclusion ICP can be correlated with A/V ratio, especially if IOP is considered. Although still experimental, this method might allow assessment of intracranial pressure without the need for invasive procedures.

Introduction Retinal vessel dynamics analysis has proven to be a viable, non-invasive surrogate marker for increased intracranial pressure. We aimed to test this method in patients with suspected idiopathic intracranial hypertension. Methods Patients with suspected idiopathic intracranial hypertension were prospectively enrolled for hand-held fundus-videography during diagnostic lumbar puncture. After extracting optic disc images, peripapillary arteriole-to-venule-ratios were measured using machine-learning algorithms with manual identification control. A general linear model was applied to arteriole-to-venule-ratios and corresponding lumbar opening pressures to estimate cerebrospinal fluid pressure. Results Twenty-five patients were included with a significant difference in arteriole-to-venule-ratio between patients with ( n = 17) and without ( n = 8) idiopathic intracranial hypertension (0.78 ± 0.10 vs 0.90 ± 0.08, p = 0.006). Arteriole-to-venule-ratio correlated inversely with lumbar opening pressure (slope regression estimate −0.0043 (95% CI −0.0073 to −0.0023), p = 0.002) and the association was stronger when lumbar opening pressure exceeded 15 mm Hg (20 cm H2O) (slope regression estimate −0.0080 (95% CI −0.0123 to −0.0039), p < 0.001). Estimated cerebrospinal fluid pressure predicted increased lumbar opening pressure >20 mm Hg (27 cm H2O) with 78% sensitivity and 92% specificity (AUC 0.81, p = 0.02). A stand-alone arteriole-to-venule-ratio measurement predicting lumbar opening pressure >20 mm Hg (27 cm H2O) was inferior with a 48% sensitivity and 92% specificity (AUC 0.73, p = 0.002). Conclusion Retinal vessel dynamics analysis with the described model for estimating cerebrospinal fluid pressure is a promising non-invasive method with a high sensitivity and specificity for detecting elevated intracranial pressure at follow-up assessments of patients with confirmed idiopathic intracranial hypertension if initial lumbar opening pressure and arteriole-to-venule-ratio data are available.

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