What are retinal collaterals?

Collaterals originate from the retinal capillary bed, joining obstructedto nonobstructed adjacent vessels, or by-passing obstructions in a single vessel; i.e. veins are linked to veins, arteries linkedto arteries, and, less frequently, arteries are joined to veins.

How does blood flow to the retina?

The retina is supplied by the central retinal artery and the short posterior ciliary arteries (Fig 2.3). The central retinal artery travels in or beside the optic nerve as it pierces the sclera then branches to supply the layers of the inner retina (i.e., the layers closest to the vitreous compartment).

What are optic disc collaterals?

Overview. Optociliary shunt vessels, also known as retinochoroidal shunt vessels of the optic disc or retinochoroidal collaterals, are collateral vessels on the optic nerve that connect the choroidal and retinal circulations.

What are the abnormal findings in the retinal vessels?

Observable changes in retinal vascular architecture, such as increased retinal vein caliber (decreased artery-to-vein ratio), retinal vascular tortuosity, increased prominence of the retinal arterial reflex, venous nicking, “copper” or “silver wire” appearance as well as the discovery of cholesterol, calcium or …

How does retinal neovascularization develop as seen on Oct?

Retinal neovascularization is the hallmark of proliferative diabetic retinopathy and it is triggered by decreased oxygen levels as a result of retinal capillary nonperfusion. It is most commonly located at or near the optic nerve head, or at the borders of perfused and nonperfused retina, sparing the foveal area.

Why does neovascularization occur?

Corneal neovascularization is a condition where new blood vessels invade into the cornea from the limbus. It is triggered when the balance between angiogenic and antiangiogenic factors are disrupted that otherwise maintain corneal transparency.

What is retinal circulation?

Retina and anterior optic nerve head autoregulation Compared to the choroidal circulation (a high flow, variable-rate system), the retinal circulation is a lower flow, constant-rate system supplying a highly metabolically active tissue.

Does circulation affect eyesight?

If you develop poor circulation to the eye, this may affect the macula and limit your vision. When the circulation to the retina is very poor, other problems can develop. If the retina doesn’t get enough blood, it may start to release a chemical that causes new blood vessels to grow.

What is retinal vein occlusion?

Retinal vein occlusion is a blockage of the small veins that carry blood away from the retina. The retina is the layer of tissue at the back of the inner eye that converts light images to nerve signals and sends them to the brain.

What is retinal vessel attenuation?

Retinal vessel attenuation is recognized as an almost universal finding in eyes with RP, 1 and is mainly thought to reflect decreased metabolic demand of the degenerating retina, 2 where loss of oxygen consumption leads to increased local oxygen levels in the inner retina that in turn results in vasoconstriction.

How is retinal neovascularization treated?

Laser photocoagulation is the standard treatment for retinal or optic disc neovascularization, and approximately 60\% of patients respond to panretinal photocoagulation (PRP) with regression of neovascularization within 3 months.

What is the difference between retinal capillaries and collateral vessels?

Retinal collateral vessels (CVs) originate from the existing retinal capillary network and become evident when one vessel is occluded, leaving the adjacent vascular channels operative. 15,16 Collateral vessels arise from processes that try to correct or compensate for vessel obstruction.

What happens if the central retinal artery is blocked?

If it becomes blocked or occluded severe swelling and damage occur. The central retinal artery is the sole provider of blood to retina. Like the retinal vein, if blocked or occluded several damage to the retina can occur from lack of oxygen.

What is the function of the retinal circulatory system?

Retinal Circulatory System. Choroid Damage to the choroid Vorticose veins Central retinal vein & artery. Capillaries contained within the choroid in the eye are responsible for the circulation of blood within the eye.

What is central retinal vein occlusion (CRVO)?

However, in cases of central retinal vein occlusion (CRVO), the redirection usually is from an occluded central retinal vein to a choroidal vein. In these instances, the collateral vessel can be seen on the surface of the optic disc, but then seems to disappear as it connects to the choroidal circulation. 2-4