NCT06436820

ICP & Outflow Study

The Relationship Between Intracranial Pressure and Aqueous Outflow in Idiopathic Intracranial Hypertension

• Status: Not Yet Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 66 (estimated)
• Sponsor: Guy's and St Thomas' NHS Foundation Trust · Academic / Other
• Sex: All
• Age: 18 Years – 80 Years
• Healthy volunteers: —

Summary

This study aims to investigate the relationship between intracranial pressure (ICP) and aqueous outflow (the flow of the eye's internal fluid out of the eye), in patients with increased intracranial pressure (idiopathic intracranial hypertension (IIH)). Through observing changes in aqueous outflow facility in patients scheduled for lumbar Puncture (LP) as part of their routine care the objectives we aim to answer include: * Investigating the effect of lumbar puncture induced reduction in ICP on patients with known or suspected IIH, compared to control patients, who will be receiving LP for reasons not pertaining to high pressure. * Comparing pre lumbar puncture aqueous outflow facility between patients with idiopathic intracranial hypertension and control patients. Outside of the standard care provided for these patients as part of their scheduled lumbar puncture, they will have measurements of their eye taken before and after their lumbar puncture.

Detailed description

This study aims to investigate the relationship between intracranial pressure (ICP) and aqueous outflow (the flow of the eye's internal fluid out of the eye), in patients with increased intracranial pressure (idiopathic intracranial hypertension (IIH)). The effect of lowering intracranial pressure on aqueous outflow will be examined by taking additional measurements before and after a procedure called a lumbar puncture (LP). These measurements include a scan to measure the dimensions of the eye, intraocular pressure reading, and a non-invasive technique to measure aqueous outflow (electronic Schiotz tonography) which is used regularly in the eye research unit at St Thomas' Hospital. Study participants will already be scheduled for a lumbar puncture as they have known or suspected IIH, and LP is routinely used to investigate this. Additionally, control participants having LP for reasons not pertaining to a condition that may elevate intracranial pressure will also be included. Study participants will finish their involvement following the second aqueous outflow reading, after their LP. A lumbar puncture procedure directly measures the intracranial pressure, but also reduces the pressure in the process. If aqueous outflow is measured before and after lumbar puncture, it will provide more information about whether the change in intracranial pressure affects the intraocular pressure due to a change in the rate of fluid flowing out of the eye. If a relationship between intracranial pressure and aqueous outflow is found to be present, it may offer an alternative non-invasive measurement for intracranial pressure. Additionally, this study would highlight an avenue of investigation into dysregulation of intraocular pressure in conditions such as glaucoma. Similarly, negative findings would help inform ongoing discussions and controversies in the literature regarding relationships between intraocular pressure and intracranial pressure.

Conditions

• Eye Change
• Idiopathic Intracranial Hypertension

Interventions

Type	Name	Description
PROCEDURE	Lumbar puncture	Lumbar puncture procedure performed within a clinical setting

Timeline

• Start date: 2024-06-01
• Primary completion: 2025-11-01
• Completion: 2025-11-01
• First posted: 2024-05-31
• Last updated: 2024-06-12