Clinical Trial: Pressure Difference Between Brain and Eye: a Possible Cause to Normal Tension Glaucoma.

Study Status: Completed
Recruit Status: Completed
Study Type: Observational

Official Title: Pathological Cerebral Venous Drainage System Giving Large Pressure Difference Between Brain and Eye at Upright Posture: a Possible Cause to Normal Tension Glaucoma.

Brief Summary: The main aim of this study is to determine the trans-laminal cribrosa pressure difference (TLCPD) for normal tension glaucoma (NTG) patients from the brain and the eye in supine, upright and minor head down tilt positions. It is also to investigate the venous drainage system in the same body positions.

Detailed Summary:

The trans-lamina cribrosa pressure difference (TLCPD), i.e. the difference between the intraocular pressure (IOP) and the intracranial pressure (ICP) has been suggested as a pathophysiological component in glaucoma. The theory is that high TLCPD, either due to elevated IOP or reduced ICP, can cause glaucomatous damage.

Normal tension glaucoma (NTG) patients has been found to have a slightly reduced ICP when measured in horizontal position. However, in a previous study in healthy adult volunteers the investigators have measured TLCPD at supine, sitting and 9 degree head down tilt positions and found that the TLCPD was posture dependent, with the largest difference in the upright position. Since humans are upright approximately two thirds of the day, one can expect that TLCPD in a diurnal perspective is primarily influenced by the ICP in the upright position.

In this study the TLCPD in different positions in patients with NTG will therefore be measured.

The study will be carried out in three parts.

  1. TLCPD will be investigated by simultaneous measurements of IOP and ICP. For IOP the Applanation resonance tonometer (ART), developed by our research group, will be used. ART is independent of gravitation and possible to use in all body postures. In this study measurements will be performed in supine, sitting and head down tilt positions. ICP is measured continuously during the period of body position changes with a CELDA lumbar pressure measurement apparatus.
  2. Brain and eye MRI investigation will be performed at a 3 Tesla GE scanner with a new generation 32-channels head coil. The images will be used to measure the cross-section area, the blood flow velocity and the f
    Sponsor: Umeå University

    Current Primary Outcome: Trans-lamina cribrosa pressure difference (TLCPD) [ Time Frame: 1 day Single time point measurement ]

    Difference between intraocular pressure (IOP) and intracranial pressure in different body positions


    Original Primary Outcome: Same as current

    Current Secondary Outcome: Postural changes on blood flow velocity and cross-section area of right and left internal jugular veins (IJV) and external jugular veins (EJV) [ Time Frame: 1 day Single time point measurement ]

    Original Secondary Outcome: Same as current

    Information By: Umeå University

    Dates:
    Date Received: May 16, 2016
    Date Started: February 2016
    Date Completion:
    Last Updated: May 2, 2017
    Last Verified: May 2016