Study on the Oxygen Saturation in Pulsating and Non-pulsating Central Retinal Veins

Retinal ischemia is thought to play an important role in the pathogenesis of glaucoma. Recent findings have confirmed that there is a direct correlation between the levels of venous oxygen saturation and the degree of the glaucomatous disease, presumably due to a decrease in retinal cell metabolism.

However, glaucoma patients have been suggested to have a different pattern in retinal venous circulation. For instance, the observation of a visible pulsating central retinal vein is a phenomenon that can be seen in up to 98% of the healthy individuals but is identifiable in less than 50% of glaucoma patients. While the nature of these venous changes are not year clear, the lack of a visible pulsating flow could suggest an increased intraluminal venous pressure due to some obstruction from both ocular or extraocular structures. This undetermined increase in venous pulse pressure could then significantly decrease perfusion pressures and therefore further decrease oxygen supply to the retinal tissues.

The investigators will therefore try to determine if there is a significant difference between the oxygen saturation of the retinal vessels in both glaucoma patients with and without a visible pulsating central vein

1. Visual field examen will be performed.
2. Structural examination of the optic disc (confocal microscopy) will be performed.
3. Spontaneous venous pulsation will be recorded after a one minute fundoscopy observation.
4. Oximetry reading in the non-contact retinal oximetry of the first 3 order retinal vessels

primary care clinic

• Open Angle Glaucoma
• Normal Tension Glaucoma

• Controls
  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

Inclusion Criteria:

• individuals over 18 years old
• willing to sign an informed consent and able to comply with the requirements of the study
• having no other ocular diseases besides glaucoma

Exclusion Criteria:

• history of ocular trauma
• intraocular surgery (except for cataract surgery)
• eye disease (except glaucoma)
• systemic diseases with ocular involvement like diabetes