Noninvasive Estimation of Intracranial Pressure Using Optic-Disc Venous Pulsation Thresholds.

Area of Science:

• Ophthalmology
• Neurology
• Medical Devices

Background:

• Retinal venous pulsations (SVP) are sensitive to intraocular and intracranial pressures (IOP and ICP).
• Glaucoma is linked to retinal venous pulsations and pressure changes.
• Estimating ICP noninvasively is crucial for managing neurological conditions.

Purpose of the Study:

• To evaluate the feasibility of estimating ICP using spontaneous retinal venous pulsation (SVP) thresholds.
• To assess the physiological concordance of noninvasive ICP estimates with reference manometry during lumbar puncture (LP).
• To compare ICP estimations using negative-pressure (NP) goggles in different patient positions.

Main Methods:

• A prospective pilot study using the Ocular Pressure Adjusting Pump (OPAP) with negative-pressure goggles.
• Noninvasive IOP modulation was applied until SVP was extinguished in adults scheduled for LP.
• ICP was predicted by averaging IOP measurements at the last presence and first absence of SVP; Bland-Altman analysis was used for agreement.

Main Results:

• 11 of 15 participants had measurable SVP thresholds.
• Mean OPAP-predicted ICP was 12.7 ± 3.2 mm Hg (upright) and 17.5 ± 3.1 mm Hg (lateral).
• Upright position showed minimal bias (-0.17 mm Hg) with wider 80% LoA (±6.19 mm Hg); lateral position showed overestimation (+4.66 mm Hg) with narrower 80% LoA (±3.56 mm Hg).

Conclusions:

• SVP-threshold-derived ICP estimates using OPAP showed minimal bias in upright patients but systematic overestimation in the lateral decubitus (LLD) position.
• ICP estimations were more consistent (narrower LoA) in the LLD position compared to the upright position.
• These exploratory findings require larger studies with standardized positioning to define accuracy and clinical utility.