Study on Ocular Blood Flow and the Orbital Cerebrospinal Fluid Pressure in Glaucoma
Ocular blood flow has been consistently demonstrated to be altered in glaucoma patients when compared to otherwise healthy individuals. Numerous Doppler studies have shown a decrease in flow velocities in the retrobulbar arteries in what appears to be related to the degree of the glaucomatous disease.
The anatomic pathway of the several arteries into the eye is intricately complicate, with at least one of them (the central retina artery) penetrating the optic nerve before entering the eye and supplying the innermost structures of the globe. As the optic nerve is surrounded by a layer of cerebrospinal fluid (CSF) which is in continuity with the rest of the central nervous system, this central retinal artery has also to cross this CSF containing compartment. Because of the intrinsic pressure this CSF - corresponding to the intracranial pressure at the orbital level - the possibility exists that this pressure around the optic disc could affect the blood flow of the arteries that go through it.
The investigators will try to detect if a correlation exists between the optic nerve sheath diameter and the blood flow in the retrobulbar vessels of glaucoma patients.
Open Angle Glaucoma
Normal Tension Glaucoma
|Study Design:||Time Perspective: Prospective|
|Official Title:||Correlation Between Ocular Blood Flow and the Optic Nerve Sheath Diameter in Patients With Primary Open-angle Glaucoma|
- Flow velocity of retrobulbar vessels [ Time Frame: Participants will be followed for the duration of hospital stay, an expected average of 2 hours ] [ Designated as safety issue: No ]
|Study Start Date:||January 2013|
|Study Completion Date:||January 2014|
|Primary Completion Date:||January 2014 (Final data collection date for primary outcome measure)|
Healthy volunteers with no family history of glaucoma, an increased or asymmetrical cup/disc ratio or any other optic disc structural change (notching, disc hemorrhage) or an intraocular pressure (IOP) above 21 mmHg that could suggest possible glaucoma suspects.
Primary open-angle glaucoma
Patients with a characteristic optic disc damage (based on cup/disc ratio, thinning of neuroretinal rim, notching, disk hemorrhages, etc.) and visual field defects, with at least one measurement of IOP of >21 mmHg required
Normal Tension Glaucoma
Patients with a characteristic optic disc damage (based on cup/disc ratio, thinning of neuroretinal rim, notching, disk hemorrhages, etc.) and visual field defects, with at maximum recorded IOP of < 21 mmHg
- Visual field testing will be performed.
- Structural analysis of the retinal nerve fiber layer (through confocal microscopy)will be performed.
- Color Doppler Imaging of the retrobulbar vessels will be performed. Peak and end diastolic velocities, resistivity index will be calculated from the Doppler waveform.
- B-scan ultrasound of the optic nerve sheath diameter will be performed. the measure will take place at 3mm behind the globe.